Abstract
Esterifications of carboxylic acids with equimolar amount of alcohols could be efficiently catalyzed by ZrOCl(2) x 8H(2)O. Acrylate esters were obtained in good yields under solvent-free conditions at ambient temperature. The esterification of other carboxylic acids with alcohols also proceeded at ambient temperature or at 50 oC to afford esters in high yields. If the esterification was performed in toluene under azeotropic reflux conditions to remove water, both the catalytic activity of ZrOCl(2) x 8H(2)O and the rate of esterification could be increased greatly. Furthermore, in the present catalytic system, the esters could be easily separated from the reaction mixtures and the catalyst could be easily recovered and reused.
Highlights
Esters are the important class of organic compounds, which are usually prepared by the esterification of carboxylic acids with alcohols catalyzed by H2SO4, TsOH [1, 2] and other catalysts [3-18]
The aim of our research described here was to develop an efficient catalytic procedure for the direct esterification of carboxylic acids with alcohols under solvent-free conditions with the following requirements: (1) esters should be obtained in high yields by the esterification of equimolar amounts of carboxylic acids and alcohols; (2) esterification should proceed at ambient or low temperature and the catalyst system should be suitable for the esterification of highly reactive carboxylic acids such as acrylic acid; (3) the esters should be easy to isolate and purify, and the catalyst should be recyclable
We have investigated the ZrOCl2·8H2O-catalyzed esterification of carboxylic acids with equimolar amount of alcohols at ambient temperature, at 50 oC or under azeotropic reflux conditions
Summary
Esters are the important class of organic compounds, which are usually prepared by the esterification of carboxylic acids with alcohols catalyzed by H2SO4, TsOH [1, 2] and other catalysts [3-18]. Among the chosen zirconium compounds, ZrOCl2·8H2O (entry 1) was very efficient in this esterification, affording methyl acrylate (3aa) in 71% yield (GC) without any removal of water, while ZrO(NO3)2·2H2O and Zr(NO3)4·5H2O showed somewhat lower catalytic activities to give 3aa in moderate yields (entries 2 and 3).
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
