294 



abundant series of investigations brought full experimental proof 

 and the exhaustive demonstration of the possibility of such one- 

 sided syntheses under the directing influence of pre-existent mole- 

 cular dissymmetry, 



If l-menthyl-benzoyl- formate was treated with ethyl-magnesium- 

 iodide, and then' the compound obtained by the aid of water: 



,OH 

 C 6 H 5 CfCOOC 10 H 19 



X C 2 H 5 



saponified by potassium-hydroxide, the phenyl-ethyl-glycolic acid 

 produced, appeared to be /^esyogyratory. If however instead of 

 C 2 H 5 Mg J , the corresponding C 6 H 5 Mg Br was ' used in this 

 reaction, the benzilic acid obtained was absolutely mactive. 



The l-menthyl-ether of pyruvic acid was reduced by A /-amalgama 

 and a little water, and the product decomposed by alcoholic caustic 

 potash: now a laevogyrate lactic acid resulted. 



Fractional saponification of l-menthyl-rac mandelate gave almost 

 always a dextrogyrate mandelic acid; it was proved by a series 

 of controlling experiments that the result was affected by the 

 racemising influence of the alkali, and that the quite opposite 

 results previously stated in many cases, could be simply explained 

 by the shorter or longer duration of this racemising action of 

 the saponifying base. The relative velocities of saponification of 

 l-menthyl-, or l-bornyl-d-, resp. -l-mandelates by dilute hydrochloric 

 acid, were also measured. It appeared that the l-borny I- esters are 

 saponified much more quickly than the corresponding l-menthyl- 

 ethers, and that in both cases the derivatives of the dextrogyrate 

 mandelic acid are the more rapidly saponifiable. 



The following dates, obtained with a 0.07725 normal hydrochloric 

 acid-solution at 40 C, may give some impression of these differences: 



Reaction-constant : 



k: 



l-bornyl-l-mandelate 8 1 ,2 



l-menthyl-l-mandelate 28.5 

 (time in minutes) 



Reaction constant: 



k: 



l-bornyl-d-mandelate 84,9 



l-menthyl-d-mandelate 35,6 



(time in minutes) 



The ratio of the velocities is here in both cases: 



V d 



for the borny ^-ethers, -==- = 1,046; 

 " 



d 

 for the menthyl- ethers, -=^ = i ,250. 



