309 



Such facts were already met with in Fischer's experiments 

 on the transformation of sugars. 



Marckwald and Paul ! ) heated racemic mandelic acid and 

 brucine for ten hours at 150 C. ; when the molten mass, after 

 solidification, was dissolved in water, and the acid set free by 

 means of sulphuric acid and extraction with ether, it appeared 

 to be dextrogyratory. 



Since 1904 MacKenzie and his collaborators 2 ) have by an 

 abundant series of investigations brought full experimental proof 

 and the exhaustive demonstration of the possibility of such one- 

 sided synthesis 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 -C^COOC 10 H 19 



C 2 H 5 



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



produced, appeared to be laevogyratory. If, however, instead of 

 C 2 H 5 MgJ, the corresponding C 6 H 5 MgBr was used in this reaction, 

 the benzilic acid obtained was absolutely inactive. 



The l-menthyi-ether of pyruvic acid was reduced by ^4/-amalgama 

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

 potash: a tewgyratory lactic acid resulted. 



Fractional saponification of l-menthyl-rac. mandelate gave almost 

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

 of controlling experiments, that the result was affected by the 

 racemizing influence of the alkali, and that the quite opposite 

 results previously found in many cases, could be simply explained 

 by the shorter or longer duration of this racemizing 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-bornyl-ethers are 

 saponified much more quickly than the corresponding l-menthyl- 

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

 mandelic acid are the more rapidly saponifiable. 



1) W. Marckwald and D. M. Paul, Ber. d. d. Chem., 38, 810, (1905). 



2 ) A. MacKenzie, Journ. Chem. Soc. London, 85, 378, 1004, 1249, (1904); 

 A. MacKenzie and H. B. Thompson, Journ. Chem. Soc., 91, 789, (1907); A. 

 MacKenzie and H. Wren, ibid., p. 1215, (1907); A. MacKenzie and H. A. 

 Miiller, ibid., p. 1814, (1907). 



