RU2161611C1 - Method of preparing 2-(p-aminophenyl)-6-amino-4h-3,1-benzoxazinone-4 - Google Patents

Abstract

FIELD: chemical industry. SUBSTANCE: described is method of preparing 2-(p- aminophenyl)-6-amino-4H-3,1-benzoxazinone-4 from authralinic acid. Aroylation with p-nitrobenzoyl chloride, formation of oxazinone ring, when reacted with acetic anhydride, and nitration with nitric acid are carried out in single stage to form 2-(p-nitrophenyl)-6-nitro-4H-3,1-benzoxazinono-4-which is then reduced with hydrogen over Raney nickel to give the desired diamine. The resulting compound is useful as monomer for preparing heat-resistant polyamides. Method makes it possible to intensify process, reduce number of technological stages and production waste and improve ecology of process. EFFECT: more efficient preparation method.

Description

который может быть использован в качестве мономера для получения термостойких полимерных материалов, в частности полиамидов.The invention relates to a new method for producing aromatic diamine with a heterocycle between benzene rings, in particular, to a method for producing 2- (p-aminophenyl) -6-amino-4H-3,1-benzoxazinone-4

which can be used as a monomer to obtain heat-resistant polymer materials, in particular polyamides.

 It is known that many characteristics of aromatic polyamides with heterocycles in the chain are higher compared to conventional polymers. The processability, thermal stability and rigidity make it possible to use such polyamides with heterocycles in the chain for the manufacture of highly heat-resistant and high-modulus fibers [Buller K.-U. Heat- and heat-resistant polymers. - M.: Chemistry, 1984, p. 434, 452, 453]. In particular, the presence of a 3,1,4-benzoxazine ring in the polymer chain gives the latter increased heat resistance [Joda M., Nakanishi R., Kurihara M., Bamba J., Tokiama S., Jkeda K. // J. Polym. Sci., 1966, B. 4, v. 8, p. 551].

 The prototype of the invention is described in the literature [Nemleva S.A., Ivanova V.M., Kaminskaya E.G. et al. Synthesis of 2- (4-aminophenyl) -6-amino-3,1,4-benzoxazinone / Sat. Tool state ped Institute of Synthesis, Analysis and Structure of Organic Compounds, 1976, c. 7, c. 44-48] a six-step method for producing 2- (p-aminophenyl) -6-amino-4H-3,1-benzoxazinone-4, which consists in the fact that the anthranilic acid is acylated, then the acyl derivative is nitrated, the acetyl protection is removed by hydrolysis, the nitroanthranyl formed the acid is aroylated with p-nitrobenzoyl chloride, an oxazinone ring is formed with a dehydrating agent (thionyl chloride), and the dinitroproduct is reduced to the target diamine of structure (I).

 In order to intensify the process, reduce the main technological stages, production wastes, and improve the process ecology, a fundamentally new solution is proposed for the synthesis of the target diamine (I) based on a two-stage method for producing 2- (p-aminophenyl) -6-amino-4H-3,1 -benzoxazinone-4 according to the scheme (see the end of the description).

 The difference of the proposed method for the preparation of the target diamine is that aroylation of anthranilic acid with n-nitrobenzoyl chloride, the formation of the oxazinone ring under the action of acetic anhydride and nitration with nitric acid are carried out in one stage without isolation of intermediate products. The 2- (p-nitrophenyl) -6-nitro-4H-3,1-benzoxazinon-4 (II) formed in the first stage is catalytically reduced with hydrogen to give the final product (I) to the second.

 The proposed method has several advantages over the prototype. Firstly, low-stage (2 stages versus 6 in the prototype) and the associated smaller assortment of raw materials and its consumption, simplified hardware design. It should be pointed out that in the proposed method there are no such aggressive media as thionyl chloride, concentrated sulfuric acid. Instead of 100% nitric acid according to the prototype, the proposed method uses a more affordable and less aggressive 65% nitric acid. In the proposed method there is no requirement for draining the solvents, while the use of dry petroleum ether and especially dioxane, capable of producing peroxide compounds, cause additional difficulties in the apparatus design of the process. The small-stage process is simpler than the multi-stage process due to the reduction of a whole series of both basic and auxiliary technological methods.

 Secondly, a cleaner ecology of the proposed method compared to the prototype. This stems from lower raw material costs, less toxicity of the substances used, less wastewater and production waste: in the prototype 3 water washes, in the proposed method none, in the prototype, in addition, there is also one recrystallization from acetic acid. Naturally, the energy costs for the regeneration of solvents - acetic acid, thionyl chloride, dioxane, petroleum ether according to the prototype are higher than according to the proposed method, when only acetic acid and ethyl alcohol have to be regenerated.

 Thirdly, a higher yield of the target monomer: according to the proposed method, 74.5% versus 31.2% of the prototype.

 The essence of the proposed method for producing 2- (p-aminophenyl) -6-amino-4H-3,1-benzoxazinone-4 is as follows. To a solution of anthranilic acid in glacial acetic acid, a solution of p-nitrobenzoyl chloride in the same solvent is added while heating and stirring. The reaction mixture was kept at boiling for 2 hours, then acetic anhydride was added thereto, boiled for 10 minutes and 65% nitric acid was added. The reaction mixture is cooled and dinitroproduct (II) is obtained, which is further reduced with hydrogen over Raney nickel to the desired diamine (I).

 The essence of the invention is illustrated by the following examples.

Example 1. Synthesis of 2- (p-nitrophenyl) -6-nitro-4H-3,1-benzoxazinone-4. To a solution of 13.7 g (0.1 mol) of anthranilic acid in 100 ml of glacial acetic acid, a solution of 20.4 g (0.11 mol) of p-nitrobenzoyl chloride in 50 ml of the same solvent is added while heating and stirring. The reaction mixture was kept at boiling for 2 hours, then 300 ml of acetic anhydride were added thereto, boiled for 10 minutes and 19.2 ml (3-fold excess) of 65% nitric acid were added. Cool the reaction mixture to room temperature, while light yellow 2- (p-nitrophenyl) -6-nitro-4H-3,1-benzoxazinone-4 crystallizes. Wash with water until neutral. Yield 25 g (80.9%). T. pl. 198 ^o C. Found,%: C 53.81, 53.52, H 2.27, 2.20, N 13.37, 13.40. C ₁₄ H ₇ N ₃ O ₆ . Calculated,%: C 53.67, H 2.24, N 13.42. IR spectrum (tablet with KBr), ν, cm ^-1 : 1773 (C = O), 1521, 1349 (NO ₂ ).

Example 2. Synthesis of 2- (p-aminophenyl) -6-amino-4H-3,1-benzoxazinone-4. 70 g of 2- (p-nitrophenyl) -6-nitro-4H-3,1-benzoxazinone-4, 700 ml of dimethylacetamide, 7 g of nickel (according to Raney) are loaded into the autoclave. After inert purging, the system is filled with hydrogen to a pressure of 1.5 MPa, the temperature is raised to 80 ^° C and the recovery process is completed in 10 minutes. The hot catalyzate after 30 minutes is separated from the catalyst and cooled. An amine precipitate is isolated by adding catalysis in 2 L of distilled water. Yield 90%. Mp 222 ^o C. Found,%: C 64.41, H 4.26, N 16.56. C ₁₄ H ₁₁ N ₃ O ₂ . Calculated,%: C 64.40, H 4.31, N 16.60. IR (tablet with KBr): ν, cm ^-1 1738 (C = O), 3468, 3376 (NH ₂ ).

 Thus, a new two-step process for the preparation of 2- (p-aminophenyl) -6-amino-4H-3,1-benzoxazinone-4 from anthranilic acid is provided.

Claims (1)

The method of obtaining 2- (p-aminophenyl) -6-amino-4H-3,1-benzoxazinone-4 of the formula

from anthranilic acid, characterized in that aroylation of p-nitrobenzoyl chloride, the formation of an oxazine ring under the action of acetic anhydride and nitration with nitric acid are carried out in one stage with the formation of 2- (p-nitrophenyl) -6-nitro-4H-3,1-benzoxazinone- 4, which is further reduced with hydrogen over Raney nickel as a whole diamine.

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