592 



H 



CooH j^ 



€OOH 



h 



which it appears that for this acid the CgHj-groups must be found 

 at 2 adjacent C-atoms, so that in connection with the formation 

 from normal cinnamic acid one of (he formulae 111 or IV must 

 be assigned to this acid. 



The /i truxillic acid forms an internal anhydride ^), and is not 

 changed into another truxillic acid bj' heating with acetic acid 

 anhydride ^). It appears from this that the COOH groups are placed 

 on the same side of the closed-chain of four carbon atoms; hence 

 we must give formula III to the acid. 



Through melting with KOH 6 truxillic acid is formed from ^ 

 truxillic acid *); this acid cannot have arisen from the former by 

 displacement of one COOH or one CgHj from one side of the ring 

 to the other side, because then in the former case 6 truxillic acid 

 with acetic acid anhydride would have to yield ^ truxillic acid, 

 and in the other case 6 truxillic acid would not be changed by 

 heating with acetic acid anhydride, neither of which is conformable 

 to the facts. It must, therefore, be assumed, that 2 groups exchange 

 places at the same time, viz. a CgHs group and a COOH group, 

 because, as is easy to see, the formation of e truxillic acid from 6 



1) Ber. 22, 834. 

 8) Id. 2240. 

 8) .1. c. 



