JPS6124582A - Purification of styrene oxide - Google Patents

Abstract

PURPOSE:To purify the titled substance useful as a raw material of 2-phenylethyl alcohol, etc. which are known raw materials of perfumes, economically in an industrial scale, in high yield, by treating a crude reaction liquid containing a styrene oxide compound with a basic aqueous solution, and distilling the treated liquid. CONSTITUTION:A styrene compound is made to react with an organic peroxide (e.g. ethylbenzene hydroperoxide) preferably at a molar ratio of 1-10:1 in the presence of an epoxidization catalyst (preferably molybdenum oxide, etc.) and a cocatalyst (e.g. trimethyl borate) usually at 70-170 deg.C for 0.01-120min. The obtained crude reaction liquid containing a styrene oxide compound is treated with a basic aqueous solution (e.g. aqueous solution of NaOH), and distilled (preferably under vacuum of 10-100mm.Hg at 80-150 deg.C) to effect the purification of the objective compound. The concentration of the basic aqueous solution is preferably 3-30wt%, and the amount of the solution is preferably 10-70vol% based on the above crude liquid.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a process for purifying styrene oxides.

According to the method of the present invention, styrene oxides can be efficiently purified.

The styrene oxides obtained by the method of the present invention are
It is useful as a raw material for polymer stabilizers, ultraviolet absorbers, medicines, fragrances, solvent stabilizers, food additives, etc.

In particular, it is important as a raw material for 2-phenylethyl alcohol, which is a raw material for perfumes, and for phenylalanine, a type of amino acid.

Prior Art Conventionally, methods for producing styrene oxide by reacting styrene with an organic peroxide in the presence of an epoxidation catalyst have been known.

However, in the known method, radical polymerization of styrene occurs simultaneously due to the radicals generated by partial thermal decomposition of the organic peroxide during the reaction, resulting in a decrease in the selectivity of styrene oxide to styrene. Since the conversion rate of 100% is not sufficiently increased, there is a drawback that the post-treatment and purification steps become complicated.

As a method to solve these drawbacks, there is a method of carrying out the reaction in the presence of an aliphatic or alicyclic monoamine and an epoxidation catalyst (Japanese Patent Publication No. 1982-8'106), and a method of carrying out the reaction in the presence of an epoxidation catalyst with an organic amine compound and an epoxidation catalyst. Method of coexistence (4)
G (Kokai No. 56-133, 279) has been proposed.

All of these methods have in common the use of amine compounds, but the selectivity of styrene oxide to styrene and the conversion rate of organic peroxides are still not high enough, making it difficult to call them industrially advantageous. .

On the other hand, there has been no reported example of a method for obtaining pure styrene oxides from the styrene oxides-containing crude reaction solution obtained by the above-mentioned known method. Therefore, when the present inventors separated and purified styrene oxides by distillation, there was a problem that styrene oxides had poor thermal stability and a low recovery rate.

SUMMARY OF THE INVENTION The present inventors have improved the drawbacks of the above-mentioned methods and developed a method for producing, separating and purifying the desired styrene oxides in an industrially advantageous manner and with a lower yield. As a result of intensive study, we have arrived at the present invention.

The method of the present invention provides styrene obtained by a method with excellent characteristics such as (1) high selectivity of styrene oxide to styrene, (2) high conversion rate of organic peroxide, and also high epoxidation rate. Styrene oxides can be obtained with a high recovery rate from the oxide-containing reaction crude liquid.

That is, the present invention is characterized in that a crude reaction solution containing styrene oxides obtained by reacting styrenes and an organic peroxide in the presence of an epoxidation catalyst and a promoter is treated with a basic aqueous solution and then distilled. The present invention provides a method for purifying styrene oxides.

Detailed Description of the Invention (Epoxidation Catalyst) The epoxidation catalyst used in the method of the present invention is a compound of a metal selected from molybdenum, vanadium, and titanium, which is known as an olefin epoxidation catalyst, and oxides of these metals. , trigonides, naphthates, stearates, octoates, carbonyl complexes, acetylacetonates, etc.

Specifically, molybdenum compounds include sodium molybdate, molybdenum oxide, molybdenum sulfide, phosphomolybdic acid, sodium phosphomolybdate, molybdenum oxide acetylacetonate, molybdenum acetylacetonate, molybdenum hexacarbonyl, and pentachloride. Molybdenum, ammonium molybdate, ammonium paramolybdate, silicomolybdic acid, molybdenum naphthenate, stearic acid/molybdenum, molybdenum octylate, etc. Vanadium compounds include sodium vanadate, vanadium oxide, vanadium oxytrichloride, Vanadium acetylacetonate, etc., and titanium compounds include titanium trichloride, titanium oxide, etc.

Among these, molybdenum compounds are preferred, and molybdenum oxide, molybdenum acetylacetonate, molybdenum hexacarna)levonyl, molybdenum naphthenate, molybdenum octylate, etc., which are soluble in organic solvents, are particularly preferred.

The amount of the epoxidation catalyst used is 0.000001 to 0.000001 to 1 mole of organic peroxide, more preferably 0.000001 to 1 mole, more preferably
, o o o o i ~ o, o i times the mole.

(Co-catalyst) Co-catalysts used in the method of the present invention include boron-containing compounds, organic nitrone compounds, organic amine compounds,
These include phenolic compounds and alkali metal salts.

Examples of such co-catalysts include boron-containing compounds such as trimethyl borate, triethyl borate, tributyl borate, triphenyl borate, cyclohexyl metaborate, tripropyl borate, phenyl metaborate, etc. FiN-nitron diphenylamine as an organic nitroso compound;
Organic amine compounds such as nitrosobenzene, N-nitrodietheraniline, nitrosotoluene, nitrosonaphthol, and nitrosophenol include butylamine,
Octylamine, nonylamine, diethylamine, triethylamine, ethylenediamine, aniline, N, N-
Dimethylaniline, pyridine, picoli/butylamine, nato, phenolic compounds include hydroquinone,
Alkali metal salts include t-butylcatechol, di-t-butylhydroxytoluene, dihydroxybiphenyl, phenol, naphthol, sodium acetate, lithium acetate, potassium acetate, sodium propionate,
These include basic alkali metal salts such as potassium nanthenate, sodium hydrogen carbonate, potassium hydrogen carbonate, sodium carbonate, and cesium carbonate.

The amount of these promoters to be used is not particularly limited, but is 1 to 100 times the mole of the epoxidation catalyst, preferably 1 to 100 times the mole of the epoxidation catalyst.
A 0 to 80 times molar amount is used.

(Styrenes) As the styrenes, those represented by the following formula are used.

(In the formula, R1, R2 and R8 may be the same or different, hydrogen, C1-1o alkyl group, C6-15 aryl group, C1-1o alkoxy group, Cs-35 phenoxy group, hydroxy (representing groups, halogen groups, and amino groups) These styrenes are produced by (1) dehydrogenation of the corresponding ethylbenzenes, (2)
It can be easily obtained by reduction reaction and dehydration reaction of the corresponding artphenones. The purity of these styrenes may be within a range that does not affect this reaction, but it is preferably about 80 or higher. □Specific examples of these include styrene, methoxystyrene, methylstyrene, dimethylstyrene, inbutylstyrene, vinylphenol, 3-chloro-4-allyloxystyrene, chlorostyrene, bromostyrene, vinylbiphenyl, 3,
4゜5-trimethoxystyrene, phenoxystyrene,
Examples include dimethylaminostyrene.

(Organic Peroxide) As the organic peroxide, a compound represented by R'OOH is used. Here, R4 is a C1-15 alkyl group or aralkyl group.

Specific examples include ethylbenzene hydroperoxide, cumene hydroperoxide, menthane hydroperoxide, diimpropylbenzene monohydroperoxide, diisobrobylbenzene dihydroperoxide, tetralin hydroperoxide, cyclopentyl hydroperoxide, and cyclohexyl hydroperoxide. Examples include peroxide and t-butyl hydroperoxide.

These organic peroxides may be used in their highly pure form, or may be diluted with a solvent.

The amount of organic peroxide to be used is 1 to 30 times, preferably 1 to 10 times, styrenes by mole per mole of organic peroxide.

(Reaction) In the method of the present invention, the reaction can be carried out without a solvent, but since the thermal decomposition reaction of organic peroxide is an exothermic reaction, a solvent is used to suppress the runaway reaction and the polymerization reaction of styrene. It is preferable.

This solvent is not particularly limited as long as it is inert to the reaction, but examples include benzene, toluene, ethylbenzene,
Aromatic hydrocarbons such as cumene, hexane, heptane,
Fatty raw carbons such as octane, alicyclic hydrocarbons such as cyclohexane, and cyclododecane are used. There is no particular restriction on the amount of solvent used, but it is important to consider the lightness and ease of separation and purification. For this reason, the concentration of the organic peroxide is 5 to 60% by weight, preferably R7, 5 to 40% by weight relative to the reaction solution.

Although the reaction temperature and reaction time vary depending on the type of organic peroxide used, usually the reaction temperature is 70 to 170°C and the reaction time is 0.01 to 120 minutes. in this case,
In order to achieve a high selectivity of styrene oxides to styrenes and a high conversion of organic peroxides, preferably a reaction temperature of 90 to 150°C and a reaction time of 0.1 to 90 minutes are used.

The above reaction can be carried out either batchwise or continuously. Since the reaction is exothermic, a continuous method is preferable when selecting conditions where the reaction temperature is high and the reaction time is short.

In this case, the above-mentioned reaction time is expressed by the time it takes for the reaction solution to pass through the reaction tube. If the liquid supply rate is Am11 minutes, and the volume of the reaction tube is BInl, the reaction time is B/A.
Shown in minutes.

The reaction crude liquid of the above reaction contains the target styrene oxides, a compound having a hydroxyl group corresponding to the organic peroxide used, unreacted styrenes, unreacted organic peroxide, epoxidation catalyst, and co-catalyst. contains. For example, when using cumene hydroperoxide, cumyl alcohol, when using ethylbenzene hydroperoxide, 1-phenylethyl alcohol, and when using t-butyl hydroperoxide, Ut-butyl alcohol is the desired styrene oxide. Generate each along with the class.

The above cumyl alcohol, 1-phenylethyl alcohol and t-butyl alcohol are useful in their own right;
Further, σ-methylstyrene, styrene/and imbutylene obtained by dehydrating these compounds are also useful compounds.

(Basic aqueous solution and treatment) The method of the present invention is characterized in that the crude reaction solution containing styrene oxides obtained by the above reaction is washed with a basic aqueous solution and then purified by distillation. .

The basic aqueous solution used in the method of the invention is an aqueous solution of alkali metal and/or alkaline earth metal hydroxides and/or salts thereof.

Specifically, the alkali metal hydroxide includes lithium hydroxide, sodium hydroxide, potassium hydroxide, cesium hydroxide, and the like. Also, carbonates, hydrogen carbonates, or carboxylates of alkali metals, and specific examples include lithium carbonate, sodium carbonate, sodium hydrogen carbonate, potassium acetate, potassium carbonate, and cesium carbonate.

Specifically, the alkaline earth metal hydroxides include magnesium hydroxide, calcium hydroxide, strontium hydroxide, and barium hydroxide.

Salts, carbonates, hydrogen carbonates, and carboxylates of alkaline earth metals, such as magnesium carbonate, calcium carbonate, calcium acetate, strontium carbonate, and barium acetate.

These should be used in an amount sufficient to maintain the basicity of the treatment solution after washing, but it is sufficient to add a basic aqueous solution of 3 to 30 parts by weight and 11 parts to the reaction crude solution containing styrene oxides. It is preferable for operation to use about 10 to 70 volumes.

The treatment of the crude reaction solution containing styrene oxides with the basic aqueous solution used in the above ratio is carried out by thoroughly mixing these two solutions. Since this process is completed very quickly, no special operations such as heating are required, but for example, a temperature range of 0 to 100°C and a time of about 1 to 60 minutes are sufficient.

By allowing the above-mentioned product to stand still, styrene oxide,
Separates into oil layer containing sides and water layer. The styrene oxide-containing oil layer after this washing treatment is subjected to a distillation process.

(Distillation) Although distillation can be carried out by either normal pressure distillation or reduced pressure distillation, it is preferable to perform flash distillation depending on the type of styrene oxide in view of its thermal stability. For example, when separating and purifying styrene oxide as a target compound by distillation,
The distillation is carried out at a pressure range of about 10 to about 100 bits of Hg and a bottom temperature of the distillation column of about 80 to about 150°C.

EXPERIMENTAL EXAMPLE Next, the present invention will be explained in more detail using an experimental example. Judgment was made based on the residual rate shown in the formula.

Styrene oxide residual rate (4) Styrene oxide (mol) in the charged reaction crude liquid Reference example 1 (Synthesis of styrene oxide) Inner diameter 2.6 wa,
A glass tube with an internal volume of 14 cc and 22 styrene ribs s, s
ow cumene hydroper, l-side 21.2% by weight,
Molybdenum oxide acetylacetonate 0.033% by weight
boric acid trimethyl ester 0.6% by weight and cumene 5
A liquid containing 6.2% by weight was allowed to flow and react at a reaction temperature of 115° C. and a residence time of 10 minutes. When styrene and cumene were distilled off under reduced pressure from the reaction product solution, the remaining solution contained 40.7% by weight of styrene oxyl, 5B in cumyl alcohol,
It contained 6% by weight.

Comparative Example 1 Using the residual liquid obtained by distilling styrene and cumene under reduced pressure from the reaction product liquid obtained in Reference Example 1, a thermal stability test was conducted by heating at the temperature and time shown in Table 1.

After this stability test, the content of styrene oxide in the residual liquid was determined to determine the residual rate of styrene oxide.

The results are shown in Table 1.

Table 1 Examples 1 to 4 Using the residual liquid obtained by distilling styrene and cumene under reduced pressure from the reaction product liquid obtained in Reference Example 1, 20 m of this residual liquid was shaken and washed for 2 minutes with 10 cc of the basic aqueous solution shown in Table 2. The organic layer was separated and taken, and a heating stability test was conducted in the same manner as in Comparative Example 1, except that the heating temperature was set as shown in Table 2. The results are shown in Table 2.

(Margin below) Table 2 Example 5 5 occ of the residual liquid obtained by distilling styrene and cumene under reduced pressure from the reaction product liquid obtained in Reference Example 1 was heated to 20 'llr Na0
After shaking and washing with 30 cc of FI aqueous solution for 2 minutes, the organic layer was separated. The styrene oxide was separated and purified using a rotating band type rectification column having 40 theoretical plates. The operation was carried out at a tower top pressure of 2.0 + mHg, a tower bottom temperature of 94°C, and a reflux ratio of 10, and a pure product of styrene oxide was obtained at a distillation temperature of 84°C. The recovery rate of styrene oxide was 97%.

Reference example 2 Internal volume 1000 equipped with thermometer, stirrer and reflux condenser
In a CC three-necked flat bottom flask, 5 thymolybdenaphthenate o, a9r (o, 2 mmol), N-nitrosodiphenylamine 0.7'59 (3,8 mmol), 8
0 chikumen hydroperoxide 4 sp (2 as
1 mmol), styrene 47f (453 mmol), and cumene 350 CC, and heated at 115°C under nitrogen atmosphere for 30 min.
The mixture was heated and stirred for a minute.

After the reaction was completed, styrene and cumene were distilled off from the reaction solution under reduced pressure, and 33.3% of styrene oxide was found in the residual solution.
It contained 7% by weight and 63.5% by weight of cumyl alcohol.

Example 6 Using the residual liquid obtained by distilling styrene and cumene under reduced pressure from the reaction product liquid obtained in Reference Example 2, 20 cc of the residual liquid was
After shaking and washing with 1 NaOH and 1 oac for 3 minutes, the organic layer was separated and taken, and this was subjected to a heating stability test at 150° C. for 3 hours. As a result, the residual rate of styrene oxide was 1
It was 00chi.

Comparative Example 2 Using the residual liquid obtained by distilling styrene and cumene under reduced pressure from the reaction product liquid obtained in Reference Example 2, a heat stability test was conducted in the same manner as in Example 6, except that it was not washed with 20% NaOH. . As a result, the residual rate of styrene oxide was 81.
It was 2.1.

Claims (1)

[Claims] (1) Styrene oxide, which is produced by treating a styrene oxide-containing crude reaction solution obtained by reacting styrene and an organic peroxide in the presence of an epoxidation catalyst and a co-catalyst with a basic aqueous solution and then distilling it. kind of purification method.