Cyanide antidote (4)-dimethylamino-phenol prodn. - by reacting (4)-amino-anisole with dimethyl sulphate, heating with sodium hydroxide and (O)-dimethylating

摘要

In the production of pure-4-dimethylamino-phenol (I), 4-amino-anisole (II) is treated in weakly alkaline aqueous solution with dimethyl sulphate to give N-(4-methoxyphenyl)-N,N,N-trimethylammonium methylsulphate (III) in quantitative yield; (III) is isolated by crystallization from aqueous solution and subsequently converted into 4-di-methlamino-anisole (IV) in practically quantitative yield by heating with concentrated alkali hydroxide at normal pressure. The (IV) pptd. in solid form is converted into (I) hydrohalide by boiling in aq. hydrobromic acid or by heating in highly concentrated hydrochloric acid under pressure. (I) is useful as an antidote for hydrogen cyanide poisoning. It is simple process giving pure (I) in very high yield (overally yield ca. 80%) from inexpensive raw materials and reagents. In an example, (II) is reacted with dimethyl sulphate in aq. NaHCO3 to give (III) in 97-100% yield, and this is boiled 2-2.5 hrs. with aq. NaOH to give (IV), which is subsequently refluxed 8-9 hrs. with aq. 62% HBr to give (I). Overall yield for the first two steps of the process is 88-91%, while yield for the final step is 92.8-93.5%.