Chemistry. — "The Structure of TrnxilUc Acids.'") By A. W. K. 

 DE Jong. (Communicated by Prof. P. van Romburgh). 



(Communicated in the meeting of Sept. 20, 1917). 



Up to now tlie following truxiilic acids are known ; a, ^, y, d, e 

 truxillic acid and {i cocaic acid, which belong to two series, because 

 the members of one series cannot be converted to those of the 

 other without previous depolymerisation to cinnamic acid. 



The 7 acid belongs to the series of the « truxillic acid ; it is 

 formed by heating of the « truxillic acid with acetic acid anhydride '); 

 the /? cocaic acid, which is formed by melting from « truxillic 

 acid with KOH, ') belongs to the same series. 



The second series is derived from ^ truxillic acid, which through 

 melting with KOH passes into (f truxillic acid "*). The last acid yields 

 8 truxillic acid through heating with acetic acid anhydride; the s 

 truxillic acid possesses the same melting point as y truxillic acid ; 

 a mixture of the two acids melts, however, about 20° lower, from 

 which the difference of these acids can already appear. Also in the 

 solubility of their salts there are found great differences. 



By the formation of a truxillic acid from a normal cinnamic acid *) 

 and of [S truxillic acid from ,i normal cinnamic acid ^) it is known 

 that one of the 4 following structural formulae, corresponding with 

 the 4 different ways in which 2 molecules of cinnamic acid can 

 combine under formation of a tetramethylene ring, belongs to these 

 truxillic acids. 



These 4 structural formulae belong to 2 series viz. the two first 

 to one, and the two last to the other series. The members of these 

 series cannot be transformed into each other without previous 

 depolymerisation to cinnamic acid. 



We know from Liebermann's researches that ^ truxillic acid 

 yields benzil ^) on oxidation with potassium permanganate, from 



1) Ber. 22, 2255 ; Ber. 23, 2516 ; Ber. 26, 834 ; Ber. 27. 1410. 



3) LiEBERMANN, Ber. 22, 2240. 



3) Hesse, Ann. 271, 202. 



*) LiEBERMANN, Ber. 22, 2240. 



*) Ruber, Ber. 35, 2908. 



8) These Proc. 1915, Vol. XVIII p. 181. 



7) Ber. 22, 2253. 



