WO2021120895A1 - Method for preparing polymercapto pentaerythrithiol derivative - Google Patents

Abstract

The present invention relates to the technical field of sulphur-containing compounds, in particular to a method for preparing a polymercapto pentaerythrithiol derivative. A thiol compound prepared by the method of the present invention has a high sulphur content, and ensures a high refractive index of a product; and in addition, same has four branched chains, forms a high three-dimensional network structure when cured and shaped with isocyanate, can be used to prepare a resin monomer with a high refractive index, and has high mechanical and optical properties.

Description

A kind of preparation method of polymercapto pentaerythritol derivative

This application claims the priority of a Chinese patent application filed with the Chinese Patent Office, the application number is 201911305956.1, and the invention title is "a method for preparing a polymercapto pentaerythritol derivative" on December 16, 2019, and its entire contents Incorporated in this application by reference.

Technical field

The invention relates to the technical field of sulfur-containing compounds, in particular to a preparation method of a polymercapto pentaerythritol derivative.

Background technique

Polyurethane material has excellent wear resistance, impact resistance and light transmission properties, so it has occupied a very important position in the field of optical plastics in recent years. Polyurethane is formed by the addition reaction of an active hydrogen-containing compound with bifunctionality or higher and isocyanate with bifunctionality or higher, and has thermoplastic and thermosetting types. In order to destroy the crystalline properties of polyurethane and make the material have better light transmittance, cross-linking is a necessary measure, so the thermosetting type is mainly used.

Active hydrogen-containing compounds mainly contain OH-containing alcohols and phenols, and SH-containing mercaptans and thiophenols. In order to pursue a high refractive index, in recent years, almost all SH-containing compounds have been reported in the literature. Among the most used SH-containing compounds, most of them are binary branched and ternary branched compounds, while quaternary branched SH-containing compounds are It is relatively small, but the increase of the branch chain can improve the three-dimensional network structure when curing with isocyanate, so that the polyurethane material can obtain better performance.

Summary of the invention

Aiming at the defects of the prior art, the present invention provides a method for preparing polymercapto pentaerythritol derivatives. The thiol compound prepared by the method of the present invention has a higher sulfur content, which ensures the high refractive index of the product, and at the same time It has four branches and forms a higher three-dimensional network structure when cured with isocyanate. It can be used to prepare high refractive index resin monomers and has higher mechanical and optical properties.

First discovered a kind of polymercapto pentaerythritol derivative, its structure is as formula I:

The present invention provides a method for preparing the above-mentioned polymercapto pentaerythritol derivative, and the reaction route is:

step 1):

Step 2):

Step 3):

Specifically include the following steps:

1) Add pentaerythritol into the reactor, slowly add sodium hydroxide solution dropwise, stir evenly, drop 2-chloroethanol for reaction; during this step 1) the temperature is controlled at 70-90°C;

2) Add concentrated hydrochloric acid and thiourea to the system after step 1), heat up to 100-150°C through a heating mantle, keep refluxing for 2-8 hours, and cool down to below 50°C;

3) Add ammonia water for alkaline hydrolysis, heat up to 40-80°C for 2-8 hours, then the reaction ends;

4) After step 3), the reacted materials are washed with water, separated, dehydrated and dried to obtain the target product.

In the above reaction process, based on the molar ratio of pure substances, pentaerythritol: 2-chloroethanol: sodium hydroxide: hydrochloric acid: thiourea: ammonia water = 1:4.0-4.4:4.0-4.2:4.0-6.0:4.0- 5.0: 4.0-8.0.

Preferably, the reaction temperature in step 1) is preferably 75-85°C. If the temperature is too low, the reaction speed will be slow, the conversion rate will be low, and the temperature will be too high, and the side reactions will increase, which will affect the product content.

The mass concentration of the sodium hydroxide solution in step 1) is 20-40%, preferably 25-35%.

Step 2) The mass concentration of concentrated hydrochloric acid is more than 35%. The higher the concentration of hydrochloric acid, the better, which can ensure the reaction speed.

Preferably, the step 2) reflux reaction time is preferably 3-5 hours;

Step 3) _{The mass concentration of NH 3} in ammonia water is preferably 16-25%, more preferably 18-22%.

Preferably, in step 3), the alkaline hydrolysis temperature is preferably 50-60°C, and the alkaline hydrolysis time is preferably 3-5 hours. Low alkaline hydrolysis temperature will result in slow reaction speed, incomplete alkaline hydrolysis, and intermediate residues in the product. Excessive temperature will cause high-temperature deterioration of the product, generating dithiooxidation products, and affecting product quality.

Step 4) Before washing with water, adjust the pH to 3-6, preferably 4-5; preferably, adjust with hydrochloric acid.

Step 4) Deionized water is used for water washing, preferably 2 times of water washing;

Step 4) Use Buchner funnel to filter for separation;

Step 4) The temperature of dehydration and drying is 30-80°C, the negative pressure is below -0.095MPa, and the dehydration time is 2-5 hours. Dehydration drying adopts negative pressure heating method, negative pressure can ensure complete dehydration under low temperature conditions, if the temperature is too high, it will cause the product to oxidize and deteriorate. Too low temperature will cause incomplete water removal.

Preferably, in step 1), nitrogen is introduced before the sodium hydroxide is added dropwise for anaerobic protection. The step has a higher requirement for oxygen content. This step is prone to oxidation. Although there are oxidation risks in other steps, the relative risk is relatively low.

The cooling process involved in the preparation method of the present invention all adopts ice bath cooling. The laboratory cooling condition is ice bath, and the cooling speed is fast.

The present invention provides a method for preparing a target compound. Generally speaking, the reagents used in the preparation method are easily available, the reaction conditions are mild and not harsh, the process is simple and uncomplicated, and can effectively reduce the generation of impurities and obtain the target product.

Detailed ways

Hereinafter, the above-mentioned content of the present invention is further described in detail through specific implementations in the form of examples, but it should not be understood that the scope of the above-mentioned subject of the present invention is limited to the following examples. All technologies implemented based on the foregoing content of the present invention belong to the scope of the present invention. Except for special instructions, the following embodiments are all completed by conventional existing technologies.

Example 1

Add 200g of pentaerythritol into a glass-stirred four-necked flask equipped with a thermometer, turn on the stirring, and pass in nitrogen for anaerobic protection. Use a water bath to heat up to 75-85℃, and slowly add 500g of hydrogen with a concentration of 32%. Sodium oxide solution, the temperature during the dripping process is controlled at 75-85℃; after the completion, keep stirring for 30min, add 338.1g 2-chloroethanol dropwise, adjust the temperature at 75-85℃ through water bath and the dropping rate, and keep the temperature for 30min after completion. Add 493 g of concentrated hydrochloric acid with a concentration of 37%, and add 319.2 g of thiourea. The temperature is raised to 120° C. through a heating mantle, the temperature is kept and refluxed for 4 hours, and the temperature is lowered to below 50° C. after completion. 408 g of ammonia water with a mass concentration of NH ₃ of 25% was added, and the temperature was raised to 60-65° C. to conduct heat preservation reaction for 4 hours. Transfer the reacted materials to a beaker, add 440g of deionized water, then add a small amount of hydrochloric acid to adjust the pH to between 3-6; wash at 40-80°C for 20 minutes, and then transfer to a Buchner funnel for filtration and separation After completion, the crude product is transferred to a petri dish for drying, the temperature is 40°C, the vacuum degree is above -0.095MPa, and the target product is obtained with a mass of 412g and a content of 85.6%.

Example 2

Add 200g of pentaerythritol to a glass-stirred four-necked flask equipped with a thermometer, turn on the stirring, and pass in nitrogen for anaerobic protection. Use a water bath to heat up to 75-85°C, and slowly add 525g of hydrogen with a concentration of 32%. Sodium oxide solution, the temperature during the dripping process is controlled at 75-85℃; after the completion, keep stirring for 30min, add 338.1g 2-chloroethanol dropwise, adjust the temperature at 75-85℃ through water bath and the dropping rate, and keep the temperature for 30min after completion. Add 591 g of concentrated hydrochloric acid with a concentration of 37%, and add 380 g of thiourea. The temperature is raised to 120° C. through a heating mantle, the temperature is kept and refluxed for 4 hours, and the temperature is lowered to below 50° C. after completion. Add _{544 g of ammonia water with a mass concentration of NH 3} of 25%, and raise the temperature to 60-65° C. to carry out heat preservation reaction for 4 hours. Transfer the reacted materials to a beaker, add 440g of deionized water, then add a small amount of hydrochloric acid to adjust the pH to between 3-6; wash at 40-80°C for 20 minutes, and then transfer to a Buchner funnel for filtration and separation After the completion, the crude product is transferred to a petri dish for drying, the temperature is 40°C, the vacuum degree is above -0.095MPa, and the target product is obtained with a mass of 420g and a content of 88.7%.

Example 3

Add 200g of pentaerythritol into a glass-stirred four-necked flask equipped with a thermometer, turn on the stirring, and pass in nitrogen for anaerobic protection. Use a water bath to heat up to 75-85℃, and slowly add 500g of hydrogen with a concentration of 32%. Sodium oxide solution, the temperature during the dripping process is controlled at 75-85℃; after the completion, keep stirring for 30min, add 321.6g 2-chloroethanol dropwise, adjust the temperature at 75-85℃ through the water bath and the dropping rate, and keep the temperature for 30min after completion. Add 395 g of concentrated hydrochloric acid with a concentration of 37%, and add 304 g of thiourea. The temperature is raised to 120° C. through a heating mantle, the temperature is kept and refluxed for 4 hours, and the temperature is lowered to below 50° C. after completion. Add _{272 g of ammonia water with a mass concentration of NH 3} of 25%, and heat the temperature to 60-65° C. to carry out a heat preservation reaction for 4 hours. Transfer the reacted materials to a beaker, add 440g of deionized water, then add a small amount of hydrochloric acid to adjust the pH to between 3-6; wash at 40-80°C for 20 minutes, and then transfer to a Buchner funnel for filtration and separation After completion, the crude product is transferred to a petri dish for drying, the temperature is 40°C, the vacuum degree is above -0.095MPa, and the target product is obtained with a mass of 376 g and a content of 78.2%.

Example 4

Add 200g of pentaerythritol into a glass-stirred four-necked flask equipped with a thermometer, turn on the stirring, and pass in nitrogen for anaerobic protection. Use a water bath to raise the temperature to 85-90℃, and slowly add 525g of hydrogen with a concentration of 32%. Sodium oxide solution, the temperature during the dripping process is controlled at 85-90℃; after completion, keep stirring for 30min, add 338.1g 2-chloroethanol dropwise, adjust the temperature at 85-90℃ through the water bath and the dropping rate, and keep the temperature at 85-90℃ for 30min after completion. Add 591g of concentrated hydrochloric acid with a concentration of 37%, and add 380g of thiourea. The temperature is raised to 120°C through a heating mantle, kept at reflux for 2 hours, and after completion, the temperature is lowered to below 50°C. Add _{544 g of ammonia water with a mass concentration of NH 3} of 25%, and heat the temperature to 60-65° C. to carry out heat preservation reaction for 2 hours. Transfer the reacted materials to a beaker, add 440g of deionized water, then add a small amount of hydrochloric acid to adjust the pH to between 3-6; wash at 40-80°C for 20 minutes, and then transfer to a Buchner funnel for filtration and separation After the completion, the crude product is transferred to a petri dish for drying, the temperature is 40°C, the vacuum degree is above -0.095MPa, and the target product is obtained with a mass of 401g and a content of 82.6%.

Claims (10)

1. A preparation method of polymercapto pentaerythritol derivatives, which is characterized in that it specifically comprises the following steps:

   1) Pentaerythritol and 2-chloroethanol are reacted in the presence of NaOH solution, and the temperature is controlled at 70-90°C during the reaction;

   2) Add concentrated hydrochloric acid and thiourea to the system after step 1) to react, the temperature of the reaction is 100-150°C, and the reaction time is 2-8 hours; after the reaction, the system is cooled to below 50°C;

   3) Add ammonia to the reaction system for alkaline hydrolysis, and increase the temperature to 40-80°C for 2 to 8 hours;

   4) After step 3), the reacted materials are washed with water, separated, dehydrated and dried to obtain the polymercapto pentaerythritol derivative.
2. A preparation method of polymercapto pentaerythritol derivatives, which is characterized in that it specifically comprises the following steps:

   1) Add pentaerythritol into the reactor, slowly add sodium hydroxide solution dropwise, stir evenly, drop 2-chloroethanol for reaction; during this step 1) the temperature is controlled at 70-90°C;

   2) Add concentrated hydrochloric acid and thiourea to the system after step 1), heat up to 100-150°C through a heating mantle, keep refluxing for 2-8 hours, and cool down to below 50°C;

   3) Add ammonia water for alkaline hydrolysis, heat up to 40-80°C for 2-8 hours, then the reaction ends;

   4) After step 3), the reacted materials are washed with water, separated, dehydrated and dried to obtain the target product.
3. The preparation method of a polymercapto pentaerythritol derivative according to claim 2, characterized in that, based on the molar ratio of the pure substance, pentaerythritol: 2-chloroethanol: sodium hydroxide: hydrochloric acid: Thiourea: ammonia water=1: 4.0-4.4: 4.0-4.2: 4.0-6.0: 4.0-5.0: 4.0-8.0.
4. The method for preparing a polymercapto pentaerythritol derivative according to claim 2, wherein the reaction temperature in step 1) is 75-85°C; the mass concentration of sodium hydroxide solution in step 1) is 20 -40%.
5. The method for preparing a polymercapto pentaerythritol derivative according to claim 2, wherein step 2) the mass concentration of concentrated hydrochloric acid is more than 35%; step 2) the reflux reaction time is 3-5 hours.
6. The method for preparing a polymercapto pentaerythritol derivative according to claim 2, wherein step 3) the alkaline hydrolysis temperature is 50-60° C., and the alkaline hydrolysis time is 3-5 hours.
7. The preparation method of a polymercapto pentaerythritol derivative according to claim 2, characterized in that, in step 3) the mass concentration of _{NH 3 in the ammonia water is 16-25%.}
8. The preparation method of a polymercapto pentaerythritol derivative according to claim 2, characterized in that, in step 4) before washing with water, the pH is adjusted to 3-6; hydrochloric acid is used for adjustment.
9. The method for preparing a polymercapto pentaerythritol derivative according to claim 2, wherein step 4) uses deionized water for washing with water, and washes twice with water; and step 4) uses Buchner funnel filtration for separation.
10. The method for preparing a polymercapto pentaerythritol derivative according to claim 2, characterized in that, in step 4) the temperature of dehydration and drying is 30-80°C, the negative pressure is below -0.095MPa, and the dehydration time is 2-5 hours.