240 



AROMATIC ALDEHYDES AND KETONES [146 B-149. 



stannous chloride, sodium stannite, or 

 phosphorus and water (Schiitzenberger 

 and Schiffert, Bull. Soc. [a] 4, 12 ; 

 Rosenstiehl, Ann. Chim. [5], 18, 224; 

 Corap. Rend. 19, 764; Liebermann 

 and Fischer, Ann. 183, 213). 



Or purpurin on heating with aqueous 

 ammonia gives an amide (Stenhouse, 

 Ann. 130, 337 ; Liebermann, Ann. 

 183, 212), which yields purpuroxanthin 

 by the diazo-method (Liebermann, he. 

 cit. 213). 



147. Hystazarin; 

 2 : 3-Dihydroxyanthraquinone. 



148. Anthragallol ; 

 1:2: 3-Trihydroxyanthraquinone. 



CO 



OH 

 II 



NATURAL SOURCE. 



The methyl ether occurs in Chay root 

 from Oldentandia umbellata (see under 

 m-hydroxyanthraquinone [144] ; A. G. 

 Perkin and Hummel, Trans. Ch. Soc. 

 67, 822). 



SYNTHETICAL PROCESSES. 



[A.] Catechol [69] and phthalic an- 

 hydride [54; R] give (with alizarin) 

 hystazarin when heated at 140150 

 with strong sulphuric acid (Liebermann, 

 Ber. 21, 2501 ; Scholler, Ibid. 2503). 



Or veratrole (see under methyl- 

 eugenol [81; A]) on condensation with 

 phthalic anhydride by means of alu- 

 minium chloride gives 3 : 4-dimethoxy- 

 benzoylbenzoic acid, which, on heat- 

 ing with strong sulphuric acid, yields 

 hystazarin dimethyl ether, and finally, 

 by demethylation, free hystazarin (La- 

 godzinski and Loretan, Ber. 28, 118; 

 Liebermann and Hohenemser, Ber. 35, 

 I 77 8). 



NOTE : The monomethyl ether has not been 

 synthesised. 



CO 



HO 



,OH 



H 



NATURAL SOURCE. 



The three isomeric dimethyl ethers 

 occur in Chay root (A. G. Perkin and 

 Hummel, Trans. Ch. Soc. 63, 1168; 

 67, 819). 



SYNTHETICAL PROCESSES. 



[A.] JPrGBipyrogattol [84] 

 anhydride [54 ; B] by heating a mixture 

 of the two compounds with strong sul- 

 phuric acid (Seuberlich, Ber. 1O, 39). 



[B.] From benzoic and gallic acids 

 [Vol. II] by heating a mixture with 

 strong sulphuric acid (Ibid.}. 



[C.] From alizarin [145] through 

 /3-nitro- and /3-aminoalizarin (Schunck 

 and Romer, Ber. 12, 584 ; 588 : see also 

 Rosenstiehl, Bull. Soc. [2] 26, 63; 

 Brunner and Chuard, Ber. 18, 445). 

 Bromanthragallol from /3-aminoalizarin 

 gives a sulphonic acid on heating with 

 sulphurous acid, and this yields anthra- 

 gallol on heating with sulphuric acid 

 (Bayer & Co., Germ. Pat. 125575; 

 Journ. Ch. Soc. 82, Abst. I, 383). 



NOTE : The dimethyl ethers have not been 

 synthesised. 



149. Furpuriu ; 

 1:2: 4-Trihydroxyanthraquinone. 



HO 



OH 



NATURAL SOURCE. 



Occurs with alizarin, purpuroxanthin, 

 &c., in madder root, probably as an 

 unstable glucoside (Colin and Robiquet, 

 Ann. Chim. [2] 48, 69; 51, no; 



