293 



(hat hr.uin- was stopped l>ei.. ; plitting-off of carbon 



dioxide was fully completed, he undoubtedly would ha\v ioimd 

 ,i!i excess <>! the lelt antijxxie in the roidiie, alter the l>niiinc 

 was removed from it. 



An attempt of Marck wa Id and M c t h ') to render an opj 

 activity to ethyl- -at- chloro-pheny '/- acetate by heating it with two 

 molecules of brucine, and to isolate the unattacked ethei 

 the reaction-mixture, had no positive result. But when the 

 rtm/6'-formation was used, the velocity of which, according to 

 Menschutkin's investigations, is to a high degree dependent 

 on the chemical constitution of the reacting molecules, they found 

 that there was a considerable difference in velocity, if l-menthyl- 

 amine and racemic mandelic acid were used in the process. Indeed 

 the non-attacked acid appeared to be laevogyratory , and therefore 

 the ratio of the velocities V& : Vi was about: 0,86 in this case, 



If at-phenyl-ethyl-amine: C 6 H & . CH. (NH 2 ). CH 3 , was heated with 

 l-quinic acid at 165 for 4| hours, and if the quinate of this base 

 not yet transformed into amide, was decomposed by Na OH, the 

 base finally obtained appeared to have an excess of about 3% of 

 the dextrogyrate component. The ratio of the velocities, at which 

 combination with the laevogyrate acid took place, was here: 

 V d : Vi --= 0,88. 



The velocity of racemisation of two compounds of the same 

 optically active base with a left-, or righthanded acid, will also 

 appear to be different, if they be heated above their racemisation- 

 temperature. 



Such facts were 'already met with in Fischer's experiments 

 on the transformation of sugars. 



Marckwald and Paul 2 ) heated racemic mandelic acid and 

 brucine at 150 C. for ten hours; 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 

 indeed to be ^&^rogyratory. 



Since 1 904 Mac Kenzie and his collaborators 8 ) have by an 



1) W. Marckwald and R. Meth, Ber. d. d. Chem. Ges. 88. 801. (1905). 



2) W. Marckwald and D. M. Paul, Ber. d. d. Chem. Ges. 88. 810. (1905). 

 8) A. Mac Kenzie, Journ. Chem. Soc. London. 85. 378, 1004, 1249. (1904); 



A. Mac Kenzie and H. B. Thompson, Joum. Chem. Soc. 91. 789. (1907); A. 

 Mac Kenzie and H. Wren, ibid. p. 1215. (1907); A. Mac Kenzie and II A 

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



