297 



Thus Boyd l ) tried to reduce benzoyl-formic acid by means of 

 hydrogen in aqueous solutions of dextrogyratory tartaric, or laevo- 

 gyratory mandelic acid; the mandelic acid produced in this reduc- 

 tion was completely inactive, or its activity corresponded to that 

 of the active acid used in excess. 



Kipping 2 ) studied the reaction between KCN or HCN, 

 and benzaldehyde, in an alcoholic solution of optically active 

 camphor, or the reduction of pyruvic acid in an aqueous solution 

 of d-glycose; the results were equally negative. E. and O. Wede- 

 kind 3 ) investigated the addition of allyl-iodide to methyl-benzyl- 

 aniline in optically active limonene as a solvent, but they could 

 only obtain optically inactive products, and the same was true, 

 when they used as solvents l-menthol or l-chloro-methyl-menthyl-ether. 



From these experiments it may be concluded that it is highly 

 improbable that a positive difference in reaction-velocity would 

 be observed in the case of both antipodes, when optically active 

 liquids are used as solvents, namely, so long as they do not 

 themselves take part in the reactions. This may also be concluded 

 from the experiments of Bredig and his collaborators: thus 

 Bredig and Balcom 4 ) stated, that d- and l-campho-carboxylic 

 acids are split into camphor and carbon-dioxide equally quickly 

 when dissolved in d-, or in l-limonene. But, as we shall see later, 

 as soon as optically active bases (like quinine, quinidine, nicotine, 

 etc.) are used in this case as solvents, which undoubtedly take 

 part in the reaction, combining with the acids to form inter- 

 mediate compounds, the differences in reaction-velocity of 

 both antipodes can clearly be demonstrated. 



7. Thus, if the components A and A' really combine with 

 the active molecule B, a difference in reaction-speed will most 

 probably be found, notwithstanding the equal affinity of both 

 antipodes towards B, because there is some guiding influence of 

 the pre-existing dissymmetry of B in the formation of the com- 

 pounds AB and A'B. 



It is on this principle that the new method of fission of race- 

 moids, proposed in 1899 by Marckwald and MacKenzie 5 ), 



!) D. R. Boyd, Inaug. Dissert., Heidelberg, (1896). 



2 ) F. S. Kipping, Proceed. Chem. Soc., 16, 226, (1900). 



3 ) E. and O. Wedekind, Ber. d. d. Chem. Ges., 41, 456, (1908). 



4 ) G. Bredig and R. W. Balcom, Zeits. f. phys. Chemie, 41, 740, (1908). 



5) W. Marckwald and A. MacKenzie, Ber. d. d. Chem. Ges., 32, 2130, (1899). 



