382 REPOET — 1893. 



lene, and to the numerous apparent departures from this law observed in 

 the formation of sulphonic acids. Most interesting examples of the for- 

 mation of <■< -derivatives are afforded by Cleve's recent invaluable obser- 

 vations on the behaviour of the chlorides of ten of the chloronaphtha- 

 lenesulphonic acids on nitration (' Ofversigt af Kongl. Vetenakaps- 

 Akademiens Forhandlingar,' 1892, No. 9 : presented November 9 ; 1893, 

 Nos. 2, 3, and 5 : presented February 8, March 14, May 9). His results 

 are displayed in a subsequent diagram, in which also the properties of 

 the various derivatives are indicated, as the Swedish publication in 

 which they are described is not generally available. The formula of 

 the chlorosulphochloride is given in the first column of symbols ; that 

 of the resulting nitro-derivative or derivatives in the second ; and that 

 of the corresponding trichloronaphthalene obtained by the action of 

 phosphorus pentachloride in the third. In the table of /3-derivatives 

 the results obtained by Dr. Wynne and the writer on sulphonating 

 the /3-chlorosulphonic acids ' are included for comparison with those 

 obtained on nitra.ting their chlorides. It will be seen that in the case 

 of the a-chloro acids the nitro-group in every instance takes up the 

 ' opposite ' ci-position ; only in two cases are /3-compouuds obtained. In 

 the case of the /s-chloro acids the nitro-group assumes the a-position con- 

 tiguous to the /3-chlorine atom — a most interesting and significant result. 

 The results obtained on nitration are strikingly different from those 

 attending sulphonation ; it can scarcely be doubted, however, that in the 

 case of sulphonic acids the formation of /3-acids is due to secondary 

 changes, but opinions differ as to the nature of these. It appears to be 

 commonly supposed that when sulphonation takes place at high tem- 

 peratures, and in presence of excess of acid, a-sulphonic groups become 

 split off, and that sulphonation then occurs in /3-positions ; Dr. Wynne 

 and the writer have been unable to discover any proof of direct sulpho- 

 nation of the /> position, and incline to the belief that the formation of 

 /3-su1phonic derivatives is either the outcome of isomeric change or — 

 and probably most frequently — of polysulphonation followed bv hydro- 

 lysis. Thus, naphthalene-/3-sulphonic acid is not improbably the final 

 product of the following series of changes : 



/^/\, /\/\ /\y\ s ^/\ s /\/\. 



— > 



s 



\/\y \y\/ \/\/ \/\/ x/x/ 



b 



' The results of our examination of the sulphonation products of all the obtain- 

 able chloronaphthaienesulphonic acids are yet to be published. It may not be out 

 of place to state that the work which was expressly reserved in 1890 — the examina- 

 tion of the sulphonation products of the chloronaphthalenemonosulphonic acids 

 (first notice, Proc. Chem. Soc, 1890, p. 131), and of the correspondiug naphthyl- 

 aminemonosulphonic acids (first notice, Proc. Chem. Soc, 1890, p. 128)— is nearly com- 

 pleted. As the object of the work is the determination of the positions assumed by 

 the entering sulphonic radicle in the two classes of derivatives, there is little to be 

 gained in publishing the results until the constitution of each disulphonic acid has 

 been ascertained beyond question. This has involved characterising the trichloro- 

 naphthalenes more definitely than V>y melting-point determinations, and, as in the 

 case of the dichloronaphthalenes (Proc. Chem. Soc, 1890, p. 77 ; Brit. Assoc Rep., 

 1891), this is being carried out mainly by examining the acids obtained by sul- 

 phonating each of the fourteen isomeric trichloronaphthalenes (first notice, Proc. 

 Chem. Soc, 1890, p. 76). 



