Reaction CXLII.—Action of Primary Aromatic Amines on Alcohols

Reaction CXLII. Action of Primary Aromatic Amines on Alcohols.— 

The reaction is generally carried out by heating under pressure, and in presence of a mineral acid. Secondary and tertiary amines are formed. 

93 gms. pure aniline, 105 gms. pure methyl alcohol and 9-4 gms. cone, sulphuric acid are heated in an enamelled autoclave to 200°. The pressure rises to about 30 atms., and the contents are left for 6 hours at 215°. They are allowed to cool, and then 25 gms. 30% caustic soda solution added. The product is now heated to 170° in the autoclave for a further 5 hours. This second heating is necessary to decompose the sulpho-ammonium bases formed, and which are decomposed into sulphuric acid, alcohol, and tertiary amine. The contents of the autoclave, after cooling, are distilled in steam. The dimethylaniline is salted out of the distillate with common salt. It is then separated and distilled. 

—95% theoretical (117 gms.). Colourless liquid when pure turns brown on standing B.P. 192° D. 0-96 important intermediate for dyestuffs. 

Purity Test (anhydride test).—Some monomethylaniline is always present, and if 4 c.cs. of the dimethylaniline are shaken up with 2 c.cs. acetic anhydride, this should not give an increase in the temperature of more than 1° (C. Z., 34, 641). 

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