220 



AROMATIC ALDEHYDES AND KETONES 



[121-C. 



Zeit. 45, 164; Ch. Centr. 1900,, 1, 728). 

 Vanillin lias been extracted in small 

 quantity from the new bark of the lime 

 tree, Tilia sp. ? (Brautigam, Arch. 

 Pharm. 238, 556). 



According to Busse (see Ch. Centr. 

 1900, 1, 557), vanillin is produced in 

 Vanilla species in the first place as a 

 glucoside. The same view is expressed 

 by Behrens (Ibid. 2, 769 : see also 

 Molisch, Ber. deutsch. bot. Gesell. 19, 

 350). Lecomte attributes the forma- 

 tion to the hydrolysis of coniferin and 

 oxidation of coniferyl alcohol by an 

 oxidase (Comp. Rend. 133, 745). 



SYNTHETICAL PEOCESSES. 



[A.] From catecJiol [69] through 

 guaiacol by methylation with potassium 

 methyl sulphate (Gorup-Besanez, Ann. 

 147, 248), and the action of chloroform 

 [l ; D] and caustic alkali on guaiacol 

 (Reimer and Tiemann, Ber. 9, 424 ; 

 Tiemann and Koppe, Ber. 14, 2023 ; 

 Traub, Germ. Pat. 80195 of 1894; 

 Ber. 28, Ref. 524; Soc. Chim. d. 

 Usines du Rhone, Eng. Pat. 21106 of 

 1896; Journ. Soc. Ch. Ind. 16, 758). 



Or guaiacol can be converted into its 

 carboxylic acid by heating its salts in 

 an atmosphere of carbon dioxide (F. v. 

 Heyden, Nachf. Germ. Pat. 51381 of 

 1889; Ber. 23, Ref. 418). Guaiacol- 

 carboxylic acid on heating with chloro- 

 form and alkali gives aldehydoguaiacol- 

 carboxylic acid, and the latter is de- 

 composed into vanillin on heating (Ibid. 

 Germ. Pat. 71162 of 1892; Ber. 26, 

 Ref. 995; Germ. Pat. 72600 of 1893; 

 Ber. 27, Ref. 218). 



The aldehyde group can also be 

 introduced into guaiacol by means of 

 nitrobenzenesulphonic acid and formic 

 aldehyde [9l], and hydrolysis of the 

 product (Geigy & Co., Eng. Pat. 27236 

 of 1898; Journ. Soc. Ch. Ind. 19, 

 41). Or by the action of hydrogen 

 cyanide [172] and hydrogen chloride, in 

 presence or absence of aluminium 

 chloride, and hydrolysis of the product 

 (Bayer & Co., Germ. Pat. 106508 of 

 1898 and previous Patents; Ch. Centr. 

 1900, 1, 742). 



Or aniline and formic aldehyde may 



be condensed with guaiacol to form 

 hydroxymethoxybenzylaniline, which 

 can be oxidised to a benzylidene de- 

 rivative, and finally to vanillin (Meister, 

 Lucius, and Briining, Germ. Pat. 109498 

 of 1898 ; Ch. Centr. 1900, 2, 457 : see 

 also the Pats, of this Firm under p- 

 hydroxybenzaldehyde [119 ; E]). 



NOTE : Catechol can be converted into 

 protocatechuic aldehyde by chloroform and 

 alkali (Tiemann and Reimer, Ber. 9, 1269 ; T. 

 and Koppe, Ber. 14, 2015), or by the action of 

 formic aldehyde and aromatic hydroxylamine 

 sulpho-acids, &c., as in the process applied to 

 guaiacol above (Geigy & Co., loc. cil. and 

 Germ. Pat. 105798 of 1898 ; Ch. Centr. 1900, 1, 

 523). From protocatechuic aldehyde as below 

 under E. 



[B.] From phenol [60] through o- 

 nitrophenol and its methyl ether (o- 

 nitroanisole), o-anisidine, and guaiacol 

 (for references see under catechol [69 ; 

 A]), and then as above. 



Or from anisidine through its com- 

 pound with alloxan [Vol. II], which is 

 decomposed on heating with sulphuric 

 acid with the formation of p-amino- 

 m-methoxybenzoic aldehyde (Pellizari, 

 Gazz. 17, 412; Bohringer & Sohne, 

 Germ. Pat. 108026 of 1898 ; Ch. Centr. 

 1900, 1, 1115). The latter can be con- 

 verted into vanillin as below under C. 



Or phenol on bromination at 150 

 1 80 gives o-bromphenol (see under 

 catechol [69; A]). The latter can be 

 converted into 3-brom-4-hydroxybenzoic 

 aldehyde (Geigy & Co., Germ. Pat. 

 105798 of 1898; Ch. Centr. 1900, 1, 

 523), and this yields protocatechuic 

 aldehyde on heating with caustic soda- 

 lye to 150200 (Baum, Germ. Pat. 

 82078 of 1894; Ber. 28, Ref. 803). 

 From the aldehyde as below under E. 



NOTE : o-Bromphenol is obtained also from 

 o-nitrophenol through o-aminophenol by the 

 diazo-method (Meldola and F. H. Streatfeild, 

 Trans. Ch. Soc. 73, 685). 



[C.] From benzoic aldehyde [114] 

 through the m-nitro-aldehyde by nitra- 

 tion (Widmann, Ber. 13, 678 ; Fried- 

 lander and Henriques, Ber. 14, 2802 ; 

 Ehrlich, Ber. 15, 2010; Camps, Arch. 

 Pharm. 24O,i), the m-amino-aldehyde by 

 reduction, and the m-hydroxy -aldehyde 

 [118] by the diazo-method (Meister, 

 Lucius, and Briining, Germ. Pat. 18016 



