CN1785964A - Synthesis method of non symmetrical hydroazobenzene - Google Patents

Abstract

The invention belongs to a synthesis method of unsymmetrical hydroazobenzene. Such compounds are important fine organic chemical raw materials and important organic synthesis intermediates, and can be used in the dye industry, pharmaceutical industry and for the preparation of corresponding azo compounds, benzidine compounds, etc. In the present invention, 2,4-dinitrofluorobenzene is used as nucleophilic substrate, phenylhydrazine compounds are used as nucleophilic reagents, DMSO is used as solvent, and a series of asymmetric hydrogenated azobenzenes are synthesized through nucleophilic substitution reaction. compound. The invention has low reaction temperature (r.t-60°C), short reaction time (0.5h), high chemical yield (93-98%) and diverse product structures.

Description

A kind of synthetic method of unsymmetrical hydroazobenzene

The invention belongs to a synthesis method of unsymmetrical hydroazobenzene.

The asymmetric hydroazobenzene compounds of the present invention are yellow or orange needle-like crystals with the following structure:

The structures of R ₁ , R ₂ , R ₃ , and R ₄ in the formula are shown in Table 1. It is known that such compounds are important fine organic chemical raw materials and important organic synthesis intermediates, and can be used in the dye industry, pharmaceutical industry and for the preparation of corresponding azo compounds, benzidine compounds, etc. Conventional methods for the synthesis of this series of compounds are prepared by reduction of substituted azobenzenes or by corresponding nucleophilic substitution reactions. In the former method, there are strict restrictions on the substrates that can be coupled with aromatic diazonium salts. The R group in the product can only be hydroxyl, ammonia (amine) group or other strong electron-donating groups, and the product structure lacks diversity. property; the latter method is rarely reported, and the reaction takes three to four days to complete at room temperature, and the yield is only 56 to 58%.

The purpose of the present invention is to propose a new synthetic method. The method has low reaction temperature, short reaction time, high chemical yield and diverse product structures.

The present invention is characterized in that 2,4-dinitrofluorobenzene is used as a nucleophilic substrate, phenylhydrazine compounds are used as nucleophiles, and DMSO is used as a solvent to synthesize a series of asymmetric hydrides through nucleophilic substitution reactions. Nitrogen compounds. The chemical reaction equation is as follows:

Table 1 The position and structure of various R Entry R1 R2 R3 R4 Entry R1 R2 R3 R4 3a3b3c3d3e3f HCH3HHCH3H HHCH3HHH HHHCH3HF HHHHCH3H 3g3h3i3j3k3l HHClBrHNO2 HHHHHH ClBrHHNO2NO2 HHHHHH

The molar ratio of materials in the reaction system is: 2,4-dinitrofluorobenzene: substituted phenylhydrazine=1:1.1

During the reaction, the reaction temperature is r.t-60°C. The synthesis of 3a-3j was carried out at room temperature, and the synthesis of 3k-31 was carried out at 40°C and 60°C, respectively.

The present invention selects DMSO as a solvent, and DMSO not only has a good promoting effect on the departure of ^F- ions in the substrate, but also facilitates post-treatment of the product.

The reaction time of the present invention is 0.5h, and the chemical yield is 93-98%. The structure of the product was confirmed by elemental analysis and IR, ¹ H NMR. The yield and physical properties of the product are shown in Table 2; the spectral analysis data and elemental analysis results of the product are shown in Table 3.

The present invention is described further below by embodiment.

Embodiment 1: the synthesis of 2,4-dinitrohydroazobenzene

Add 1.1ml (0.011mol) phenylhydrazine and 15mlDMSO to a three-necked flask with a reflux condenser and a dropping funnel, add dropwise 1.26ml (0.01mol) of 2,4- Dinitrofluorobenzene was added dropwise in 15 minutes, and continued to stir for 15 minutes to terminate the reaction (the reaction process was followed by TLC and the end point was determined). Add 2 times the volume of distilled water, a yellow solid precipitated, suction filtered, the filter cake was washed with ethanol and ether, dried, and recrystallized with chloroform to obtain 2.67 g of yellow needle-shaped crystals, with a yield of 97%, m.p: 119-120°C . Spectral analysis data and elemental analysis results showed that the compound was 2,4-dinitrohydroazobenzene (3a).

Example 2: Synthesis of 2,4-dinitro-2',4'-dinitrohydroazobenzene

Add 2.18g (0.011mol) 2,4-dinitrophenylhydrazine and 15ml DMSO to a three-necked flask with a reflux condenser and a dropping funnel, and add 1.26ml diluted with 5ml DMSO dropwise at 60°C under electromagnetic stirring (0.01mol) of 2,4-dinitrofluorobenzene was added dropwise in 15 minutes, and the reaction was continued to be stirred for 15 minutes to terminate the reaction (the reaction process was tracked by TLC and the end point was determined). After the reaction solution was cooled to room temperature, 2 times the volume of distilled water was added, and a yellow solid was precipitated, which was filtered with suction, and the filter cake was washed with ethanol and ether, then dried, and recrystallized with a mixed solvent of chloroform and DMSO to obtain 3.57 g of yellow needle-like crystals. Yield 98%, m.p: 250-251°C. Spectral analysis data and elemental analysis results showed that the compound was 2,4-dinitro-2',4'-dinitrohydroazobenzene (31).

Yield, melting point and appearance of table two products product Yield (%) Melting point (°C) Exterior 3a3b3c3d3e3f3g3h3i3j3k3l 979697959697959696958065 119-120101-102100-101101-102193-194125-126128-129138-139124-125152-153199-200250-251 Yellow Needle Crystals Yellow Needle Crystals Orange Needle Crystals Orange Needle Crystals Yellow Needle Crystals Yellow Needle Crystals Yellow Needle Crystals Yellow Needle Crystals Yellow Needle Crystals Yellow Needle Crystals Yellow Needle Crystals Yellow Needle Crystals Yellow Needle Crystals Yellow Needle Crystals

Spectral analysis data and elemental analysis results of the products in Table 3 compound IR(KBr)ν(cm ^-1 ) H NMR, δ (ppm) Elemental analysis (%) measured value (theoretical value) C h N 3a 3337, 3110, 1625 9.60(s, 1H), 9.16(d, 1H,), 8.30(dd, 1H), 7.65(d, 1H), 7.33(m, 2H), 7.02(m, 1H), 6.86(d, 2H), 5.99( s, 1H) 52.26 (52.56) 3.30(3.68) 20.08 (20.43) 3b 3338, 3112, 2928, 2857, 1626 9.53(s, 1H), 9.17(d, 1H,), 8.29(dd, 1H), 7.63(d, 1H), 7.18(m, 2H), 6.94(d, 1H), 6.77(d, 1H), 5.91 (s,1H)2.34(s,3H) 54.49 (54.16) 4.00(4.20) 19.58 (19.44) 3c 3331, 3106, 2922, 2870, 1622 9.53(s, 1H), 9.16(d, 1H,), 8.29(dd, 1H), 7.65(d, 1H), 7.19(m, 1H), 6.83(d, 1H), 6.65(d, 2H), 5.93 (s,1H)2.33(s,3H) 53.54 (54.16) 4.08(4.20) 9.61 (19.44) 3d 3331, 3105, 2928, 2874, 1621 9.59(s, 1H), 9.17(d, 1H,), 8.29(dd, 1H), 7.67(d, 1H), 7.12(d, 2H), 6.76(d, 2H),, 5.87(s, 1H), 2.32 (s, 3H) 54.51 (54.16) 4.02 (4.20) 19.66 (19.44) 3e 3337, 3110, 2928, 2863, 1625 9.56(s, 1H), 9.19(d, 1H,), 8.30(dd, 1H), 7.64(d, 1H), 7.08(d, 1H), 6.76(d, 1H), 6.58(s, 1H), 5.82(s, 1H), 2.27(d, 6H) 55.19 (55.63) 4.37(4.67) 18.06 (18.54) 3f 3327, 3099, 1623 9.60(s, 1H), 9.17(d, 1H,), 8.32(dd, 1H), 7.66(d, 1H), 7.02(m, 2H), 6.82(m, 2H), 5.92(s, 1H), 49.14 (49.32) 2.92(3.10) 19.45 (19.17) 3g 3326, 3112, 1622 9.59(s, 1H), 9.17(d, 1H,), 8.31(dd, 1H), 7.60(d, 1H), 7.26(d, 2H), 6.80(m, 2H), 5.99(s, 1H), 46.39 (46.69) 2.66 (2.94) 7.86 (18.15) 3 hours 3325, 3109, 1622 9.58(s, 1H), 9.17(d, 1H,), 8.35(dd, 1H), 7.60(d, 1H), 7.40(d, 2H), 6.75(d, 2H), 5.98(s, 1H), 40.53 (40.81) 2.38(2.57) 15.57 (15.87) 3i 3348, 3110, 1620 9.57(s, 1H), 9.19(d, 1H,), 8.33(dd, 1H), 7.60(d, 1H), 7.40(d, 1H), 7.21(m, 1H), 6.95(m, 1H), 6.84 (d, 1H), 6.50(s, 1H), 46.35 (46.69) 2.61 (2.94) 17.81 (18.15) 3j 3377, 3113, 1621 9.59(s, 1H), 9.19(d, 1H,), 8.33(dd, 1H), 7.57(d, 2H), 7.21(m, 2H), 7.26(m, 1H), 6.87(m, 2H), 6.51(s, 1H), 40.51 (40.81) 2.30(2.57) 15.49 (15.87) 3k 3310, 3116, 1621 10.38(s, 1H), 9.48(s, 1H,), 8.90(dd, 1H,), 8.33(dd, 1H), 8.10(m, 2H), 7.31(d, 1H), 6.87(m, 2H), 6.92(d, 2H) 44.78 (45.15) 2.662 (2.84) 21.60 (21.94) 3l 3321, 3105, 1615 10.52(s, 2H), 8.92(d, 2H,), 8.30(dd, 2H,), 7.40(d, 2H) 39.50 (39.57) 2.00(2.21) 23.01 (23.07)

Claims (4)

1. A synthetic method of unsymmetrical hydroazobenzene. The structural formula of this series of compounds is: The R groups in the formula are hydrogen, methyl, halogen (fluorine, chlorine, bromine) and nitro respectively. It is characterized in that 2,4-dinitrofluorobenzene is used as nucleophilic substrate, phenylhydrazine compounds are used as nucleophilic reagents, DMSO is used as solvent, and a series of asymmetric hydrogenated azobenzenes are synthesized through nucleophilic substitution reactions. class of compounds. 2. According to the synthetic method of asymmetric hydroazobenzene described in claim 1, the mol ratio of reaction process 2,4-dinitrofluorobenzene and substituted phenylhydrazine is 1: 1.1; Reaction temperature is r.t-60 ℃; The reaction time is 0.5h; the chemical reaction equation is as follows.

Entry R ₁ R ₂ R ₃ R ₄ Entry R ₁ R ₂ R ₃ R ₄ 3a3b3c3d3e3f _{HCH3HHCH3H _} HHCH ₃ HHH HHHCH ₃ HF HHHHCH3H 3g3h3i3j3k3l _HHClBrHNO2 HHHHHH ClBrHHNO ₂ NO ₂ HHHHHH 3a-3j were synthesized at room temperature, and 3k-3l were synthesized at 40°C and 60°C, respectively. 3. according to the synthetic method of the described asymmetric hydroazobenzene of claim 1 or 2, select DMSO as solvent for use, be that 2,4-dinitrofluorobenzene is at first diluted with an appropriate amount of DMSO in the reaction process, then dropwise To the substituted phenylhydrazine for reaction. 4. According to the synthetic method of asymmetric hydroazobenzene described in claim 1 or 2 or 3, the recrystallization of 3a-3j uses chloroform as a solvent, and the recrystallization of 3k-3l is carried out with a mixed solvent of chloroform and DMSO.