Studies on the Conversions of Diols and Cyclic Ethers. Part 48. Dehydration of alcohols and diols on the action of dimethylsulfoxide

Abstract

SummaryThe transformations of 13 alcohols and 13 diols in the presence of a small amount dimethylsulfoxide (1/ 16 mol) were studied. Relationships were found between the type of the hydroxy compound and the selectivity of the transformation, and conclusions were drawn regarding the transformation mechanism. The ether formation observed with certain alcohols proceeds via a carbenium cation. The reaction conditions applied were found suitable for inducing water elimination from the ditertiary 1,2-and 1,3-diols (pinacol rearrangement, 1,2-elimination). From the 1,4-and 1,5-diols the corresponding oxacycloalkanes can be obtained in good yield. Cyclodehydration occurs by intramolecular nucleophilic substitution, via a concerted mechanism. The effect of DMSO is exerted directly, and protoncatalysis occurs simultaneously. It has recently been demonstrated in the transformations of various benzyl alcohols [ l l ] that at very high alcohol: DMSO ratios (16:l) the olefin formation and certain oxidation reactions to be observed when the reagent is in high excess over the alcohol can be totally suppressed, and ethers can be obtained in excellent yields.

Kinetics and Mechanism of Tetrahydrofuran Synthesis via 1,4-Butanediol Dehydration in High-Temperature Water

“…In the Reppe and propylene oxide processes, BD dehydration is achieved in the presence of an acid catalyst at temperatures above 100 °C and near atmospheric pressure . Effective catalytic agents include strong mineral acids, heteropolyacids, , zeolites, sulfonic acids, , and dimethyl sulfoxide (DMSO) . Strong mineral acids, aluminum silicates, and ion-exchange resins are the preferred commercial catalysts, ,, and THF is typically produced at 95% yield…”

Synthesis and Polymerization of Renewable 1,3‐Cyclohexadiene Using Metathesis, Isomerization, and Cascade Reactions with Late‐metal Catalysts

“…In comparison, reduction reactions of benzene usually produce 1,4‐cyclohexadiene (1,4‐CHD) 9, 10. Examples of starting materials for the synthesis of 1,3‐CHD include 1,2‐dibromocyclohexane,2 bromocyclohexene,11 chlorocyclohexene,12 cyclohexenol,13 allylic phosphites,14 allyl ethers,15 1,2‐cyclohexane diol,16 cyclohexane,17 and cyclohexene 17, 18. From a green chemistry standpoint, producing 1,3‐CHD with elimination reactions generates larger quantities of waste and utilizes stoichiometric reagents compared to catalytic reactions.…”