82 AARON BENDICH 



living," the viruses. These compounds, in the free form as well as in a 

 wide variety of chemical combinations, have caught the attention and 

 imagination of biologists, enzymologists, chemists, oncologists, physicists, 

 and many students of chemotherapy. 



Recognition of this group of compounds dates back to the discovery in 

 1776 of uric acid by Scheele and by Bergmann and of alloxan in 1818 by 

 Brugnatelli.'^ It includes the pioneering studies on uric acid of Liebig and 

 Wohler^'* begun in 1834 and those of Baeyer^ in 1863 which led to the 

 cycHc formulation (1875) of uric acid and guanine by Medicus^ and the 

 pyrimidine nucleus (1884-5) by Pinner.^ '^ The classic studies on purines 

 (1882-1907) by Fischer have been collected in a single volume^ which also 

 contains a description of the early work. There are other excellent treatises 

 which deal with the history and development of these substances and their 

 occurrence as components of the nucleic acids. ^"'^^ 



2. Nomenclature 

 The term pyrimidine was coined by Pinner^ from a combination of the 

 words pyridine and amidine. He was the first* to point out the structural 

 similarity of pyrimidines to benzene, pyridine, and s-triazine, and, ac- 

 cordingly, depicted the ring system in the form of a regular hexagon .''•^•i^ 

 Although the hexagonal representation of pyrimidines (I) has been adopted 

 by Chemical Ahstracts^^ and The Ring Index,^'' many authorities have pre- 

 ferred the rectangular form (11)9. 13,14,18,19 numbered as shown (II), or as 



2 G. Brugnatelli, Ann. Cheni. Phijs. [2] 8, 201 (1818). 



3 J. Liebig, Ann. 10, 47 (1834). 



< F. Wohler and J. Liebig, Ann. 26, 241 (1838). 



^ A. Baeyer, Ann. 130, 129; 131, 291 (1864); See also Ann. 127, 199 (1863). 

 6 L. Medicus, Ann. 175, 230 (1875). 

 ^ A. Pinner, Ber. 17, 2519 (1884). 

 8 A. Pinner, Ber. 18, 759, 2845 (1885). 



^ E. Fischer, "Untersuchungen in der Puringruppe." Springer, Berlin, 1907. 

 '" C. Brahm and J. Schmid, in "Biochemisches Handle.xikon" (Abderhalden, ed.), 



Vol. 4, pp. 1014, 1131. Springer, Berlin, 1911. 

 " W. Jones, "Nucleic Acids, Their Chemical Properties and Physiological Conduct." 



Longmans. Green and Co., London, 1920. 

 ^^ R. Feulgen, "Chemie und Physiologic der Nucleinstoffe nebst Einfiihrung in die 



Chemie der Purinkorper." Borntraeger, Berlin, 1923. 

 ^3 P. A. Levene and L. W. Bass, "Nucleic Acids." Chemical Catalog Co., New York, 



1931. 

 1^ T. B. Johnson and D. A. Hahn, Chem. Revs. 13, 193 (1933). 

 '5 A. Pinner, Ber. 20, 2361 (1887); 22, 1600, 1612 (1889); 26, 2122 (1893). 

 i« Chem. Abstr. 39, 5867 (1945). 

 " A. M. Patterson and L. T. Capell, "The Ring Inde.x," p. 52. Reinhold, New York, 



1940. 

 '* T. B. Johnson, m "Organic Chemistry, An Advanced Treatise" (Gilman, ed.). 



Vol. 2, p. 948. Wiley, New York, 1938. 

 '^ F. Schlenk, Advances in Enzymol. 9, 455 (1949). 



