289 



will be changed by an aqueous solution of ammonia into the dextro- 

 gyratory aspartic acid. By the same succession of reactions the latter 

 will now be transformed into the original laevogyratory acid, etc. 



These highly remarkable "inversions" have been observed almost 

 exclusively in cases in which the atoms and radicals: Cl, Br, OH, 

 and NH 2 , when linked directly to the asymmetric carbon-atom, 

 are replaced by a cyclic of substitutions; however, as has already 

 been said, the occurrence of a change of the optical rotation from 

 positive to negative, or vice versa, is greatly dependent on the 

 reagents employed in the transformations. *) 



Fischer 2 ) has made an application of the inversion produced 

 by the mutual substitution of halo gen-atoms, and the ammo-group, 

 for the purpose of obtaining both the antipodes of racemic 

 polypeptides, as for instance in the case of l-alanyl-glycine. 



A certain, although small number of regularities have been 

 found. Thus the substitution of hydroxyl-groups in hydroxy-acids 

 and their ethers by Cl or Br, is commonly connected with a change 

 of the rotatory effect from positive to negative, and vice versa, 

 if PC1 5 and PBr 5 be used in the reaction. An exception to this 

 rule, which in many cases appears to hold good, was found by 

 Guye and Jordan 3 ), who showed that the laevogyratory isobutyl- 

 ether of normal-a-hydroxy-butyric acid: CH 3 .CH 2 .CH(OH).COOC^H 9 , 

 was transformed by PC7 5 into a laevogyratory chlorinated, but 

 by PBr 5 into a dextrogyratory brominated derivative. However, even 

 in this instance it is by no means certain, that these two cases also, 

 correspond to a real difference in configuration; for it is quite 

 possible, that if both Cl and Br come into the same place in space 



(1909); 97, 1016, 2564, (1910); 101, 390, (1912); P. F. Frankland, Journ. Chem. 

 Soc. London, 103, 713, (1913); B. Holmberg, Ber. d. d. Chem. Ges., 45, 1713, 

 (1912); Journ. f. prakt. Chemie, 87, 456; 88, 553, 590, (1913); B. Holmberg and 

 K. J. Lenander, Arkiv for Kemi, Min., och Geol., 6, (1916) and (1917); B. G. W. 

 Clough, Journ. Chem. Soc. London, 113, 526, (1918); P. Karrer and W. Kaase, 

 Helv. Chim. Acta, 2, 436, (1919); W. P. Wynne, Chem. News, 108, 146, (1913). 

 J ) Cf.: O. Lutz, Ber. d. d. Chem. Ges., 41, 841, (1908); Zeits. f. phys. Chemie, 

 70, 256, (1909); B. Holmberg, Journ. fur prakt. Chemie, N. F., 87, 471; 

 88, 553, (1913). 



2 ) E. Fischer, Ber. d. d. Chem. Ges., 39, 2895, (1906); 40, 489, (1907); Cf. 

 also: E. Fischer and K. Raske, Ber. d. d. Chem. Ges., 40, 1051, (1907); E. 

 Fischer and H. Scheibler, ibid., 41, 889, 2891, (1908); 42, 1219, (1909); E. 

 Fischer, H. Scheibler and R. Groh, Ber. d. d. Chem, Ges., 43, 2020, (1916); 

 E. Fischer, Chem. Zeitg., (1910), p. 825. 



3 ) Ph. A. Guye and Ch. Jordan, Bull, de la Soc. Chim., (3), 15, 495, (1806). 



19 



