CS276460B6 - Process for preparing 3- (N-methylamino) -6-X-7-Y-8-Z-2H-1-benzopyran-2-one compounds - Google Patents

Abstract

Process for preparing 3- (N-methylamino) -6-X-7-Y-8- '-Z-2H-1-benzopyran-2-one compounds of formula (I) wherein I, Υ, Ζ is as defined in the description that have not yet been prepared. The compounds have utility as light stabilizers for polymers and near-UV laser media. The compounds of formula (I) are prepared by m.p. nodemethylation of the corresponding 3- (N, N-dimethylamino) -6-X-7-Y-8-Z-2H-1-benzopyran-2-one by UV irradiation (ω = 290 nm) in the presence of substituted nitrobenzenes of general formula of formula (II).

Description

The present invention relates to a process for the preparation of substituted 3- (N-methylamino) -6-X-7-Y-8-Z-2H-1-benzopyran-2-one compounds which have not been prepared heretofore. Said compounds can be used as photostabilizers for polymers and laser media in the near UV region. The advantage of these compounds is that they are colorless and do not cause discoloration of the polymer.

The present invention provides a process for the preparation of substituted 3- ('N-methylamino) -6-X-7-Y-8-Z-2H-1-benzopyran-2-one compounds of formula (I).

OF

wherein X represents hydrogen, chlorine or nitro

Y is hydrogen, bromine or methoxy

From a hydrogen, chlorine or methoxy group by the action of UV radiation (290 Τ '290 nm) on 3- (N, N-dimethylamino) -6-X-7-Y-8-Z-2H-1-benzopyran-2-one compounds in the presence of substituted nitrobenzenes of general formula (II)

wherein A represents hydrogen or a nitro group. B hydrogen, chlorine or a nitro group gives a compound of formula (I).

Mono-demethylation produces products in satisfactory purity with high yields using accessible and industrially produced passive components.

The method of preparation is clear from the following examples:

Example 1. :

0.9 g (0.005 mol) of 3- (N, N-dimethylamino) -2H-1-benzopyran-2-one and 4.7 g (0.03 mol) of 1-chloro-4-nitrobenzene were dissolved in 480 ml benzene. The solution thus prepared was irradiated with ultraviolet light> 290 nm. A 400 W high pressure mercury lamp was used as the light source. After 6 hours of irradiation, the reaction mixture was concentrated in vacuo and the product was isolated by _{preparative column chromatography on SiO 2.} Petroleum ether-benzene mixture was used as eluent.

81% of product was obtained. The NMR and IR spectra confirm its presumed structure.

Example 2

0.9 g (0.005 mol) of 3- (N, N-dimethylamino) -2H-1-benzopyran-2-one and 5 g (0.03 mol) of 1,4-dinitrobenzene were dissolved in 480 ml of benzene. The solution thus prepared was irradiated with ultraviolet light A _exc > -290 nm. A 400 W high pressure mercury lamp was used as the light source. After 8 hours of irradiation, the reaction mixture was concentrated in vacuo and the product _{was isolated by preparative column chromatography on SiO 2.} Petroleum ether-benzene was used as eluent.

48% of product was obtained. The NMR and IR spectra confirm its presumed structure.

. CS 276 460 B6 2

Example 3

0.9 g (0.005 mol) of 3- (N, N-dimethylamino) -2H-1-benzopyran-2-one and 5 g (0.03 mol) of 1,3-dinitrobenzene were dissolved in 480 ml of benzene. The solution thus prepared was irradiated with ultraviolet light Λ _exc > 290 nm. A 400 W high-pressure mercury lamp was used as the light source. After 6 hours of irradiation, the reaction mixture was concentrated in vacuo and the product was isolated by preparative column chromatography on S1O2. Petroleum ether-benzene was used as eluent.

64% of the product was obtained. The NMR and IR spectra confirm its presumed structure.

Example 4

0.9 g (0.005 mol) of 3- (N, N-dimethylamino) -2H-1-benzopyran-2-one and 3.6 g (0.03 mol) of nitrobenzene were dissolved in 480 ml of benzene. The solution thus prepared was irradiated with ultraviolet light λ exc. ^{290 290} nm. A 400 W high-pressure mercury lamp was used as the light source. After 8 hours of irradiation, the mixture was concentrated in vacuo and the product was isolated by preparative column chromatography on S1O2. Petroleum ether-benzene was used as eluent.

70% of the product was obtained. The NMR and IR spectra confirm its presumed structure.

Claims (1)

Process for the preparation of substituted 3- (N-methylamino) -6-X-7-Y-8-Z-2H-1-benzopyran-2-ones of general formula (I) ‘------- Z wherein X represents hydrogen, chlorine or nitro Y is hydrogen, bromine or methoxy Z is hydrogen, chlorine or methoxy, characterized in that the 3- (N, N-dimethylamino) -6-X-7-Y-8-Z-2H-1-benzopyran-2-ones are treated with UV radiation 290 nm in the presence of substituted nitrobenzenes of formula