30 



HYDROCARBONS 



477), or by passing ethylene chloride 

 over hot soda-lime (Wilde, Ber. 7, 352). 

 [IV.] From normal or isopropyl alco- 

 hol [15 ; 16] through propylene and 

 allylene (see under benzyl alcohol [54 ; 

 E]). The latter gives mesitylene when 

 treated with sulphuric acid (Schrohe, 

 Ber. 8, 17). Mesitylene oxidises to 

 trimesic =1:3: 5-benzenetricarboxylic 

 acid (Fittig, Ann. 141, 153), and this 

 gives benzene on distillation with lime. 



NOTE : Generators of allylene (see under 

 benzyl alcohol [54 ; P, Q, &c.]) thus become 

 generators of benzene. Generators of propylene 

 are given under glycerol [48]. 



[V.] From butyl alcohols normal or 

 iso- [17; 18] through normal or iso- 

 butylene or pseudobutylene (see under 

 isobutyl alcohol [18 ; A] ; tertiary butyl 

 alcohol [19 ; B] ; and secondary butyl 

 isothiocyanate [165 ; A and B]). Butyl- 

 ene or pseudobutylene bromide gives 

 crotonylene on treatment with alcoholic 

 potash (Caventou, Ann. 127, 347 ; Al- 

 medingen, Journ. Russ. Soc. 13, 392; 

 J. Wislicenus and Schmidt, Ann. 313, 

 ail), and this by the action of sulphuric 

 acid gives hexamethylbenzene (Alme- 

 dingen, loc. cit.). The latter on oxida- 

 tion with permanganate gives mellitic 

 acid (Friedel and Crafts, Ann. Chim. 

 [6] 1, 470), which gives benzene as 

 above under I. 



Benzene is a product of pyrogenic 

 synthesis from isobutylene (Noyes ; 

 Beilstein, I, 115). 



[VI.] Methyl alcohol [13] is said to 

 give a small quantity of hexamethyl- 

 benzene by the action of zinc chloride 

 (Greene and LeBel, Jahresber. 1878, 

 388). 



A passage from methyl alcohol to 

 benzene is also possible through methyl 

 chloride and the further chlorination of 

 the latter to chloroform (Damoiseau, 

 Comp. Rend. 02,42). From chloroform 

 through acetylene as above under III. 



[VII.] From carbon disulphide [16O] 

 through carbon tetrachloride (see under 

 methane [l ; L]). The latter is reduced 

 by zinc and dilute sulphuric acid to 

 chloroform (Geuther, Ann. 107, 212). 



[VIII.] From acetone [106] through 

 mesitylene (see under benzyl alcohol 

 [54 ; D]), and then as above under IV. 



Or from acetone through phorone 

 and pseudocumene (see under ortho- 

 cresol [61 ; B]). The latter oxidises to 

 a-xylic = methylterephthalic acid and 

 finally to trimellitic = I : 2 : 4-benzene- 

 tricarboxylic acid (Fittig and Laubin- 

 ger, Ann. 151, 276; Krinos, Ber. 10, 

 1494), which gives benzene on fusion 

 with alkali (Barth and Schreder, Ber. 



12, 1257)- 



Or acetone 2^^. formic acid [Vol. II] 

 condense when the ethyl ester of the 

 latter and the ketone are acted upon 

 by sodium ethoxide. The product is 

 hydroxymethylene-acetone, and this 

 undergoes further condensation to tri- 

 aeetylbenzene. which is oxidised to 

 trimesic acid by nitric acid (Claisen 

 and Stylos, Ber. 21, 1144). 



[IX.] From formic and acetic acids 

 [Vol. II]. A mixture of the esters 

 when acted upon by sodium gives 

 /3-hydroxyacrylic = hydroxymethylene- 

 acetic = f ormylacetic acid, which readily 

 condenses to trimesic ester (Piutti, Ber. 

 20, 537 ; Claisen and Stylos, Ber. 21, 

 1146; see also Wislicenus and Binde- 

 mann, Ann. 316, 18). 



Or a mixture of monochlor- or (better) 

 monobromacetic acid and ethyl formate 

 when acted upon by zinc condenses to 

 trimesic ester, from which the acid can 

 be obtained by hydrolysis (Reformatsky, 

 Journ. Russ. Soc. 30, 280). 



Or acetic acid on boiling potassium 

 dichloracetate with potassium acetate 

 solution gives the potassium salt of 

 diacetyldihydroxyacetic = diacetyigly- 

 oxylic acid (Doebner, Ann. 311, 129). 

 The latter (salt) condenses with pyro- 

 racemic acid (see below under XIV) in 

 presence of alkali to phthalidetricarb- 

 oxylic acid, the aqueous solution of which 

 gives phthalidedicarboxylic acid on boil- 

 ing. The dicarboxylic acid gives toluene 

 when the barium salt is heated with 

 barium oxide (Doebner, loc. cit. 132). 

 Toluene can be oxidised to benzoio acid 

 [Vol. II], which gives benzene on dis- 

 tillation with lime. 



NOTE : Generators of toluene are given under 

 benzyl alcohol [54] passim, 



[X.] From isobutyric and. formic acid 

 [Vol. II]. Isobutyric acid is brominated 



