232 



AROMATIC ALDEHYDES AND KETONES [135-136 D. 



135. Methylhydrocotoin ; 



2:4: 6-Trimethoxybeiizoplienoiie ; 



Benzoylphloroglucinol Trimethyl 



Ether. 



OCH 3 



NATURAL SOURCE. 



Occurs in paracoto bark (see above 

 under hydrocoto'in) (Jobst and Hesse, 

 Ann. 199, 53; Ciamician and Silber, 

 Ber. 26, 799). 



SYNTHETICAL PROCESS. 



[A.] From hydrocoto'in [134] and 

 methyl alcohol [13] by further methyla- 

 tion with methyl iodide and potassium 

 hydroxide in methyl alcohol (Ciamician 

 and Silber, Ber. 24, 300; 25, 1120). 



Or directly from phloroglucinol [86] 

 through the trimethyl ether (Will, Ber. 

 21, 603), and the action of benzoyl 

 chloride on the latter in benzene solu- 

 tion in presence of zinc chloride (Ciami- 

 cian and Silber, Ber. 27, 1497)- 



136. Enxanthone. 

 HO 



NATURAL SOURCE. 



The complex exists in euxanthic acid, 

 the glycuronic congugate acid of eux- 

 anthone which occurs in 'purreV or 

 Indian Yellow,- prepared from the urine 

 of cows fed upon mango leaves. Eux- 

 anthone is sometimes found in the free 

 state in the colouring-matter, resulting 

 from the decomposition (? bacterial) of 

 euxanthic acid. 



NOTE : For the constitution of euxanthic acid 

 see Graebe, Ber. 33, 3360 ; Graebe, Aders, and 

 Heyer, Ann. 318, 345. 



SYNTHETICAL PROCESSES. 



[A.] From resorcinol [70] and quinol 

 [7l]. Resorcinol is converted into /3- 

 resorcylic acid by heating with aqueous 

 ammonium carbonate or acid potassium 

 carbonate (Brunner and Senhofer, Ber. 

 13, 2356 ; Bistrzycki and Kostanecki, 

 Ber. 18, 1985). Quinol is converted 

 into its carboxylic acid, gentisic = 2:5- 

 phenediolcarboxylic = 2 : 5-dihydroxy- 

 benzoic 5-hydroxysalicylic acid, by a 

 similar process (Senhofer and Sarlaz, 

 Monats. 2, 448). Gentisic and /3-re- 

 sorcylic acids or resorcinol when heated 

 together with acetic anhydride give 

 euxanthone (Graebe, Ber. 22, 1405 ; 

 Kostanecki and Nessler, Ber. 24, 3983). 

 [B.] From resorcinol [70] and salicy- 

 lic acid [Vol. II]. The latter can be 

 converted into gentisic acid by the 

 following processes : 



By iodising with iodine in presence 

 of alkali, or by the action of iodine on 

 silver salicylate 5-iodosalicylic acid is 

 formed (Lautemann, Ann. 120, 302 ; 

 Demole, Ber. 7, 1437 ; Birnbaum and 

 Reinherz, Ber. 15, 458). Or 5-brom- 

 salicylic acid is obtained by the brom- 

 ination of the acid (Henry, Ber. 2, 275 ; 

 Hiibner and Heinzerling, Zeit. [2] 7, 

 709; Hand, Ann. 234, 133). The5-iodo- 

 or bromo-acid gives gentisic acid on 

 fusion with alkali (Lautemann, loc. cit. 

 311; Liechti, Ann. Suppl. 7, 144; 

 Demole, loc. cit. 1438 ; Goldberg, Journ. 

 pr. Ch. [2] 19, 371 ; Miller, Ann. 220, 

 124; Rakowski and Leppert, Ber. 8, 

 789). 



Or salicylic acid on nitration yields 

 5-nitro-, and the latter on reduction 5- 

 aminosalicylic acid (see under quinol 

 [71; C]). The amino-acid gives gen- 

 tisic acid by the diazo-method (Gold- 

 berg, loc. cit.). 



[C.] From resorcinol [70] and phenol 

 [60]. The latter on nitration gives 

 (with o-) p-nitrophenol, and this on 

 heating with carbon tetrachloride [l ; L] 

 and alcoholic potash yields,5-nitrosalicy- 

 lic acid (Hasse, Ber. 10, 2188), which 

 can be transformed into gentisic acid as 

 above under B. 



[D.] From resorcinol [70] and benzole 

 acid [Vol. II]. The latter can be con- 



