Thiopropane trithiol compound and preparation method thereof

Abstract

The invention relates to a thiopropane trithiol compound as shown in a formula I and a preparation method thereof. The compound is thiol containing a thioether bond and three sulfydryl groups, and the preparation method of the compound comprises the following three steps: step 1, carrying out vulcanization reaction on sulfydryl propylene glycol and a sulfur halide reagent in a solvent to obtain sulfo-polyhydric alcohol; 2, carrying out a substitution reaction of changing hydroxyl into sulfydryl in an acid environment by using thio-polyol and thiosemicarbazide, so as to obtain an intermediate product isothiourea salt; and 3, carrying out hydrolysis catalysis on the isothiourea salt to finally generate the thiopropane trithiol compound. The thiopropane trithiol compound monomer disclosed by the invention is high in light transmittance, large in refractive index and low in yellow index; the preparation method is easy in reaction route control and short in reaction time. # imgabs0 #

Description

Technical Field

[0001] The invention belongs to the technical field of synthesis and preparation of polythiocarbamate optical materials, and particularly relates to a thiopropane trithiol compound and a preparation method thereof. Background Art

[0002] Thiols are a class of organic compounds containing a sulfhydryl (-SH) functional group. Trithiols are organic compounds containing three sulfhydryl (-SH) groups, some of which are bonded to sulfur atoms. Because the SH bond in trithiols is longer than the OH bond and contains a higher sulfur content, they are more easily broken, allowing hydrogen atoms to dissociate more easily. Trithiols are also more acidic than typical alcohols. Consequently, trithiols are more susceptible to oxidation and nucleophilic reactions.

[0003] Trithiol compounds are important raw materials for optical materials and pharmaceutical intermediates. In the field of optical materials (components), trithiol compounds are used to replace glass as raw materials for optical device production, leveraging their excellent thermal properties and high refractive index. In the pharmaceutical field, some compounds containing thiol structures possess special physiological activities. For example, penicillamine, containing a thiol group, is used to treat certain metal poisonings and some autoimmune diseases. With the advancement of polymer materials chemistry, the application of trithiol compounds as raw materials is expected to expand.

[0004] Common methods for synthesizing trithiols include alkylation and hydrolysis of thiourea, addition of olefins to hydrogen sulfide, alkylation of sulfhydryl salts, hydrolysis of thiol esters, disulfide reduction, and sulfonyl chloride reduction. There are relatively early references to the synthesis of trithiols abroad, such as Japanese Mitsui Chemicals patent CN1215737A, which primarily uses epichlorohydrin and mercaptoethanol to prepare polyols, which are then salted with thiourea and hydrolyzed to synthesize the target thioalkyl trithiols. The specific reaction route is as follows:

[0005]

[0006] The preparation methods of the above patents have high requirements on equipment and safety. The exchange reaction between oxygen and sulfur atoms is prone to produce harmful gases, sulfhydryl oxidation, insufficient conversion of oxygen and sulfur during the reaction process, and is often accompanied by side reactions, which may affect the purity and color of the product.

[0007] In order to make up for the shortcomings of the existing patented synthesis methods, it is necessary to develop and introduce new methods and process routes, so the present invention is proposed. Summary of the Invention

[0008] The present invention aims to provide a thiopropane trithiol compound and its preparation method. The compound has a transmittance of ≥90%, a refractive index of ≥1.67, and a yellowness index of ≤1.25, and can be used to prepare polythiocarbamate optical materials with high refractive index and high transmittance. To achieve the above objectives, the present invention provides the following technical solutions:

[0009] In one aspect, the present invention provides a thiopropane trithiol compound, the structural formula of which is shown in Formula I:

[0010]

[0011] In another aspect, the present invention provides a method for preparing the thiopropane trithiol compound as described above, the method comprising the following steps:

[0012] I. Add mercaptopropylene glycol and a solvent to a reaction vessel equipped with an agitator, a vent tube, and a temperature control device, start stirring and continuously introduce nitrogen, and then add a sulfur halide reagent with stirring, wherein the weight ratio of the sulfur halide reagent, mercaptopropylene glycol, and solvent is (1-2):(2-7):(10-30); control the temperature at 0-10° C. and stir the reaction for 5-10 hours, separate and elute the organic phase, and remove the solvent by distillation under reduced pressure to obtain a thiopolyol represented by Formula II;

[0013]

[0014] II. To a reactor equipped with a stirrer and a temperature-controlled microwave generator were added thiopolyol, thiosemicarbazide and hydrochloric acid, the weight ratio of thiosemicarbazide, thiopolyol and hydrochloric acid being (1 to 2): (1 to 3): (1 to 3); after stirring, microwave heating to 75 to 110 ° C, holding for 6 to 9 hours and then allowing the mixture to cool naturally;

[0015] III. After the mixture is cooled to 30-45 ° C, an alkaline hydrolysis agent is added dropwise, the amount of the alkaline hydrolysis agent is 90-150wt% of the amount of hydrochloric acid used in step II, and the mixture is heated to 45-65 ° C for 2-3 hours and allowed to stand until the system is separated. The organic phase is decolorized by adsorption with attapulgite, filtered, and the organic solvent is evaporated under reduced pressure to obtain a colorless and transparent thiopropane trithiol compound.

[0016] In the preparation method as described above, preferably, the sulfur halide reagent in step I is selected from one of disulfur chloride, sulfur chloride, disulfur bromide and sulfur bromide.

[0017] In the preparation method as described above, preferably, the alkaline catalyst in step I is selected from a sodium hydroxide or potassium hydroxide aqueous solution with a concentration of 15 to 30 wt%.

[0018] In the preparation method as described above, preferably, the solvent in step I is selected from at least one of toluene, methanol, ethanol, acetone, ethyl ether, xylene, n-propanol, isopropanol, ethylene glycol, propylene glycol, glycerol ethyl ether, n-hexane, cyclohexane, petroleum ether, methyl chloride, tetrahydrofuran and ethylene glycol monobutyl ether.

[0019] In the preparation method as described above, preferably, the concentration of hydrochloric acid in step II is 30-38 wt%.

[0020] In the preparation method as described above, preferably, the alkaline hydrolysis agent in step III is selected from aqueous ammonia, sodium carbonate or potassium carbonate solution with a concentration of 25-40 wt%.

[0021] The preparation method of the thiopropane trithiol compound of the present invention comprises the following three steps:

[0022] 1. A thiopolyol (Formula II) is obtained by a sulfurization reaction between mercaptopropylene glycol and a sulfur halide reagent in a solvent. The specific reaction process and main equations are as follows:

[0023]

[0024] Wherein, X=C1 or Br; n is 1 or 2.

[0025] 2. The thiopolyol (II) and thiosemicarbazide are subjected to an oxygen-sulfur molecule exchange reaction in an acidic environment to convert the hydroxyl group into a thiol group, thereby obtaining the intermediate product isothiouronium salt. The specific reaction process and equation are as follows:

[0026]

[0027] 3. The isothiouronium salt is hydrolyzed with sulfhydryl groups, and the isothiouronium salt is hydrolyzed to release sulfhydryl groups (-SH), completing the oxygen-sulfur molecular exchange, and finally generating a thiol compound containing three sulfide bonds and three sulfhydryl groups, namely, thiopropane trithiol compound (I). The specific reaction process is as follows:

[0028]

[0029] The beneficial effects of the present invention are as follows: the preparation method of the present invention has a short reaction process time, hydrogen chloride gas discharged during the reaction is neutralized and collected by a NaOH alkaline solution, is safe and environmentally friendly, has few by-products in the reaction, and is easy to control the process route. The prepared thiopropane trithiol compound has a high sulfur content, a transmittance of ≥90%, a refractive index of ≥1.67, and a yellowness index of ≤1.25, and can be used to prepare polythiocarbamate optical materials with high refractive index and high transmittance. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the infrared spectrum of the thiopropane trithiol compound prepared in Example 1.

[0031] Figure 2 This is the HNMR nuclear magnetic resonance hydrogen spectrum of the thiopropane trithiol compound prepared in Example 1. DETAILED DESCRIPTION

[0032] The present invention will be further described below with reference to specific examples, which are not intended to limit the scope of protection of the present invention.

[0033] Preparation Example 1

[0034] To a reaction vessel equipped with a stirrer, a vent tube, and a temperature control device, 500 g of mercaptopropylene glycol, 650 g of ether, and 1050 g of acetone were added, respectively. Under N2 protection, 135 g of sulfur dichloride was slowly added with stirring within 10 minutes. The temperature was controlled at 2°C with ice water. The reaction was stirred for 9 hours. The organic phase was separated and eluted, and the solvent was distilled under reduced pressure to obtain 567 g of the thiopolyol represented by formula II.

[0035] Preparation Example 2

[0036] To a reaction vessel equipped with an agitator, a vent tube and a temperature control device, 500 g of mercaptopropylene glycol, 650 g of ether and 1050 g of acetone were added respectively. Under N2 protection, 128 g of S2Cl2 was added slowly with stirring within 10 minutes. The temperature was controlled at 0°C with ice water. The reaction was stirred for 9 hours. The organic phase was separated and eluted, and the solvent was distilled under reduced pressure to obtain 572 g of the thiopolyol represented by formula II.

[0037] Example 1

[0038] 100 g of the thiopolyol prepared in Preparation Example 1 was added to a reactor equipped with a stirrer and a temperature-controlled microwave generator. 165 g of thiosemicarbazide and 195 g of 35 wt% hydrochloric acid were then added with stirring. After uniform mixing, the mixture was microwave-heated to 95°C, held for 7 hours, and then naturally cooled. The mixture was cooled to 45°C, and 130 g of 38 wt% sodium carbonate hydrate was added dropwise over 35 minutes. The mixture was heated to 60°C for hydrolysis for 2.5 hours, and allowed to stand for stratification. The organic phase was washed with water, decolorized by adsorption with attapulgite, filtered, and the organic solvent was evaporated under reduced pressure to obtain 112 g of a colorless, transparent thiopropane trithiol compound (Formula I). ​​The yield was 87.2%.

[0039] Infrared spectrum FT-IR test: The product prepared in Example 1 was subjected to Fourier transform infrared spectrum FT-IR) test, and the results are as follows Figure 1 As shown, 2944cm -1 The absorption peak of methylene (-CH2-) is at 2560cm -1 The absorption peak is the characteristic peak of thiol, 915~632cm -1 The bending vibration absorption peak of SH group is 710 cm -1The absorption peak at is the stretching vibration of the CS bond.

[0040] H NMR nuclear magnetic resonance hydrogen spectrum analysis: Figure 2 As shown, the multiple peaks at δ = 2.97 to 3.06 ppm are CH peaks adjacent to S, 2.50 to 2.82 ppm are mixed peak shifts caused by mercapto H atoms and secondary carbon H atoms, and SH characteristic triplet peaks appear at δ = 1.78 to 1.82 ppm.

[0041] Example 2

[0042] 100g of the thiopolyol prepared in Preparation Example 2 was added to a reactor equipped with a stirrer and a temperature-controlled microwave generator, and 170g of thiosemicarbazide and 200g of 35wt% hydrochloric acid were added with stirring. After stirring, the mixture was heated to 95°C in a microwave oven, kept warm for 7 hours, and then naturally cooled. The mixed solution was cooled to 45°C, 140g of 38wt% sodium carbonate hydrate was added dropwise within 35 minutes, and the mixture was heated to 60°C for hydrolysis for 2.5 hours. The mixture was allowed to stand for stratification, and the organic phase was washed with water and then decolorized by adsorption with attapulgite. The mixture was filtered, decompressed, and the organic solvent was evaporated to obtain 113g of a colorless, transparent thiopropane trithiol compound (Formula I). ​​The infrared spectrum FT-IR and H NMR nuclear magnetic resonance hydrogen spectrum test results of the obtained compound were basically the same as those of Example 1.

[0043] Example 3

[0044] 100 g of the thiopolyol prepared in Preparation Example 1 was added to a reactor equipped with a stirrer and a temperature-controlled microwave generator, and 180 g of thiosemicarbazide and 205 g of 36 wt% hydrochloric acid were added with stirring. After stirring evenly, the mixture was heated to 105 ° C in a microwave oven, kept warm for 7 hours, and then naturally cooled; after the mixed solution was cooled to 45 ° C, 130 g of 36 wt% sodium carbonate hydrate was added dropwise within 35 minutes, heated to 58 ° C for hydrolysis for 2.5 hours, allowed to stand and decompose, the organic phase was washed with water and then decolorized by adsorption with attapulgite, filtered, decompressed, and the organic solvent was evaporated to obtain 115 g of a colorless and transparent thiopropane trithiol compound.

[0045] Example 4

[0046] 100 g of the thiopolyol prepared in Preparation Example 2 was added to a reactor equipped with a stirrer and a temperature-controlled microwave generator, and 175 g of thiosemicarbazide and 205 g of 35 wt% hydrochloric acid were added with stirring. After stirring evenly, the mixture was heated to 105 ° C in a microwave oven, kept warm for 7.5 h, and then naturally cooled; the mixed solution was cooled to 42 ° C, 130 g of 38 wt% sodium carbonate hydrate was added dropwise within 35 min, and the mixture was heated to 62 ° C for hydrolysis for 2.5 h, allowed to stand and decompose, the organic phase was washed with water and then decolorized by adsorption with attapulgite, filtered, decompressed, and the organic solvent was evaporated to obtain 114 g of a colorless and transparent thiopropane trithiol compound.

[0047] Example 5

[0048] 100 g of the thiopolyol prepared in Preparation Example 1 was added to a reactor equipped with a stirrer and a temperature-controlled microwave generator, and 182 g of thiosemicarbazide and 210 g of 36 wt % hydrochloric acid were added with stirring. After stirring, the mixture was heated to 100 ° C. in a microwave oven, kept warm for 7 h, and then naturally cooled; the mixed solution was cooled to 48 ° C., 130 g of 38 wt % sodium carbonate hydrate was added dropwise within 35 min, and heated to 65 ° C. for hydrolysis for 2.3 h. The mixture was allowed to stand for stratification, and the organic phase was washed with water and then decolorized by adsorption with attapulgite. The organic solvent was filtered, reduced pressure, and evaporated to obtain 115 g of a colorless and transparent thiopropane trithiol compound.

[0049] Example 6

[0050] 100 g of the thiopolyol prepared in Preparation Example 2 was added to a reactor equipped with a stirrer and a temperature-controlled microwave generator, and 185 g of thiosemicarbazide and 195 g of 38 wt% hydrochloric acid were added with stirring. After stirring evenly, the mixture was heated to 100 ° C in a microwave oven, kept warm for 7 hours, and then naturally cooled; the mixed solution was cooled to 48 ° C, 130 g of 38 wt% sodium carbonate hydrate was added dropwise within 35 minutes, heated to 65 ° C for hydrolysis for 2.3 hours, allowed to stand and decompose, the organic phase was washed with water and then decolorized by adsorption with attapulgite, filtered, decompressed, and the organic solvent was evaporated to obtain 116 g of a colorless and transparent thiopropane trithiol compound.

[0051] Example 7

[0052] Optical Property Testing of Thiopropane Trithiol Compounds: The optical properties of the thiopropane trithiol compounds prepared in Examples 1-6 were tested. Transmittance was measured using a UV-8000 UV-Visible photometer from Shanghai Yuanxi Instrument Co., Ltd. The test method was to directly apply the compound monomer to the prism of the UV-Visible photometer and measure the transmittance. Refractive index was measured using a WZS1 refractometer from Shanghai Optical Instrument Equipment Co., Ltd. The test method was to directly apply the resin monomer to the prism of the refractometer and measure the refractive index. The yellowness index was calculated from the spectrophotometer reading according to the formula: YI = 100(1.28X - 1.06Z) ÷ Y, where X, Y, and Z are the tristimulus values ​​of illuminant C. The test results are shown in Table 1. The test results indicate that the thiopropane trithiol compound monomer of the present invention has a transmittance of ≥90%, a refractive index of ≥1.67, and a yellowness index of ≤1.25.

[0053] Table 1 Optical properties test results of thiopropane trithiol compounds

[0054]

[0055] Example 8 Preparation of Anti-Blue Light Lenses

[0056] 180 g of diphenylmethane diisocyanate, 170 g of the thiopropane trithiol compound prepared in Example 1, and 4.2 g of a light absorber mixture were uniformly mixed, and 7 g of a phosphate and 3.2 g of dibutyltin dilaurate were added; the mixture was prepolymerized at 45°C for 40 min, and bubbles were removed under vacuum before injection into a lens mold; the mold containing the prepolymer was placed at 60°C for 8 hours, then heated to 90°C at a rate of 10°C / 30 min, and continued to be placed for 2.5 hours. Finally, it was cooled to room temperature and demolded to obtain a high-refractive polyurethane anti-blue light lens. The optical performance test results of the lens are shown in Table 2.

[0057] Table 2 Lens optical performance test results

[0058]

[0059] The test results show that the polythiocarbamate optical lens prepared from the thiopropane trithiol compound of the present invention has a high refractive index and high light transmittance.

Claims

1. A thiopropane trithiol compound, characterized in that The structural formula of the compound is shown in Formula I:

2. The method for preparing a thiopropane trithiol compound according to claim 1, wherein: The method comprises the following steps: I. Add mercaptopropylene glycol and a solvent to a reaction vessel equipped with an agitator, a vent tube, and a temperature control device, start stirring and continuously introduce nitrogen, and add a sulfur halide reagent with stirring, wherein the weight ratio of the sulfur halide reagent, mercaptopropylene glycol, and solvent is (1-2):(2-7):(10-30); control the temperature at 0-10° C. and stir the reaction for 5-10 hours, separate and elute the organic phase, and remove the solvent by distillation under reduced pressure to obtain a thiopolyol represented by formula II; II. To a reactor equipped with a stirrer and a temperature-controlled microwave generator were added thiopolyol, thiosemicarbazide and hydrochloric acid, the weight ratio of thiosemicarbazide, thiopolyol and hydrochloric acid being (1 to 2): (1 to 3): (1 to 3); after stirring, microwave heating to 75 to 110 ° C, holding for 6 to 9 hours and then allowing the mixture to cool naturally; III. After the mixture is cooled to 30-45 ° C, an alkaline hydrolysis agent is added dropwise, the amount of the alkaline hydrolysis agent is 90-150wt% of the amount of hydrochloric acid used in step II, and the mixture is heated to 45-65 ° C for 2-3 hours and allowed to stand until the system is separated. The organic phase is decolorized by adsorption with attapulgite, filtered, and the organic solvent is evaporated under reduced pressure to obtain a colorless and transparent thiopropane trithiol compound.

3. The preparation method according to claim 2, wherein The sulfur halide reagent in step I is selected from one of disulfur chloride, sulfur chloride, disulfur bromide and sulfur bromide.

4. The preparation method according to claim 2, wherein The alkaline catalyst in step I is selected from sodium hydroxide or potassium hydroxide aqueous solution with a concentration of 15-30 wt%.

5. The preparation method according to claim 2, wherein The solvent in step I is selected from at least one of toluene, methanol, ethanol, acetone, ethyl ether, xylene, n-propanol, isopropanol, ethylene glycol, propylene glycol, glycerol ethyl ether, n-hexane, cyclohexane, petroleum ether, methyl chloride, tetrahydrofuran and ethylene glycol monobutyl ether.

6. The preparation method according to claim 2, wherein The concentration of hydrochloric acid in step II is 30-38 wt %.

7. The preparation method according to any one of claims 1 to 6, characterized in that In step III, the alkaline hydrolysis agent is selected from aqueous ammonia, sodium carbonate or potassium carbonate solution with a concentration of 25-40 wt%.

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