154 



Dr. K. J. P. Orton. 



[Dec. 1, 



changed into isomeric substances in which the substituent is contained 

 in the Irydrocarbon nucleus. 



The transformation of the aniline derivative appears to take place 

 only in the presence of some other substance : in the case of the 

 phenylacylchloramines, such as CoHs.NCl.COCHo, for example, appa- 

 rently the change into the isomeric chloroacetanilides takes place only 

 under the specific influence of hydrogen chloride.* The investigation 

 of such cases of isomeric change is, in fact, of special interest as the}^ 

 are, so to speak, " fermentative " in character, often taking place with 

 remarkable facility, and under the influence of minute amounts of 

 the substance, which apparently provokes the change — the catalyst. 

 Measurements of the velocity at which changes of this type occur, for 

 example, of diazoaminobenzene into aminoazobenzene,f show that a 

 velocity-coefficient of constant value is given by the equation, 



k = r 1 loga/(a-x). 



The isomeric change is, therefore, apparently a so-called mono- 

 molecular change ; but, as in other cases, the slowest of the series of 

 simple changes which make up the complete transformation is alone 

 measured ; moreover, the substance which conditions the change is not 

 taken into account. 



This paper deals with a new case of intramolecular change of a 

 particularly interesting character : that of s-trichloro- and s-tribromo- 

 benzenediazonium hydroxide, C c ,H2X 3 .N(OH):N, into hydroxybenzene 

 derivatives, by the interchange of the hydroxyl for one of the ortho- 

 halogen atoms. The change takes place under all conditions under 

 which it is possible for the diazonium hydroxide to be present. Thus 

 in dilute aqueous solutions of the neutral diazonium nitrate, or even 

 of the hydrogen sulphate, chloride is just recognisable by means 

 of silver nitrate after 21 hours ; at the same time the solution 

 becomes yellow, owing to the formation of the diazophenol. But as 

 the extent to which the nitrate, and more especially the sulphate, 

 undergoes hydrolytic dissociation is extremely small, the isomeric 

 change takes place very slowly; and in the presence of a considerable 

 excess of acid nO appreciable change occurs during 5 days. On the 

 other hand, using diazonium acetate, 50 per cent, of the material 

 changes within 30 — 10 hours; and in the case of diazonium bicar- 

 bonate the change is nearly instantaneous. That the change is a 

 transformation of the diazonium hydroxide is further emphasised by 

 the fact that the addition of a solution of the diazonium salt to a 

 considerable excess of an aqueous solution of an alkali carbonate, is 

 not followed by elimination of halogen ; the solution remains colour 



* Compare Armstrong, 'British Association Report,' 1899, p. 683; 'Trans. 

 Ghem. Soc,,' 1900, vol. 77, p. 1053. 



f Goldschmidt and Reinders, ' Berichle,' .1896, vol. 29, p. 1369. 



