CS250563B1 - 2-Nitrophenylhydrazone-propanedinitriles and their preparation - Google Patents

Abstract

The solution relates to a method for preparing new substances 2-nitrophenylhydrazonopropanedinitriles of the general formula I R NH-N=c (CN)^ N0„ from (1) where R represents a carboxyl, chlorocarbonyl and acetyl group. The essence of the method for preparing the above substances consists in coupling a diazotized 4-R-substituted 2-nitroaniline, where R has the above-mentioned meaning, at 0 to 5°C with propanedinitrile.

Description

250563

BACKGROUND OF THE INVENTION The present invention relates to 2-nitro-phenylhydrazone-propylenitriles of the formula I wherein R is carboxyl, chlorocarbonyl and acetyl. 2-Nitrophenylhydrazonopropanedinitriles as reversible thiol reagents vetmiperspective for reversible covalent chromatography and for stimulating the production of microorganism metabolites. The reactivity of phenylhydrazone propanedinitriles increases with the decreasing pKa value of the imino group, ie the reaction rate dependence on the substituents on the benzene nucleus appears to be related. Biophys. Acta 585, 462 (1979)). The pK a of the constituents of said phenylhydrazone propanedinitriles are greater than 5.7 and their reversible reactions occur only at high pH values, with most SH groups being oxidized by disulfide.

The above drawbacks are substantially discouraged by the preparation of the compounds according to the invention, wherein the sadiazotized 4-R-substituted 2-nitroaniline, where R is as defined above, coalesces at 0 to 5 ° C with propanedinitrile. The substituted 2-nitrophenylhydrazonopropane dinitriles have a pKa value of imino group of 5.3-5.6, which in principle means that their more reactive and reversible reactions occur at pH 6.4-8.0. The advantage of the proposed method of making it possible to use sparingly substituted 2-nitroanilines gives the possibility of preparing substituted 2-nitrophenylhydrazone propanediitriles with a targeted functional group content in their skeletons, is simple and does not apply to the chemicals and apparatus used. 4-carboxy-2-nitrophenylhydrazonopropanedinitrile. 1.68 g of 3-nitro-4-aminobenzoic acid are added to 0.69 g of sodium nitrite in 8 g of concentrated sulfuric acid at 20 DEG C. with stirring for 10 minutes. The resulting diazonium salt solution is coupled with 0.66 g of propanedionitrile in 3 ml of ethanol at 0-5 ° C. After addition of 2.5 g of finely divided sodium acetate and treatment with H 3 to 4 with diluted sodium hydroxide solution (15%), the product is isolated. By crystallization from dichloroethane, a pure product of 70% yield was isolated, m.p. 274-277 degrees Celsius. IR spectrum (KBr): ν (c = N) = 2235 cm -1.

H, 1.94; N, 27.02. Found: C, 46.28; H, 2.12; N, 27.11. 2 Preparation of 4-acetyl-2-nitrophenylhydrazone-propanedinitrile. 2.2 g of 3-nitro-4-aminoacetophenone are dissolved in a mixture of 12 ml of water and 2.5 ml of concentrated hydrochloric acid. The reaction mixture was cooled to 0 ° C and a 1-hour solution of 0.85 g of sodium nitrite in 8 ml of water was slowly added dropwise over 15 minutes.

The solution of the resulting diazonium salt was stirred at 0-5 ° C by addition of 0.8 propanedionitrile in 4 mL ethanol. Then a solution of 4.1 g of sodium acetate in 12 ml of water was added and the reaction mixture was allowed to stand at room temperature. After an hour, the product was washed with water and dried in silica gel silica gel.

The pure product is isolated by crystallization from a chloroform-ether mixture in 75% yield with m.p. 143-144 ° C. IR spectrum (KBr): ν (C = n) = 2235 cm @ -1.

For C11H7N5O3 (257.21) calculated: 51.36% C, 2.74% H, 27.22% N, found: 51.54% C, 2.99% H, 26.85% N. Example 3 Preparation 4-chlorocarbonyl-2-nitrophenylhydrazonopropanedinitrile. 4-Carboxy-2-nitrophenylhydrazonopropane dinitrile (0.26 g) was refluxed with thionyl chloride (4 mL) for 1 h. Unreacted thlonyl chloride was removed by vacuum distillation. The crude product is recrystallized from tetrachloromethane. The yield of pure product with mp 284-288 UC is 80%. IR spectrum (KBr): more = N) = 2235 cm @ -1.

Claims (3)

1. 2-Nitrophenylhydrazonopropanedinitriles of the general formula I R = NH-C N0 _o INVENTION where R represents a carboxyl, chlorocarbonyl and acetyl group. 2. A process for the preparation of the compounds of the formula I as claimed in claim 1, characterized in that the diazotized 4-R-substituted-2-nitroaniline, where R is as defined in point 1, is coupled with propanedinitrile at 0-5 ° C.