JPS62103033A - Separation of cyclohexanol - Google Patents

Abstract

PURPOSE:To economically and readily obtain the titled compound, by treating a reaction solution prepared by hydration reaction of cyclohexene in the presence of an acid with a hydrocarbon as an extracting solvent and efficiently extracting and separating cyclohexanol without increasing the amount of an aqueous solution so much. CONSTITUTION:Cyclohexene is hydrated in the presence of an acid, e.g. aromatic sulfonic acid, while heating and the resultant reaction solution is separated into a cyclohexene phase and an aqueous slution phase, which can be directly or diluted with water and brought into contact with a hydrocarbon, e.g. benzene, toluene or cyclohexene, etc., at ordinary temperature-20 deg.C for several minutes to separate the aimed cyclohexanol from the aqueous solution of the acid. The above-mentioned aqueous solution of the acid can be directly reused for the hydration reaction. the amount of the hydrocarbon to be used is 0.1-10pts. wt. based on 1pts.wt. hydration reaction solution. EFFECT:When cyclohexene is particularly used as the extracting solvent, this method has an advantage since the cyclohexanol is increased in extracting operation.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for separating cyclohexanol in an aqueous acid solution.

More specifically, the present invention relates to a method for hydrating cyclohexene in the presence of an acid and then separating cyclohexanol from the reaction solution.

<Prior art> Normally, when cyclohexene is hydrated to obtain cyclohexanol, the reaction is carried out in the presence of an acid, but when a soluble acid such as aromatic sulfonic acid is used, a highly concentrated aqueous solution is used. (Japanese Patent Publication No. 43-16125), the reaction product cyclohexanol is mostly present in the aqueous phase of this highly concentrated acid.

Cyclohexanol in these highly concentrated acid aqueous solutions has a very strong bond with the acid, and it is not easy to separate and obtain hexanol from the reaction solution. Conventional methods for separating cyclohexanol from the reaction solution As a method, a method of distilling the reaction solution is known (Japanese Patent Application Laid-open No. 43227/1983).

Another method includes neutralizing the acid with a base and then extracting and separating with an organic solvent.

(Problems to be solved by the invention) In the distillation method, cyclohexanol is azeotropic with water, and the azeotropic composition is less than 0.2 in the 1iff ratio of cyclohexanol/water, so a large amount of water can be distilled. I will have to let it out.

Therefore, a large amount of heat is required, and since the solubility of cyclohexanol in water is 3.6% by weight at 20°C, treatment such as extraction with an organic solvent is required to separate cyclohexanol again after extraction. Therefore, the distillation method is economically disadvantageous.

The method of neutralizing the acid in the reaction solution and then extracting and separating it with an organic solvent requires a large amount of base for neutralization due to the high acid concentration, and it is usually industrially difficult to regenerate and recover the salt produced as an acid. is difficult.

In addition, both methods involve a large amount of wastewater and require a great deal of effort for subsequent treatment.

Therefore, the development of a simple method for separating cyclohexanol from a reaction solution in which cyclohexene is hydrated in the presence of an acid is strongly desired.

<Means for Solving the Problems> In view of this situation, the present inventors have devised a method for easily and economically separating cyclohexanol from a reaction solution containing an acid such as an aromatic sulfonic acid. After thorough study and completion of the present invention.

That is, the present invention provides a method for separating cyclohexanol, which is characterized in that cyclohexene is subjected to a hydration reaction in the presence of an acid, the reaction liquid is brought into contact with hydrocarbons, and cyclohexanol is extracted and separated from the reaction liquid. It is related to.

The present invention will be explained in detail below.

Cyclohexanol is produced by heating cyclohexene in the presence of an acid such as an aromatic sulfonic acid and performing a hydration reaction.

The resulting reaction solution is separated into a cyclohexene phase and an aqueous solution phase, and the aqueous solution phase is brought into contact with hydrocarbons as is or diluted with water to extract cyclohexanol and separate it from the acid aqueous solution.

When extracting cyclohexanol, the lower the acid concentration of the acid aqueous solution, the better the extraction efficiency of cyclohexanol, but if the concentration is too low, it will be necessary to separate and concentrate the recovered acid aqueous solution when reusing it for the hydration reaction. occurs and requires a large amount of heat.

Therefore, it is desirable to adjust the acid concentration of the acid aqueous solution to a range of 30 to 70% by weight (weight% excluding organic substances) using water or a low concentration acid aqueous solution.

Examples of the hydrocarbons used include aromatic hydrocarbons, linear aliphatic hydrocarbons, branched aliphatic hydrocarbons, and alicyclic hydrocarbons. Preferably, aromatic hydrocarbons and alicyclic hydrocarbons are used. Hydrogens, particularly preferably benzene, toluene,
Examples include xylene, tetralin, and cyclohexene.

In view of the extraction efficiency of cyclohexanol, the amount of these hydrocarbons to be used is 0.00 parts by weight per 1 part by weight of the hydration reaction aqueous solution.
It is used in an amount of 1 to 10 parts by weight, preferably 0.5 to 2 parts by weight.

There are no particular restrictions on the extraction temperature, but the higher the temperature, the higher the extraction efficiency.

When a chemical compound other than cyclohexene, such as benzene, is used as an extraction solvent, when the extraction temperature becomes high, cyclohexanol produced by a hydration reaction returns to cyclohexene, which is economically unfavorable.

When cyclohexene is used as an extraction solvent, there is an advantage that cyclohexene reacts during the extraction operation and cyclohexanol increases. Therefore, the extraction temperature is usually from room temperature to about 200°C.

Furthermore, even a very short contact time of several minutes between the extraction solvent and the acid aqueous solution is sufficient for extraction and separation.

Furthermore, the separated extraction solvent phase and mature tree solution phase are each treated by the following means.

In other words, a very small amount of acid migrates into the extraction solvent phase, but
This can be easily recovered by washing with a small amount of water.
The cyclohexanol can then be separated by distillation.

On the other hand, although a small amount of hydrocarbons migrate into the acid aqueous solution phase, they can be reused as they are in the hydration reaction.

<Effects of the Invention> The method of the present invention efficiently extracts cyclohexanol from a reaction solution obtained by performing a hydration reaction in the presence of cyclohexene acid using hydrocarbons without significantly increasing the amount of aqueous solution. This is an industrially excellent method.

In particular, when cyclohexene is used as an extraction solvent, it has the advantage that cyclohexanol increases during the extraction operation.

<Examples> The present invention will be specifically described below using Examples, but the present invention is not limited to these Examples.

The extraction rate of cyclohexanol shown in the examples is: cyclohexanol extraction rate (%) = Total amount after extraction
given in the amount of cyclohexanol.

The rate of increase or decrease in cyclohexanol is given by cyclohexanol + li rate (%) = total amount of cyclohexanol before extraction.

That is, when this increase/decrease rate is positive, cyclohexanol increases due to the extraction operation, and when it is negative, cyclohexanol decreases.

Examples 1 to 4 A 200 ml flask was charged with 50 g of an aqueous hydration solution containing 58% by weight of p-to)reninsulfonic acid and 8% by weight of cyclohexanol, and a predetermined amount of water was added thereto.

Furthermore, add benzene in an amount equal to that of the aqueous solution phase, and add 20
Stirred at ℃ for 1 hour. After standing for several minutes, the liquid was separated and cyclohexanol in benzene was analyzed.

The results are shown in Table 1.

Table 1 Examples 5 to 7 50 g of a hydration reaction aqueous solution containing 45% by weight of p-toluenesulfonic acid and 7% by weight of cyclohexanol was mixed with 5% by weight of benzene.
The benzene was stirred with 0 g at a predetermined temperature, and after liquid separation, cyclohexanol in benzene was analyzed. The results are shown in Table 2.

Table 2 Examples 8 to 1 O3 p-) Hydration reaction aqueous solution containing 45% by weight of luenesulfonic acid and 7% by weight of cyclohexanol 508G with 4a solvent 5
The mixture was stirred at 20° C. with 0 g, and after liquid separation, cyclohexanol in the organic solvent was analyzed.

The results are shown in Table 3.

Table 3 Example 11-14 50g of hydration reaction aqueous solution containing 10% by weight of 1)-) luenesulfonic acid and cyclohexanol prepared at various times was placed in a 2001 flask, 50g of cyclohexene was added thereto, and the mixture was heated at 20°C. Stirred for 1 hour.

After standing for several minutes, the liquid was separated and cyclohexanol in cyclohexene was analyzed.

The results are shown in Table 4.

Table 4 Examples 15 to 17゜p-) 50 g of a hydration reaction aqueous solution containing 11% of 45i luenesulfonic acid and 10% by weight of cyclohexane was stirred at a predetermined temperature with 50 g of cyclohexene, and after liquid separation, cyclohexanol in cyclohexene was analyzed. did.

The results are shown in Table 5.

Table 5 Comparative Examples 1 to 3 50 g of a hydration reaction solution containing 45% by weight of p-toluenesulfone #10 and 10% by weight of cyclohexanol was mixed with benzene 5
After stirring at a predetermined temperature with 0 g of benzene, the cyclohexanol in benzene was analyzed after liquid separation.

The results are shown in Table 6.

Table 6

Claims (1)

[Claims] A method for producing cyclohexanol, which is characterized in that after hydrating cyclohexene in the presence of an acid, the reaction solution is brought into contact with hydrocarbons, and cyclohexanol in the reaction solution is extracted and separated. Separation method.