An improved process for the preparation of 4,4,'-dimethexytrityl chloride (DMTR CL)

摘要

An improved process for the preparation of 4,4'-dimethoxytrityl chloride which comprises : (i) Mixing benzotrihalide with lewis acid catalyst at room temperature, (ii) cooling the resultant reaction mixture to a temperature in the range of 0 to 30 C, (iii) adding anisole dropwise over a period in the range of 1 to 2 hours while stirring the reaction mixture at room temperature for a period in the range of 30 to 60 min, (iv) refluxing the resulting mixture for a period in the range of 2 to 3 hours, (v) cooling of the resulting mixture, (vi) hydrolyzing the Lewis acid complex formed by known methods, (vii) extracting the 4,4'-dimethoxytritanol with a hydrocarbon solvent followed by washing of hydrocarbon phase with an alkaline solution and water, respectively. (viii) separating the organic phase, drying over anhydrous sodium sulphate followed by concentrating the organic phase on a rotary evaporator under reduced pressure to yield the 4,4'-dimethoxytritanol, (ix) converting the 4,4'-dimethoxytritanol so obtained to 4,4'-dimethoxytrityl chloride by addition of an organic acid chloride in the presence of a hydrocarbon solvent followed bv cooling to a temperature in the range of 4 to 6 C, (x) recovering the 4,4'-dimethoxytrityl chloride by washing with an organic solvent under nitrogen atmosphere and drying under vacuum.