83 B-84 C.] 



DIMETHYLTHYMOQUINOL 



159 



[B.] Carvacrol [66] on oxidation also 

 gives thymoquinone (Carstanjen, loc. 

 cit. 15, 410; Glaus, Journ. pr. Ch. [2] 

 39, 356 ; Reychler, Bull. Soc. [3] 7, 32). 

 Subsequent steps as above. 



84. Pyrogallol ; Pyrogallic Acid ; 

 1:2: 3-Fhenetriol. 



HO 



NATURAL SOURCES. 



The pyrogallol complex exists in. gallic 

 acid [Vol. II], and in myricetin from 

 the bark of the box-myrtle, Myrica nagi 

 = M. sapida M. integrifolia = M. rubra, 

 &c., from India, China, Singapore, and 

 Japan (A. G. Perkin and Hummel, 

 Trans. Ch. Soc. 69, 1293 > A. & ^ an d 

 Clifford, Ibid. 81, 203). 



Myricetin is contained also in Sicilian 

 sumach from Rims coriaria (A. G. P. 

 and Allen, Ibid. 1302), in the colouring-- 

 matter from the leaves of Pistacia 

 lentiscus, in ' gambruzzo ' from the 

 stalk of Rhus coriaria, and in the galls 

 of Pistacia terebinthus (A. G. P. and 

 Wood, Proc. Ch. Soc. 14, 104; Trans. 

 73, 374 et seq.}. Myricetin is present 

 in Venetian sumach from the leaves of 

 Rhus cotinus (A. G. P. Trans. Ch. Soc. 

 73, 1017), in the leaves of R/ins 

 metopium, Myrica gale, and (probably) 

 of logwood, HfKmatoxylon campeachianum 

 (Ibid. Proc. 16, 45; Trans. 77, 426). 

 A rhamnoside of myricetin is contained 

 in the bark of Myrica nagi (Ibid. Proc. 

 18, 11). 



The pyrogallol complex is probably 

 contained in hsematoxylin from logwood 

 (see under catechol [69]). 



Mezcalin, one of the cactus alkaloids 

 from Echinocactus lewinii, probably con- 

 tains the pyrogallol complex (Heffter, 

 Ber. 34, 3009). 



The dimethyl- (methyl) pyrocatechol 

 complex exists in iridin, a glucoside 



found in the orris-root from Iris floren- 

 lina from Macedonia, coasts of Black 

 Sea, and Asia Minor (G. de Laire and 

 Tiemann, Ber. 26, 2011). 



Sinalbin, a glucoside which occurs in 

 the seed of white mustard [171], con- 

 tains the sinapic acid complex, and the 

 latter is a derivative of dimethylpyro- 

 gallol (Gadamer, Arch. Pharm. 235, 

 570; Ch. Centr. 1898, i, 500; Ber. 

 30, 2330). 



Syringin, a glucoside found in the 

 bark of Syringa vulgaris, Ligustrum vul- 

 gare, and Robinia pseudacacia, also con- 

 tains (through syringenin) the same 

 complex. 



The alkaloid narcotine from opium 

 contains the methyl-methylene-pyro- 

 gallol complex. Anthragallol [148] 

 dimethyl ether contains the dimethyl- 

 pyrogallol complex. The pyrogallol 

 complex is possibly contained in kinom 

 from Malabar kino from Pterocarpus 

 marsupium. 



SYNTHETICAL PROCESSES. 



[A.] From phenol [60] through p- 

 chlorphenol by various chlorinating 

 processes (Dubois, Zeit. [2] 2, 705; 

 3, 205 ; Schmitt and Cook, Ber. 1, 67 ; 

 Petersen and Bahr-Praderi, Ann. 157, 

 123), a- and /3-p-chlorphenolsulphonic 

 acid by sulphonation (Petersen and 

 Bahr-Praderi, loc. cit. 128), and potash 

 fusion of either sulphonic acid (Ibid. 



I3 6 )- 



[B.] Salicylic acid [Vol. II] can by 

 various iodising processes be converted 

 into 3 : 5-diiodosalicylic acid (Laute- 

 mann, Ann. 120, 304 ; Liechti, Ann. 

 Suppl. 7, 141 ; Demole, Ber. 7, 1439 ; 

 Weselsky, Ann. 174, 103; Birnbaum 

 and Reinherz, Ber. 15, 459). Accord- 

 ing to Lautemann (loc. cit. 317), this 

 diiodosalicylic acid when heated with 

 aqueous potash gives pyrogallol (?by 

 isomeric change). 



[C.] Gallic acid [Vol. II] gives pyro- 

 gallol when heated (Braconnot, Ann. 1, 

 26; Pelouze, Ann. 10, 159; Liebig,Ann. 

 101, 47 ; De Luynes and Esperandieu, 

 Zeit. [2] 1, 702 ; Thorpe, Pharm. Journ. 

 [3] 11, 990; Cazeneuve, Bull. Soc. [3] 

 7, 549)- 



