239 



How. ver it i> ju-t in this respect that the weak point .i (.uye's 

 -live theory lies: for if the asymmetric carbon-atom be linked 

 tn two i-omeric radicals A and A', which accidently possess equal 



s, the molecule can yet have optical artivitv. a^ ha- 

 slio\\n by din-rt experiments. 



Thus Fischer and Flatau 1 ) succeeded in performing the 

 of propyl-isopropyl-cyano-acetic acid: 



(C 3 # 7 ) x /CN 

 C 



into its antipodes, and demonstrated that these have a rather large 

 specific rotation (11), notwithstanding the equality of mass of 

 the propyl-, and isopropyl-groups. 



Indeed, the mass-differences of the substitutes appear to have 

 quite a secondary importance for the magnitude of the specific 

 rotatory power of the molecules, as may be seen from the following 

 examples. 



Werner 2 ) in his masterly investigations on complex inorganic 

 salts exhibiting optical activity, has demonstrated that derivatives 

 of the atoms of trivalent Co, Cr, Rho, Fe, etc., which all have 

 the co-ordinative number six, and which belong to the type: 

 Me[(X") 3 }R 3 , in which X" is a bivalent radical or base, can be 

 resolved by suitable means and under favorable circumstances, 

 into two enantiomorphously related antipodes which, although all 

 substitutes X" are here equal and thus have the same mass, exhibit 

 an enormous rotatory power, surpassing all that has been observed 

 up till now in carbon-compounds. These optically active salts belong 

 to the -most interesting and remarkable objects chemistry offers, 

 and their physical properties are so wonderful, that their detailed 

 study will certainly reveal many surprises yet. 



Fig. 163 for example may give some impression of the enormous 

 rotatory power and rotation-dispersion of the tri-cthylcnediamine- 

 cobalti-ssAts, which may be compared with the dispersion-cur ve 

 of ordinary cane-sugar, represented by the almost straight line 

 beneath 3 ). Often abnormal dispersion-phenomena are observed here 



1) E. Fischer and E. Flatau, Ber. d. d. Chem. <',i-s. 42. 981. (1909). 



2) A. Werner, Ber. d. d. Chem. Ges. 45. 121. (1912); 47. 1960,3093, 

 (1914); etc. 



8) F. M. Jaeger, Proceed. Ron. Akad.v. Wet. Amsterdam, Vol. 17. 1231. (1915). 



