Investigating the mechanism of chiral surface reactions: The interaction of methylacetoacetate with (S)-glutamic acid modified Ni{111}

TE Jones, CJ Baddeley*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

29 Citations (Scopus)

Abstract

The enantioselective hydrogenation of beta ketoesters over Ni-based catalysts is a rare example of a heterogeneously catalyzed chiral reaction. The key step in catalyst preparation is the adsorption from solution of chiral molecules (modifiers). One particularly interesting modifier is (S)-glutamic acid because the dominant enantiomeric product in the catalytic reaction depends upon the modification temperature. We report a reflection absorption infrared spectroscopy (RAIRS) study of the adsorption of methylacetoacetate (the simplest beta ketoester) onto (S)-glutamic acid modified Ni {111} surfaces as functions of the modifier coverage and modification temperature. We show that the sticking probability of methylacetoacetate is close to 0 on saturated (S)-glutamic acid covered surfaces. At lower modifier coverage, methylacetoacetate adsorption can occur. Adsorption of methylacetoacetate onto a Ni{111} surface modified by (S)-glutamic acid at 300 K results in the diketo tautomeric form, with evidence being observed for a 1:1 interaction between zwitterionic (S)-glutamate and methylacetoacetate. In contrast, adsorption of methylacetoacetate onto a Ni{111} surface modified by (S)-glutamic acid at 350 K occurs exclusively in the enol tautomeric form. The implications for the heterogeneous catalytic reaction are discussed.

Original languageEnglish
Pages (from-to)148-152
Number of pages5
JournalLangmuir
Volume22
Issue number1
DOIs
Publication statusPublished - 3 Jan 2006

Keywords

  • ENANTIOSELECTIVE HETEROGENEOUS CATALYSIS
  • SCANNING-TUNNELING-MICROSCOPY
  • KETO-ENOL-TAUTOMERISM
  • (R,R)-TARTARIC ACID
  • METHYL ACETOACETATE
  • R,R-TARTARIC ACID
  • CU(110) SURFACE
  • GLUTAMIC-ACID
  • TARTARIC ACID
  • L-LYSINE

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