Kinetics and mechanism of oxime formation from pyruvic acid

Abstract

The following lines of evidence establish that oxime formation from pyruvic acid occurs with ratedetermining carbinolamine dehydration under acidic and neutral conditions. First, saturation effects observed at pH 7 are strongly suggestive of carbinolamine accumulation, requiring that dehydration of the intermediate be the ratedetermining step. Second, the reaction occurs exclusively with general acid catalysis in the entire range investigated.The pH-rate plot shows a break at pH near 2, which can be interpreted in terms of protolytic equilibrium of the substrate.

Alanine Formation in a Zero‐Gap Flow Cell and the Role of TiO2/Ti Electrocatalysts

“…[11] The α-keto acid precursors allow for the direct formation of α-amino acids via ERA using a nitrogen source (e. g. NH 3 or NH 2 OH) in an aqueous acidic environment (e. g. H 2 SO 4 ). The reaction comprises two steps: 1. the formation of an intermediate imine or oxime using aqueous NH 3 or NH 2 OH respectively via homogeneous condensation of the keto acid and nitrogen source at low pH, [21] 2. the subsequent reduction of the intermediate to the corresponding amino acid. The second step is a two-electron reaction in case the nitrogen source is NH 3 and the intermediate is an imine, or a four-electron transformation if the nitrogen source is NH 2 OH and the intermediate is the corresponding oxime.…”