Hydrogenation of (E)-2-methyl-2-butenoic acid over cinchona-modified Pd catalyst in the presence of achiral amines: Solvent and modifier effect

Zsolt Makra, György Szollosi

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

The effect of the solvent, modifier structure and concentration on the enantioselective hydrogenation of (E)-2-methyl-2-butenoic acid over Pd/Al 2O3 modified by cinchona alkaloids was influenced by the addition of achiral amines to the reaction slurry. The solvent dependence in the presence of achiral amines showed that additives are involved in the rate determinant step of the reaction, whereas the effect of the dilution pointed to the presence of the acid dimers in the intermediate responsible for enantioselection. The dependence of the enantioselectivity on the cinchonidine concentration in the presence of amines and results obtained using cinchona derivatives and mixtures thereof were in line with our earlier assumptions related to the participation of the amine additive in the formation of the surface intermediate. Based on these and previously published results possible structures of this intermediate are suggested.

Original languageEnglish
Pages (from-to)113-117
Number of pages5
JournalCatalysis Communications
Volume46
DOIs
Publication statusPublished - Feb 10 2014

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Keywords

  • Amine additive
  • Cinchona alkaloid
  • Enantioselective hydrogenation
  • Palladium
  • Solvent effect
  • Unsaturated acid

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Process Chemistry and Technology

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