RU2024484C1 - Method of synthesis of aromatic 1,2-diketones - Google Patents

Abstract

FIELD: organic chemistry. SUBSTANCE: products - aromatic 1,2-diketones: 1,4-di-(2-phenylethane-1,2-dione-1-yl)-benzene; 1,2-diphenylethane-1,2-dione. Reagent 1: bicyclic bis-ureas of the formula

where R - Ph,

,

Description

 The invention relates to diketones, in particular an improved method for producing aromatic 1,2-diketones, for example, 1,2B-diphenylethan-1,2-diode (DC) and 1,4-di (2-phenylethin-1,2-dion-1 -ol) benzene (TK), used as monomers for heat-resistant polymers with a wide range of useful properties, are synthons for the preparation of new, active compounds, as well as those widely used in organic synthesis.

 The purpose of the invention is to increase the yield of the target product, simplifying the process.

окисляют концентрированной азотной кислотой в присутствии серной кислоты в 80-90%-ной водной уксусной кислоте при молярном соотношении бисмочевин, азотной кислоты, серной кислоты, равном 0,01:(9,06-0,08):(0,03-0,08).The goal is achieved by the proposed method for producing aromatic 1,2-diketones by oxidation in an organic solvent by heating, the distinctive feature of which is that the bicyclic bismoureas of the general formula

oxidized with concentrated nitric acid in the presence of sulfuric acid in 80-90% aqueous acetic acid with a molar ratio of bismourea, nitric acid, sulfuric acid equal to 0.01: (9.06-0.08) :( 0.03-0 , 08).

 The use of acetic acid as a solvent greatly facilitates and simplifies the isolation of the desired products, which is achieved by simply diluting the reaction mass with water and filtering the obtained crystalline precipitate, in contrast to the prototype, where it is necessary to distill off the solvent o-dichlorobenzene with water vapor, then inorganic impurities are extracted with hot water, recrystallized from o-dichlorobenzene, followed by drying under vacuum. Acetic acid when used in the inventive process avoids the multi-stage isolation and purification due to the fact that it is a convenient and effective solvent for both the initial BBM and the inorganic reagents used (nitric and sulfuric acids).

 The presence of water in acetic acid introduced into the reaction mass is necessary to suppress the side process of nitration of the original YuM in both the aromatic nucleus and nitrogen atoms. It was found that the use of acetic acid with a water content of 0-10% (Table 3) as a solvent leads to the formation of side nitro compounds, which complicates the purification of the target products. However, an increase in the percentage of water in acetic acid over 20% reduces the solubility of the initial BBMs, thereby increasing the process time.

 Thus, the optimal concentration of aqueous acetic acid is 80-90%.

 The use of sulfuric acid can increase the solubility of the initial BBM in the reaction medium. In addition, sulfuric acid, as you know, activates nitric acid as an oxidizing agent, which is used in the described process. Although the presence of sulfuric acid increases the likelihood of side processes of nitration of BBM. However, these processes are suppressed in the claimed invention by the presence of water in the reaction mass.

 The choice of nitric acid is due, firstly, to the simplicity, availability and sufficient oxidizing ability of the reagent, and secondly, to the absence of any nitric acid conversion products that could impair the quality of the target products due to contamination, in contrast to the analogue used in as an oxidizing agent, selenium dioxide.

With a decrease in temperature below the boiling point, the solubility of the initial BBMs decreases and their oxidation rate decreases, which leads to an increase in the process time (Table 1). Increasing the reaction temperature above the boiling point (120 ° ^C) is unacceptable due to possible release of the reaction mass by overheating. The lower and upper limits of the molar amount of nitric acid are, respectively, a necessary and sufficient condition for the oxidation of the starting products and the oxidation of their decomposition products. A decrease in the amount of nitric acid (less than 0.06 mol) leads to an incomplete conversion of the starting products and an increase in the reaction time (Table 1), and an increase in excess of 0.08 mol leads to unproductive costs of nitric acid. A decrease in the amount of sulfuric acid above 0.02 mol leads to a decrease in the solubility of BBM and, consequently, to an increase in the duration of the process (Table 1), and an increase in excess of 0.08 mol leads to the formation of by-products of nitration, which is a consequence of the binding of reaction water and activation of nitric acid.

The structures of the obtained DCs and TCs were proved by comparison with authentic samples, as well as by using elemental analysis data, IN, ¹ H NMR and ¹³ C spectroscopy.

 PRI me R 1. In a three-necked flask (V = 100 ml) equipped with a stirrer, reflux condenser and dropping funnel, 2.94 g (0.01 mol) of 1,5-diphenyl-2,4- 6.8-tetraazabicyclo (3.3.0) octane-3,7-dione, pour 20 ml of 80% aqueous acetic acid, 1.6 ml (3 g: 0.03 mol, d = 1.84) sulfuric acid and 3.75 ml (0.06 mol, d = 1.42) of nitric acid. The mixture is heated to boiling and stirred for 4 hours. At the end of the process, the reaction mass is diluted with water (50 ml), the precipitate is filtered off, dried under draft. The yield of 1,2-diphenylethan-1,2-dione was 1.81 g (86%).

Т.пл. = 94-95^оС,
ИК-спектр, ν, см^-1: 1680 (С=0)
ПМР-спектр, δ, м.д.: 8,01 g (Н² 6,4 Н),
7,48-7,37 м (6 Н).

Mp = 94-95 ^about C,
IR spectrum, ν, cm ^-1 : 1680 (С = 0)
¹ H-NMR spectrum, δ, ppm: 8.01 g (H ² 6.4 N),
7.48-7.37 m (6 N).

¹³ NMR spectrum, δ, ppm: 194.8 (С = 0) elemental analysis,% (found / calculated): С = 79.71 / 79.98, Н = 5.01 / 4 , 80.

 PRI me R 2. Synthesis of 1,4-di (2-phenylethan-1,2-dion-1-yl) benzene by oxidation of 1- (2-phenylethan-1,2-dion-1-yl) - 4- (5-phenyl-2,4,6,8-tetraazabicyclo (3.3.0) octane -3.7 is carried out analogously to example 1, except that they load 4.30 g (0.01 mol) of 1b and 3 , 2 ml (6 g, 0.06 mol, d = 1.84) of sulfuric acid, and incubated for 6 hours. Isolation analogously to example 1. The yield of TC 3.04 g (89%).

H₃
Т.пл. 0 124-5^оС, М=342,4.

H ₃
Mp 0 124-5 ^about C, M = 342.4.

IR spectrum, ν, cm ^-1 : 1698 (C = 0).

¹ H-NMR spectrum, δ, ppm: 8.41 C (4 H, H ¹ ), 8.22 (4H, H ² ); 7.79 m (6H, H ³ ).

NMR ¹³ C spectrum, δ, ppm: 194.63 (C ¹ ), 192.96 (C ² );
Elemental analysis,%: (found / calculated): C = 77.51 / 77.18, H = 4.25 / 4.13.

 PRI me R 3 Synthesis of TA by oxidation of 1,4-di (5-phenyl-2,4,6,8-tetraazabicyclo (3.3.0) octane-3,7-dion-1-yl) benzene (1B ) is carried out similarly to example 1 except that 2.58 g (0.005 mol) 1 in and 3.8 ml (8 g 0.08 mol, d = 1.84) of sulfuric acid are charged and incubated for 8 hours. Isolation is similar Example 1. The yield of TC 1.47 gr 86%. The physico-mechanical analysis data are given at the end of Example 2.

 The effect of molar ratios and temperature during oxidation of 1a are given in Table 2.

 The effect of molar ratios and temperature during oxidation of 1b is given in Table 2.

 The effect of molar ratios and temperature during oxidation of 1c is given in Table 3.

 The proposed method allows to increase the yield of the target product to 85-90% against 44% to simplify the process by eliminating the toxic and expensive oxidizing agent - selenium dioxide.

Claims (1)

METHOD FOR PRODUCING AROMATIC 1,2-DICETONES by oxidation in an organic solvent by heating, characterized in that, in order to increase the yield of the target product, simplify the process, bicyclic bismoureas of the general formula

where R = Ph,

_,

oxidized with concentrated nitric acid in the presence of sulfuric acid in 80-90% aqueous acetic acid with a molar ratio of bisurea, nitric acid, sulfuric acid 0.01: (0.06 - 0.08): (0.03 - 0.08 )

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