260 



ASCORBIC ACID 



Absorption spectrum in slightly acid aqueous solu- 

 tion characterized by a single intense band with 



head at wavelength 245 m^ 245 m/i 



Molecular extinction coefficient 10,000 10,000 



Ultimate analysis, C 40.9%« 40.95% 



Ultimate analysis, H 4.6%« 4.6% 



" Theoretical. 



Further detailed data (some being more recent) are as follows:* 



Empirical formula 

 Molecular weight 

 Melting point 

 Acidic dissociation pKi 

 Acidic dissociation pK^ 

 Solubility 



Specific rotation in water 

 Specific rotation in methyl alcohol 

 Absorption maxima in water 

 Oxidation-reduction potential, £"„ 



CeHgOb 



176 



192° 



4.2 



11.6 



Soluble in water, methyl alcohol, ethyl alco- 

 hol; insoluble in ether, xylene, benzene, 

 chloroform, petroleum ether, etc. 



24° 



48° 



265 m/x small band between 250 and 400 m^t 



0.166 V. at pH 4.0 and 35° 



The physical constants given by the United States Pharmacopeia are as 

 follows:* 



Solubility 



Specific rotation [a]; 



1 g. dissolves in about 3 ml. of water and 30 



ml. of alcohol 

 In a solution containing the equivalent of 10 



g. in 100 ml. of solution using a 200-mm. 



tube, between -|-20.5° and +21.5° 



The following constants and method of assay are given by the British 

 Pharmacopoeia:^ 



Molecular weight 

 Melting point 

 Specific rotation 



Ultraviolet absorption 



176.1 



190° to 192° with decomposition 



Determined in a 2% w/v solution in water, 



-f 22° to -f 23° 

 In 2% w/v solution in methyl alcohol, -|-50° 



to +51° 

 In 2% w/v solution in a mixture of 12 ml. N 



sodium hydroxide and water to 100 ml., 



+ 112° to +115° 

 Determined in a 0.002% w/v solution in water 



at pH 3 or less, at 245 mju, 550 



2 P. Gyorgy, Vitamin Methods, Vol. 2, p. 244. Academic Press, New York, 1951. 

 * United States Pharmacopeia, 14th revision, p. 57. Mack Printing Co., Easton, 



Pa., 1948. 

 s The General Medical Council, The British Pharmacopoeia 1948, p. 20. Constable 



and Co., London, 1948. 



