Azo Derivatives of the Pyrimidines

VOL. 18, 1932

CHEMISTRY: BOGERT AND DA VIDSON

215

AZO DERIVATIVES OF THE P YRIMIDINES* By MARSTON T. BOGERT AND DAVID DAVIDSON DEPARTMENT OF CHEMISTRY, COLUMBIA UNIVERSITY

Communicated February 15, 1932

Introduction.-This paper contains a preliminary survey of the azo derivatives of the pyrimidines with particular reference to derivatives of uracil. These derivatives fall into five natural types according to the nature of the components entering into their formation as follows: Those formed by (1) The coupling of aromatic diazonium salts with pyrimidine phenols. (2) The coupling of diazopyrimidines with aromatic phenols. (3) The coupling of diazopyrimidines with pyrimidine phenols. (4) The condensation of aromatic hydrazines with 5-keto-6-hydroxy5,6-dihydropyrimidines. (5) The condensation of hydrazinopyrimidines with 5-keto-6-hydroxy5,6-dihydropyrimidines. Examples of each of these types of azo derivatives had already been studied by us when the paper of Johnson, Baudisch and Hoffmann' on diazouracil appeared. Since these authors have indicated their intention of continuing the study of derivatives of this diazopyrimidine, we are publishing the results of our preliminary work at this time. Azopyrimidines of Type 1.-Pelizzari2 was the first investigator who attempted to condense alloxan (I) with phenylhydrazine. He failed owing to the occurrence of an oxidation-reduction reaction in which the alloxan was reduced to alloxantine and the phenylhydrazine oxidized to benzene and nitrogen. By using phenylhydrazine hydrochloride rather than the base, Kuhling3 succeeded in obtaining alloxan-5-phenylhydrazone NH-CO CO

NH-CO

NH-CO ONHNH2-HC1 I CO -- +C Co NNH

CO

NH-CO

NH-CO

I

II

CHN N

NH-CO 1 4 1-

NH-CO lo CO

NH-CO CH2

cJO

NH-CO N2C1

1

NH-CO

ANNO CN: N,0 ~ oC1

NH-COH III

NH-COH IV

(II). Several years later, Kuihling coupled benzene diazonium chloride with barbituric acid (IV) and found the product to be identical with alloxan-5-phenylhydrazone. II and III are, therefore, desmotropes of

CHEMISTRY: BOGERT AND DA VIDSON

216

PROC. N. A. S.

the quinonehydrazone-azophenol type. The isolated material appears to be represented by formula II, since the 1,3-dialkyl derivatives are not soluble in alkali. Kuhling also prepared the ortho- and para-nitro derivatives of II. Whitely4 coupled benzene diazonium chloride with 1,3-diphenyl barbituric acid and found the product to be identical with that obtained by condensing phenylhydrazine with 1,3-diphenyl-5,5-dibromobarbituric acid (1,3-diphenylalloxan-5-phenylhydrazone). This author confirmed the idea that formula II represents the structure of the alloxan-5-hydrazones by preparing compounds typified by formula V, which proved to be quite similar to the former in their properties.

ON-CO

ON-CO

JO LNNRR'

ON-CO

CIO

CO CR COC ON-SON:NRI VII

~~I I