OF ARTS AND SCIENCES. 65 



Van Dorp,* in 1872, obtained the same result, and proved that 

 the oil Cj^llj^, which Limpricht had thought was dibcnzjl, is benzyl- 

 toluol. Finally Zincke,t in 1874, showed that this reaction resem- 

 bled that of zinc-dust on a mixture of benzylchloride and benzol, and 

 succeeded in isolating a chloride CgIIjCIl2CgII^CII.,Cl and a complex 

 hydrocarbon. He proved, further, that this synthesis was of little 

 value in determining the constitution of anthracene, since neither an- 

 thracene nor benzyltoluol was present in the product of the reaction, 

 but they were formed during distillation by the breaking up of the 

 more complex substances just mentioned. 



2. In the year after Limpricht's synthesis was published, Berthelot, 

 in developing his general method for the synthesis of complex hydro- 

 carbons by passing simpler ones through a porcelain tube, heated to 

 redness, obtained anthracene t from toluol (confirmed by Graebe § 

 in 1874), xylol, cumol, and mixtures of benzol with ethylene,|| and of 

 benzol with styrol ; also traces of it by heating acetylene to redness 

 in a glass tube over mercury. The same method was applied success- 

 fully by Van Dorp T[ to benzyltoluol, that obtained from benzylchloride 

 toluol and zinc-dust, as well as that from benzylchloride and water; 

 by Kramers ** to phenol (yellow heat) ; by Claus and Suckert ft to 

 azobenzol ; and by Barbier |$ to the mixture of toluol with benzol, 

 and to that of diphenyl with ethylene, although the latter yielded 

 only traces of anthracene. Barbier, JJ in 1874, substituted for red- 

 hot porcelain tubes vacuous sealed glass tubes heated to dull redness 

 for a few minutes, and obtained in this way anthracene from benzyl- 

 toluol, phenylxylol, diphenylmethan, and liquid ditolyl. While Behr 

 and Van Dorp §§ obtained the same result a year earlier by passing 

 liquid benzyltoluol, or liquid tolylphenylketone over gently heated 

 plumbic oxide. The synthesis from orthotolylphenylketone by the 

 aid of heat has been recently repeated by Ador and Rilliet.|||| 



3. The next synthesis of anthracene was published in 1872 by 

 Kekule and Franchimont,T[ir who obtained a small quantity of anthra- 



* Ber. d. ch. G., 72, p. 1070. Ann. Chem. Pharm., clxix. 207. 



t Ber. d. ch. G., '74, p. 276. J Bull. Chem. Soc, vii. 222. 



§ Ber. d. ch. G., '74, p. 48. || Bull. Chem. Soc, vii. 279. 



T Ber. d. ch. G., '72, p. 1070. Ann. Chem. Pharm., clxix. 207. 

 ** Ann. Chem. Pharm., clxxxix. 131. 

 ft Ber. d. ch. G., '75, p. 37. 



tt Comptes Rend., Ixxix. 121, 660, 810. Also, Ann. Ch. Phys., ser. 5, vii. 615 

 §§ Ber d. ch. G , '73, p. 753. 



nil Ibid., '79, p. 2298. liH Ibid., '72, p. 909. 



VOL. XVI. (n. S. VIII.) 5 



