Diphenylamine reaction and, III

Traditional routes to phenoxazines (e.g., 72) include the thermolysis of 2-aminophenol 70 and catechol 71 (Scheme 40) or catechol and ammonia. Phenothiazines are prepared by heating diphenylamines with sulfur as exemplified in Scheme 41 < 1985AXC1062, CHEC-III(8.09.9.2)655>. 2-Hydroxy- (or mercapto-) 2,4-dinitrodiphenylamines 73 cyclize to phenoxazines (or phenothiazines) in the presence of base by elimination of nitrous acid. These reactions are complicated by Smiles-type rearrangements of the amines 73 so that mixtures of isomeric products 74 and 75 are obtained (Scheme 42). 

Acardite III or Ethylacardite (N -Ethyl-N,N-diphenylurea)(Akardit III, in GerX C, H, NH.CO.N(C H,, row 240.29, N 11.66%, OB to CO, -246.4%, OB to CO -146.5%. White cry St, rop 72.3° for a tech sample and 73.1° for samples recrytd from ethanol or chlf(Ref 4). It was prepd in Germany by treating with p>hosgene a soln in carbon tetrachloride of equimolar quantities of ethyl-amine and diphenylamine in the presence of limestone. This was followed by fractional distillation. The following reaction took place ... 

---