ON OUR PRESENT KNOWLEDGE OF AROMATIC DIAZO-COMPOUNDS. 201 



when X and Y are radicles derived from diflFerent hydrocarbons, and sub- 

 stances of this type containing naphthalene and tetrahydronaphthalene 

 nuclei have been isolated.' 



The migration of the diazo-group is prevented by the alkylation of the 

 primary aromatic amine, and the couples XN^Cl, YNHR and YN.^Cl, 

 XNHR give rise to two isomeric mixed alkyl diazo-amines, XNgNRY 

 andYN.NRX. 2 



The comparative stability of the diazoamines and their production 

 from ■isodiazo-oxides point to their having the an^i-diazo contiguration ; 

 the syn-isomerides have not been produced, although Hantzsch and 

 P. M. Perkin {loc. cit.) obtained abnormal diazoamines which form an 

 exception to the rule governing the formation of mixed diazoamines. The 

 compound ClCcH^ISrsHCfiHs, for example, exists in two modifications, 

 which give rise to the same products on fission with hydrochloric acid or 

 phenylcarbimide. The suggestion that these two isomerides should be repre- 

 sented by the formulae C«H5N:N.NH.C6H4C1 and CcHs-NH.N: NCfiHiCl, 

 is not justified by the result of their fission. 



D. The Diazonium Eadicle compared with Quaternary Ammonium Ions. 



The change of opinion in favour of the Strecker-Blomstrand formula 

 for the diazonium salts was in the first place based on certain general 

 analogies existing between the salts of nitrogenous bases. 



The older view of the constitution of diazonium salts indicates that 

 these substances form an exception to the rule that basic nitrogen is 

 pentavalent in its salts, and yet the compounds in question behave as the 

 salts of bases more powerful than the aromatic amines from which they 

 are derived. The diazonium bases are capable of combining with the 

 weaker acids, and yield soluble alkaline carbonates, e.g. (C6H5N2)2C03, and 

 unstable nitrites and acetates. Moreover, this view involves the assump- 

 tion that the compound C6H.5N:NOH can react as a strong ammonium 

 base towards acids and as a distinctly acidic substance towards the alkali 

 hydroxides. Hantzsch showed that the diazonium salts of the mineral 

 acids are strongly ionised in dilute solution, but do not exhibit any trace 

 of hydrolytic dissociation j the ionisation is, however, considerably dimi- 

 nished by the introduction of negative radicles into the aromatic nucleus 

 of the diazonium compound.^ 



Determinations of the electrical conductivity of solutions of benzene- 

 diazonium chloride and nitrate showed that the benzenediazonium radicle 

 is strictly comparable with other quaternary ammonium ions. The rate 

 of migration of the benzenediazonium ion at 25° is 45-7, the correspond- 

 ing constants for the methylpyridinium, Cr,H5NCH3, and tetramethyl- 

 ammonium ions, N(CH3)^, being 44-3 and 43-6 respectively. 



The molecular conductivity of the solutions of diazonium salts increases 

 with the dilution, just as in the case of the corresponding potassium and 

 ammonium compounds. 



A physico-chemical study of the solutions of benzenediazonium 

 hydroxide showed that the affinity constant of this base at 0° is seventy 

 times greater than that of ammonium hydroxide, and somewhat exceeds 



' Morgan, Trans., 1902, 81, 91 ; and C. Smith, ibid. 901. 



- Meklola and Streatfeild, Tram., 1887, 51, 818; 1889, 65, 610, 1105; 1890, 67, 

 785. ' Ber., 1895, 28, 1734. 



