Theoretical Study of the Ring-Opening of Epoxides Catalyzed by Boronic Acids and Pyridinic Bases

• Type: Article in International Scientific Journal
• Date: 2017

Authors

da Silva, LP (Author) FCUP

Journal

Title: Journal of Physical Chemistry C

Vol. 121

ISSN: 1932-7447

Publisher: American Chemical Society

Indexing

ISI Web of Knowledge - 15 Citations

Scopus - 16 Citations

Other information

Authenticus ID: P-00M-XDF

DOI: 10.1021/acs.jpcc.7b04157

Abstract (EN): The ring-opening reaction of epoxides is a key step in the conversion of carbon dioxide (CO2), a greenhouse waste product of fossil fuel combustion, into value-added heterocyclic carbonates. Being an essential step in CO2 conversion, controlling its activation energy is essential in the development of methods in which heterocyclic carbonates can be obtained under mild conditions. We have employed a theoretical approach to obtain mechanistic insight into the ring-opening of a model epoxide, when catalyzed by both 2,6-phenylboronic acids and pyridinic bases. The presence of both catalysts decreases the activation energy of this process from similar to 60 to similar to 20 kcal mol(-1). The electronic character of the substituent at the C-2,C-6-position of phenylboronic acid has little effect on the activation energy. Nevertheless, electron-withdrawing substituents decrease the activation energy by increasing the acidity of the boronic acid group. It was also found that nonhalogenated pyridinic bases present similar results to those provided by halide nucleophiles. Thus, two-component systems composed by phenylboronic acids and pyridinic bases appear to be a good choice for catalyzing the ring opening reaction of epoxides under mild, metal-free, and nonhalogenated conditions.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 8