98 



EEroET — 1888. 



would follow that a-dicUoronaplithalene is the third ;8-/S-, i.e., ft^- jS'-dichlo- 

 ronaphthalene. 



K and t-dichloronaplithalenes have thus far been omitted from con- 

 sideration ; the former is probably non-existent, the method by which it 

 is said to have been prepared being one which is very unlikely to afford 

 a dichloronaphthalene. It is not improbable that the i-compound will 

 also be found non-existent : if on treating naphthalene with chlorine a 

 small quantity of an isomeric heteronucleal tetrachloride be formed, and 

 this lose its a-chlorine atoms, e- dichloronaphthalene would result, and it 

 is possible that this substance in an impure state may have been reo'arded 

 by mistake as a distinct substance. 



ECl 



HCl 



HCl 



HCl 



HCl 



Naphthalene homo- 

 tetrachloride. 



HCl 



HCl 



HCl 



Naphthalene hetero- 

 tetrachloride. 



6-dichloro- 

 naphthalene. 



Isomeric clichloroyiapJitJtalenesulpJionic acids. — With the object of further 

 characterising and determining the individuality of the dichloronaphtha- 

 lenes, the study of their sulphonic acids, to which reference was made in 

 the last report, has now been extended to all. The chief result of interest 

 is the fact that the dichloronaphthalene melting at 34^° yields certainly 

 two, perhaps three, isomeric sulphonic acids ; the sulphochloride of the 

 one acid crystalhses in minute prisms melting at 168°, that of the other 

 in massive prisms melting at 105°. 



The dichloro-acids prepared by Widman by chlorinating naphthalene- 

 a- and /3-sulphochlorides have also been examined. That from the /3-sul- 

 pho-chloride yields when hydrolysedyS-, that from the alpha-sulphochloride 

 what appears to be ^-dichloronaphthalene, m.p. Gl°'5. 



Addendum. — Since the meeting of the Association, Brdmann and Kirch- 

 hoff (' Annalen,' 247, 366) have described the results of experiments on the 

 synthetic production of chloronaphthalene derivatives which they contend 

 afford proof of the constitution of the y, rj and varieties of dichloro- 

 naphthalene. Their method consists in preparing chlorophenylparaconic 

 acids by interaction of succinic acid and chlorobenzaldehydes ; by distilling 

 the acids, chloronaphthols are obtained from which corresponding dichloro- 

 naphthalenes are prepared by distillation with phosphorus pentachloride. 

 The conversion of phenylparaconic acid itself into alphanaphthol is 

 supposed by Fittig and Erdmann to take place in the manner indicated 

 by the following symbols : 



CO 



O ^CH^ 

 I CH-COOH = 



\CH 



C(OH) 



CH 



Phenylparaconic acid. 



+ CO2 + H2O. 



