200 REPORT— 1902. 



•iso-diazo-hydroxides results, whilst the latter experiment gives rise to 

 the alkali isodiazo-oxide. 



Migration of the Diazo -radicle. — Griess noticed that a solution of 

 diazobeozenesulphonic acid and ^5-toluidino hydrochloride gave the 

 reactions of a mixture containing ;;-toluenediazonium chloride and sul- 

 phanilic acid,^ and more recently Schraube and Fritsch ^ showed that a 

 similar rearrangement occurs in the case of a dilute solution of p-nitro- 

 benzenediazonium chloride and ^j-toluidine. These investigators state 

 that the direction of the change is constant either in acid or neutral 

 solution ; the velocity of migration, however, diminishes rapidly as the 

 amount of acid is increased, and a large excess of this reagent altogether 

 prevents the transformation. These results appear to show that the 

 diazo-radicle passes from the less to the more positive radicle, but 

 Hantzsch and F. M. Perkin found that a migration in the opposite 

 sense occurs with benzenediazonium chloride and />-bromaniline.^ It 

 may therefore be supposed that generally, when neutral or slightly acid 

 solutions of a diazonium salt and a primary aromatic amine are mixed, 

 there will be a certain amount of rearrangement due to the migration of 

 the diazo-group. 



This migration of the diazo-radicle is probably associated with the 

 changes which occur when this group passes from the diazonium to the 

 diazo configuration. Bamberger ^ found that, in the inverse change, a 

 transitory elimination of nitrous acid occurred, 



RN:NOH + H,0 = R.NH2 + ONOH 

 R.NH2 + 0N0H + HC1 = 2H2O + R.N.CI 



N 



this reaction being effected by dissolving an alkali iso-diazo-oxide in cold 

 mineral acid. If the transitory elimination of nitrous acid is assumed to 

 occur in the change from the diazonium to the diazo condition, then an 

 explanation of the migration of the diazo-radicle is obtained, which also 

 accounts for the fact that the same mixed diazoamine is produced from 

 the couple XN.Cl and YNH. as from the combination of YNjCl and 

 XNHo. In the former case the diazonium hydroxide, liberated from itg 

 salt by the addition of sodium acetate, would undergo hydrolysis, 



X.KOH + HoO = XNH., + ONOH, 



N 



and the nascent nitrous acid would at once isodiazotise a portion of each 

 of the primary amines XNHg and YNH.,, giving rise to the diazo- 

 hydroxides X.N : NOH and YN : NOH. The latter substances and the 

 unaltered primary bases would then condense, and a mixed diazoamine 

 would be produced, this substance consisting of a solid solution of 

 XNo.NHY in YN2.NHX, the proportion of the two constituents de- 

 pending on the nature of the two aromatic radicles X and Y. In certain 

 cases the product may consist largely of the symmetrical diazoamines 

 XNo.NHX and YN^.NHY, but the formation of these compounds is 

 equally well explained by the hypothesis based on the transitory elimina- 

 tion of nitrous acid. The formatioQ of the mixed diazoamine occurs even 



' Ber., 1882, 15, 2190. ? Ber., 1896, 29, 287. 



» Ber., 1897, 30, 1412, f Ber., 1S95, 29, 826. 



