66 PROCEEDINGS OF THE AMERICAN ACADEMY 



chinone from the by-products of the distillation of calcic benzoate. 

 Their results were confirmed by Behr* and Staedel.f 



4. Related to this method is that of Barth and Scnfhofer,^ pub- 

 lished in 1873, whicli consists in heating oxybenzoic acid alone, or 

 with sulphuric acid. 



5. In 1873, also, anthracene was first obtained by Zincke's reaction ; 

 for, although Zincke § had not succeeded in finding it, Radziszewski 

 and Zaleski || got it from zinc-dust benzylchloride and benzol, and 

 Paterno and Filetti 1[ by the action of zinc-dust on a mixture of 

 benzylchloride and j^henol ; the latter, however, think that it is not 

 formed directly, but by a secondary reaction from the benzylphenol, 

 and this view is supported by a paper published in the following year 

 by Zincke and Weber,** who obtained it from a mixture of zinc- 

 dust benzylchloride and toluol, but suppose that all the anthracene is 

 formed by the breaking up of complex hydrocarbons during the sub- 

 sequent distillation, in the same way that it is formed from the product 

 of the action of water on benzylchloride. More interesting, there- 

 fore, is the synthesis of Piccard.ft who obtained anthrachinone by the 

 action of zinc dust on the chloride of phtalic acid and benzol at 220°. 



Under this head should come also the recent experiments of Friedel 

 and Crafts, tt who, among their beautiful syntheses with aluminic 

 chloride, made anthrachinone from the same mixture, and finally of 

 Ador and Killiet,§§ who, in 1879, obtained it from the chloride of 

 orthotoluylic acid benzol and aluminic chloride. 



6. Paterno and Filetti, |||( in a paper published somewhat later, 

 in 1873, describe the synthesis of anthracene by the distillation of 

 benzylphenol with phosphoric pentoxide. 



7. In the same year appeared a paper by Grimm,^1[ from Baeyer's 

 laboratory, describing the synthesis of chinizarine from phtalic anhy- 

 dride hydrocliinone and sulphuric acid; while in 1874, Baeyer and 

 Caro,*** found that phtalic anhydride yielded, with phenol, benzol- 

 sulphoacid, anisol, anisic acid, or salicylic acid, either oxyanthra- 

 chinone or erythroxyanthrachinone, both of v»'hich give alizarine by 

 fusion with potassic hydrate ; with pyocatechin, guaiacol, or protoca- 



« Ber. d. ch. G., '72, p. 971. tt Bcr. d. ch. G., '74, p. 1785. 



t Ibid , '73, p. 178. tt Comptcs Ik-ndiis, Ixxxiv. 1450- 



t Ann. Chcm. riiarm., clxx. 100. §§ Ber. d. ch. G., '79, p. 2:!'.)8. 



§ Bcr d. ch. G , '73, p. 137. |||| Giizz. Cliim., '73, p. 2ol. 



II Ibid , '73, p. 810. Ill Bcr. d. ch. G., '73, p. 606. 



ir G;izz. Cliim.. '73, p. 121. **» Ibid., '74, p. 908. 

 •* Ber. d. ch. G., '74, p. 1163. 



