- i 5 6 - 



also from synthetic cinnamic acid. W. Marckwald and R. Meth 1 ) 

 now have severally proved that Erlenmeyer's inactive salt cannot 

 consist of equal molecules of brucine and cinnamic acid, as they always 

 obtained under the same conditions solutions of [«] D — 19,5°. Mix- 

 tures of cinnamic acid and brucine in the molecular proportion of 

 2 : 1 also still gave a specific rotation of — 4,2°; the melting point 

 of the mixture lay, however, also at 135 . The true neutral brucine 

 salt of storax cinnamic acid, on the other hand, melted indistinctly 

 between 107 and 113 , and contained 1 mol. crystal-alcohol. 



In his last work, published in conjunction with Barkow and Herz, 

 Erlenmeyer jun. 2 ) states that there are at least six different cinnamic 

 acids in existence. Five of these can be distinguished from each other 

 by the crystal-form, which has been examined in detail, and also by 

 the differences in melting point and solubility. The acids are: — 



1. Isocinnamic acid of Erlenmeyer sen.; m. p. 37 to 38 ; 



2. Allocinnamic acid of Liebermann; m. p. 68°; 



3. Isocinnamic acid of Liebermann; m. p. 59 ; 



4. a -cinnamic acid from Storax, m. p. 134 to 135 ; 



5. ft- cinnamic acid prepared from a-acid by rearrangement, m. p. 

 132 to 133 . 



To these acids which have all been examined in detail must 

 be added: — 



6. Isocinnamic acid of Erlenmeyer jun. and Allen; m. p. 59 ; 



7. New, triclinic cinnamic acid, m. p. 127 to 12 8°. 



The acid mentioned under 6. was obtained from the second, more 

 readily soluble amorphous brucine salt, which is formed from anhydrous 

 brucine and allocinnamic acid in absolute alcohol. The crystal-form 

 is the same as that of the acid under 3., but there are differences in 

 the development. 



The triclinic acid was obtained: 



1. from the brucine salt of the m. p. 1 5 1° from allocinnamic acid; 

 2. from synthetic cinnamic acid by means of frequently repeated 

 recrystallisation from 75 per cent, alcohol, and evaporation to dryness 

 and recrystallisation of the residue of the mother liquor in each 

 case. The crystals separating off from the solutions were identical 

 with storax cinnamic acid. 



Marckwald's statements with regard to the composition of the 

 brucine salt (m. p. 13 5 ) of storax cinnamic acid, were confirmed. 



x ) Berl. Berichte 38 (1905), 3499; 39 (1906), 1176, 1966, 2598. 

 2 ) Berl. Berichte 40 (1907), 653. 



