'IHE ALUMNI JOURNAL. 



87 



of an aliphatic side chain group in the 

 mother substance to yield an aldehyde 

 group, while the hydroxyl and methoxy 

 groups were already in their proper posi- 

 tion in the original substance. Lands- 

 berg devised a process in which a simple 

 crude material was selected in toluol, 

 which was successively converted into 

 /«£'/a-chloro- toluol, nitro ch loro- toluol (i, 

 3,4), nitro-chlorotolyl bromide (i, 3, 4), 

 and nitro-chloro-benzaldehyde (i, 3, 4), 

 this latter compound being converted by 

 the action of a methyl alcoholic solution 

 of a caustic alkali, into para nitro- /?z-me 

 thoxy-benzaldehyde, which through re- 

 duction of the nitro group, diazotating 

 and boiling the resulting amido com- 

 pound yielded vanillin ; the various phases 

 being represented by the following : 



CgH^C 



a,Hr,CH3 



C.H4 



yCH, (i) 



CI 



(3) 



Ullrich (1884) patented a method for 

 the production of para-nitro-m-methoxy- 

 benzaldehyde, which is used in the above 

 process, he, however, starts out from 

 /«^/«-methoxy-cinnamic ester, converting 

 itf. into />ara-nitro-m-methoxy-cinnamic 

 ester, which on oxidation yields^, nitro- 

 ?«-methoxy-benzaldehyde, from which 

 vanillin is obtained as already explained, 

 thus : 



.CH=:CH— COOC,H5 (i) 

 OCH3 (3) 



m — Methoxy-cinnaniic ester 



/CH^:--CH -COOC.H5 (l) 



C3H3-OCH3 (3) _— 



\N0, (4) 



p — Nitro-m-methoxy ciuuainic ester. 



/COH (i) /COH (i) 



C,H.-0.CH3 (3) -— C.H — OCH3 (3) 



\N0, (4) \OH (4) 



p— Nitro-m-methoxy-benzaldehyde. Vanillin. 



In the various processes thus far men- 

 tioned, the aldehyde group is introduced 

 by oxidation, or other processes, into the 

 benzene nucleus. Since benzaldehyde is 

 readily produced this has been selected 

 by Messrs. Meister, Lucius & Briining as 

 material for production, introducing the 

 necessary hydroxyl and methoxy groups. 

 Meta-amido-benzaldehyde (a derivative 

 of benzaldehyde) is converted into a diazo 

 compound which on boiling yields m- 

 oxy-benzaldehyde ; this is nitrated and 

 methylated, giving w^/a-nitro-w-methoxy 

 benzaldehyde, which is converted into 

 vanillin as explained above. 



Another class of syntheses start out 

 from protocatechuic-aldehyde, of which 

 vanillin is a direct derivative, through 

 the introduction of a methyl group. 



( COH (i) 



C^Hs - OH (3) 



(OH (4) 



Protocatechuic Aldehyde. 



(COH (i) 

 C6H3- OCH3 (^ 



(oh 



.0) 

 (4) 



Vanillin (methyl-proto- 

 catechuic aldehyde.) 



This process of the introduction of a 

 methyl group in protocatechuic aldehyde 

 was first patented by Bertram (1890) who 

 laid out the following rules for alkylat- 

 ing : 



I. Vanillin is formed when the methyl 

 group replaces the hydrogen of the 

 hydroxyl which stands in \\i^ para 

 position to the aldehyde group : 

 a) in methylating dimetallic salts of 



protocatechuic aldehyde ; 

 U) in methylating mono-acetyl deriv- 



