Acta Phys. -Chim. Sin. ›› 2004, Vol. 20 ›› Issue (08S): 911-916.doi: 10.3866/PKU.WHXB200408zk04

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Mechanisms of Unimolecular Reactions for Ground-state Pyruvic Acid

Ding Wan-Jian;Fang Wei-Hai;Liu Ruo-Zhuang   

  1. Department of Chemistry, Beijing Normal University, Beijing 100875
  • Received:2003-11-11 Revised:2004-01-06 Published:2004-08-15
  • Contact: Liu Ruo-Zhuang

Abstract: Eight possible unimolecular reaction pathways for ground-state pyruvic acid(PA) have been investigated in this work at the MP2/cc-pVDZ and B3LYP/cc-pVDZ levels of theory. The results indicate that hydrogen bond interaction and relative orientation of the two carbonyl groups play an important role in the stability of pyruvic acid rotamers. Moreover, the barriers for Tc isomerization to other isomers through internal rotation are high, suggesting that the isomerization reactions occur difficultly at room temperature. The barrier for transformation of Ct and Tt isomers through proton migration is higher than that through internal rotation, showing that the former cannot compete with the later. Under the investigation on decarboxylation and decarbonylation reactions, it can be concluded that the decarboxylation reaction takes place through stepwise mechanism involved in a five-center transition state and produces methyl hydroxycarbene firstly, and the concerted mechanism associated with a four-center transition state is disadvantageous.

Key words: Pyruvic acid, Isomerization, Decarboxylation, Decarbonylation, Reaction mechanism