Regiochemical Effects on Molecular Stability: A Mechanochemical Evaluation of 1,4-and 1,5-Disubstituted Triazoles

作者：Brantley Johnathan N; Konda Sai Sriharsha M; Makarov Dmitrii E; Bielawski Christopher W^*

来源：Journal of the American Chemical Society, 2012, 134(24): 9882-9885.

DOI：10.1021/ja303147a

Poly(methyl acrylate) chains of varying molecular weight were grown from 1,4- as well as 1,5-disubstituted 1,2,3-triazoles. Irradiating acetonitrile solutions of these polymers with ultrasound resulted in the formal cycloreversion of the triazole units, as determined by a variety of spectroscopic and chemical labeling techniques. The aforementioned reactions were monitored over time, and the rate constant for the cycloreversion of the 1,5-disubstituted triazole was measured to be 1.2 times larger than that of the 1,4-disubstituted congener. The difference was attributed to the increased mechanical deformability of the 1,5-regioisomer as compared to the 1,4-isomer. This interpretation was further supported by computational studies, which employed extended Bell theory to predict the force dependence of the activation barriers for the cycloreversions of both isomers.

• 出版日期2012-6-20