CN111978179A - Synthetic method of 6-hydroxyhexanoate - Google Patents

Abstract

The invention provides a method for synthesizing 6-hydroxycaproic acid ester. First, 6-hydroxycaproic acid is neutralized to neutrality with alkali, then alcohol, a catalyst and a certain amount of solvent are added, and the temperature is 50-150° C. The reaction was carried out under pressure for 1-5h, and after the reaction was completed, a water-carrying agent was added to remove water and solvent to obtain 6-hydroxycaproic acid ester. The beneficial effects of the present invention are: (1) The technical steps are simple, the production cost is low, and the economic benefit is high. (2) No side reaction products are produced in this technology, and other product salts such as NaCl, KBr, water, etc. are easy to separate and have little impact on the environment, and the process safety factor is high. (3) The yield of 6-hydroxycaproic acid ester is above 95%, the production effect is good, and the product quality is high.

Description

A kind of synthetic method of 6-hydroxycaproate

technical field

The invention belongs to the chemical industry, and particularly relates to a method for synthesizing 6-hydroxycaproate.

Background technique

6-Hydroxycaproate is a very useful organic chemical intermediate. The polymerization of 6-hydroxycaproate can synthesize poly-6-hydroxycaproate, and can further generate polycaprolactone or polycaprolactone polyol. , Polycaprolactone has a wide range of uses in medical materials, drug carriers, plastic modifiers and plasticizers.

In the current production information on 6-hydroxycaproate, patent CN101945847A produces 6-hydroxyl from a mixture of by-products of a process produced during the oxidation of cyclohexane to cyclohexanone and cyclohexanol using oxygen or an oxygen-containing gas mixture Caproic acid ester, 6-hydroperoxycaproic acid, 6-hydroxycaproic acid, 5-formylvaleric acid, and α,ω- having 4-6 carbon atoms in a mixture after cyclohexane has been oxidized Dicarboxylic acid is used as raw material, 6-hydroxycaproic acid is prepared by hydrogenation, then esterified and purified by distillation to obtain 6-hydroxycaproic acid ester.

Patent CN109796420A uses trihydroxyethyl isocyanurate and caprolactone as raw materials, under the action of nitrogen atmosphere and catalyst at 100-180 ° C, to generate trihydroxyethyl isocyanurate 3 (6-hydroxyl-hexanoic acid) ester, Its essence is the modification of trihydroxyethyl isocyanurate to improve its water resistance, curing speed and pigment dispersion performance, so as to facilitate the synthesis of trihydroxyethyl isocyanurate by esterification of trihydroxyethyl isocyanurate and acrylate. Ethyl isocyanurate triacrylate reduces the viscosity at room temperature, and makes it difficult to crystallize at low temperature, so as to facilitate its use. The ε-caprolactone used in it is currently low in domestic production, and most of it needs to be imported from abroad. keep its price high.

SUMMARY OF THE INVENTION

In order to solve the above-mentioned problems, the present invention provides a specific experimental scheme: firstly neutralize 6-hydroxyhexanoic acid with alkali to neutrality, then add alcohol, catalyst and a certain amount of solvent to mix and place in the reactor, at 50-150 The reaction is carried out under pressure (saturated vapor pressure of water at the corresponding temperature) for 1-5 hours at a temperature of ℃. After the reaction, a water-carrying agent is added, and a rotary evaporator is used to remove water and solvent to obtain 6-hydroxycaproic acid ester.

Preferably, the base is selected from one or more of sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium bicarbonate, potassium bicarbonate, sodium carbonate and potassium carbonate.

Preferably, the amount of base is 50%-200% of 6-hydroxyhexanoic acid.

Preferably, the concentration of the alkali is all 0.1 mol/L.

Preferably, the amount of alcohol is 50% to 500% of 6-hydroxycaproic acid.

Preferably, the alcohol is selected from 2-bromoethanol, 2-chloroethanol, 3-chloro-1-propanol, 3-bromo-1-propanol, 4-bromo-1-butanol, 4-chloro-1-propanol One or more of butanol, 5-chloro-1-pentanol, 5-bromo-1-pentanol, 6-bromo-1-hexanol and 6-chloro-1-hexanol.

Preferably, the catalyst is selected from tetraethylammonium bromide, tetrabutylammonium bromide, tetraethylammonium chloride, tetrabutylammonium chloride, benzyltriethylammonium chloride, tetrabutylammonium bicarbonate , trioctyl methyl ammonium chloride, tributylamine, dodecyl trimethyl ammonium chloride, tetradecyl trimethyl ammonium chloride, 15-crown-5, 18-crown-6 one or more of them.

Preferably, the amount of the catalyst is 0-8% of the mass of 6-hydroxycaproic acid.

Preferably, the solvent is selected from one or more of DMF, THF, ethylene glycol monophenyl ether, glycerol, DMSO, acetonitrile, NMP, methanol, cyclohexane, dichloromethane, acetone, isopropanol, and heptane. kind.

Preferably, the water-carrying agent is selected from one of cyclohexane, dichloromethane, ethyl acetate, ethyl propionate, n-butyl propionate, toluene, ethanol, diethyl ether, benzene, n-propanol, and isobutanol. species or several.

Compared with CN101945847A, in the present invention, the reaction starts from cyclohexane to finally obtain 6-hydroxycaproic acid ester and needs to be carried out in five steps, the product yield of the side reaction is low, and the by-product components of the main reaction are many and complex , it is difficult to ensure the purity of the product, and there is a one-step hydrogenation reaction. The hydrogenation reaction is one of the "Catalogue of Key Supervision and Hazardous Chemical Processes (2013 Full Version)" of the State Administration of Work Safety. The reaction itself has certain dangers. A lot of unstable factors are added to the whole process. The present invention uses 6-hydroxycaproic acid as a raw material to first neutralize and then esterify the 6-hydroxycaproic acid ester in two steps, which not only ensures the intrinsic safety, but also improves the output. and product purity.

The beneficial effects of the present invention are:

(1) The technical steps are simple, the production cost is low, and the economic benefit is high.

(2) There is no side reaction product production in this technology, and other product salts such as NaCl, KBr, water, etc. are easy to separate and have little impact on the environment, and the process safety factor is high.

(3) The yield of 6-hydroxycaproic acid ester is above 95%, the production effect is good, and the product quality is high.

Detailed ways

The present invention is further described below in conjunction with examples. However, the protection scope of the present invention is not limited to this.

Example 1

30g of 6-hydroxyhexanoic acid was neutralized to neutrality with 0.1mol/L potassium hydroxide solution, 40g of 2-bromoethanol was added, 30g of DMF was added and mixed and placed in a 250ml round-bottomed flask, and tetraethyl was added at 60°C. 0.2 g of ammonium bromide was placed in a collector-type constant temperature heating magnetic stirrer to obtain 6-hydroxyhexanoate through esterification for 2h, and then 30ml of cyclohexane was added to the obtained 6-hydroxyhexanoate to remove water. and solvent to obtain 32.6 g of 6-hydroxycaproate, and the yield of 6-hydroxycaproate is 98.8%.

Example 2-5

The quality of 6-hydroxycaproic acid is the same as that of Example 1, and other is different from that of Example 1, see Table 1 for details.

Examples 6-10

The mass of 6-hydroxycaproic acid is 40g, and other is different from Example 1, see Table 1 for details.

Examples 11-15

The mass of 6-hydroxyhexanoic acid is 50g, and the others are different from Example 1, see Table 1 for details.

The experimental data of Examples 1-15 are shown in Table 1.

Table 1 embodiment experimental data summary

As can be seen from Table 1, the yield of 6-hydroxycaproic acid ester is above 95%, the production effect is good, and the product quality is high.

Claims (10)

1. a synthetic method of 6-hydroxycaproic acid ester, is characterized in that, at first 6-hydroxycaproic acid is neutralized to neutrality with alkali, then add alcohol, catalyzer and a certain amount of solvent, at 50-150 ℃ of temperature The reaction is carried out under pressure for 1-5 hours. After the reaction is completed, a water agent is added to remove water and solvent to obtain 6-hydroxycaproic acid ester. 2. the synthetic method of a kind of 6-hydroxycaproic acid ester as claimed in claim 1 is characterized in that, alkali is selected from sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium bicarbonate, potassium bicarbonate, sodium carbonate, One or more of potassium carbonate. 3. the synthetic method of a kind of 6-hydroxycaproic acid ester as claimed in claim 1, is characterized in that, alkali consumption is 50%-200% of 6-hydroxycaproic acid. 4. the synthetic method of a kind of 6-hydroxycaproic acid ester as claimed in claim 1, is characterized in that, the concentration of alkali is 0.1mol/L. 5. the synthetic method of a kind of 6-hydroxycaproic acid ester as claimed in claim 1 is characterized in that, alcohol consumption is 50%-500% of 6-hydroxycaproic acid. 6. the synthetic method of a kind of 6-hydroxycaproic acid ester as claimed in claim 1 is characterized in that, alcohol is selected from 2-bromoethanol, 2-chloroethanol, 3-chloro-1-propanol, 3-bromo- 1-Propanol, 4-bromo-1-butanol, 4-chloro-1-butanol, 5-chloro-1-pentanol, 5-bromo-1-pentanol, 6-bromo-1-hexanol, One or more of 6-chloro-1-hexanol. 7. the synthetic method of a kind of 6-hydroxycaproic acid ester as claimed in claim 1, is characterized in that, catalyzer is selected from tetraethylammonium bromide, tetrabutylammonium bromide, tetraethylammonium chloride, tetrabutyl ammonium chloride, benzyl triethyl ammonium chloride, tetrabutyl ammonium bicarbonate, trioctyl methyl ammonium chloride, tributylamine, dodecyl trimethyl ammonium chloride, tetradecyl trimethyl ammonium chloride One or more of methylammonium chloride, 15-crown-5 and 18-crown-6. 8. the synthetic method of a kind of 6-hydroxycaproic acid ester as claimed in claim 1 is characterized in that, the amount of catalyst consumption is 0-8% of the quality of 6-hydroxycaproic acid. 9. the synthetic method of a kind of 6-hydroxycaproic acid ester as claimed in claim 1, is characterized in that, solvent is selected from DMF, THF, ethylene glycol monophenyl ether, glycerol, DMSO, acetonitrile, NMP, methyl alcohol, cyclohexane One or more of alkane, dichloromethane, acetone, isopropanol and heptane. 10. the synthetic method of a kind of 6-hydroxycaproic acid ester as claimed in claim 1 is characterized in that, the water-carrying agent is selected from cyclohexane, methylene dichloride, ethyl acetate, ethyl propionate, n-butyl propionate One or more of ester, toluene, ethanol, ether, benzene, n-propanol and isobutanol.