Dimethylaniline: Autoclave Methylation of Aniline (Cain, 1919)

The German works method for dimethylaniline: aniline and methyl alcohol with a little sulphuric acid are heated to 230-235 °C in an acid-lined autoclave at 28-32 atmospheres, then neutralised with caustic soda and steam-distilled; the oil separates from the water and is drummed. One 280-litre autoclave charge of 80 kg aniline gives about 98 kg of dimethylaniline, 94 per cent of theory. Source: J. C. Cain, The Manufacture of Intermediate Products for Dyes (1919), pp. 62-65, after Walter (1910). Picture: the book's Fig. 17.