48 



VITAMINS A AND CAROTENES 



TABLE XIII 

 Physical Properties of Vitamin A Acid 



6. AnHYDRO VITAMIN Ai 



When vitamin A in all its isomeric forms is treated with small concentra- 

 tions of hydrogen chloride in ethanol, a hydrocarbon is formed whose ultra- 



4000 



3000- 



!f 5 2000 



1000- 



40 50 60 70 80 90300 10 20 30 40 50 60 70 80 90 400 10 20 30 40 

 Wavelength, m// 

 Fig. 10. Ultraviolet absorption spectra of anhydrovitamin Ai and anhydrovita- 

 min A2. 



violet absorption spectrum shows a fine structure of three maxima at 351, 

 371, and 392 m/x, respectively (Fig. 10). The same hydrocarbon is found in 

 small quantities in fish liver oils and in other natural sources of vitamin A. 

 Quite frequently it is also produced as a by-product in most of the synthetic 

 processes of vitamin A, 



