10 



P-AMINOBENZOIC ACID 



Peterson^^ have obtained the N-D-ribosido- and N-L-arabinosido-p-amino- 

 benzoic acids. N-Glucosido-p-aminobenzoic acid has also been reported.^" 

 Cherbuliez and Mori^' mercurated PABA by means of mercuric acetate. 

 The reaction results in the formation of an inner salt in which the mercury 



HoN- 



-COOH 



Hg(0Ac)2 

 H2O 



HgOH 

 HN 



\ // 



-COOH 



] 



Hg 



.0 



H2N- 



^ // 



\ 



o 



atom is linked to the ring in the 2 position. Support for this structure is 

 to be found in the fact that when the internal salt is made to react with 

 iodine the mercury is displaced, and 2-iodo-4-aminobenzoic acid is obtained. 



D. DERIVATIVES 



A number of solid derivatives useful for the identification of PABA are 

 Usted in Table II. 



TABLE II 

 Derivatives for the Identification op PABA 



Compound 



Melting 

 point Reference 



Compound 



Melting Ref- 

 point erence 



Acetyl 250-251 8, ' 



Benzoyl 278 73 



Benzylamide 89-90 74 



m-Nitrophenylthiourea 221-222 75 



«9 J. O. Lampen and W. H. Peterson, Arch. Biochem. 2, 443 (1943). 



70 A. Dansi, Farm. sci. e tec. (Pavia) 2, 195 (1947) [C.A. 42, 639 (1948)]. 



'1 E. Cherbuliez and M. Mori, Helv. Chim. Acta 28, 17 (1945). 



"A. Kaiser, Ber. 18, 2942 (1885). 



'3 A. Bruckner, Ann. 205, 113 (1880). 



■'^ O. C. Derner and J. King, /. Org. Chem. 8, 168 (1943). 



" W. L. Tung, C. H. Kao, C. H. Kao, and P. P. T. Sah, Science Repts. Natl. Tsinghua 



Univ. A3, 285 (1935) [C.A. 30, 2875 (1936)]. 

 '"B. C. Saunders, /. Chem. Soc. 1938, 1397. 

 7' S. P. Mulliken, Identification of Pure Organic Compounds, Vol. 2, p. 68, John 



Wiley and Sons, New York, 1916. 

 '8 J. S. Sudborough and S. H. Beard, /. Chem. Soc. 97, 773 (1910) 



