Abstract
Various methylthio alcohols, methoxy(methylthio)alkanes and bis(methylthio)alkanes have been used as regioselectivity modifiers in the chlorination reactions of various phenols at room temperature. The process involves the use of a slight excess of sulfuryl chloride in the presence of aluminum or ferric chloride as an activator. Methylthio alcohols, methoxy(methylthio)alkanes and bis(methylthio)alkanes having 2 and 3 methylene groups as a spacer were found to be good for the para-selective chlorination of o-cresol and phenol. On the other hand, methylthio alcohols, methoxy(methylthio)alkanes and bis(methylthio)alkanes having 6 and 9 methylene groups were found to be good for the selective para-chlorination of m-xylenol and m-cresol. Calculations using density functional theory on bis(methylthio)alkanes have suggested two different types of stable chlorinated intermediates depending on the number of methylene units as a spacer.