CN107488133A - A kind of method of carbonitride photocatalysis synthesis of carbamates class compound - Google Patents

Abstract

The invention discloses a kind of method of carbonitride photocatalysis synthesis of carbamates class compound, belong to technical field of organic synthesis.In the reactor, using benzyl bromine as substrate, photochemical catalyst, oxidant are added, solvent, at room temperature stirring reaction 24h, reaction are extracted with ethyl acetate after terminating, and merge organic relevant dry, filtering, decompression boil off solvent and obtain crude product, purify to obtain carbamate compounds through column chromatography.The synthetic method safe operation of the present invention is simple, and the carbon dioxide that can directly adsorb in air is reacted, and Atom economy is high, environment-friendly, wide application range of substrates, has potential application value.

Description

A kind of carbon nitride photocatalytic method for synthesizing carbamate compound

technical field

The invention belongs to the technical field of photocatalytic organic synthesis, and in particular relates to a method for photocatalytically synthesizing carbamate compounds with carbon nitride.

Background technique

Carbamate compounds have a wide range of uses and can be used as intermediates in pesticides, medicines, synthetic resin modification, and organic synthesis. Carbamate can be prepared by reacting chloroformate with ammonia or amine, or by reacting carbamoyl chloride with alcohol or phenol (BK Nefedov, VI Manov-Yuvenskii, SS Novikov, Doklady Chem. 1977, 234 , 347 ; CN201180049440.0). However, the use of acid chlorides has problems such as chemical toxicity and high cost, resulting in the lack of economic efficiency of these synthetic methods, which are not in line with green chemistry. Although the reaction between amines and dimethyl carbonate has also been reported, the required dimethyl carbonate raw material is relatively expensive and does not conform to the idea of green chemistry (CN 201380065090.6). Therefore, the development of new carbamate backbone synthesis strategies that are efficient, convenient, and have a wide range of substrates is still a research hotspot in this field.

Carbon dioxide is a gas with relatively stable thermodynamics and linear molecular structure. The reduction process of ordinary CO ₂ will be accompanied by greater energy consumption, which may lead to more fossil energy consumption and more CO ₂ gas emissions. Using photocatalytic technology, under the direct drive of solar energy, the use of _CO2 to prepare fuels and chemicals is the most ideal way to convert and utilize _CO2 , and it is also one of the ideal ways to achieve sustainable human development (W. Leitner, Coordin. Chem. Rev. 1996, 153 , 257; AAG Shaikh, S. Sivaram, Chem. Rev. 1996, 96 , 951; SN Habisreutinger, L. Schmidt-Mende, JK Stolarczyk, Angew. Chem., Int. Ed. 2013, 52, 7372; Q. Xiang, B. Cheng, J. Yu, Angew. Chem., Int. Ed. 2015, 54 , 11350.). gC ₃ N ₄ is applied to the research of photocatalytic reduction of CO ₂ under visible light, and it has the following advantages: 1) The surface of gC ₃ N ₄ is alkaline, which is easy to combine with molecular CO ₂ ; 2) gC ₃ N ₄ has visible light absorption ; 3) gC ₃ N ₄ has adjustable catalytic performance; 4) gC ₃ N ₄ can maintain the stability of structure and activity in the acid-base range (CN201410738727.X; CN201310174297.9). Therefore, the use of carbon nitride for the development and utilization of _CO2 not only solves the environmental problems caused by carbon emissions, but also develops new carbon sources, which will meet the dual requirements of human energy needs and environmental governance, and has potential application prospects. In addition, the synthesis of carbamates by capturing the greenhouse gas carbon dioxide under the visible light catalysis of recyclable metal-free carbon nitride through photocatalytic reaction has not been reported yet.

Contents of the invention

The object of the present invention is to provide a method for carbon nitride photocatalytic synthesis of carbamate compounds in order to solve the above shortcomings and deficiencies of the prior art.

To achieve the above object, the present invention is achieved through the following technical solutions:

A kind of synthetic method of carbamate compound, comprises the following steps:

1. A carbon nitride photocatalyst synthesized with urea as a precursor, comprising the following steps:

(1) Grind and mix the precursor urea evenly;

(2) Calcining the solid powder obtained in step (1) at 450-650° C. in an air atmosphere to obtain a carbon nitride photocatalyst.

2. In the reactor, add benzyl bromide compound as the substrate, carbon nitride photocatalyst, solvent and amine, light and stir the reaction for 24 hours at room temperature, extract with ethyl acetate after the reaction, combine the organic phases to dry, filter, reduce The solvent is removed by steaming under pressure to obtain a crude product, which is purified by column chromatography to obtain carbamate compounds. The reaction equation is as follows:

Wherein, R ¹ includes any one of H, methyl and halogen, R ² includes any one of H, methyl and phenyl, R ³ is ethyl; the addition amount of carbon nitride photocatalyst and substrate The mass ratio is 0.1:1; the solvent is acetonitrile or ionic liquid; the pH value of the initial reaction solution is 8-10; the column chromatography purification is based on the volume ratio of sherwood oil and ethyl acetate as (5 ~20):1 mixed solvent as the eluent for column chromatography purification.

The principle of the invention is as follows: photocatalyze carbon nitride to form photoelectrons, reduce benzyl halide to obtain benzyl free radicals, and then couple with carbon dioxide free radicals to obtain carbamate compounds.

The preparation method of the present invention has the following advantages and beneficial effects:

(1) The synthesis method of the present invention avoids the use of precious metals or high-pressure carbon dioxide, and can react with carbon dioxide in the air only at room temperature. The method is simple, the conditions are mild, and the operation is safe;

(2) The synthesis method of the present invention does not require additional heating, has good adaptability to functional groups, wide adaptability to substrates, is environmentally friendly, and has good industrial application prospects.

Description of drawings

Fig. 1 is the hydrogen spectrogram of embodiment 1 gained product;

Fig. 2 is the carbon spectrogram of embodiment 1 gained product;

Fig. 3 is the hydrogen spectrogram of the product of embodiment 3;

Fig. 4 is the carbon spectrogram of the product of embodiment 3;

Fig. 5 is the hydrogen spectrogram of the product of embodiment 5;

Fig. 6 is the carbon spectrogram of the product of embodiment 5.

detailed description

Below are several embodiments of the present invention to further illustrate the present invention, but the present invention is not limited thereto.

Example 1

1. A carbon nitride photocatalyst synthesized with urea as a precursor, comprising the following steps:

(1) Grind and mix the precursor urea evenly;

(2) Calcining the solid powder obtained in step (1) at 450° C. under an air atmosphere to obtain a carbon nitride photocatalyst.

2. In the open reactor, add 100 mg of substrate benzyl bromide, 10 mg of carbon nitride photocatalyst, 3 ml of acetonitrile and 1.2 equivalents of diethylamine, adjust the pH of the initial reaction solution to 8, open the system in the atmosphere, and absorb in the air carbon dioxide, under room temperature light and stirring reaction for 24h, after the reaction is finished, extract with ethyl acetate, combine the organic phases to dry, filter, evaporate the solvent under reduced pressure to obtain the crude product, the column chromatography eluent used is a volume ratio of 20:1 Petroleum ether: ethyl acetate mixed solvent, yield 72%.

The hydrogen spectrum and carbon spectrum of the product obtained in this example are shown in Figure 1 and Figure 2 respectively, and its structural characterization data are as follows: ¹ H NMR (400 MHz, CDCl ₃ ) δ = 7.42 - 7.30 (m, 2H), 5.16 (s, 2H), 3.33 (s,4H), 1.15 (t, J =6.5, 3H). ¹³ C NMR (101 MHz, CDCl ₃ ) δ = 155.82, 137.16, 128.44, 127.81, 127.73, 66.74, 41.87 , 41.31, 14.06, 13.54. IR (KBr, cm ^-1 ) ν 1738, 1586, 1545, 1445, 1394, 1258, 1051, 1004, 905, 801, 726, 686.

According to the above data, the structure of the resulting product is deduced as follows:

.

Example 2

1. A carbon nitride photocatalyst synthesized with urea as a precursor, comprising the following steps:

(1) Grind and mix the precursor urea evenly;

(2) Calcining the solid powder obtained in step (1) at 650° C. under an air atmosphere to obtain a carbon nitride photocatalyst.

2. In the reactor, add 100mg of 1-bromoethylbenzene, 10mg of carbon nitride photocatalyst, 3ml of acetonitrile and 1.2 equivalents of diethylamine, adjust the pH value of the initial reaction solution to 9, and react under light and stirring for 24 hours at room temperature. Extract with ethyl acetate after the end, combine the organic phases to dry, filter, and evaporate the solvent under reduced pressure to obtain the crude product. The rate is 63%.

The structural characterization data of the product obtained in this example are as follows: ¹ H NMR (400 MHz, ) δ = 7.34 – 7.30 (m, 4H), 7.26 – 7.23 (m, 1H), 5.81 (q, J =6.6, 1H), 3.28 (q, J =7.1, 4H), 1.51(d, J =6.6, 3H), 1.10 (t, J =7.1, 6H). ¹³ C NMR (101 MHz, CDCl ₃ ) δ 155.30,142.79, 128.40, 127.47, 125.85, 72.75, 41.52, 41.31, 22.87, 14.07, 13.74. IR(KBr, cm ^-1 ) ν 1693, 1474, 1421, 1269, 1168, 1066, 763, 697.

According to the above data, the structure of the resulting product is deduced as follows:

.

Example 3

1. A carbon nitride photocatalyst synthesized with urea as a precursor, comprising the following steps:

(1) Grind and mix the precursor urea evenly;

(2) Calcining the solid powder obtained in step (1) at 550° C. under an air atmosphere to obtain a carbon nitride photocatalyst.

2. In the reactor, add 100mg of 4-bromo(1-bromoethyl)benzene, 10mg of carbon nitride photocatalyst, 3ml of ionic liquid and 1.2 equivalents of ethylenediamine, and adjust the pH value of the initial reaction solution to 10. The reaction was stirred under light for 24 hours. After the reaction was completed, it was extracted with ethyl acetate, the combined organic phases were dried, filtered, and the solvent was evaporated under reduced pressure to obtain a crude product. The column chromatography eluent used was petroleum ether: acetic acid with a volume ratio of 5:1 Ethyl ester mixed solvent, yield 59%.

The hydrogen spectrum and carbon spectrum of the product obtained in this example are shown in Figure 3 and Figure 4 respectively, and its structural characterization data are as follows: ¹ H NMR (400 MHz, ) δ = 7.46 (d, J =8.4, 2H), 7.22 (d, J =8.3, 2H), 5.76 (q, J =6.6, 1H), 3.29 (q, J =14.1, 7.0, 3H), 1.50 (d, J =6.6, 4H), 1.12 (t, J =6.9,6H). ¹³ C NMR (101 MHz, CDCl ₃ ) δ = 155.09, 141.86, 131.54, 127.65, 121.34,72.09, 41.82, 41.17, 22.68, 14.15, 13.53. IR (KBr, cm ^-1 ) ν 1738, 1586, 1545, 1445, 1394, 1258, 1051, 1004, 905, 801, 726, 686.

According to the above data, the structure of the resulting product is deduced as follows:

.

Example 4

1. A carbon nitride photocatalyst synthesized with urea as a precursor, comprising the following steps:

(1) Grind and mix the precursor urea evenly;

(2) Calcining the solid powder obtained in step (1) at 500° C. in an air atmosphere to obtain a carbon nitride photocatalyst.

2. In the reactor, add 100 mg of 4-methyl (1-bromoethyl) benzene, 10 mg of carbon nitride photocatalyst, 3 ml of acetonitrile and 1.2 equivalents of ethylenediamine, and adjust the pH value of the initial reaction solution to 9. The reaction was stirred under light for 24 hours. After the reaction was completed, it was extracted with ethyl acetate, the combined organic phases were dried, filtered, and the solvent was evaporated under reduced pressure to obtain a crude product. The column chromatography eluent used was petroleum ether: acetic acid with a volume ratio of 10:1 Ethyl ester mixed solvent, yield 65%.

The structural characterization data of the product obtained in this example are as follows: ¹ H NMR (400 MHz, CDCl ₃ ) δ = 7.23(s, 2H), 7.14 (d, J =7.9, 2H), 5.79 (q, J =6.6, 1H ), 3.29 (q, J =6.9, 4H), 2.33(s, 3H), 1.52 (d, J =6.6, 3H), 1.12 (t, J =7.1, 6H). ¹³ C NMR (101 MHz, CDCl ₃ ) δ= 155.35, 139.83, 137.13, 129.07, 125.87, 72.64, 41.60, 41.25, 22.81, 21.12,14.12, 13.67. IR (KBr, cm ^-1 ) ν 1516, 1492, 1359, 1432, 1336, 1128, 1071 , 993, 952, 894, 843, 805, 796, 770, 736.

According to the above data, the structure of the resulting product is deduced as follows:

.

Example 5

1. A carbon nitride photocatalyst synthesized with urea as a precursor, comprising the following steps:

(1) Grind and mix the precursor urea evenly;

(2) Calcining the solid powder obtained in step (1) at 550° C. under an air atmosphere to obtain a carbon nitride photocatalyst.

2. In the reactor, add 100mg of diphenylbromomethane, 10mg of carbon nitride photocatalyst, 3ml of acetonitrile and 1.2 equivalents of ethylenediamine, adjust the pH value of the initial reaction solution to 10, and stir the reaction under light for 24 hours at room temperature, and the reaction is over After extraction with ethyl acetate, the combined organic phases were dried, filtered, and the solvent was evaporated under reduced pressure to obtain a crude product. The column chromatography eluent used was a volume ratio of 20:1 petroleum ether: ethyl acetate mixed solvent, the yield 69%.

The hydrogen spectrum and carbon spectrum of the product obtained in this example are shown in Figure 5 and Figure 6 respectively, and its structural characterization data are as follows: ¹ H NMR (400 MHz, CDCl ₃ ) δ = 7.33 (q, J =7.8, 8H ), 7.27 – 7.22 (m, 2H), 6.82(s, 1H), 3.35 (d, J =25.3, 4H), 1.14 (d, J =18.3, 6H). ¹³ C NMR (101 MHz, CDCl ₃ ) Δ = 155.04, 141.24, 128.44, 127.61, 127.00, 76.76, 42.00, 41.38, 14.33, 13.53.IR (KBR, CM ^-1 ) ν 1620, 1595, 1571, 1500, 14314, 1314, 1119, 1033 ,940, 802, 784, 736, 611.

According to the above data, the structure of the resulting product is deduced as follows:

.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, Simplifications should be equivalent replacement methods, and all are included in the protection scope of the present invention.

Claims (7)

1. A kind of 1. method of carbonitride photocatalysis synthesis of carbamates class compound, it is characterised in that：With benzyl bromine class compound For raw material, carbonitride is photochemical catalyst, adds solvent and amine, at room temperature stirring reaction 24h under visible ray illumination, reaction terminate Purified obtained carbamate compound again afterwards；The chemical structural formula of obtained carbamate compound is：

   ；Wherein, R¹Including any of H, methyl and halogen, R²Including H, methyl and phenyl Any of, R³For ethyl.
2. 2. the method for carbonitride photocatalysis synthesis of carbamates class compound according to claim 1, it is characterised in that： The specific surface area of the carbon nitride photocatalyst is 10-200 m²/ g, band edge is absorbed in 450-700nm, using urea as presoma The carbon nitride photocatalyst is synthesized, specifically includes following steps：

   （1）Presoma urea ground and mixed is uniform；

   （2）By step（1）450 ~ 650 DEG C of calcinings in air atmosphere of obtained solid powder, obtain carbon nitride photocatalyst.
3. 3. the method for carbonitride photocatalysis synthesis of carbamates class compound according to claim 1, it is characterised in that： Described solvent is acetonitrile or ionic liquid.
4. 4. the method for carbonitride photocatalysis synthesis of carbamates class compound according to claim 1, it is characterised in that： The mass ratio of the carbon nitride photocatalyst and benzyl bromine class compound is 0.1:1.
5. 5. the method for carbonitride photocatalysis synthesis of carbamates class compound according to claim 1, it is characterised in that： It is 8-10 to regulate and control initial reaction liquid pH value.
6. 6. the method for carbonitride photocatalysis synthesis of carbamates class compound according to claim 1, it is characterised in that： Described purification comprises the following steps that：Reaction is extracted with ethyl acetate after terminating, and merging is organic relevant dry, and filtering, decompression boils off Solvent obtains crude product, purifies to obtain carbamate compound through column chromatography.
7. 7. the method for carbonitride photocatalysis synthesis of carbamates class compound according to claim 6, it is characterised in that： Described column chromatography purification be using the volume ratio of petroleum ether and ethyl acetate as（5~20）:1 mixed solvent is the post of eluent Chromatographic purification.