Claisen Condensation(ngưng tụ claisen)

<h2 style="font-family: Arial, Helvetica, 'sans serif'; font-size: 12pt; margin-bottom: 20px; margin-top: 20px;"></h2><h2><i>Acetoacetic-Ester Condensation</i></h2><h2><i>Claisen Condensation</i></h2><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgEnkP4E8B2yHNhNiR4kOeDTD-0Tn4aGBPZktp48wzOdjdcjq5MiQiVSz8Ff4SSCpg0RCwt522VTRqRW_uxYwAjb462m5Erv_7M-QEH-LTk_Sfz2KsD0gm6E99MADaix0ePZWrQo_7xXdQ/s1600/claisen.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Claisen Condensation" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgEnkP4E8B2yHNhNiR4kOeDTD-0Tn4aGBPZktp48wzOdjdcjq5MiQiVSz8Ff4SSCpg0RCwt522VTRqRW_uxYwAjb462m5Erv_7M-QEH-LTk_Sfz2KsD0gm6E99MADaix0ePZWrQo_7xXdQ/s1600/claisen.gif" title="Claisen Condensation" /></a></div><div><h4>Summary</h4><ul><li>The Claisen condensation is the ester analogue of the <b><i>Aldol condensation</i></b>.</li><li>Reagents : most commonly the base would be the alkoxide, <b>R'O^{-<a name="more"></a>}</b></li><li>The reaction involves an ester enolate reacting with another molecule of the ester.</li><li>Remember enolates are good nucleophiles and the ester carbonyl <b>C</b> are electrophilic.</li><li>The products of these reactions are <b><i><span style="font-family: Symbol;">b-</span>ketoesters</i></b> which are important, useful synthetic intermediates.</li><li>Note that the product is the original ester with an acyl group added <i>i.e.</i> an <b>acylation</b> reaction has occurred.</li><li>A simple example of a Claisen condensation is the reaction of ethyl ethanoate which is shown below in two representations:</li></ul></div><h1><img alt="Claisen condensation" height="53" src="http://www.organic-chemistry.org/namedreactions/claise14.gif" style="border: 0px; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;" title="Claisen condensation" width="333" /></h1><h1><div><div class="MsoNormal" style="font-family: Arial, Helvetica, 'sans serif';"><span style="font-family: 'Times New Roman', serif; font-size: 12pt; font-weight: normal;">The </span><span style="font-family: 'Times New Roman', serif; font-size: 12pt;"><i>Claisen Condensation </i></span><span style="font-family: 'Times New Roman', serif; font-size: 12pt; font-weight: normal;">between esters containing α-hydrogens, promoted by a base such as sodium ethoxide, affords </span><span style="font-family: 'Times New Roman', serif; font-size: 12pt;"><i>β-ketoesters</i>.</span><span style="font-family: 'Times New Roman', serif; font-size: 12pt; font-weight: normal;"> The driving force is the formation of the stabilized anion of the </span><span style="font-family: 'Times New Roman', serif; font-size: 12pt;"><i>β-keto ester</i>.</span><span style="font-family: 'Times New Roman', serif; font-size: 12pt; font-weight: normal;"> If two different esters are used, an essentially statistical mixture of all four products is generally obtained, and the preparation does not have high synthetic utility.<o:p></o:p></span></div><div class="MsoNormal" style="font-family: Arial, Helvetica, 'sans serif';"><span style="font-family: 'Times New Roman', serif; font-size: 12pt; font-weight: normal;">However, if one of the ester partners has enolizable α-hydrogens and the other does not (e.g., aromatic esters or carbonates), the mixed reaction (or crossed Claisen) can be synthetically useful. If ketones or nitriles are used as the donor in this </span><i><span style="font-family: 'Times New Roman', serif; font-size: 12pt;">condensation </span><span style="font-family: 'Times New Roman', serif; font-size: 12pt;">reaction</span></i><span style="font-family: 'Times New Roman', serif; font-size: 12pt; font-weight: normal;">, a β-diketone or a β-ketonitrile is obtained, respectively.<o:p></o:p></span></div><div class="MsoNormal" style="font-family: Arial, Helvetica, 'sans serif';"><span style="font-family: 'Times New Roman', serif; font-size: 12pt; font-weight: normal;">The use of stronger bases, e.g. sodium amide or sodium hydride instead of sodium ethoxide, often increases the yield.<o:p></o:p></span></div><div style="font-family: Arial, Helvetica, 'sans serif';"><span style="font-family: 'Times New Roman', serif; font-size: 12pt; font-weight: normal; line-height: 115%;">The </span><span style="font-family: 'Times New Roman', serif; font-size: 12pt; line-height: 115%;"><i>intramolecular</i></span><span style="font-family: 'Times New Roman', serif; font-size: 12pt; font-weight: normal; line-height: 115%;"> version is known as</span><span style="font-family: 'Times New Roman', serif; font-size: 12pt; font-weight: normal; line-height: 115%;"> </span><span style="font-family: 'Times New Roman', serif; font-size: 12pt; line-height: 115%;"><span style="color: #5a3696; line-height: 115%;"><a href="http://www.organic-chemistry.org/namedreactions/dieckmann-condensation.shtm" rel="nofollow" target="_blank"><i>DieckmannCondensation</i></a></span></span></div><h4 style="font-family: Arial, Helvetica, 'sans serif';"><span style="font-family: 'Times New Roman', serif; font-size: large; line-height: 115%;">Translate to Vietnamese:</span></h4><div><span style="font-family: Times New Roman, serif; font-size: small;"><span style="line-height: 18.399999618530273px;"> <span style="font-weight: normal;">Hiểu sơ bộ:</span></span></span></div></div><div><ul><li><span style="font-size: small;"><span style="font-weight: normal;">Là phản ứng giữa 2 ester có </span></span><span style="font-family: 'Times New Roman', serif; font-size: 16px; font-weight: normal;">α-hydrogen</span></li><li><span style="font-family: 'Times New Roman', serif; font-size: 16px; font-weight: normal;">Xúc tác: base như EtONa, MeONa,NaNH2,NaH</span></li><li><span style="font-family: 'Times New Roman', serif; font-size: 16px; font-weight: normal;">Tạo ra sản phẩm trung gian ổn định: anion của </span><span style="font-family: 'Times New Roman', serif; font-size: 16px;"><i>β-keto ester</i></span></li><li><span style="font-family: Times New Roman, serif; font-size: small;"><span style="font-weight: normal;">Sản phẩm tạo ra là </span></span><span style="font-family: 'Times New Roman', serif; font-size: 16px;"><i>β-keto ester</i></span></li><li><span style="font-family: Times New Roman, serif; font-size: small;"><span style="font-weight: normal;">Khi 2 ester là khác nhau: tạo ra một hỗn hợp 4 sản phẩm </span></span><span style="font-family: 'Times New Roman', serif; font-size: 16px;"><i>β-keto ester</i></span></li></ul></div></h1><h3 style="font-family: Arial, Helvetica, 'sans serif'; margin-bottom: 0px; margin-top: 0px;"><span style="font-size: large;"><i>Mechanism of the Claisen Condensation</i></span></h3><h1><div style="font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;"><img alt="Mechanism of the Claisen Condensation" height="74" src="http://www.organic-chemistry.org/namedreactions/claise16.gif" style="border: 0px;" title="Mechanism of the Claisen Condensation" width="459" /></div><div style="font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;"><img alt="Mechanism of the Claisen Condensation" height="81" src="http://www.organic-chemistry.org/namedreactions/claise17.gif" style="border: 0px;" title="Mechanism of the Claisen Condensation" width="400" /></div><div><div style="font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;"><img alt="Mechanism of the Claisen Condensation" height="57" src="http://www.organic-chemistry.org/namedreactions/claise15.gif" style="border: 0px;" title="Mechanism of the Claisen Condensation" width="628" /></div><div style="font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;"><br /></div><h3><i style="font-family: Arial, Helvetica, 'sans serif'; font-size: x-large;"><u>Example</u></i></h3><h3><span style="font-family: Arial, Helvetica, 'sans serif'; font-size: large; font-weight: normal;">1.</span></h3></div></h1><h1><div><div class="separator" style="clear: both; font-family: Arial, Helvetica, 'sans serif'; font-weight: normal; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhZ9nutjkeGlfGoqOsEGUSn5hmprv6_MLNV1rrWox-Z_zR71zkbPCcnMvQT6rf_KAH6no320AoYuAlsSX8EV0_AvG7aur4PncaXFdKRwoXbO7s9dRBjK3EW3BVDRZYemMHHDrH73h6jgqc/s1600/claisen+condensation+2.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="claisen condensation" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhZ9nutjkeGlfGoqOsEGUSn5hmprv6_MLNV1rrWox-Z_zR71zkbPCcnMvQT6rf_KAH6no320AoYuAlsSX8EV0_AvG7aur4PncaXFdKRwoXbO7s9dRBjK3EW3BVDRZYemMHHDrH73h6jgqc/s1600/claisen+condensation+2.gif" title="claisen condensation" /></a></div><div style="font-family: Arial, Helvetica, 'sans serif'; font-weight: normal;"><span style="font-size: large;"><br /></span></div><table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="font-family: Arial, Helvetica, 'sans serif'; font-weight: normal; margin-left: auto; margin-right: auto; text-align: center;"><tbody><tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgw43XSEqY6rLxY5MJ4wDYUpNh6MlhD98RSzeJ9Dmo57JOSzNlT-JqTYlnILR03ry17K9yknYkCyH6RV1CEn9TqL-pDIokpbidxVwahNkTVPWEDPh8pePJsgD5EKu277ik9LodornuNeno/s1600/claisen+condensation.gif" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="claisen condensation" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgw43XSEqY6rLxY5MJ4wDYUpNh6MlhD98RSzeJ9Dmo57JOSzNlT-JqTYlnILR03ry17K9yknYkCyH6RV1CEn9TqL-pDIokpbidxVwahNkTVPWEDPh8pePJsgD5EKu277ik9LodornuNeno/s1600/claisen+condensation.gif" title="claisen condensation" /></a></td></tr><tr><td class="tr-caption" style="text-align: center;"><b><i>claisen condensation </i></b></td></tr></tbody></table><div class="separator" style="clear: both; font-family: Arial, Helvetica, 'sans serif'; font-weight: normal; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEibM6zL68x0rgjkO-FFge9mbk8w8Xwy_9zVzHrdqNTK6mVYBBzGD6en1LnhHrFSUT2oD6eNxjA8rcOHkeJYB0WTz0hJY9kBACVJx1ps1a_V-A-wf0RjDs3HAiiBvf79EGp1ziq8Rl2eusc/s1600/claisen+condensation+1.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="claisen condensation" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEibM6zL68x0rgjkO-FFge9mbk8w8Xwy_9zVzHrdqNTK6mVYBBzGD6en1LnhHrFSUT2oD6eNxjA8rcOHkeJYB0WTz0hJY9kBACVJx1ps1a_V-A-wf0RjDs3HAiiBvf79EGp1ziq8Rl2eusc/s1600/claisen+condensation+1.gif" title="claisen condensation" /></a></div><div style="font-family: Arial, Helvetica, 'sans serif'; font-weight: normal;"><span style="background-color: white; font-size: 13px;">General, Robust, and Stereocomplementary Preparation of α,β-Disubstituted α,β-Unsaturated Esters</span><br /><span style="background-color: white; font-size: 13px;">H. Nakatsuji, H. Nishikado, K. Ueno, Y. Tanabe, </span><i style="background-color: white; font-size: 13px;">Org. Lett.</i><span style="background-color: white; font-size: 13px;">, </span><b style="background-color: white; font-size: 13px;">2009</b><span style="background-color: white; font-size: 13px;">, </span><i style="background-color: white; font-size: 13px;">11</i><span style="background-color: white; font-size: 13px;">, 4258-4261.</span></div><div style="font-family: Arial, Helvetica, 'sans serif'; font-weight: normal;"><span style="background-color: white; font-size: 13px;"><br /></span></div><h4 style="font-family: Arial, Helvetica, 'sans serif';"><span style="background-color: white;"><span style="font-size: large;">Translate to Vietnamese:</span></span></h4><div><ul><li><span style="font-family: Arial, Helvetica, sans serif; font-size: small;"><span style="font-weight: normal;">NEt3(TEA): Triethylamin, là xúc tác base</span></span></li><li><span style="font-family: Arial, Helvetica, sans serif; font-size: small;"><span style="font-weight: normal;">TiCl4: vai trò phản ứng với EtOH tạo ra, thúc đẩy phản ứng xảy ra theo chiều thuận.<br />TiCl4 + 4EtOH -----------------> Ti(OC2H5)4 + 4 HCl</span></span></li><li><span style="font-family: Arial, Helvetica, sans serif; font-size: small;"><span style="font-weight: normal;">Dung môi CH2Cl2 hoặc toluen: Phải dùng dung môi hòa tan cả 2 chất phản ứng, tạo nên hệ đồng thể thì hiệu suất mới cao( nói đúng hơn phản ứng mới xảy ra)</span></span></li></ul></div><h4 style="font-family: Arial, Helvetica, 'sans serif'; font-weight: normal;"><span style="background-color: white;"><span style="font-size: large;">2.</span></span></h4></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-Na_glRLdo6ET6U7hbVC1hpmi_RZgiqBKcUYV3Qf-7j9omKqrIMqlyt2cDwaIxQmD2c5HbK0Ok49s0OZETZUqMslBL5Z0JqPqWJIHRaBu-munDmCamb-dT4BHklf3cn27OZmcWzdsp3s/s1600/claisen+condensation+1.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="claisen condensation" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-Na_glRLdo6ET6U7hbVC1hpmi_RZgiqBKcUYV3Qf-7j9omKqrIMqlyt2cDwaIxQmD2c5HbK0Ok49s0OZETZUqMslBL5Z0JqPqWJIHRaBu-munDmCamb-dT4BHklf3cn27OZmcWzdsp3s/s1600/claisen+condensation+1.gif" title="claisen condensation" /></a></div> <b style="font-family: Arial, Helvetica, 'sans serif'; font-size: 13px;">Abstract</b><br /><div style="font-family: Arial, Helvetica, 'sans serif'; font-size: 13px;"><span style="font-weight: normal;">Thioesters undergo chemoselective soft enolization and acylation by <i>N</i>-acylbenzotriazoles on treatment with MgBr<sub style="line-height: 1;">2</sub>·OEt<sub style="line-height: 1;">2</sub> and <i>i </i>-Pr<sub style="line-height: 1;">2</sub>NEt to give β-keto thioesters without prior enolate formation. The reaction is conducted using untreated CH<sub style="line-height: 1;">2</sub>Cl<sub style="line-height: 1;">2</sub> open to the air. The coupled products can be converted directly into </span><i>β-keto esters</i><i>, β-keto amides, </i><span style="font-weight: normal;">and</span><i> β-diketones</i><span style="font-weight: normal;"> under mild conditions.</span></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi4aFKpON1PxvdqKUJ4yPArhlJaM7kBpYSnbGz9JqFZEvTxoBqkeJNyhrqM4ZHWqXNh0HVy81rfHsfCadtFH6-EcPaiENOWWBSIEGtfwI_Wqowkkgc3ICToqZjk8PTwAbVRR1vPAe3ciQ4/s1600/claisen+condensation2.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="claisen condensation" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi4aFKpON1PxvdqKUJ4yPArhlJaM7kBpYSnbGz9JqFZEvTxoBqkeJNyhrqM4ZHWqXNh0HVy81rfHsfCadtFH6-EcPaiENOWWBSIEGtfwI_Wqowkkgc3ICToqZjk8PTwAbVRR1vPAe3ciQ4/s1600/claisen+condensation2.gif" title="claisen condensation" /></a></div><div class="separator" style="clear: both; text-align: center;"><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal; text-align: start;">Direct Carbon-Carbon Bond Formation via Chemoselective Soft Enolization of Thioesters: A Remarkably Simple and Versatile Crossed-Claisen Reaction Applied to the Synthesis of LY294002</span></div><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal; text-align: start;">G. Zhou, D. Lim, D. M. Coltart, </span><i style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal; text-align: start;">Org. Lett.</i><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal; text-align: start;">, </span><b style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; text-align: start;">2008</b><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal; text-align: start;">, </span><i style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal; text-align: start;">10</i><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal; text-align: start;">, 3809-3812.</span><br /> </h1><h4 style="font-family: Arial, Helvetica, 'sans serif'; font-size: 32px;"><span style="background-color: white;"><span style="font-size: large;">Translate to Vietnamese:</span></span></h4><div><span style="font-family: Arial, Helvetica, 'sans serif'; font-size: 13px;">MgBr</span><sub style="font-family: Arial, Helvetica, 'sans serif'; line-height: 1;">2</sub><span style="font-family: Arial, Helvetica, 'sans serif'; font-size: 13px;">·OEt</span><sub style="font-family: Arial, Helvetica, 'sans serif'; line-height: 1;">2 </sub><span style="font-family: Arial, Helvetica, 'sans serif'; font-size: 13px;">and</span><span style="font-family: Arial, Helvetica, 'sans serif'; font-size: 13px;"> </span><i style="font-family: Arial, Helvetica, 'sans serif'; font-size: 13px;">i </i><span style="font-family: Arial, Helvetica, 'sans serif'; font-size: 13px;">-Pr</span><sub style="font-family: Arial, Helvetica, 'sans serif'; line-height: 1;">2</sub><span style="font-family: Arial, Helvetica, 'sans serif'; font-size: 13px;">NEt có vai trò: tránh tạo ra enolate.</span></div><div><span style="font-family: Arial, Helvetica, 'sans serif'; font-size: 13px;"><br /></span></div><h1><div><span style="background-color: white;"><span style="font-size: large;">3.</span></span></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjFekHR_XTW-reyozGQ0SMnmwmcwKhAkmQJ-rqJvgAbZ2y5aUqu5l0vFSbN78B6ClOZpC2Uy33tjNjDdvFqcQr4Ts_utwhY7dia8L2eWBIVfD3RX8eQz3WDqHJLHrGJ7lFrQfY2P9o0iuk/s1600/1.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="claisen condensation" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjFekHR_XTW-reyozGQ0SMnmwmcwKhAkmQJ-rqJvgAbZ2y5aUqu5l0vFSbN78B6ClOZpC2Uy33tjNjDdvFqcQr4Ts_utwhY7dia8L2eWBIVfD3RX8eQz3WDqHJLHrGJ7lFrQfY2P9o0iuk/s1600/1.gif" title="claisen condensation" /></a></div><br /><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">Mild and Efficient Pentafluorophenylammonium Triflate (PFPAT)-Catalyzed C-Acylations of Enol Silyl Ethers or Ketene Silyl (Thio)Acetals with Acid Chlorides</span><br style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;" /><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">A. Iida, J. Osada, R. Nagase, T. Misaki, Y. Tanabe, </span><i style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">Org. Lett.</i><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">, </span><b style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px;">2007</b><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">, </span><i style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">9</i><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">, 1859-1862.</span><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-zvOWZ0rPxpa4M44DreOJqcVX59aZ_L4CotSAVL6uQM9XE8pQK9Vnupe-_XfWw1OudRMed2xi6gkdsf6IfhFfACNjsk5fEpSSM-INWCcxOzaLZ8ICp_dldq6uQaWcQXSV5h83JBdRccQ/s1600/2.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="claisen condensation" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh-zvOWZ0rPxpa4M44DreOJqcVX59aZ_L4CotSAVL6uQM9XE8pQK9Vnupe-_XfWw1OudRMed2xi6gkdsf6IfhFfACNjsk5fEpSSM-INWCcxOzaLZ8ICp_dldq6uQaWcQXSV5h83JBdRccQ/s1600/2.gif" title="claisen condensation" /></a></div><br /><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">Powerful Ti-Crossed Claisen Condensation between Ketene Silyl Acetals or Thioacetals and Acid Chlorides or Acids</span><br style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;" /><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">A. Iida, S. Nakazawa, T. Okabayashi, A. Horii, T. Misako, Y. Tanabe, </span><i style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">Org. Lett.</i><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">, </span><b style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px;">2006</b><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">, </span><i style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">8</i><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">, 5215-5218.</span><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgYCZO5U7uEIc2tExk4npbIxAyAzSg2c5vB_160I3OMOEUJJ_-YNZE-70Ze5a2aM4eYJWRgeoZVLV_v_hUWnODNE26MiZRj105yUBbdiNb8somheUKN2Q0oBDI-0wpRsrYU9eCz9bbLoVQ/s1600/3.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="claisen condensation" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgYCZO5U7uEIc2tExk4npbIxAyAzSg2c5vB_160I3OMOEUJJ_-YNZE-70Ze5a2aM4eYJWRgeoZVLV_v_hUWnODNE26MiZRj105yUBbdiNb8somheUKN2Q0oBDI-0wpRsrYU9eCz9bbLoVQ/s1600/3.gif" title="claisen condensation" /></a></div><br /><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">Synthesis of Trifluoromethyl Ketones via Tandem Claisen Condensation and Retro-Claisen C-C Bond-Cleavage Reaction</span><br style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;" /><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">D. Yang, Y. Zhou, N. Xue, J. Qu, </span><i style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">J. Org. Chem.</i><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">, </span><b style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px;">2013</b><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">, </span><i style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">78</i><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">, 4171-4176.</span><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhnPpHcD2MrlWXcFAaNXkrJsEDHXmOo2iDI0NHvEpZwxGC5wxyfb3tR7GkQRHnM_o_mp0Pyl4aBohTiSNHwso4k1i8Xn8Rgr-UoHWO052jFu53boXDwkexukQDD4HGl3Rg-On2bqhx61lw/s1600/4.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="claisen condensation" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhnPpHcD2MrlWXcFAaNXkrJsEDHXmOo2iDI0NHvEpZwxGC5wxyfb3tR7GkQRHnM_o_mp0Pyl4aBohTiSNHwso4k1i8Xn8Rgr-UoHWO052jFu53boXDwkexukQDD4HGl3Rg-On2bqhx61lw/s1600/4.gif" title="claisen condensation" /></a></div><br /><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">Consecutive </span><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px;"><i>Michael</i></span><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">-</span><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px;"><i>Claisen </i></span><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">Process for Cyclohexane-1,3-dione Derivative (CDD) Synthesis from Unsubstituted and Substituted Acetone</span><br style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;" /><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">D. Sharma, Bandna, A. K. Shil, B. Singh, P. Das, </span><i style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">Synlett</i><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">, </span><b style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px;">2012</b><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">, </span><i style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">23</i><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">, 1199-1204.</span><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh5RBiywnwCbjQ_xR2a0i-NZ6I13bbxJVqzMSJ9IiRkXYN8i6i23zfgzwJsvah_s3lqkU_YhdT5FFa2YeayRIJZaZtGE0H54WOWzZNWHv9sHr7P0PZ8q2yFoGzc3W2PLGbtTc_IGSswBoc/s1600/5.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="claisen condensation" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh5RBiywnwCbjQ_xR2a0i-NZ6I13bbxJVqzMSJ9IiRkXYN8i6i23zfgzwJsvah_s3lqkU_YhdT5FFa2YeayRIJZaZtGE0H54WOWzZNWHv9sHr7P0PZ8q2yFoGzc3W2PLGbtTc_IGSswBoc/s1600/5.gif" title="claisen condensation" /></a></div><div><span style="background-color: white;"><span style="font-size: large;"><br /></span></span></div><div><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">"One-Pot" Synthesis of 4-Substituted 1,5-Diaryl-1</span><i style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">H</i><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">-pyrazole-3-carboxylic Acids via a MeONa/LiCl-Mediated Sterically Hindered Claisen Condensation-Knorr Reaction-Hydrolysis Sequence</span><br /><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">J.-A. Jiang, C.-Y. Du, C.-H. Gu, Y.-F. Ji, </span><i style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">Synlett</i><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">, </span><b style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px;">2012</b><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">, </span><i style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">23</i><span style="background-color: white; font-family: Arial, Helvetica, 'sans serif'; font-size: 13px; font-weight: normal;">, 2965-2968.</span></div></h1>

Claisen Condensation(ngưng tụ claisen)

Acetoacetic-Ester Condensation Claisen Condensation Summary The Claisen condensation is the ester analogue of the  Aldol condensation . Reag...

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Exercises about Claisen condensation

<h2><span style="color: #af0000; font-family: Times; font-size: large;"><i>The Claisen Condensation</i></span></h2><div><span style="font-family: Times;">The <b><i>nucleophilic </i></b>carbon of the enolate ion adds to the <b><i>electrophilic </i></b>carbon of a molecule of ethyl acetate that has not been deprotonated. A carbon-carbon bond is formed. The reaction produces yet another tetrahedral intemediate as shown in Equation 1.</span><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhsWnMi_oJ6NkQY5X5USWz-VurP_-Np4LLSKzXaeKvqB57EQe9WL5HSpSn6MThJdkk6q7Sg4DrmdvBtG78BvAKw8t_n76PUifMUxOjvK0rCIEeWB9pRRQzxerddTXN4g-yHoHasmAD8eRw/s1600/Equation_1.GIF" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Exercises about Claisen condensation" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhsWnMi_oJ6NkQY5X5USWz-VurP_-Np4LLSKzXaeKvqB57EQe9WL5HSpSn6MThJdkk6q7Sg4DrmdvBtG78BvAKw8t_n76PUifMUxOjvK0rCIEeWB9pRRQzxerddTXN4g-yHoHasmAD8eRw/s1600/Equation_1.GIF" title="Exercises about Claisen condensation" /></a></div><div><span style="font-family: Times;">Since the newly formed tetrahedral center has an electronegative atom attached to it, reformation of the carbonyl group, as shown in Equation 2, is a reasonable process.</span><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjbsqRBkOzlEX3TDcrP_vYSIguHU406Cj65CXdzC3CYYGUZDl1gq6CPc2wLitG28cxDKnWdmfNMOc7p5QwOzAd4TgWXX_N7TfCpbrRXZC3HVvho-97FpPyAla4uyQgW1nqHTl-FzMafJFU/s1600/Equation_2.GIF" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Exercises about Claisen condensation" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjbsqRBkOzlEX3TDcrP_vYSIguHU406Cj65CXdzC3CYYGUZDl1gq6CPc2wLitG28cxDKnWdmfNMOc7p5QwOzAd4TgWXX_N7TfCpbrRXZC3HVvho-97FpPyAla4uyQgW1nqHTl-FzMafJFU/s1600/Equation_2.GIF" title="Exercises about Claisen condensation" /></a></div><div class="separator" style="clear: both; text-align: center;"><br /></div><h4 style="clear: both; text-align: left;"><i><span style="font-size: large;"><b><span style="color: #0000af; font-family: Times;">         Exercise 1</span></b><span style="font-family: Times;"> </span></span></i></h4><div class="separator" style="clear: both; text-align: left;"><span style="font-family: Times;">Draw the structure of the major product you would expect to be formed in each of the following situations:</span></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiJlYd8Ex4vs2e-tjAQnXRT0HSr5wQpVWh8TgCdFfAMi2X-bua6bjT4godlPQYmbBBqicqdIsd0UcJQCfBaB5u3qpU_fWFJh1Wyj0_h-CtO1mC44_Z574ij9ViEYMhYDrRsbgEREJg4I_Y/s1600/Ex1.GIF" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Exercises about Claisen condensation" border="0" height="296" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiJlYd8Ex4vs2e-tjAQnXRT0HSr5wQpVWh8TgCdFfAMi2X-bua6bjT4godlPQYmbBBqicqdIsd0UcJQCfBaB5u3qpU_fWFJh1Wyj0_h-CtO1mC44_Z574ij9ViEYMhYDrRsbgEREJg4I_Y/s1600/Ex1.GIF" title="Exercises about Claisen condensation" width="400" /></a></div><div class="separator" style="clear: both; text-align: left;"><br /></div><div class="separator" style="clear: both; text-align: left;"><span style="font-family: Times;"><br /></span></div><br /><div><h4><b><span style="color: #0000af; font-family: Times; font-size: large;"><i>        Exercise 3:</i></span></b></h4></div><div><span style="font-family: Times;">An <b><i>intramolecular </i></b>version of the <b><i><a href="http://forum-chemistry.blogspot.com/2014/08/claisen-condensationngung-tu-claisen.html" target="_blank">Claisen </a></i></b><i><b><a href="http://forum-chemistry.blogspot.com/2014/08/claisen-condensationngung-tu-claisen.html" target="_blank">condensation</a> </b></i>is known as the </span><span style="color: #af0000; font-family: Times;"><i><b>Dieckmann condensation</b></i></span><span style="font-family: Times;">. Equation 3 shows how this reaction was put to good use as part of the total synthesis of the prostaglandin </span><span style="font-family: Times;">PGA</span>_{<span style="font-family: Times;">2</span>}<span style="font-family: Times;"><a href="https://www.blogger.com/null" name="PGA2"></a></span><span style="font-family: Times;">.</span><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgfBJXP7x2qI2PxcwrzbAoMm1-eTPvjwW-cEnpTD51Bm2LbYMEMp3skVyRzensg0XSeZmsVhRKbG58FFKJlHiCkPfaeNGYTLkXJae8ugHK2w5sCAJwuEkE_RB7z1Yk3vi_e57Zh_kyMafo/s1600/Equation_5.GIF" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Exercises about Claisen condensation" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgfBJXP7x2qI2PxcwrzbAoMm1-eTPvjwW-cEnpTD51Bm2LbYMEMp3skVyRzensg0XSeZmsVhRKbG58FFKJlHiCkPfaeNGYTLkXJae8ugHK2w5sCAJwuEkE_RB7z1Yk3vi_e57Zh_kyMafo/s1600/Equation_5.GIF" title="Exercises about Claisen condensation" /></a></div><div class="separator" style="clear: both; text-align: left;"></div><div style="-webkit-text-stroke-width: 0px; color: black; font-family: 'Times New Roman'; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px;"></div><br /><div style="-webkit-text-stroke-width: 0px; color: black; font-family: 'Times New Roman'; font-size: medium; font-variant: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px;"><span style="font-family: Times;">Equation 4 offers another example of the <b><i>Dieckmann condensation </i></b>that was involved in the synthesis of tropinone, a degradation product that was produced during the determination of the structure of the physiologically active alkaloid </span><span style="font-family: Times; font-style: normal; font-weight: normal;">atropine</span><span style="font-family: Times; font-style: normal; font-weight: normal;"><a href="https://www.blogger.com/null" name="Atropine"></a>.</span></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjrxGCsRfx_PRxCrnDBy3ueVC2ukhX8aQuQ92XUWPG3sa3eMdlcsrlJprZmofHvX9GFtVKrXXN8qcWt89l1YHkZ3IVshZ0hscngGn_Q9-HBqpMwDUsHaheDPGBjfkQuSg0B6Jnywir8NvE/s1600/Equation_6.GIF" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Exercises about Claisen condensation" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjrxGCsRfx_PRxCrnDBy3ueVC2ukhX8aQuQ92XUWPG3sa3eMdlcsrlJprZmofHvX9GFtVKrXXN8qcWt89l1YHkZ3IVshZ0hscngGn_Q9-HBqpMwDUsHaheDPGBjfkQuSg0B6Jnywir8NvE/s1600/Equation_6.GIF" title="Exercises about Claisen condensation" /></a></div><div class="separator" style="clear: both; text-align: left;"></div><div style="-webkit-text-stroke-width: 0px; color: black; font-family: 'Times New Roman'; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px;"></div><br /><div style="-webkit-text-stroke-width: 0px; color: black; font-family: 'Times New Roman'; font-size: medium; font-variant: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px;"><span style="font-family: Times; font-style: normal; font-weight: normal;">An early synthesis of </span><span style="font-family: Times; font-style: normal; font-weight: normal;">cholesterol</span><span style="font-family: Times;"><a href="https://www.blogger.com/null" name="Cholesterol"></a> involved the "mixed <b><i>Claisen </i></b><i><b>reaction</b></i>" shown if Equation 5.</span></div><div style="-webkit-text-stroke-width: 0px; color: black; font-family: 'Times New Roman'; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px;"><span style="font-family: Times;"><br /></span></div><div style="-webkit-text-stroke-width: 0px; font-variant: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px;"><h4><span style="font-family: Times;"><span style="font-size: large;"><i><span style="color: blue;">      Example 4</span></i><span style="color: black; font-style: normal; font-weight: normal;">  </span></span><span style="color: black; font-size: small; font-style: normal; font-weight: normal;">:</span></span><span style="background-color: white; color: black; font-family: 'PT Sans', arial, serif; font-size: small; letter-spacing: 1px; line-height: 28px;"><b><i>Dieckmann Condensation</i></b></span></h4></div><div><br /></div><div style="-webkit-text-stroke-width: 0px; color: black; font-family: 'Times New Roman'; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px;"><span style="font-family: Times;"><br /></span></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEixGgbKNup9sg56CvHYsJTVyNmn-BiF1KhE-G3AIq8iQn3v6kgspFxEep_YJq6HpHWZ2-f4yW6KV-V6tuw70gebXSGykAOsaMbr1qtZa4iL11PAGbk2zGl2J41C94z3-xGNv0Efs-J7ONA/s1600/ex.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Exercises about Claisen condensation" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEixGgbKNup9sg56CvHYsJTVyNmn-BiF1KhE-G3AIq8iQn3v6kgspFxEep_YJq6HpHWZ2-f4yW6KV-V6tuw70gebXSGykAOsaMbr1qtZa4iL11PAGbk2zGl2J41C94z3-xGNv0Efs-J7ONA/s1600/ex.jpg" title="Exercises about Claisen condensation" /></a></div><h4 style="clear: both; text-align: left;"><i><span style="color: blue;">      <span style="font-size: large;">Example 5 </span></span></i>:<span style="background-color: white; font-family: 'PT Sans', arial, serif; font-size: small; letter-spacing: 1px; line-height: 28px;"><b><i>Crossed Claisen Condensation</i></b></span></h4><div style="background-color: white; border: 0px; font-family: 'PT Sans', arial, serif; letter-spacing: 1px; line-height: 28px; margin: 30px 0px 5px; padding: 0px; visibility: visible;"><br /></div><div><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjkKQptSKV64gIn-u_tBSKNwqG1_Q4d0sbjOeZDKztP52_T9VU4JRnQSOULqE4cIyqjQKsTkxUIKBTpDNS2btQ9DozU6lXm2hbqtusyW81zHPvq0ghyphenhyphenuIt6UH0HUHCazHzomQlS6MGwv2Q/s1600/download.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Exercises about Claisen condensation" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjkKQptSKV64gIn-u_tBSKNwqG1_Q4d0sbjOeZDKztP52_T9VU4JRnQSOULqE4cIyqjQKsTkxUIKBTpDNS2btQ9DozU6lXm2hbqtusyW81zHPvq0ghyphenhyphenuIt6UH0HUHCazHzomQlS6MGwv2Q/s1600/download.jpg" title="Exercises about Claisen condensation" /></a></div><h4 style="clear: both;"><span style="color: blue; font-size: large;"><i>     Example 6:</i></span></h4><div style="clear: both;"><span style="background-color: white; color: #252525; font-family: sans-serif; font-size: 14px; line-height: 22.399999618530273px;">The classic </span><b style="background-color: white; color: #252525; font-family: sans-serif; font-size: 14px; line-height: 22.399999618530273px;"><i>Claisen condensation</i></b><span style="background-color: white; color: #252525; font-family: sans-serif; font-size: 14px; line-height: 22.399999618530273px;">, a self-condensation between two molecules of a compound containing an enolizable ester.</span></div><dl style="background-color: white; font-family: sans-serif; line-height: 22.399999618530273px; margin-bottom: 0.5em; margin-top: 0.2em;"><dd style="color: #252525; font-size: 14px; line-height: 1.6; margin-bottom: 0.1em; margin-left: 1.6em; margin-right: 0px;"><a class="image" href="http://en.wikipedia.org/wiki/File:Claisen_ethyl_acetate.png" style="background: none; color: #0b0080; text-decoration: none;"><img alt="Exercises about Claisen condensation" data-file-height="245" data-file-width="1200" height="80" src="http://upload.wikimedia.org/wikipedia/commons/thumb/0/0b/Claisen_ethyl_acetate.png/350px-Claisen_ethyl_acetate.png" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/0/0b/Claisen_ethyl_acetate.png/525px-Claisen_ethyl_acetate.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/0/0b/Claisen_ethyl_acetate.png/700px-Claisen_ethyl_acetate.png 2x" style="border: none; vertical-align: middle;" title="Exercises about Claisen condensation" width="400" /></a></dd><dd style="line-height: 1.6; margin-bottom: 0.1em; margin-left: 1.6em; margin-right: 0px;"><h4 style="clear: both; font-family: 'Times New Roman'; line-height: normal;"><span style="color: blue; font-size: large;">Example 7:</span></h4></dd><dd style="line-height: 1.6; margin-bottom: 0.1em; margin-left: 1.6em; margin-right: 0px;"><div style="clear: both; color: black; font-family: 'Times New Roman'; line-height: normal;"><span style="color: #252525; font-family: sans-serif; font-size: 14px; line-height: 22.399999618530273px;">The mixed (or "crossed") Claisen condensation, where one enolizable ester or ketone and one nonenolizable ester are used.</span></div></dd></dl><dl style="background-color: white; font-family: sans-serif; line-height: 22.399999618530273px; margin-bottom: 0.5em; margin-top: 0.2em;"><dd style="color: #252525; font-size: 14px; line-height: 1.6; margin-bottom: 0.1em; margin-left: 1.6em; margin-right: 0px;"><a class="image" href="http://en.wikipedia.org/wiki/File:Mixed_claisen_example.png" style="background: none; color: #0b0080;"><img alt="Exercises about Claisen condensation" data-file-height="358" data-file-width="2000" src="http://upload.wikimedia.org/wikipedia/commons/thumb/a/a8/Mixed_claisen_example.png/500px-Mixed_claisen_example.png" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a8/Mixed_claisen_example.png/750px-Mixed_claisen_example.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/a8/Mixed_claisen_example.png/1000px-Mixed_claisen_example.png 2x" style="border: none; vertical-align: middle;" title="Exercises about Claisen condensation" /></a></dd><dd style="line-height: 1.6; margin-bottom: 0.1em; margin-left: 1.6em; margin-right: 0px;"><h4 style="clear: both; font-family: 'Times New Roman'; line-height: normal;"><span style="color: blue; font-size: large;"><i>Example  8:</i></span></h4><div style="color: #252525; font-size: 14px;">The <b><i>Dieckmann condensation</i></b>, where a molecule with two ester groups reacts intramolecularly, forming a cyclic <b><i>β-keto ester</i></b>. In this case, the ring formed must not be strained, usually a 5- or 6-membered chain or ring.</div></dd></dl><dl style="background-color: white; font-family: sans-serif; line-height: 22.399999618530273px; margin-bottom: 0.5em; margin-top: 0.2em;"><dd style="color: #252525; font-size: 14px; line-height: 1.6; margin-bottom: 0.1em; margin-left: 1.6em; margin-right: 0px;"><a class="image" href="http://en.wikipedia.org/wiki/File:Dieckmann_example.png" style="background: none; color: #0b0080; text-decoration: none;"><img alt="Exercises about Claisen condensation" data-file-height="313" data-file-width="2000" src="http://upload.wikimedia.org/wikipedia/commons/thumb/c/cc/Dieckmann_example.png/500px-Dieckmann_example.png" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/cc/Dieckmann_example.png/750px-Dieckmann_example.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/cc/Dieckmann_example.png/1000px-Dieckmann_example.png 2x" style="border: none; vertical-align: middle;" title="Exercises about Claisen condensation" /></a></dd><dd style="line-height: 1.6; margin-bottom: 0.1em; margin-left: 1.6em; margin-right: 0px;"><h4 style="clear: both; font-family: 'Times New Roman'; line-height: normal;"><span style="color: blue; font-size: large;"><i>Example 9:</i></span></h4></dd><dd style="color: #252525; line-height: 1.6; margin-bottom: 0.1em; margin-left: 1.6em; margin-right: 0px;"><br /></dd><dd style="color: #252525; font-size: 14px; line-height: 1.6; margin-bottom: 0.1em; margin-left: 1.6em; margin-right: 0px;"><div style="margin-bottom: 0.5em; margin-top: 0.5em;">The <b>Stobbe condensation</b> <sup class="reference" id="cite_ref-5" style="line-height: 1; unicode-bidi: -webkit-isolate;">[5]</sup> is a modification specific for the diethyl ester of succinic acid requiring less strong bases.<sup class="reference" id="cite_ref-6" style="line-height: 1; unicode-bidi: -webkit-isolate;">[6]</sup>An example is its reaction with benzophenone:<sup class="reference" id="cite_ref-7" style="line-height: 1; unicode-bidi: -webkit-isolate;">[7]</sup></div><div style="margin-bottom: 0.5em; margin-top: 0.5em;"><a class="image" href="http://en.wikipedia.org/wiki/File:StobbeCondensation.svg" style="background: none; color: #0b0080; text-decoration: none;" title="Stobbe condensation"><img alt="Stobbe condensation" data-file-height="93" data-file-width="683" height="93" src="http://upload.wikimedia.org/wikipedia/commons/thumb/f/ff/StobbeCondensation.svg/683px-StobbeCondensation.svg.png" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/f/ff/StobbeCondensation.svg/1025px-StobbeCondensation.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/f/ff/StobbeCondensation.svg/1366px-StobbeCondensation.svg.png 2x" style="border: none; margin: 0px; vertical-align: middle;" width="683" /></a></div><div style="margin-bottom: 0.5em; margin-top: 0.5em;">A reaction mechanism that explains the formation of both an ester group and a carboxylic acid group is centered around alactone intermediate (<b>5</b>):</div><div style="margin-bottom: 0.5em; margin-top: 0.5em;"><a class="image" href="http://en.wikipedia.org/wiki/File:StobbeMechanism.svg" style="background: none; color: #0b0080;" title="Stobbe condensation mechanism"><img alt="Stobbe condensation mechanism" data-file-height="285" data-file-width="664" height="285" src="http://upload.wikimedia.org/wikipedia/commons/thumb/d/d4/StobbeMechanism.svg/664px-StobbeMechanism.svg.png" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/d/d4/StobbeMechanism.svg/996px-StobbeMechanism.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/d/d4/StobbeMechanism.svg/1328px-StobbeMechanism.svg.png 2x" style="border: none; margin: 0px; vertical-align: middle;" title="Stobbe condensation mechanism" width="664" /></a></div></dd><dd style="line-height: 1.6; margin-bottom: 0.1em; margin-left: 1.6em; margin-right: 0px;"><h4 style="clear: both; font-family: 'Times New Roman'; line-height: normal;"><span style="color: blue; font-size: large;"><i>Example 10:<a href="https://www.blogger.com/null" name="more"></a></i></span></h4></dd><dd style="font-size: 14px; line-height: 1.6; margin-bottom: 0.1em; margin-left: 1.6em; margin-right: 0px;"><div class="separator" style="clear: both; text-align: center;"><br /></div></dd><dd style="line-height: 1.6; margin-bottom: 0.1em; margin-left: 1.6em; margin-right: 0px;"><div class="separator" style="clear: both; color: #252525; font-size: 14px; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgCUur3lcpNL97pbt0d2Dd6jWsWme8cWRry4zujQwElCf-_ukZB295qVNyl2iAqu65VnS72sxqHsKNggGXaiwa_RdWeI-7b2syi3sKRwijdsJo5zm8-lp2jDU9UahgjNkAGqKyp_IfMlLI/s1600/claisen4.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Exercises about Claisen condensation" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgCUur3lcpNL97pbt0d2Dd6jWsWme8cWRry4zujQwElCf-_ukZB295qVNyl2iAqu65VnS72sxqHsKNggGXaiwa_RdWeI-7b2syi3sKRwijdsJo5zm8-lp2jDU9UahgjNkAGqKyp_IfMlLI/s1600/claisen4.gif" title="Exercises about Claisen condensation" /></a></div><h4 style="clear: both; font-family: 'Times New Roman'; line-height: normal;"><span style="color: blue; font-size: large;"><i>Example 11:</i></span></h4><div class="separator" style="clear: both; color: #252525; font-size: 14px; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiNu5KZbjY_sh2F-bUaIXIpK_iwAlhafUn2sef_4zq0HPwlOtlT7k9v9PGyqflE3xowcVTW2-lUibP7NQhYawafgJKRgBSzb-wpzqjB0bhQoJuaik2Gl-mT86SbG20phtt-lD45_LwsFHw/s1600/dieckmann.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Exercises about Claisen condensation" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiNu5KZbjY_sh2F-bUaIXIpK_iwAlhafUn2sef_4zq0HPwlOtlT7k9v9PGyqflE3xowcVTW2-lUibP7NQhYawafgJKRgBSzb-wpzqjB0bhQoJuaik2Gl-mT86SbG20phtt-lD45_LwsFHw/s1600/dieckmann.gif" title="Exercises about Claisen condensation" /></a></div></dd><dd style="line-height: 1.6; margin-bottom: 0.1em; margin-left: 1.6em; margin-right: 0px;"><div class="separator" style="clear: both; color: #252525; font-size: 14px; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgMXDewwd46isdpF9Ns4YMH6tC7BC9JLUaQiPHRWE64C-m8Vdk300d58TGiAb4nJzx-hwwrlrNNvalcSWAeQq42gIh8pIS1dVUJIvJG8iq_OCs9tKRvxxhahA_4XtKseYqydxy460x1qVA/s1600/claisen05.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Exercises about Claisen condensation" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgMXDewwd46isdpF9Ns4YMH6tC7BC9JLUaQiPHRWE64C-m8Vdk300d58TGiAb4nJzx-hwwrlrNNvalcSWAeQq42gIh8pIS1dVUJIvJG8iq_OCs9tKRvxxhahA_4XtKseYqydxy460x1qVA/s1600/claisen05.gif" title="Exercises about Claisen condensation" /></a>  </div><h4 style="clear: both; font-family: 'Times New Roman'; line-height: normal;"><span style="color: blue; font-size: large;"><i>Example 12:</i></span></h4><div class="separator" style="clear: both; color: #252525; font-size: 14px; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhELHOBwg0P9LZyAKwfy0kt317YObNuMxgu35WcvHmL-tWTt6-w39L2jA6usSowl9ACJmylaCe6gD4BM3sAYmL2cVa7QNHrIJLNNPlnLxIeYgC487nZwolPXAuHjxIYHtHEhe9htJBM0_0/s1600/11.jpg" imageanchor="1" style="line-height: 1.6; margin-left: 1em; margin-right: 1em;"><img alt="Exercises about Claisen condensation" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhELHOBwg0P9LZyAKwfy0kt317YObNuMxgu35WcvHmL-tWTt6-w39L2jA6usSowl9ACJmylaCe6gD4BM3sAYmL2cVa7QNHrIJLNNPlnLxIeYgC487nZwolPXAuHjxIYHtHEhe9htJBM0_0/s1600/11.jpg" title="Exercises about Claisen condensation" /></a></div></dd><dd style="color: #252525; font-size: 14px; line-height: 1.6; margin-bottom: 0.1em; margin-left: 1.6em; margin-right: 0px;"><div class="separator" style="clear: both; text-align: center;"><br /></div></dd><dd style="line-height: 1.6; margin-bottom: 0.1em; margin-left: 1.6em; margin-right: 0px;"><div style="color: #252525; font-size: 14px;"><br /></div><div class="separator" style="clear: both; color: #252525; font-size: 14px; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjuf6LAyAy40TNG7Qsyb7Ob1l-yn1O_PYFXa3Z1CV8DQOTVhcNq-KHPwXjEgbBSqYnYxWLdyI4XJU4v8zad5Z09_48bum2hy_qFBXMj7yu2Vdz24qKytHMiFNEuM2u-s4Aad-ntpaROKDo/s1600/12.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Exercises about Claisen condensation" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjuf6LAyAy40TNG7Qsyb7Ob1l-yn1O_PYFXa3Z1CV8DQOTVhcNq-KHPwXjEgbBSqYnYxWLdyI4XJU4v8zad5Z09_48bum2hy_qFBXMj7yu2Vdz24qKytHMiFNEuM2u-s4Aad-ntpaROKDo/s1600/12.jpg" title="Exercises about Claisen condensation" /></a></div><h4 style="clear: both; font-family: 'Times New Roman'; line-height: normal;"><span style="color: blue; font-size: large;"><i>Example 13:</i></span></h4><div class="separator" style="clear: both; color: #252525; font-size: 14px; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiyX-JPV9PZwIz6sxQCt_M3I0NJ_OMu3Ga2_gg8FaZCPdHt9WhY9n9NMCnjCCE2TlriTdD0xjdN1vST6W1AzxpUJ-llnci-bqutdHx0I5NiE1fkPDJMpd7_bipIg7K0rgdjbQlepkjmohc/s1600/ClaisenExample1.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Exercises about Claisen condensation" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiyX-JPV9PZwIz6sxQCt_M3I0NJ_OMu3Ga2_gg8FaZCPdHt9WhY9n9NMCnjCCE2TlriTdD0xjdN1vST6W1AzxpUJ-llnci-bqutdHx0I5NiE1fkPDJMpd7_bipIg7K0rgdjbQlepkjmohc/s1600/ClaisenExample1.png" title="Exercises about Claisen condensation" /></a></div><h4 style="clear: both; font-family: 'Times New Roman'; line-height: normal;"><span style="color: blue; font-size: large;"><i>Example 14:</i></span></h4><div class="separator" style="clear: both; color: #252525; font-size: 14px; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgp1_k7MZIUUuEDmkBSQnSsAMiw3g44MV-cPMw7jlbGqVLAYl64cJ6-RHSZvjeNJzv3VM35NqH3DVQzSjTUG0rYVZDv1re0zbNe1CkbDngm9ZL5LuB4dWuFAGWngFgJfclHt1o6YeOVhxU/s1600/dieckmann-condensation-reaction-mechanism.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Exercises about Claisen condensation" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgp1_k7MZIUUuEDmkBSQnSsAMiw3g44MV-cPMw7jlbGqVLAYl64cJ6-RHSZvjeNJzv3VM35NqH3DVQzSjTUG0rYVZDv1re0zbNe1CkbDngm9ZL5LuB4dWuFAGWngFgJfclHt1o6YeOVhxU/s1600/dieckmann-condensation-reaction-mechanism.png" title="Exercises about Claisen condensation" /></a></div><h4 style="clear: both; font-family: 'Times New Roman'; line-height: normal;"><span style="color: blue; font-size: large;"><i>Example 15:</i></span></h4><div class="separator" style="clear: both; color: #252525; font-size: 14px; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj7ohkdAsHxFckdami2RbWnwY9evsZMbG3XfgbleS2c7isFheoq8DkZrhNBtCk7CMA765jH2JxknncXFOlHF9GGUqnnOvgp83JMsTqZ8HXCQQQlmEjHUo-OIZ2TD_bmyYanG8thulclFwk/s1600/dieckmann_condensation01.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Exercises about Claisen condensation" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj7ohkdAsHxFckdami2RbWnwY9evsZMbG3XfgbleS2c7isFheoq8DkZrhNBtCk7CMA765jH2JxknncXFOlHF9GGUqnnOvgp83JMsTqZ8HXCQQQlmEjHUo-OIZ2TD_bmyYanG8thulclFwk/s1600/dieckmann_condensation01.jpg" title="Exercises about Claisen condensation" /></a>                                                                           </div><h4 style="clear: both; font-family: 'Times New Roman'; line-height: normal;"><span style="color: blue; font-size: large;">Example 16:</span></h4><div style="color: #252525; font-size: 14px;"><br /></div><div class="separator" style="clear: both; color: #252525; font-size: 14px; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjtrrRVNBb1PZQRjKwpPInw26kkgu4rfbhYZmDe5_pvH4FrS5x5DkFRkXfmJaKviXJ2CQUD7pMqF1Gue7GqhKb4xDWrEOsij14VXkSwSwcB6sKAimQljM-OLqMObFHGB4uZ18NwPMj3_fU/s1600/DieckmannCondensationMechanism.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Exercises about Claisen condensation" border="0" height="139" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjtrrRVNBb1PZQRjKwpPInw26kkgu4rfbhYZmDe5_pvH4FrS5x5DkFRkXfmJaKviXJ2CQUD7pMqF1Gue7GqhKb4xDWrEOsij14VXkSwSwcB6sKAimQljM-OLqMObFHGB4uZ18NwPMj3_fU/s1600/DieckmannCondensationMechanism.png" title="Exercises about Claisen condensation" width="400" /></a></div><h4 style="clear: both; font-family: 'Times New Roman'; line-height: normal;"><span style="color: blue; font-size: large;"><i>Example 17:</i></span></h4><div style="color: #252525; font-size: 14px;"><br /></div><div class="separator" style="clear: both; color: #252525; font-size: 14px; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhCxnCml9zhvcPwuv4iVL2wvOugC7YQ2EDNCT00LMJ8A6TjqUrzukjvqBjXYsUr7_GZfVDQQgq3RIxLyZfPLMt_ToOTzjEWhDyBKhsqXqNWDpGlAKA41GnPX15L7PTdbBBnuIYdS9aiz88/s1600/intramech.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Exercises about Claisen condensation" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhCxnCml9zhvcPwuv4iVL2wvOugC7YQ2EDNCT00LMJ8A6TjqUrzukjvqBjXYsUr7_GZfVDQQgq3RIxLyZfPLMt_ToOTzjEWhDyBKhsqXqNWDpGlAKA41GnPX15L7PTdbBBnuIYdS9aiz88/s1600/intramech.gif" title="Exercises about Claisen condensation" /></a></div><h4 style="clear: both; font-family: 'Times New Roman'; line-height: normal;"><span style="color: blue; font-size: large;"><i>Example 18:</i></span></h4><div style="color: #252525; font-size: 14px;"><br /></div><div class="separator" style="clear: both; color: #252525; font-size: 14px; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEifhgUzJuUy4-QW4Wex31wwEl-4Y9b75wSFdgXvmBtsaK30xkft0OXc6GidNBbTc5Zl5JSXwqsOO08Fb1rgCHoiR3bAQpyWBqtlx79wDtf2P8z2Akzpg8oJY62c5OBTVoI4H9-1eP56ZeA/s1600/Ketogenesis.gif" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Exercises about Claisen condensation" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEifhgUzJuUy4-QW4Wex31wwEl-4Y9b75wSFdgXvmBtsaK30xkft0OXc6GidNBbTc5Zl5JSXwqsOO08Fb1rgCHoiR3bAQpyWBqtlx79wDtf2P8z2Akzpg8oJY62c5OBTVoI4H9-1eP56ZeA/s1600/Ketogenesis.gif" title="Exercises about Claisen condensation" /></a></div><div class="separator" style="clear: both; color: #252525; font-size: 14px; text-align: center;"><br /></div></dd><dd style="color: #252525; font-size: 14px; line-height: 1.6; margin-bottom: 0.1em; margin-left: 1.6em; margin-right: 0px;"><div class="separator" style="clear: both; text-align: center;"><br /></div></dd></dl></div></div></div>

Exercises about Claisen condensation

The Claisen Condensation The nucleophilic carbon of the enolate ion adds to the electrophilic carbon of a molecule of ethyl acetate that has...

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Mechanism of the Claisen Condensation

<h2><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiFdBbJHxNA6dpU1TQLpTMmmLmgBiDNSKbxqQ1M3-t0jEOlzAEpmNqe278I9VCYeQYajLGN4RWDIZOb1MLIghv41nq1ACkt4swGjj3cxLDCQ90DhVsX6QLnsHIzaDN8iFbEhxf0TemnyXA/s1600/claisen.gif" imageanchor="1" style="font-size: medium; font-weight: normal; margin-left: 1em; margin-right: 1em; text-align: center;"><img alt="Mechanism of the Claisen Condensation" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiFdBbJHxNA6dpU1TQLpTMmmLmgBiDNSKbxqQ1M3-t0jEOlzAEpmNqe278I9VCYeQYajLGN4RWDIZOb1MLIghv41nq1ACkt4swGjj3cxLDCQ90DhVsX6QLnsHIzaDN8iFbEhxf0TemnyXA/s1600/claisen.gif" title="Mechanism of the Claisen Condensation" /></a></h2><h2><i style="font-family: Arial, Helvetica, 'sans serif';"><span style="font-size: large;">Mechanism of the Claisen Condensation</span></i></h2><h3><b><i>Reaction type : Nucleophilic Acyl Substitution<a name="more"></a></i></b></h3><div><h4>Summary</h4><ul><li>The Claisen condensation is the ester analogue of the Aldol condensation.</li><li>Reagents : most commonly the base would be the alkoxide, <b>R'O^-</b></li><li>The reaction involves an ester enolate reacting with another molecule of the ester.</li><li>Remember enolates are good nucleophiles and the ester carbonyl <b>C</b> are electrophilic.</li><li>The products of these reactions are <b><i><span style="font-family: Symbol;">b-</span>ketoesters</i></b> which are important, useful synthetic intermediates.</li><li>Note that the product is the original ester with an <b>acyl<span style="color: #3333ff;"> </span></b>group added <i>i.e.</i> an <b>acylation</b> reaction has occurred.</li><li>A simple example of a <b><i>Claisen condensation </i></b>is the reaction of ethyl ethanoate which is shown below in two representations:</li></ul></div><div><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgRvroNWaiQqc0BfEoj5ZrHmV1qlVqm9h4IisnLrQsue59e9_6ME7BJdS5Zqdl9Fmj-j2gycZknUjwJ26yJxP1UwwgyXjcQm58X8fOcHo_Tvi6Z87SORWYbWM_dkAwdOnPdOmWg37waCIU/s1600/claisenmech.gif" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"><img alt="Mechanism of the Claisen Condensation" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgRvroNWaiQqc0BfEoj5ZrHmV1qlVqm9h4IisnLrQsue59e9_6ME7BJdS5Zqdl9Fmj-j2gycZknUjwJ26yJxP1UwwgyXjcQm58X8fOcHo_Tvi6Z87SORWYbWM_dkAwdOnPdOmWg37waCIU/s1600/claisenmech.gif" title="Mechanism of the Claisen Condensation" /></a></div><div><b style="background-color: white; font-family: Arial;"><br /></b></div><div><b style="background-color: white; font-family: Arial;"><br /></b></div><div><b style="background-color: white; font-family: Arial;">Step 1:</b><span style="background-color: white; font-family: Arial;"> </span><br /><span style="background-color: white; font-family: Arial;">First, an acid-base reaction. The alkoxide functions as a base and removes the acidic </span><span style="background-color: white; font-family: Symbol;">a</span><span style="background-color: white; font-family: Arial;">-hydrogen giving the reactive ester enolate</span></div><div><span style="background-color: white; font-family: Arial;"><br /></span></div><div><span style="background-color: white; font-family: Arial;"><br /></span></div><div><b style="background-color: white; font-family: Arial;">Step 2:</b><span style="background-color: white; font-family: Arial;"> </span><br /><span style="background-color: white; font-family: Arial;">The nucleophilic ester enolate attacks the carbonyl </span><b style="background-color: white; font-family: Arial;">C</b><span style="background-color: white; font-family: Arial;"> of another ester in a </span><a href="http://www.chem.ucalgary.ca/courses/351/Carey5th/Ch20/ch20-2-1.html" rel="nofollow" style="background-color: white; font-family: Arial;" target="_blank">nucleophilic substitution process</a><span style="background-color: white; font-family: Arial;"> giving the tetrahedral intermediate.</span></div><div><span style="background-color: white; font-family: Arial;"><br /></span></div><div><span style="background-color: white; font-family: Arial;"><br /></span></div><div><span style="background-color: white; font-family: Arial;"><br /></span></div><div><span style="background-color: white; font-family: Arial;"><b>Step 3:</b><br />The intermediate collapses, reforming the <b>C=O</b>, resulting in loss of the leaving group, the alkoxide, leading to the </span><span style="background-color: white; font-family: Symbol;">b</span><span style="background-color: white; font-family: Arial;">-ketoester product.</span></div><div><span style="background-color: white; font-family: Arial;"><br /></span></div><div><span style="background-color: white; font-family: Arial;"><br /></span></div><div><span style="font-family: Arial;"><span style="background-color: white;">(nguồn: </span>http://www.chem.ucalgary.ca/courses/351/Carey5th/Ch21/ch21-3-1.html</span><br /><span style="font-family: Arial;">http://www.mhhe.com/physsci/chemistry/carey/student/olc/graphics/carey04oc/ref/ch21enolatereactions.html)</span><br /><span style="font-family: Arial;"><br /></span><span style="font-family: Arial;"><br /></span><br /><h4><span style="font-family: Arial; font-size: large;"><i>More than:</i></span></h4></div><div><div style="background-color: white;"><span style="font-family: Arial, Helvetica, sans-serif;">The general form of a <a href="http://forum-chemistry.blogspot.com/2014/08/claisen-condensationngung-tu-claisen.html" target="_blank">Claisen condensation</a> is as follows:</span></div><div style="background-color: white;"><span style="font-family: Arial, Helvetica, sans-serif; font-size: x-small;"><br /><img alt="Mechanism of the Claisen Condensation" height="67" src="http://www.chemhelper.com/images/pictures/claisen1.gif" title="Mechanism of the Claisen Condensation" width="344" /></span></div><div style="background-color: white;"><span style="font-family: Arial, Helvetica, sans-serif;">The first step involves adding a strong base to an ester to generate an enolate at the <span style="font-family: Symbol;">a</span> carbon (note that the enolate has an additional resonance structure).</span></div><div style="background-color: white;"><img alt="Mechanism of the Claisen Condensation" height="276" src="http://www.chemhelper.com/images/pictures/claisen2.gif" title="Mechanism of the Claisen Condensation" width="468" /></div><div style="background-color: white;"><span style="font-family: Arial, Helvetica, sans-serif;">The enolate can then add to another ester molecule by attacking the carbonyl to make the tetrahedral intermediate. The carbonyl reforms with loss of the alcoxy group to make the <span style="font-family: Symbol;">b</span>-keto ester.</span></div><div style="background-color: white;"><br /></div><div style="background-color: white;"><h4><span style="font-family: Arial, Helvetica, sans-serif;"><b><i>Example of a Claisen condensation:</i></b></span></h4></div><div style="background-color: white;"><img alt="Mechanism of the Claisen Condensation" height="292" src="http://www.chemhelper.com/images/pictures/dieckmann.gif" title="Mechanism of the Claisen Condensation" width="386" /></div><div style="background-color: white;"><span style="font-family: Arial, Helvetica, sans-serif;">This is an example of an intramolecular Claisen reaction, called a Dieckmann condensation.</span></div><div style="background-color: white;"><span style="font-family: Arial, Helvetica, sans-serif; font-size: x-small;"><br /></span></div><h3 style="background-color: white;"><span style="font-family: Arial, Helvetica, sans-serif; font-size: x-large;"><i>Learn More:</i></span></h3><div><h3><span style="font-family: Arial, Helvetica, sans-serif; font-size: large;"><i><a href="http://forum-chemistry.blogspot.com/2014/08/mechanism-of-claisen-condensation.html" target="_blank">Claisen condensation mechanism</a></i></span></h3></div><div><h4 style="background-color: white; border: 0px; color: #333333; font-family: Arial, Helvetica, sans-serif; line-height: 18px; margin-bottom: 8px !important; margin-top: 0.25em; padding: 0px; visibility: visible;">1) Enolate formation</h4></div><div><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhqCA1Bqlfd4N-eqJVlDQvjlGecMn93w17pMLYxYrvwvUWRhyQakRR6Cfpey0BZABkRvkz5O5eP2SBeDXOG69b4sQ2DompA02Up6Z-A9TjjwyGlLZcYPhcp3qoT5l_HQR4FcILqHz8zUcE/s1600/Claisen+condensation+mechanism.jpg" imageanchor="1" style="clear: left; display: inline !important; margin-bottom: 1em; margin-right: 1em; text-align: center;"><img alt="Mechanism of the Claisen Condensation" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhqCA1Bqlfd4N-eqJVlDQvjlGecMn93w17pMLYxYrvwvUWRhyQakRR6Cfpey0BZABkRvkz5O5eP2SBeDXOG69b4sQ2DompA02Up6Z-A9TjjwyGlLZcYPhcp3qoT5l_HQR4FcILqHz8zUcE/s1600/Claisen+condensation+mechanism.jpg" title="Mechanism of the Claisen Condensation" /></a></div><div><h4 style="background-color: white; border: 0px; color: #333333; font-family: Arial, Helvetica, sans-serif; line-height: 18px; margin-bottom: 8px !important; margin-top: 0.25em; padding: 0px; visibility: visible;">2) Nucleophilic attack</h4></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEikMXxJrVLN_xk94Mmf5Xfel7CGlJUcXtXr1MysQnSshFtw-cdbxVjunMc40PQL6fTUozJ6fJx8G4XXjIbTW5th1IOgN1urn-JAT3izR42LffRpCzmuScmZVpR4hwbabI164Ov5p5VHi-w/s1600/Claisen+condensation+mechanism2.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Mechanism of the Claisen Condensation" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEikMXxJrVLN_xk94Mmf5Xfel7CGlJUcXtXr1MysQnSshFtw-cdbxVjunMc40PQL6fTUozJ6fJx8G4XXjIbTW5th1IOgN1urn-JAT3izR42LffRpCzmuScmZVpR4hwbabI164Ov5p5VHi-w/s1600/Claisen+condensation+mechanism2.jpg" title="Mechanism of the Claisen Condensation" /></a></div><h4 style="background-color: white; border: 0px; color: #333333; font-family: Arial, Helvetica, sans-serif; line-height: 18px; margin-bottom: 8px !important; margin-top: 0.25em; padding: 0px; visibility: visible;">3) Removal of leaving group<span style="background-color: transparent;"> </span></h4><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgZaNkEnkIu_qAZ02xY6apqPvH0TaqO6JORtkfRy0T-RCu06XCA1HTzz44CBoIUBw0K2lqLxWT0dm9ommqUOnFc6Yt-VRV07FUVn5nfpbRZW-PPAOXbJw-1mP_t6HZoDSK9s3lLtxceuHo/s1600/Claisen+condensation+mechanism3.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="Mechanism of the Claisen Condensation" border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgZaNkEnkIu_qAZ02xY6apqPvH0TaqO6JORtkfRy0T-RCu06XCA1HTzz44CBoIUBw0K2lqLxWT0dm9ommqUOnFc6Yt-VRV07FUVn5nfpbRZW-PPAOXbJw-1mP_t6HZoDSK9s3lLtxceuHo/s1600/Claisen+condensation+mechanism3.jpg" title="Mechanism of the Claisen Condensation" /></a></div><br /></div>

Mechanism of the Claisen Condensation

Mechanism of the Claisen Condensation Reaction type : Nucleophilic Acyl Substitution Summary The Claisen condensation is the ester analogue ...

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