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THE JOURNAL OF PHARMACOLOGY. 



bromic acid, yields vanillin. Another method consists in introducing a 

 benzyl rest into the hydroxyl group of eugenol, then by heating with po- 

 tassium hydrate the iso compound results, which on oxidation yields ben- 

 zyl-vanillin. This ester, when heated with hydrochloric, yields vanillin 

 under saponification. Another method closely related to the above is a 

 modification, in which the benzyl rest is replaced by phenyl-chloro-acetic 

 acid or chloro-toluic acid, these differing from benzyl-chloride in that they 

 contain an additional C0 2 group. 



II. Thus far the various processes depend upon the oxidation of the ali- 

 phatic side chain group in the mother substitute to yield an aldehyde 

 group, while the OH and OCH 3 groups were already in their position in 

 the original substance. In this group toluene is selected as the mother sub- 

 stance, or cinnamic-acid or Ixnzaldehyde is employed. Starting with toluol, 

 it is successively converted into m-chloro-toluol, nitro-chloro-toluol, nitro- 

 ehloro-toltyl-bromide, and finally into nitro-chloro-benzaldehyde. This 

 latter compound is by action of a methylic-alcoholic solution of caustic al- 

 kali converted into p-nitro-m-methoxy-benzaldehyde, through reduction 

 of the nitre group, diazotating and boiling, the resulting amido compound 

 yields vanillin. 



In the above processes the aldehyde group is introduced by oxidation 

 or other moans into benzene nucleus. 



Since bcnzaldehyde is readily produced this lias been selected as ma- 

 terial production, introducing the necessary hydroxyl and methoxyl groups. 



III. From protocatechuic aldehyde. This class of syntheses start from 

 protocatechuic aldehyde, of which vanillin is a direct derivative through 

 the introduction of a methyl group. 



IV. From guaiacol. 



(a) By introduction of an aldehyde group by action of chloroform and 

 caustic potassa, guaiacol, a monomethyl ether of protocatechuic aldeyde 

 yields vanillin direct, but the process is open to the objection that a side 

 product is formed, in which the aldehyde group enters the ortho instead 

 of the para position. 



(b) By convertion into the guaiacol-carboxylic acid, by the introduction 

 of the aldehyde group and separation of C0 2 , guaiacol-carboxylic acid is 

 treated with chloroform and alcoholic potassa, yielding vanillic acid, from 

 which the vanillin may be obtained upon removing the C0 2 group by 

 heating. 



(c) A modification of this consists in converting guaiacol-sodium by ac- 

 tion of carbonic acid at 180° 0. into guaiacol-di-carboxilic acid, which, upon 

 treatment with chloroform and alcoholic potassa, yields vanillic acid, in 

 which the para earboxyl group is replaced by a methylal radical. The con- 

 vertion of vanillic acid into vanillin then proceeds as given above. 



