OCCURRENCE AND STRUCTURE OF RELATED COMI'OTTNDS 711 



formula which has been assigned to it is C4oH58(OH)2. This corresponds 

 to a molecular weight of 572; actually the observed value is 575. It was 

 shown by microhydrogenation studies that this substance has 8 double 

 bonds (7.85 found). The assumption that kitol is a dihydric alcohol is 

 based upon the fact that it forms a dinitrobenzoate. It also contains at 

 least one asymmetric carbon atom, as it displays optical activity 

 ([«]546.i mn = —1.35° in chloroform). 



Kitol possesses a number of distinctive properties. It can be crystallized 

 from methyl alcohol in the form of elongated prisms which melt at 88-90°C-. 

 It is quite stable toAvard atmospheric oxidation; no change was observed in 

 the absorption curve after 53 hours at room temperature in the dark. 

 However, in daylight, a 56% destruction occurred after 46 hours under 

 similar temperature conditions. Kitol was found to be relatively stable in 

 ethanol, inasmuch as it was shown that the extinction coefficient had dropped 

 only 7% after storage for 10 days in the dark at room temperature.^*"^ 



Kitol gives a maximum absorption at 290 mix, at which wave length the 

 extinction coefficient, E (1%, 1 cm.), has been shown to be 707. ^^^ The 

 presence of a peak in this area of the ultraviolet region in whale oil was 

 noted a number of years ago by Pritchard et al.^^^ and by Willstaedt and 

 Jensen. ^^"^ Inasmuch as the absorption is considerable at 328 m/x, the pres- 

 ence of kitol will mask the presence of vitamin A. Although kitol reacts 

 with antimony trichloride, the maximum absorption band is at 570 m^u; 

 the amount of chromogen produced at 620 m^ in this reaction can be used 

 for the determination of the amount of vitamin A in the presence of kitol. 

 The kitol present in the northern pike has the absorption band at 310 m/x 

 instead of at 290 m/x. With antimony trichloride, it reaches a peak at 510 

 m/i. A\Tien it is subjected to distillation, the resulting product shows a 

 maximum absorption with antimony trichloride at 690 m/x. The authors 

 believe that this indicates that it is vitamin A2. The kitol from fresh-water 

 fishes is therefore referred to as kitol2. 



The most important property of kitol is its conversion by heat to vitamin 

 A. According to the results of Embree and Shantz^*^ which are given in 

 Table 11, one molecule of vitamin A is produced for each molecule of kitol 

 destroyed. The destruction of kitol was based upon the decrease of the 

 E (1%, 1 cm., 286 m/x) value, while the amount of vitamin A produced was 

 judged by the increase of the E (1%, 1 cm., 620 m/x) after antimony tri- 

 chloride was added. On the basis of later work, Clough et al.^^'^ reported 

 that, on distillation of a peanut oil solution of kitol palmitate in the molec- 

 ular still, 0.67 to 0.75 molecule of vitamin A originated for each molecule 

 of the kitol ester destroyed. Kitol palmitate was found to have an extinc- 

 tion coefficient of 379 at the maximum absorption (290 m/x) . 



'»9 H. Pritchard, II. Wilkinson, J. R. Edisbury, and R. A. Morton, Biochem. J., 31, 

 258-265 (1937). 



"0 H. Willstaedt and H. B. Jensen, Nature, 143, 474 (1939). 



