6.] 



CYMENE 



31 



(Markownikoff, Ann. 153, 229; Hell 

 and Waldbauer, Ber. 10, 448) and 

 a mixture of bromisobutyric ester and 

 formic ester acted upon by zinc. Tri- 

 mesic (with tetramethyloxyglutaric) 

 ester is formed (Blaise, Comp. Rend. 

 126, 1808). 



[XI.] From succcinic acid [Vol. II] 

 through acetylenedicarboxylic acid (see 

 under methane [1; T]). The acid 

 potassium salt of the latter gives pro- 

 piolic = propargylic acid on boiling with 

 water (Bandrowski, Ber. 13, 2340), and 

 this on long exposure to light out of 

 contact with air partially condenses to 

 trimesic acid (Baeyer, Ber. 19, 2185). 



Or from succinic acid through ethyl- 

 ene by electrolysis (see under methane 

 [l; T]), ethylene bromide and acetylene 

 as above under III, and polymerisation 

 as under I. 



[XII.] From fumaric or maleic acid 

 [Vol. II] through acetylene by electro- 

 lysis (see under methane [l ; TJ]). 



[XIII.] Isovaleric acid [Vol. II] gives 

 mesitylenic acid among other products 

 when the dry sodium salt is mixed with 

 sodium ethoxide and heated to 160 in 

 an atmosphere of carbon monoxide 

 (Loos, Ann. 202, 321). Mesitylenic 

 acid oxidises to trimesic acid (Fittig, 

 Ann. 141, 153). 



[XIV.] From tartaric acid [Vol. II] 

 through pyroracemic acid (see under 

 benzyl alcohol [54; N]). The latter 

 gives uvitic acid (54 ; I), and this oxi- 

 dises to trimesic acid (Baeyer, Zeit. [2] 

 4, 119; Fittig and Furtenbach, Ann. 

 147, 301). 



Pyroracemic acid condenses also with 

 acetaldehyde [92] or homologues (by 

 heating the mixture with baryta water) 

 to form uvitic = methylisophthalic acid 

 and homologues (Doebner, Ber. 23, 

 2377; 24, 1746). These alkyliso- 

 phthalic acids all oxidise to trimesic acid. 



NOTE : Generators of pyroracemic acid are 

 given under benzyl alcohol [54]. 



[XV.] From malonic acid [Vol. II] 

 and acetal [93]. The latter is con- 

 verted into monobromacetal (Pinner, 

 Ber. 5, 149; Fischer and Landsteiner, 

 Ber. 25, 2551), and this by interaction 

 with sodio-malonic ester gives acetal- 



malonic ester (W. H. Perkin, junr., and 

 Sprankling, Trans. Ch. Soc. 75, 13), 

 which by hydrolysis to acetalmalonic 

 acid and the action of water at 180- 

 190 gives /3-aldehydopropionic acid 

 (Jbid. 1 6). The latter on heating with 

 sodium hydroxide solution gives tere- 

 phthalic acid (Ibid. 18), and this gives 

 benzene on distillation with lime. 



Or from malonic acid and ethyl alcohol 

 [14] and chloroform through dicarboxy- 

 glutaconic ester by the interaction of 

 chloroform and sodio-malonic ester in 

 alcoholic solution (Conrad and Guthzeit, 

 Ann. 222, 250 ; Guthzeit and Dressel, 

 Ber. 22, 1414). The sodium deriva- 

 tive of dicarboxyglutaconic tetraethyl 

 ester on heating with alcohol at 150 

 gives the triethyl ester of trimesic acid 

 (Lawrence and W. H. Perkin, junr., 

 Proc. Ch. Soc. 17, 47). 



NOTE : Dicarboxyglutaconic ester can also be 

 obtained from sodio-malonic ester and ethoxy- 

 methylenemalonic ester (Claisen and Haase, 

 Ann. 297, 86), or from sodio-malonic ester and 

 trichloracetic ester (Ruhemann, Ber. 29, 1017), 

 or from sodio-malonic ester and carbon tetra- 

 chloride (Dimroth, Ber. 35, 2881). 



[XVI.] Malic acid [Vol. II] by the 

 action of fuming sulphuric acid gives 

 coumalic acid = formylglutaconic anhy- 

 dride (v. Pechmann, Ber. 17, 936 ; Ann. 

 264, 272). The methyl ester of the 

 latter is converted into trimesic mono- 

 methyl ester by dilute alkali (Tbid. Ann. 

 264, 294), and this can be hydrolysed 

 and converted into benzene as before. 



NOTE: Formylglutaconic = hydroxymethyl- 

 eneglutaconic ester can also be obtained 

 by the action of dilute sulphuric acid on 

 sodium-etbylformylacetate (see above under 

 IX). The ester condenses to trimesic ester on 

 standing (oily form) or on distillation under 

 reduced pressure (Wislicenus and Bindemann, 

 Ann. 316, 18). 



[XVII.] Tiglic acid [Vol. II] com- 

 bines with bromine to form a dibromide 

 which by the action of alcoholic potash 

 is converted into /3-bromangelic acid. 

 By the extreme action of alkali the 

 latter gives crotonylene (Wislicenus and 

 Henze, Ann. 313, 243). Subsequent 

 steps through hexamethylbenzene and 

 mellitic acid as above under V. 



[XVIII.] From glycerol [48] through 

 acrolein [101] by dehydration (Redten- 



