Improvements in or relating to the production of amino-phenols or aromatic amino-acids

摘要

Aminophenols and aromatic amino acids are obtained by reduction of corresponding nitro- or azo-compounds by sulphuretted hydrogen in the presence of an alkaline carbonate; the sulphuretted hydrogen may be employed in the form of waste gases, such as those coming from ammonia scrubbers in the manufacture of ammonium p compounds. According to examples the following bodies are obtained by reduction in hot sodium carbonate solution with a gas containing about 15 per cent of sulphuretted hydrogen:-aminosalicylic acid and aniline from benzene-azosalicylic acid (the solution obtained by coupling diazobenzene solution with salicylic acid may be directly reduced); aminosalicylic acid and p-chloraniline from p-chlorobenzeneazosalicylic acid; 5-aminosalicylic acid from 5-nitrosalicylic acid; p-aminophenol and aniline from benzene-azophenol; aminosalicylic acid and p-phenylene diamine from Alizarin yellow R (p-nitrobenzene-azosalicylic acid). The reduction of phenol-azophenetole, Brilliant orange R, Orange II., and Chrysamine G is also mentioned. Specification 5697/97 is referred to.