JPH0699343B2 - Manufacturing method of 1,6-hexanediol - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid mixture of an esterified product having a high acid value obtained by esterifying a carboxylic acid compound obtained by oxidation of cyclohexane and separating and purifying the carboxylic acid compound. , Contact with a basic solid substance to form a mixed solution of an ester compound with a very low acid value (low acid value ester compound), and hydrogenate the low acid value ester compound to lower the ester value (EV value). High purity 1,
It relates to a method for producing 6-hexanediol at a high conversion rate.

[Description of Prior Art]

Conventionally, as a method of producing 1,6-hexanediol, for example, as described in JP-B-53-33567, cyclohexane is oxidized to give a carboxylic acid compound such as adipic acid or oxycaproic acid. Produce, esterify the carboxylic acid compound with alcohols such as ethanol, butanol, 1,6-hexanediol, and separate and purify the reaction product to produce an esterified product,
Finally, a method is known in which the obtained esterified product is hydrogenated with hydrogen in the presence of a hydrogenation catalyst to produce 1,6-hexanediol.

In the known method for producing 1,6-hexanediol,
Hydrogenation of highly oxidized esterified compounds in the presence of hydrogenation catalysts can easily degrade the hydrogenated catalysts, resulting in a lower conversion of esterified compounds to 1,6-hexanediol, or ultimately When the ester value (EV value) of the resulting 1,6-hexanediol is high and 1,6-hexanediol with a high EV value is used to manufacture chemicals (eg polyester, curing agent, etc.) , There was a problem that the quality deteriorates.

[Problems to be Solved by the Present Invention]

In the above-mentioned method for producing 1,6-hexanediol, it is industrially very difficult to sufficiently reduce the acid value of the esterified product so that the hydrogenation catalyst does not substantially deteriorate, and as a result, It was not possible to obtain highly pure 1,6-hexanediol at the conversion rate.

The object of the present invention is to sufficiently reduce the acid value of the esterified product used in the hydrogenation reaction in the process for producing 1,6-hexanediol to convert highly pure 1,6-hexanediol having a low EV value into high conversion. It is to provide a way to get at a rate.

[Means for solving problems]

In this invention, a carboxylic acid compound obtained by the oxidation of cyclohexane is esterified with alcohols and separated.
After purification to obtain a liquid mixture of the esterified product, the liquid mixture of the esterified product is contacted with a basic solid substance to obtain an acid value (AV value) of the mixture of 0.8 mgKOH / g or less, and It relates to a method for producing 1,6-hexanediol, which comprises hydrogenating a liquid mixture of an esterified product having a reduced acid value in the presence of a hydrogenation catalyst to produce 1,6-hexanediol.

[Detailed description of each requirement of the present invention]

Hereinafter, the method for producing 1,6-hexanediol of the present invention will be described in detail.

The liquid mixture of the esterified product used in the present invention is, for example, as described in JP-B-53-33567, cyclohexane in the presence of a catalyst, at a temperature of about 100 to 200 ° C., and about Various carboxylic acids by-produced with cyclohexanone, cyclohexanol, etc. by oxidation with molecular oxygen under a pressure of ^{2 to 20} kg / cm ² G (monovalent carboxylic acids such as caproic acid, valeric acid, butyric acid, A carboxylic acid compound (mixture) containing divalent carboxylic acids such as adipic acid, glutaric acid, succinic acid, and oxyacids such as oxyvaleric acid and oxycaproic acid;
Obtained by separating from the oxidation reaction solution by a suitable means, and then obtaining the carboxylic acid compound (mixture) thereof with methanol, ethanol, n-propanol, n-butanol, amyl alcohol, n-hexanol, n-heptanol, etc. C1-C8 monohydric lower alcohols, ethylene glycol, propylene glycol, 1,4
-In the presence of an esterifying agent consisting of alcohols such as dihydric alcohols having 2 to 8 carbon atoms such as butanediol, 1,5-pentanediol, and 1,6-hexanediol, in the presence of no catalyst, about The esterification is carried out at a high temperature of 150 to 300 ° C. and normal pressure or pressure, or in the presence of an esterification catalyst at a temperature of 50 to 150 ° C. and normal pressure or pressure, and finally, It may be a liquid mixture of esterification products containing adipic acid diester, oxycaproic acid ester, etc. as the main components, which are obtained by separating and purifying the product of the esterification reaction by an appropriate means.

In this invention, the liquid mixture of the esterified product is
Adipic acid diester, oxycaproic acid ester,
About 30-90% by weight, especially about 40-80% by weight,
Acid value (AV value) is about 1.0 to 10 mgKOH / g, especially 1.0 to 5.0 mgKOH / g.
It is preferably about g, and if necessary, a solution in which the esterified product is dissolved in a suitable organic solvent (in particular, an organic solvent used for extracting the carboxylic acid compound described below). May be.

As a method for separating the carboxylic acids from the cyclohexane oxidation reaction solution, for example, the cyclohexane oxidation reaction solution is saponified with caustic soda and the aqueous layer is separated to contain various carboxylates. Obtaining an alkaline solution, neutralizing the alkaline solution with sulfuric acid to a pH of 3 or less to produce Glauber's salt and carboxylic acids, and from the Glauber's salt aqueous solution of the aqueous layer separated from the neutralized solution, Various carboxylic acids of methyl ethyl ketone,
Extract with organic solvents such as methyl isobutyl ketone, ketones such as cyclohexanone, esters such as ethyl acetate, butyl acetate, methyl caproate, and lower alcohols such as butyl alcohol and isopropyl alcohol to obtain a carboxylic acid compound (mixture) You can take the method.

In the present invention, a liquid mixture of the above-mentioned esterified product is brought into contact with a basic solid substance to obtain an acid value (AV) of the mixture.
Value) is 0.8 mgKOH / g or less, preferably about 0.01 to 0.5 mgKOH / g, and the liquid mixture of the esterified product having a reduced acid value is hydrogenated in the presence of a hydrogenation catalyst to give 1,6- Hexanediol is produced.

The basic solid substance mentioned above may be in the form of powder or granules that are basic when contacted with water or slightly dissolved in water to show basicity, and are relatively stable at high temperatures (about 150 to 350 ° C). Solid substances or those in the form of tablets, for example, barium carbonate, barium hydroxide, barium compounds such as barium oxide, magnesium hydroxide, magnesium, alkali zeolite,
Examples thereof include calcium hydroxide and calcium oxide, and barium compounds are particularly preferable.

As a method of contacting the liquid mixture of the esterified product with a basic solid substance, a powdery basic solid substance is added to the liquid mixture to bring it into a suspended state, and the contact is about 30 to 400 ° C. By subjecting the suspension to a temperature of about 50 to 350 ° C. and normal pressure or pressure for about 0.01 to 5 hours, particularly 0.05 to 2 hours, and then filtering the suspension to remove basic solid substances. Method to be carried out, or by forming a fixed bed in the container by the granular or tablet-like material of the basic solid substance, the liquid mixture of the esterified product is fed into the container, and the inside of the fixed bed is about 30 to 400. ℃, especially 50
Examples include a method in which the contact is carried out for about 0.01 to 2 hours, particularly 0.02 to 1 hour by flowing at a temperature of about 350 ° C. and normal pressure or pressure.

Furthermore, the method of hydrogenating the liquid mixture of the esterified product whose acid value is lowered in the presence of a hydrogenation catalyst can be carried out by a known method, in particular, in the presence of a catalyst, 200 to 4
00 ° C., in particular at a temperature of 250 to 350 ° C., is preferably carried out at a hydrogen partial pressure of 150~500kg / cm ² G, particularly 200~350kg / cm ² G.

Examples of the hydrogenation catalyst include iron, nickel, cobalt, copper, and a hydrogenation catalyst containing copper-chromite as a main component, and the form thereof is in the form of powder or tablet. It may be present, and the amount used is about several wt% with respect to the liquid mixture of the esterified product obtained by esterifying the carboxylic acid compound.

〔Example〕

Hereinafter, the production method of the present invention will be described in more detail with reference to Examples and Comparative Examples.

Example 1 An alkaline solution obtained by saponifying a liquid-phase oxidation reaction solution obtained by aerial oxidation of cyclohexane with caustic soda was neutralized with sulfuric acid, and at that time, the density of the sodium sulfate solution in the aqueous layer of the neutralized solution was neutralized. Balance the water to be 1.25 g / cm ^3, and after separating the neutralizing solution into an aqueous layer and an oil layer, adipic acid, carboxylic acid compounds such as oxycaproic acid contained in the aqueous sodium sulfate solution of the aqueous layer , Extracted with methyl isobutyl ketone (MIBK),
Then, MIBK was evaporated and removed from the extract to obtain a mixture of carboxylic acid compounds.

Next, the "liquid mixture of the carboxylic acid compound (water content: 5% by weight)" heated to 80 ° C was supplied to the esterification step at a supply rate of 740 / hour, and a liquid product of 1,6-hexanediol was also added. (Concentration: 60% by weight) is supplied to the esterification step at a supply rate of 820 / hour to form a carboxylic acid compound.
Esterification reaction with 1,6-hexanediol at a temperature of 200-250 ° C under atmospheric pressure, the reaction rate of esterification is about 99.2%
, "Adipic acid diester content is 30% by weight, oxycaproic acid ester content is 35% by weight, and a liquid mixture of esterified products having an acid value of 3.1 mgKOH / g" is obtained. .

Liquid mixture of esterified product obtained as described above 10
Add 100 kg of powdered barium hydroxide to 00 kg, and add 100
After stirring the liquid mixture with a basic solid substance (barium hydroxide) by stirring for 30 minutes at 30 ° C., barium hydroxide is removed from the liquid mixture by filtration through a filter to give an acid value of 0.2 mgKOH / A liquid mixture of esterified products of g was obtained.

A copper-chromite catalyst was added to the "liquid mixture of esterified product having an acid value of 0.2 mgKOH / g" obtained as described above.
Add 0.6% by weight, hydrogen pressure 290kg / cm ² G, temperature 285-29
Hydrogenation reaction was carried out at 5 ° C. to produce 1,6-hexanediol with a conversion of 97%, which was separated and purified to obtain purified 1,6-hexanediol.

The purified 1,6-hexanediol obtained as described above had an EV value of 0.2 mgKOH / g and a purity of 1,6-hexanediol of 99.2% by weight (freezing point: 40.7 ° C.).

Example 2 A column (internal diameter: 15 mm, length: 300 mm) packed with powdered metallic magnesium (apparent volume: about 50 cm ³ ) was used to obtain the “acid value of 3.1 mgKOH obtained in the esterification step of Example 1. The liquid mixture of the esterified product, which is / g, is continuously supplied at a supply rate of 110 ml / hour, and is brought into contact with the metal magnesium at 80 ° C., and the acid value is 0.1 mgKOH / g for 400 minutes. A liquid mixture of some esterified product was obtained.

Example 1 was repeated except that the "liquid mixture of esterified product having an acid value of 0.1 mgKOH / g" obtained as described above was used.
Pure 1,6-hexanediol was obtained in the same manner as in.

The conversion rate in the hydrogenation was about 98%.

The purified 1,6-hexanediol obtained as described above had an EV value of 0.1 mgKOH / g and a purity of 1,6-hexanediol of 99.4% by weight (freezing point: 40.8 ° C.).

Comparative Example 1 The acid value of 3.1 mg KOH obtained in the esterification step of the carboxylic acid mixture and 1,6-hexanediol in Example 1
liquid phase mixture of esterified product of 1 / g was used as it was and hydrogenation was carried out as it was without contacting with the basic solid substance, and purified 1,6-hexanediol was added. Obtained.

The conversion rate in the hydrogenation was about 87.5%.

The purified 1,6-hexanediol obtained as described above had an EV value of 50 mgKOH / g and a purity of 1,6-hexanediol of 99.0% by weight (freezing point: 40.3 ° C).

[Operation and effect of the present invention]

The present invention is a "liquid mixture of esterified products having a high acid value" obtained by esterifying a carboxylic acid compound (mixture) obtained by the oxidation of cyclohexane and separating and purifying it.
By contacting it with a basic solid substance to form a liquid mixture of an esterified product having a very low acid value (low acid value esterified product), and hydrogenating the low acid value esterified product in the presence of a catalyst, EV High-purity 1,6 with a value of 30 mg KOH / g or less
-Hexanediol can be industrially produced with a high conversion rate (95% or more).

Furthermore, since the basic solid substance is hardly soluble in the hydrogenation reaction liquid, the unreacted basic solid substance can be easily removed from the hydrogenation reaction liquid by a simple known operation (for example, filtration). Can be removed.

Claims (1)

[Claims] 1. A carboxylic acid compound obtained by the oxidation of cyclohexane is esterified with alcohols and separated.
After purification to obtain a liquid mixture of the esterified product, the liquid mixture of the esterified product is contacted with a basic solid substance to obtain an acid value (AV value) of the mixture of 0.8 mgKOH / g or less, and A process for producing 1,6-hexanediol, which comprises hydrogenating a liquid mixture of an esterified product having a reduced acid value in the presence of a hydrogenation catalyst to produce 1,6-hexanediol.