Reactions of formaldehyde with aromatic amines

As a result of the re‐examination of earlier work on these reactions, the following findings are recorded: Reaction of certain primary arylamines with formaldehyde in neutral solution has given substances of two new types, viz. 3,5,1‐dioxazines and 1,5‐dioxa‐3,7‐diazacyclo‐octanes. A study of the complex reactions which occur between formaldehyde and para‐substituted primary arylamines in acid solution has led to the revision of some structures in the literature, and the preparation of novel compounds. Reaction of formaldehyde with o‐tolidine and with o‐dianisidine in concentrated sulphuric acid has given derivatives of dibenz(c,e)oxepin. Formaldehyde reacts with arylamines having a free para‐position, in the presence of acidified thiosulphate, to give derivatives of dibenzyl sulphide and dibenzyl polysulphides.