fulltext.study @t Gmail

Achiral amine additives in the enantioselective hydrogenation of aliphatic α,β-unsaturated acids over cinchonidine-modified Pd/Al2O3 catalyst

Paper ID Volume ID Publish Year Pages File Format Full-Text
55439 47053 2012 6 PDF Available
Title
Achiral amine additives in the enantioselective hydrogenation of aliphatic α,β-unsaturated acids over cinchonidine-modified Pd/Al2O3 catalyst
Abstract

The effect of the achiral amine additive structure was studied on the enantioselective hydrogenation of (E)-2-methyl-2-butenoic acid and (E)-2-methyl-2-hexenoic acid over Pd/Al2O3 catalyst modified by cinchonidine. It was found that secondary amines are similarly or even more efficient in increasing the enantioselectivity as primary amines. The right basicity of the amine, which may vary in a rather wide range, should be coupled with appropriate steric properties to be effective in increasing the enantioselectivity. The best performing amines was the earlier widely used benzylamine and N-methylbenzylamine. The influence of these amines on the effect of the catalyst amount, H2 pressure and reaction temperature was studied. The effect of the amine amount on the hydrogenation of the two acids was also investigated. Based on the results the involvement of the amine additive in the formation of surface intermediates responsible for enantioselection is proposed.Decrease of the reaction temperature to 273 K increased the enantiomeric excess in the presence of amines, resulting in the hydrogenation of (E)-2-methyl-2-hexenoic acid in up to 71% enantioselectivity in favour of the S product enantiomer, the highest value obtained until now in the enantioselective hydrogenation of aliphatic unsaturated carboxylic acids over chirally modified heterogeneous catalyst.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (181 K)Download as PowerPoint slideHighlights► The hydrogenation of aliphatic unsaturated acids was studied over cinchonidine-modified Pd. ► The achiral secondary amine additives were found to be similarly efficient as the primary amines. ► The amines influenced the effect of the catalyst amount, H2 pressure and reaction temperature. ► It was suggested the participation of additives in the formation of the intermediate complex.

Keywords
Aliphatic unsaturated acid; Amine additive; Cinchonidine; Enantioselective hydrogenation; Heterogeneous catalyst; Palladium
First Page Preview
Achiral amine additives in the enantioselective hydrogenation of aliphatic α,β-unsaturated acids over cinchonidine-modified Pd/Al2O3 catalyst
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us
Publisher
Database: Elsevier - ScienceDirect
Journal: Catalysis Today - Volume 181, Issue 1, 12 February 2012, Pages 56–61
Authors
, , ,
Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us