2QO HISTORY OF CHEMISTRY. [LECTURE XI V. 



Silvn, starting from acetone. 118 Wurtz 119 converted glycol 

 chlorhydrine into choline (neurine) by means of trimethylamine, 

 whilst Reimer and Tiemann obtained vanilline from guaiacol. 1 ' 20 

 Grimaux synthetically prepared allantoi'n, 121 alloxantine, 1 ' 22 and 

 citric acid ; 123 and, more recently, Erlenmeyer prepared 

 tyrosine, 124 Ladenburg, piperidine 125 and coniine, 1 ' 26 and Hor- 

 baczewsky, uric acid. 127 The synthesis of indigo blue by 

 Baeyer 128 also deserves to be mentioned, since not only did it 

 familiarise us with the preparation and furnish us with an 

 explanation of the constitution of an important colouring 

 matter, but it was accomplished, besides, by means of new 

 and peculiar reactions. 



Special attention is due to the general methods which 

 permit the synthesis of whole groups of substances. The 

 most important of these methods will be specified here. 



Frankland was the first who succeeded in building up 

 hydrocarbons. 1 ' 29 He obtained dimethyl (ethane) from zinc 

 and methyl iodide, and diethyl (butane) from zinc and ethyl 

 iodide. This reaction was extended by Wurtz, who treated 

 mixtures of alkyl iodides with sodium 136 a method which 

 Fittig and Tollens turned to account in the synthesis of aro- 

 matic hydrocarbons. 13t It had already been found possible to 

 obtain hydrocarbons, according to a reaction discovered by 

 Berthelot, by the distillation of benzoates with salts of the 

 fatty acids. 132 A synthetical method was elaborated by Zincke, 

 which permits of the preparation of hydrocarbons with two 

 phenyl groups, and depends upon the action of benzyl chloride 

 upon aromatic hydrocarbons in presence of zinc dust. 133 These 

 compounds can also be obtained, according to Baeyer, from 

 aldehydes and aromatic hydrocarbons, by the aid of substances 



118 Bull. Soc. Chim. [2] 20, 98. 119 Annalen. Supplementband 6, 116. 

 120 Berichte. 9, 424. 121 Ann. Chim. [5] II, 389. ia3 Jahresbericht 

 1878, 361. 123 Comptes Rendus. 90, 1252. 124 Annalen. 219, 161. 



ia5 Berichte. 18, 2956 and 3100. 126 Ibid. 19, 439 and 2578. 127 Mon- 

 atsheftc. 3, 796 ; 6, 356. 128 Berichte. 13, 2254. 12B Annalen. 71, 



171 ; 74, 41; -77, 221. 13 Ibid. 96, 364. 15J1 Ibid. 131, 303. 



13> - Ann. Chim. [4] 12, 81. 133 Annalen. 155, 59, etc. 



