SN1 reactions in supercritical carbon dioxide in the presence of alcohols: the role of preferential solvation.
Ethanol () inhibits SN1 reactions of alkyl halides in supercritical carbon dioxide (scCO2) and gives no ethers as products. The unexpected behaviour of alcohols in the reaction of alkyl halides with 1,3-dimethoxybenzene () in scCO2 under different conditions is rationalised in terms of Brønsted and Lewis acid-base equilibria of reagents, intermediates, additives and products in a singular solvent characterised by: (i) the strong quadrupole and Lewis acid character of carbon dioxide, which hinders SN2 paths by strongly solvating basic solutes; (ii) the weak Lewis base character of carbon dioxide, which prevents it from behaving as a proton sink; (iii) the compressible nature of scCO2, which enhances the impact of preferential solvation on carbon dioxide availability for the solvent-demanding rate determining step.
Departamento de Química Orgánica, Facultad de Farmacia, Universidad de Valencia, Avda. Vicente Andrés Estellés s.n. 46100-Burjassot, Valencia, Spain. elena.gonzalez@uv.es.
Thais
T
Delgado-Abad
Departamento de Química Orgánica, Facultad de Farmacia, Universidad de Valencia, Avda. Vicente Andrés Estellés s.n. 46100-Burjassot, Valencia, Spain. elena.gonzalez@uv.es.
Jaime
J
Martínez-Ferrer
Departamento de Química Orgánica, Facultad de Farmacia, Universidad de Valencia, Avda. Vicente Andrés Estellés s.n. 46100-Burjassot, Valencia, Spain. elena.gonzalez@uv.es.
Rafael
R
Acerete
Departamento de Química Orgánica, Facultad de Farmacia, Universidad de Valencia, Avda. Vicente Andrés Estellés s.n. 46100-Burjassot, Valencia, Spain. elena.gonzalez@uv.es.
Gregorio
G
Asensio
Departamento de Química Orgánica, Facultad de Farmacia, Universidad de Valencia, Avda. Vicente Andrés Estellés s.n. 46100-Burjassot, Valencia, Spain. elena.gonzalez@uv.es.
Rossella
R
Mello
Departamento de Química Orgánica, Facultad de Farmacia, Universidad de Valencia, Avda. Vicente Andrés Estellés s.n. 46100-Burjassot, Valencia, Spain. elena.gonzalez@uv.es.
María Elena
ME
González-Núñez