1051 



of VAN RoMBURGH, ') niostlj of the iiietlijl ester of cimianiic acid. 

 Erlenmeyek ') states that on treatment with etiier the cinnamic acid 

 prepared from Alpinia gave crystals on the sides of tlie beaker 

 which resembled the S3nthetic acid, while on the bottom beautifnl 

 crystals of «-storaxcinnamic acid were formed. 



The ethereal oil was saponitied, (he solution extracted three times 

 with light petroleum, and the acid precipitated, filtered, and washed. 

 On oxidation with potassium permanganate the mixture foamed up 

 vigorously so that the distillation had to be continually interrupted 

 in order to avoid frothing over, although the flask was sufïiciently 

 large. For this leason (he yield was very poor. In order to purify 

 it, the acid was therefore dissolved by heating in sodium carbonate 

 solution. On cooling the solution was extracted three times with 

 light j)etroleum, and (he acid again precipitated. This product gave 

 no frothing on oxidation with potassium permanganate. Cinnamic 

 acid prepared by the Perkin synthesis separates out, according to 

 Erlenmkyer *), after treatment with ether in characteristically developed 

 crystals of «-cinnamic acid, which exhibited no perceptible difference 

 from the original acid. 



The cinnamic acid was then dissolved in caustic soda solution in 

 just sufficient quantity of (he latter, so that 1 gr. of the 9 gr. acid 

 present remained uimeutralised *). The solution was then well boiled, 

 and the acid separated completely by shaking after cooling. From 

 solution in ether the acid crystallised in large flat plates which 

 differed from the original acid in their size and thinness. Hetero- 

 cinnamic acid, which, according to Erlenmeyer, should result from 

 this procedure, was not obtained. The crystals did not correspond 

 with those of the so-called synthetic cinnamic acid, since (he edges 

 were straight and the angles well formed. They approximated closely 

 to them, however, and showed also iridescence. 



The possibility was not excluded that the difference from the 

 naturally occurring acid was due (o an impurity in the cinnamic 

 acid used. F'or this reason 1 have subjected the substance to different 

 processes of purification, which may be briefly indicated in the 

 following. 



Parificdtion of the methi/lester hi/ crystal! Nation. 



For this purpose more than 5 kilos of the ethereal oil were (aken 



1) These Proceedings, April 1898. 



3) Ber. 39, 1581. 



3j Biochem. Zeitschr. 34, 406. In place of beakers Erlenmeyek used flasks. 



*j Ber. 42, 519, 



