6 F-7 A.] CYMENE 



terpin hydrate (Tiemann and Schmidt, 

 Ber. 28, 1781), which can be converted 

 into cymene as above under D. 



[G.] Cineole [40] (eucalyptol) gives 

 cymene on distillation with phosphorus 

 pentasulphide (Faust and Homeyer, 

 Ber. 7, 428). 



[H.] Menthol [4l] gives cymene on 

 heating with copper sulphate solution 

 at 260 (Briihl, Ber. 24, 3375). Also 

 (with hexahydrocymene and other pro- 

 ducts) on treatment with strong- sul- 

 phuric acid (Wagner, Ber. 27, 1 638). 



[I.] From thymol [67] by distilling 

 with phosphorus pentasulphide (Pott, 

 Ber. 2, 121). Or by the action of 

 phosphorus pentachloride on thymol and 

 reduction of the chloride (C 10 H la Cl) 

 with sodium amalgam (Carstanjen, 

 Jahresber. 1871, 456). 



[J.] Citral [104] gives cymene on 

 heating with aqueous hydrochloric acid 

 (Dodge, Am. Ch. Journ. 12, 561 ; 

 see also Tiemann, Ber. 32, 108), with 

 acid potassium sulphate at 170 (Semm- 

 ler, Ber. 24, 204), with acetic acid 

 (Barbier and Bouveault, Comp. Rend. 

 118, 1051), or on treatment with zinc 

 chloride solution, with hydriodic or 

 sulphuric acid (Verley, Bull. Soc. [3] 

 21, 408). 



[K.] Citronellal [105] combines with 

 bromine to form a dibromide which 

 gives cymene on heating (Beilstein's 

 < Handbuch/ III, 475). 



[L.] From cumic aldehyde [116] 

 through cumic alcohol (Kraut, Ann. 

 92, 66 ; 192, 224 ; Fileti, Gazz. 14, 

 498). The latter gives cymene on 

 boiling with zinc dust (Kraut, loc. cit, ; 

 Jacobsen, Ber. 12, 434). 



[M.] Carvone [127] gives cymene by 

 the action of the sulphides of phos- 

 phorus (Kekule" and Fleischer, Ber. 6, 

 1088) and among the products formed 

 by passing the vapour over heated zinc 

 dust (Arndt, Ber. 1, 204). 



[N.] From terpinene [10], which forms 

 a nitrite which on reduction with 

 sodium in alcohol gives cymene among 

 other products (Wallach, Ann. 313, 361 ; 

 Semmler, Ber. 34, 715). 



33 



7. Styrene; Styrolene ; Fhenyl- 

 etliylene; Cinnamene. 



CH : CH, 



NATURAL SOURCES. 



Occurs in liquid storax, a balsam 

 from the Liquidambar orientalis of Asia 

 Minor and N. Syria (Bonastre, Journ. 

 Pharm. 17, 338 ; Simon, Ann. 31, 265 ; 

 Blyth and Hofmann, Ann. 63, 293; 

 325). Also in American storax from 

 Liquidambar styraciflua (W. v. Miller, 

 Arch. Pharm. 220, 648) and in the 

 oil from the yellow resin of XanthorrJuea 

 hastilis of Australia (SchimmeFs Ber. 

 Oct. 1897 ; Ch. Centr. 1898, 1, 258). 



Styrene exists as such in storax and 

 is not a product of distillation (Van 

 Itallie, Ch. Centr. 1901, 2, 856 : see 

 also Tschirch and Van Itallie, Arch. 

 Pharm. 239, 506 ; 532). 



SYNTHETICAL PROCESSES. 



[A.] Among the products formed by 

 the action of Tieat on acetylene [l; A, 

 &c.] (Berthelot, Comp. Rend. 62, 905; 

 947 ; Ann. 141, 181). Also among the 

 products formed by passing acetylene 

 over finely divided nickel at 200 (Saba- 

 tier and Senderens, Comp. Rend. 134, 

 1185). Also by passing ethylene [l; D, 

 &c.] or ethylene and benzene vapour [6 ; 

 I, &c.] through a hot tube (Berthelot, 

 Bull. Soc. [2] 9, 456 ; Zeit. [2] 4, 384 ; 

 Ann. 142, 257 ; Ferko, Ber. 20, 660). 



Toluene vapour, alone or mixed with 

 ethylene, gives styrene by pyrogenic 

 synthesis (Ferko, loc. cit.}. Acetylene 

 passed through benzene in presence of 

 aluminium chloride gives styrene (Varet 

 and Vienne, Bull. Soc. [2] 47, 918; 

 Comp. Rend. 104, 1375). 



Or from ethylene through the brom- 

 ide and monobromethylene (vinyl brom- 

 ide) by the action of alcoholic potash 

 (Regnault, Ann. China. [2] 69, 358 ; 

 Beilstein, Jahresber. 1861, 609 ; Glb'ck- 



