Dual bifunctional catalysis and the α-effect in the reaction of hydroxylamine with phenylacetate

Journal of the Brazilian Chemical Society

Deise J. Mazera¹  Josefredo R. Pliego Jr.²  Gizelle I. Almerindo²  José C. Gesser² 

[1] ,Instituto Federal de Educação, Ciência e Tecnologia de Santa CatarinaSão José SC ,Brazil

关键词: acid-base catalysis;    organocatalysis;    alpha-effect;    zwitterionic intermediate;    solvent effect;   

DOI  :  10.1590/S0103-50532011001100020

来源: SciELO

【 摘 要 】

The reaction of hydroxylamine with phenyl acetate was theoretically investigated to shed light on the role of catalysis and the origin of the α-effect in this system. Calculations at the B3LYP/6-311+G(2df,2p)//HF/6-31G(d) level and the solvent effect included at the PCM/HF/6-31G(d) level predict that the direct attack of hydroxylamine to the carbonyl centre has a high ΔG‡ barrier, close to 50 kcal mol-1. A second hydroxylamine molecule can catalyse the process through bifunctional catalysis using both the NH2 and OH groups simultaneously. This dual bifunctional catalysis decreases the ΔG‡ to 19 kcal mol-1 and is able to explain the experimentally observed kinetics and product ratio.

【 授权许可】

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