202 REPORT— 1902. 



that of piperidine. The affinity constants of methoxybenzenediazonium 

 hydroxide and \//-cumidinediazonium hydroxide are even greater, and 

 approximate closely to those of the alkali hydroxides. The effect of intro- 

 ducing halogen radicles into the aromatic nucleus is indicated in a striking 

 manner in the following table : — 



A comparison of the electrical conductivity experiments with the 

 results obtained in the hydrolysis of ethyl acetate by benzenediazonium 

 hydroxide shows that, in 1/128 N solutions at 0°, approximately 33 per 

 cent, of the base exists in the ionised condition. 



The ionisation detected in the hydrolysis experiment is greater than 

 that indicated by the conductivity determinations, and this shows that 

 the electrolytic dissociation is exclusively due to the reaction 



C6H5N2OH Z CeHsN + HO, 



N 

 and not to the electrolysis of a diazonium s^/n-diazo-oxide, 



CcH,N-O.No.CcH5. 

 N 



Condition of the Non-ionised Diazonium Hydroxide. — The solution 

 of benzenediazonium hydroxide differs essentially from one containing 

 piperidine in its behaviour towards alkali hydroxides, generating with 

 these reagents an appreciable amount of heat exactly like a weak acid. 

 This reaction is also indicated by determinations of the electrical con- 

 ductivities of solutions of the diazonium hydroxide when treated with one, 

 two, or more molecular proportions of sodium hydroxide. 



The simplest explanation of this phenomenon is based on the assump- 

 tion that the non-ionised portion of the diazonium hydroxide exists in 

 solution in a hydrated form which, on the addition of alkali hydroxide, 

 yields the alkali salt, the acidic .si/^i-diazo-hydroxide behaving in this 

 respect precisely like the similarly constituted oximes. 



Before the addition of alkali the equilibrium may be thus repre- 

 sented : — 



CfiH.H.N CeHgN.OH 



H^o-t- -i-oh;^ I 



N HO.N.H 



The addition of the alkali hydroxide causes the hydrate to lose water 

 forming the s2/n-diazo-hydroxide, which then gives rise to a certain amount 

 pf sodiupi derivative, 



M ; <- II ;^ I! 



HO.NiH ; HO.N NaO.N. 1 



> Hantzsch and Davidson, Ber., 1898, 31, 1612. 



