Method for synthesizing sulfolane by oxidizing thiophane

Abstract

The invention relates to a method for synthesizing sulfolane by oxidizing thiophane, which belongs to the technical field of organic synthesis, and can solve the problems of complicated process steps, relatively harsh reaction conditions, long production period, low productivity and the like in the existing sulfolane synthesis. And the sulfolane is prepared through an oxidation reaction. The method has the advantages of mild process conditions, environmental friendliness, no need of adding any catalyst and high product yield. The method has potential industrial application value, and an efficient, green and environment-friendly novel method is provided for synthesizing sulfolane.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis, and particularly relates to a method for synthesizing sulfolane by oxidizing tetrahydrothiophene. Background Art

[0002] Sulfone compounds, as an important class of organic synthesis intermediates, are widely used in the synthesis of chemistry, medicine, pesticides and materials science. Among them, sulfolane is also an important class of compounds, with the chemical name of 1,1-dioxytetrahydrothiophene. Sulfolane slowly decomposes above 220°C to release sulfur dioxide. As a non-proton, highly polar, water-soluble organic sulfur solvent, it has excellent chemical and thermal stability, strong solubility, easy recovery, high selectivity, low corrosion and low toxicity. Sulfolane is widely used in the fields of aromatic extraction, reaction solvents, gas purification, fatty acid fractionation, and involves special uses such as polymers, chemical fiber industry, and product recovery. With the continuous expansion of application fields, the market demand for sulfolane continues to grow, showing huge market potential.

[0003] In recent years, some new methods for synthesizing sulfone compounds have also been developed. Patent 201710013937.6 A method for continuously synthesizing sulfone compounds is disclosed. The method uses water as a solvent, sodium tungstate or potassium tungstate as a catalyst, and hydrogen peroxide as an oxidant to synthesize a carboxyl-containing chain sulfone compound at a temperature of 55-80°C; Patent 202011452613.0 develops a method for synthesizing sulfone compounds under photocatalytic conditions. Using aromatic hydrazine and sulfinate as raw materials, oxygen as an oxidant, under the action of alkali and solvent, and irradiated with visible light at room temperature, sulfone compounds can be synthesized by coupling with sulfinate. Patent 202410005497.X provides a method for synthesizing sulfone compounds, which uses aryl iodide or alkenyl iodide and sodium sulfinate as raw materials, AuCl as a gold catalyst, bistrifluoromethanesulfonyl imide silver AgNTf2 as a silver salt, 1,2-dichloroethane as a solvent, and synthesizes sulfone compounds at 120°C. The above methods are mainly used for aromatic sulfone compounds; however, sulfolane usually has three synthetic pathways: 1. tetrahydrothiophene oxidation method, 2. ethylene and sulfur dioxide synthesis method, and 3. sulfolane hydrogenation method. The third method is used for industrial synthesis of sulfolane, which is 1,3-butadiene and sulfur dioxide in the presence of an inhibitor to form sulfolane through Diels-Alder reaction, and then catalytic hydrogenation to obtain sulfolane. The process of this method is cumbersome, including four stages: synthesis, desulfurization, hydrogenation, and refining. At present, the sulfolane synthesis process at home and abroad generally has the problems of long production cycle and low productivity.

[0004] The current synthesis of sulfolane has the problems of cumbersome synthesis process steps, relatively harsh reaction conditions, long production cycle and low productivity. It is of great application value to develop a new way to synthesize sulfolane with mild reaction conditions, simple process and no catalysis. Summary of the invention

[0005] The invention aims at the problems of complicated process steps, relatively harsh reaction conditions, long production cycle and low productivity in the existing synthesis of sulfolane, and provides a method for synthesizing sulfolane by oxidizing tetrahydrothiophene. The invention uses tetrahydrothiophene as a raw material, ozone as an oxidant, hydrogen peroxide as a promoter and acetonitrile as a reaction solvent, and prepares sulfolane through oxidation reaction under normal pressure.

[0006] The present invention adopts the following technical solution: A method for synthesizing sulfolane by oxidation of tetrahydrothiophene comprises the following steps: In the first step, tetrahydrothiophene, hydrogen peroxide and acetonitrile are added into the reaction bottle in sequence; The second step is to adjust the pressure reducing valve of the oxygen cylinder and set the partial pressure to 0.1 MPa. After the oxygen enters the ozone generator, an ozone mixed gas is generated. The gas flow rate is set to 150 L / h. The ozone mixed gas enters the reaction bottle to react with the reactants. The gas phase concentration of ozone is controlled to be 100-200 mg / L. The third step is to introduce the ozone mixed gas into the reaction bottle, and set the reaction liquid temperature to 25-55°C and the reaction time to 60-120 minutes; The fourth step is to remove the reaction solvent by distillation under reduced pressure after the reaction is completed, and then separate the product acetic acid by distillation.

[0007] Furthermore, the amount of tetrahydrothiophene used in the first step is 25-50 mL.

[0008] Furthermore, the concentration of hydrogen peroxide in the first step is 6% to 10%; the amount of hydrogen peroxide used is 0.5 to 1 mL.

[0009] Furthermore, in the first step, the volume ratio of tetrahydrothiophene to acetonitrile is 1:20 to 1:50. The beneficial effects of the present invention are as follows: The present invention uses tetrahydrothiophene as a reactant, ozone as an oxidant, and hydrogen peroxide as a promoter, and does not need to add any catalyst. Under normal pressure conditions, tetrahydrothiophene is used to prepare sulfolane with a high conversion rate. The method has the advantages of simple process, mild reaction conditions, and high product yield. The specific reaction process is that ozone and hydrogen peroxide synergistically generate more active hydroxyl radicals, which then attack sulfur atoms in tetrahydrothiophene to generate sulfolane sulfoxide, which is then further oxidized to sulfolane. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is the equation for synthesizing sulfolane by ozonation of tetrahydrothiophene according to the present invention; Figure 2 The target product of the present invention 1 H NMR spectrum; Figure 3 The target product of the present invention 13 C NMR spectrum. DETAILED DESCRIPTION

[0011] The technical solution of the present invention will be clearly and completely described below in combination with the embodiments of the present invention and the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0012] Example 1 Weigh 25 mL of tetrahydrothiophene and 1250 mL of acetonitrile and place them in a reaction bottle, then add 0.5 mL of 6% hydrogen peroxide and the gas phase concentration of ozone is 180 mg / L. After reacting for 120 minutes at a reaction temperature of 25°C, remove the reaction solvent by reduced pressure distillation, and then separate by distillation to obtain the oxidation product, and obtain cyclopentane sulfone with a yield of 81%.

[0013] 1 H NMR (400 MHz, CDCl3) δ 3.04-3.00 (m, 2H), 2.24-2.20 (m, 2H).

[0014] 13 C NMR (100 MHz, CDCl3) δ 51.07, 22.63.

[0015] Example 2 Weigh 50 mL of tetrahydrothiophene and 1000 mL of acetonitrile and place them in a reaction bottle, then add 1 mL of 10% hydrogen peroxide and the gas phase concentration of ozone is 150 mg / L. After reacting at a reaction temperature of 55°C for 100 minutes, remove the reaction solvent by reduced pressure distillation, and then separate the oxidation product by distillation to obtain cyclopentane sulfone with a yield of 75%.

[0016] 1 H NMR (400 MHz, CDCl3) δ 3.04-3.00 (m, 2H), 2.24-2.20 (m, 2H).

[0017] 13C NMR (100 MHz, CDCl3) δ 51.07, 22.63.

[0018] Example 3 30 mL of tetrahydrothiophene and 800 mL of acetonitrile were weighed and placed in a reaction bottle, and then 0.8 mL of 8% hydrogen peroxide was added, and the gas phase concentration of ozone was 100 mg / L. After the reaction temperature was 35°C for 120 minutes, the reaction solvent was removed by reduced pressure distillation, and the oxidation product was separated by distillation to obtain cyclopentane with a yield of 70%.

[0019] 1 H NMR (400 MHz, CDCl3) δ 3.04-3.00 (m, 2H), 2.24-2.20 (m, 2H).

[0020] 13 C NMR (100 MHz, CDCl3) δ 51.07, 22.63.

[0021] Example 4 Weigh 25 mL of tetrahydrothiophene and 1250 mL of acetonitrile and place them in a reaction bottle, add 0.5 mL of 10% hydrogen peroxide, the gas phase concentration of ozone is 200 mg / L, react at a reaction temperature of 45°C for 120 minutes, remove the reaction solvent by reduced pressure distillation, and then separate by distillation to obtain the oxidation product, and obtain cyclopentane sulfone with a yield of 85%.

[0022] 1 H NMR (400 MHz, CDCl3) δ 3.04-3.00 (m, 2H), 2.24-2.20 (m, 2H).

[0023] 13 C NMR (100 MHz, CDCl3) δ 51.07, 22.63.

[0024] Only the preferred embodiments of the present invention are described in detail above, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention, and various changes should be included in the protection scope of the present invention.

Claims

1. A method for synthesizing sulfolane by oxidation of tetrahydrothiophene, characterized in that: The steps include: In the first step, tetrahydrothiophene, hydrogen peroxide and acetonitrile are added into the reaction bottle in sequence; The second step is to adjust the pressure reducing valve of the oxygen cylinder and set the partial pressure to 0.1 MPa. After the oxygen enters the ozone generator, an ozone mixed gas is generated. The gas flow rate is set to 150 L / h. The ozone mixed gas enters the reaction bottle to react with the reactants. The gas phase concentration of ozone is controlled to be 100-200 mg / L. The third step is to introduce the ozone mixed gas into the reaction bottle, and set the reaction liquid temperature to 25-55°C and the reaction time to 60-120 minutes; The fourth step is to remove the reaction solvent by distillation under reduced pressure after the reaction is completed, and then separate the product sulfolane by distillation.

2. The method for synthesizing sulfolane by oxidation of tetrahydrothiophene according to claim 1, characterized in that: The amount of tetrahydrothiophene used in the first step is 25-50 mL.

3. The method for synthesizing sulfolane by oxidation of tetrahydrothiophene according to claim 1, characterized in that: The mass concentration of hydrogen peroxide in the first step is 6%~10%; the amount of hydrogen peroxide used is 0.5~1mL.

4. The method for synthesizing sulfolane by oxidation of tetrahydrothiophene according to claim 1, characterized in that: The volume ratio of tetrahydrothiophene to acetonitrile in the first step is 1:20 to 1:50.

Images