268 



KEPOET — 1891. 



It will be noticed that three modifications melt at about 80°, and four 

 near to 90° ; hence it is important to ascertain the distinctive properties 

 of the several modifications, so that their identification may be rendered 

 easy and certain. This difficult and wearisome task will, it is hoped, be 

 completed during the coming year. 



Naplithalenedisulphonic acids.- — By eliminating the NH2 group from 

 beta-naphthylaminedisulphonic acid G, Mr. Wynne and the writer, since 

 the publication of the last report, have succeeded in preparing naph- 

 thalene 1 : 3 or jjie^a-disulphonic acid ; the same acid has been inde- 

 pendently prepared in this manner in the laboratory of the Badische Anilin 

 und Soda Fabrik. It is noteworthy that although in a measure the 

 analogue of benzenemetadisulphonic acid, which readily yields resorcinol 

 on fusion with alkali, naphthalene I : o disulphonic acid is converted by 

 fusion with alkali with remarkable facility into a trihydroxynaphthalene. 

 Five of the ten possible disulphonic acids are therefore now known. 

 Their properties are summarised in a table in the ' Chemical Society's 

 Proceedings,' 1890, p. 14. 



Naphthylamine-, iiapldhol- and chloronaj^htlialene-dis^dplionic acids. — A 

 large number of disulphonic acids of the uaphthylamines and naphthols 

 are now in technical use,' and both on this account and in order to obtain 

 the material for a discussion of the comparative influence of NHg and 

 OH, the constitution of these acids has been determined by Mr. Wynne 

 and the writer, and they have also prepared disulphonic acids by sulpho- 

 nating the chloronaplithalenesiilphonic acids in oi'der to compare the 

 influence of what may be regarded as a neutral radicle with that of the 

 alkylic NH2 and acidic OH; the results have been recorded during the 

 past two years in nine communications to the Chemical Society, and 

 appear in the 'Proceedings.' One interesting result of the examination 

 of the disulphonic acids, to which attention may be called, is that ap- 

 parently there is an ' invincible objection ' on the part of two SO3H 

 groups to remain in either contiguous or para- or peri-positions. The 

 expression ' remain in ' is used advisedly, as it appears probable that 

 initially such positions are not infrequently taken up by sulphonic groups. 

 The formation of heta-derivatives. — In previous reports emphasis has 

 over and over again been laid on the fact that in the majority of cases 

 naphthalene gives rise to aZjs/ia-derivatives, ieia-derivatives being formed 

 only when a group is present which determines the entry of the new 

 group into the contiguous beta-position or owing to the occurrence of 

 secondary change. Attention must now be called to certain important 

 exceptions to this rule. 



' A very complete description of the various naphthalene derivatives which are 

 used technically will be found in the art. Naphthalene by Mr. Wynne in the recently- 

 published vol. ii. of Thorpe's ZUctMiiari/ uf Ajiplicd Chcmistri/ (Longmans). 



