121 C-I.] 



VANILLIN 



221 



of 1 88 1 ; Ber. 15, 1098; Tiemann and 

 Ludwig, Ibid. 2044). The hydroxy- 

 aldehyde by methylation gives the 

 methoxy-aldehyde, and this, on heating 

 with acetic anhydride and sodium ace- 

 tate, yields m-methoxycinnamic acid. 

 The latter (methyl ester) on nitration 

 gives m-methoxy-p-nitrocinnamic ester, 

 and this, on hydrolysis and oxidation 

 with potassium permanganate, yields 

 m-methoxy-p-nitrobenzoic aldehyde. The 

 latter, on reduction and application of the 

 diazo-method, gives vanillin (M. L. & B. 

 loc, cit.; Ulrich, Ber. 18,2571; Germ. 

 Pat. 32914 of 1884; Ber. 18, Ref. 682). 

 [D.] From p-hydroxylenzoic aldehyde 

 [119] through the m-nitro-aldehyde by 

 nitration (Mazzara, Jahresber. 1877, 

 617; Paal, Ber. 28, 241 3), the m-amino- 

 aldehyde by reduction, and replacement 

 of the amino- by the methoxy-group by 

 the diazo-method followed by methyla- 

 tion (Bergmann, Am. Pat. 571917 of 

 1896; Ber. 29, Ref. 1192). Or p-hy- 

 droxybenzoic aldehyde on bromination 

 gives the 3-bromo-derivative (Paal, Ber. 

 28, 2409). From the latter through 

 protocatechuic aldehyde (Baum: see 

 above under B), and then as below 

 under E. 



NOTE : m-Hydroxybensoic aldehyde [118] on 

 bromination gives 4-brom-3-hydroxybenzoic 

 aldehyde, and this also yields protoeatechuic 

 aldehyde on heating with soda-lye (Baum, 

 loc. cit.). 



[E.] Piperonal [122] on heating with 

 dilute hydrochloric acid at 200, or on 

 boiling the dichloro-derivative with 

 water, gives protocatechuic aldehyde 

 (Fittig and Remsen, Ann. 159, 148 ; 

 168, 97 : see also Wegscheider, Monats. 

 14, 382). The disodium salt of the 

 aldehyde, or the sodium salt of the 

 monoacetyl derivative, on methylation 

 by methyl chloride or by methyl alkali 

 sulphate, yields vanillin or its acetyl- 

 derivative; the latter can be hydrolysed 

 (Bertram, Germ. Pat. 63007 of 1890; 

 Ber. 25, Ref. 823 : the yield is better 

 with dimethyl sulphate and alkali, 

 Sommer, Germ. Pat. 122851 of 1900; 

 Ch. Centr. 1901, 2, 517). 



Or the potassium salt of the alde- 

 hyde on treatment with chloroformic- 

 methyl ester gives two carboxylic esters 



of protocatechuic aldehyde, of which the 

 p-modification yields vanillin on heating 

 with dimethyl sulphate in alcoholic 

 alkaline solution and subsequent acidifi- 

 cation (Soc. .Chim. d. Usines du Rhone, 

 Germ. Pat. 93187 of 1896; Ch. Centr. 

 1897, 2, 1016; Eng. Pat. 16239 of 

 1896; Journ. Soc. Ch. Ind. 16, 633). 



NOTES: The chloroformic ester (= rnethyl- 

 chlorocarbonate) is obtained by the action of 

 phosgene on methyl alcohol (Dumas, Ann. 10, 

 277 ; Ann. Chim. 58, 52 ; Meyer and Wurster, 

 Ber. 6, 965 ; Klepl, Journ. pr. Ch. [2] 26, 447 ; 

 Hentschel, Ber. 18, 1177). 



Processes depending on the combination of 

 protocatechuic aldehyde with benzene- or 

 toluenesulphonic acid, methylation of the ester, 

 and subsequent decomposition into vanillin 

 will be found in the following Germ. Pats, of 

 the Ch. Fab. vorm. E. Schering : 80498 of 1 893 ; 

 Ber. 28, Ref. 581 ; 82747 of l8 94 5 Ber - 28 > Ref - 

 878. The aldehyde may also be converted first 

 into a benzyl ether, and the latter methylated 

 and then decomposed by heating with acid 

 (Ibid. 82816 of 1893 ; Ber. 28, Ref. 878). 



[P.] From m-cresol [62], which gives 

 on nitration a mixture of 6-nitro- and 

 4-nitro-m-cresol (Stadel, Ann. 217, 

 51; 259, 208; Ber. 22, 215; Reissert 

 and Scherk, Ber. 31, 393). The methyl 

 ether of the latter condenses with oxalic 

 ester in the presence of sodium ethylate 

 or methylate, with the formation of the 

 nitromethoxyphenylpyroracemic acid 

 (see under p-hydroxybenzoic aldehyde 

 [119; E, p. 2 1 8]; Reissert, Ber. 31, 

 397). The latter can be converted into 

 vanillin by replacement of the nitro- 

 group by hydroxyl, and the pyroracemic 

 acid residue by the aldehyde -group, 

 CHO (Reissert, Germ. Pat. 94630 of 

 1897; Ch. Centr. 1898, 1, 296). 



[G.] From vanillic acid [Vol. II] by 

 distilling the calcium salt with calcium 

 formate (Tiemann, Ber. 8, 1124), or by 

 heating with chloroform [l ; D] and caus- 

 tic alkali in aqueous solution (Tiemann 

 and Mendelsohn, Ber. 9, 1280). 



[EL] Ferulaic acid [Vol. II] gives 

 vanillin on oxidation (Ulrich, Germ. 

 Pat. 32914 of 1884; Ber. 18, Ref. 682). 



[I.] From veratric acid [Vol. II] 

 through veratrole (see under catechol 

 [69 ; F]). The latter combines with 

 ethyloxalyl chloride or amyloxalyl 

 chloride in presence of aluminium chlor- 

 ide to form veratroylglyoxylic esters 

 (Bouveault : see under anisic aldehyde 



