Aldol condensation of campholenic aldehyde and MEK over activated hydrotalcites

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• 作者：S. Abelló ; F. Medina ; D. Tichit ; J. Pé ; rez-Ramd ; rez ; J.E. Sueiras ; P. Salagre ; Y. Cesteros
• 关键词：Solid base catalysis ; Aldol condensation ; Campholenic aldehyde ; MEK ; Hydrotalcite ; Meixnerite ; Rehydration
• 刊名：Applied Catalysis B ; Environmental
• 出版年：2007
• 期刊代码：4_09263373
• 类别：ce
• 出版时间：31 January 2007
• 卷：70
• 期：1-4
• 页码：577-584
• 文件大小：940 K

摘要

In this paper, activated Mg-Al hydrotalcites were used as catalysts in the aldol condensation of campholenic aldehyde and methyl ethyl ketone (MEK). These materials represent an attractive alternative to less environmentally friendly liquid bases in a number of base-catalyzed reactions involved in the pharmaceutical and fragrance industries. The presence of basic hydroxyl groups in the interlayer space leads to very active materials. However, the relation between the activity of reconstructed hydrotalcites and the rehydration procedure is still not well understood. Different rehydration protocols in combination with extensive characterization studies were performed, including XRD, SEM, IR spectroscopy and TPD of CH₃CN and CH₃NO₂. The materials were tested as catalysts in the aldol condensation of campholenic aldehyde and MEK, and relationships between the catalytic performance of the activated hydrotalcites and the rehydration procedure were derived. Several factors may influence the activity and selectivity of this reaction, such as the reaction temperature, the molar ratio of the reactants and the degree of rehydration of the hydrotalcite-like catalysts. The selectivity towards the formation of the desired branched isomer increases when performing the reaction at low temperatures.