KR100288122B1 - Alkylation of Hydroxylated Aromatic Compounds - Google Patents

Abstract

The present invention relates to an alkylation method of a hydroxylated aromatic compound, and more particularly, 50 to 200 ℃ and 1 to 20 atm using olefins or alcohols on a porous solid acid catalyst in which the acidity and the size of the pupil are properly selected / controlled. The present invention relates to a method of alkylating a hydroxylated aromatic compound under the conditions of the above to overcome the disadvantages of the liquid phase alkylation reaction by the conventional homogeneous catalyst system, and to alkylate the hydroxylated aromatic compound with high selectivity and conversion.

Description

[Name of invention]

Alkylation of Hydroxylated Aromatic Compounds

Detailed description of the invention

[Purpose of invention]

[Technical field to which the invention belongs and the prior art in that field]

The present invention relates to an alkylation method of a hydroxylated aromatic compound, and more particularly, 50 to 200 ℃ and 1 to 20 atm using olefins or alcohols on a porous solid acid catalyst in which the acidity and the size of the pupil are properly selected / controlled. The present invention relates to a method of alkylating a hydroxylated aromatic compound under the conditions of the above to overcome the disadvantages of the liquid phase alkylation reaction by the conventional homogeneous catalyst system, and to alkylate the hydroxylated aromatic compound with high selectivity and conversion.

Hydroxy aromatic alkylated derivatives are utilized in various fine chemical products as intermediates of antioxidants, synthetic resins, polymerization inhibitors, film developers, surface active agents, perfumes, pesticides and pharmaceuticals.

Therefore, various researches on the method of alkylating a hydroxylated aromatic compound have been advanced conventionally. It is very difficult to selectively obtain only a single alkylated derivative of a hydroxylated aromatic compound by a general preparation method, and usually two, three or more substituted derivatives are obtained together as a mixture. The position of substitution of the alkyl group introduced into the hydroxylated aromatic compound depends mainly on the type and amount of the catalyst and the reaction temperature. In other words, alkylation of hydroxylated aromatic compounds on low temperatures and small amounts of catalyst produces predominantly alkyl aryl ethers, whereas at higher temperatures, stronger acidity and more catalysts alkylated phenols are the main product. Is generated. For example, in order to obtain o- / p-alkylphenols by alkylation of phenol with propene or isobutene, the reaction should be carried out at a temperature ranging from 50 to 350 ° C. over a catalyst such as sulfuric acid, hydrofluoric acid, and BF 3. In addition, when the alkylation reaction of phenol and isobutene is carried out at 120 to 150 ° C. on an aluminosilicate catalyst, an o-derivative can be obtained as a main product.

Dihydroxylated aromatic compounds, such as catechol and hydroquinone, will exhibit stronger electrophilic substitution reactivity than phenol, and are expected to have greater steric hindrance due to the presence of two hydroxy groups in one benzene ring. do.

In addition, the size and nature of the alkyl group to be introduced can be seen as an important variable that determines the type and distribution of the product.

As an example of alkylation of dihydroxy aromatic compounds, US Pat. No. 4,323,714 discloses hydroquinone at 75 ° C. using isobutylene or t-butanol under a NafionTM resin (Du Pont) catalyst and a 2-heptanone solvent. Reaction was carried out for 2 hours to 27% (based on hydroquinone), 66% (based on isobutylene), 33% selectivity for mono-t-butylhydroquinone and 41 for di-t-butylhydroquinone Got%. On the other hand, xylene as a solvent was carried out at 105 to 110 ° C. for 0.25 hours to obtain 65% conversion (based on hydroquinone), 100% conversion (based on isobutylene) and mono-t-butylhydroquinone 39 Obtained 58% selectivity to% and di-t-butylhydroquinone.

The results of this study have much room for improvement because of their low selectivity and conversion rate.

In addition, Japanese Patent Publication No. 49-109325 discloses that catechol and t-butanol were reacted for 3 hours at 110 to 120 ° C. using Lewis acid (FeCl ₃ -HCl, ZnCl ₂ -HCl) catalysts. Although pt-butylcatechol having a conversion rate was prepared, not only was the selectivity low, but excessive waste acid was generated as a by-product, which is not environmentally friendly.

As a method for preparing methylated derivatives of catechol using methanol in a gaseous state, γ-Al ₂ O ₃ series catalysts are widely used [L. Kiwi-minsker et al Stud. Surf. Sci. & Catal. 101, 171 (1996); In S. Perchet et al Chem. Eng. Technol. 17, 108 (1994)], increased the selectivity for 3-methylcatechol from 26% to 65% by controlling the acidity of the catalyst by adding 7.5% magnesium to γ-Al ₂ O ₃ . In fact, it is difficult to selectively control the position at which the methyl group is added, which has a disadvantage of generating various by-products together.

As described above, in the technology of preparing alkylated derivatives of hydroxylated aromatic compounds, various isomers are generated together as by-products depending on the nature of the catalyst, the kind of the reactants, the reaction conditions, and the like.

In addition, homogeneous catalysts such as sulfuric acid and hydrofluoric acid, which have been generally applied in the alkylation method of a hydroxylated aromatic compound, have low selectivity and conversion for a desired product, and as a by-product, excess waste acid and waste water are generated, which can be overcome. The development of new catalysts is inevitable.

[Technical problem to be achieved]

Accordingly, the present invention has been made to develop a method for preparing alkylated derivatives of hydroxylated aromatic compounds having excellent selectivity and conversion compared with the conventional techniques, and as a result, among various known porous catalysts, specific acidity and pupil size and structure By using a solid acid catalyst having a reaction with an appropriate alkylating reagent has been developed a method for alkylation of hydroxylated aromatic compounds having excellent selectivity and conversion.

Accordingly, an object of the present invention is to provide a method for alkylating hydroxylated aromatic compounds having excellent selectivity and conversion.

[Configuration and Function of Invention]

The present invention provides a method for alkylating a hydroxylated aromatic compound, wherein the alkylation reaction is carried out under a porous solid acid catalyst having a molar ratio of silica / alumina (SiO ₂ / Al ₂ O ₃ ) of 1 to 100 and a pore size of 2 to 20 GPa. It is characterized by performing.

Referring to the present invention in more detail as follows.

The porous solid acid catalyst used in the production method according to the present invention is a heterogeneous catalyst, which has excellent selectivity and conversion for the product, minimizes the generation of waste acid and wastewater, and also has a very good selectivity of the product, thereby reacting the reactants. It is preferable from an economical and environmentally friendly point of view because it does not need to separate the product and the product, thereby simplifying the manufacturing process. In addition, the alkylation reaction of the hydroxylated aromatic compound in the presence of such a porous solid acid catalyst is carried out under mild conditions, and as a result, the alkylated hydroxylated aromatic compound can be produced in high selectivity and high yield.

Porous solid acid catalysts of the present invention include ZSM-5, β-zeolite, L, USY, mordenite, γ-alumina, or a reforming catalyst chemically modified by an ion exchange method. The above-mentioned porous solid acid catalyst has been used in the petrochemical and fine chemical fields for the purpose of effectively preparing and separating isomers having different shapes, but as in the present invention, the specific ratio of silica / alumina or the size of the pores is controlled to control carbon. It has never been used as an alkylation reaction catalyst for the high selective introduction of alkyl groups having at least three atoms into specific positions of the benzene ring of aromatic compounds under hydroxy.

In the present invention, the porous solid acid catalyst described above is limited to using a porous solid acid catalyst having a molar ratio of silica to alumina (SiO ₂ / Al ₂ O ₃ ) of 1 to 100 and a pore size of 2 to 20 kPa. When the molar ratio of silica / alumina (SiO ₂ / Al ₂ O ₃ ) of the porous solid acid catalyst selectively used by the present invention is less than 1, zeolites having a specific structure are difficult to form, and when the molar ratio exceeds 100, the acidity and the number of acid sites are small. There is a problem of very low catalytic activity. In addition, if the pore size is less than 2 μs, the reactant cannot diffuse into the zeolite pores, resulting in poor catalytic activity and a decrease in selectivity. If the pore size exceeds 20 μs, the size of the pores is much larger than the reactants. Isomers are formed, resulting in poor selectivity and yield.

In applying the porous solid acid catalyst as described above to the alkylation reaction, it is more preferable to activate the mixture by performing a pretreatment at 300 to 500 ° C. and an oxygen atmosphere. In addition, the amount of the porous solid acid catalyst used is not particularly limited, but it is more preferably used in an amount of 0.1 g or less with respect to 1 kg of the product.

On the other hand, the hydroxylated aromatic compound which can be applied to the production method according to the present invention is applicable to any aromatic compound in which one or more hydroxy groups are substituted in the aromatic ring. Examples of monohydroxylated aromatic compounds include phenol, 1-hydroxynaphthalene, 2-hydroxynaphthalene, 2-hydroxyanthracene, 3-hydroxyphenanthrene and the like. Examples of dihydroxylated aromatic compounds include 1,2-dihydroxybenzene (aka 'catechol'), 1,4-dihydroxybenzene (aka 'hydroquinone'), 1,2-dihydroxy Naphthalene, 1,4-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, and the like.

In addition, the alkylation reagent which can be applied to the alkylation reaction according to the present invention is an olefin compound having 3 to 6 carbon atoms or an alcohol. Examples of the olefin compound include ethylene, propylene, 1-butylene, 2-butylene, isobutylene, 1-pentene, 2-pentene, 2-methylpentene-2, 3-methylpentene-2, 1-hexene, 2 -Hexene, 3-hexene and the like. Alcohols include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, t-butyl alcohol, n-pentyl alcohol, sec-pentyl alcohol and the like. The alkylating reagents described above may be used in 0.5 to 4 molar ratios with respect to the hydroxylated aromatic compounds.

In addition, the alkylation reaction of the present invention is to be carried out under the conditions of 50 to 200 ℃ temperature and 1 to 20 atm.

In addition, the alkylation reaction according to the present invention may be carried out in a batch type (fixed-bed continuous type) or the like.

When carried out in a batch process, an appropriate amount of granular porous solid acid catalyst is charged to the reactor. Then, a solution in which a hydroxylated aromatic compound is dissolved in a suitable solvent, such as 2-heptanone, xylene, or the like is injected into the reactor, and the alkylation reaction is performed under a desired reaction temperature, time, and pressure while stirring with an alkylating reagent. . If the reaction is to be carried out at a high pressure may be inert gas such as nitrogen, argon, helium and the like to maintain the desired pressure. Upon completion of the reaction, the reactor is cooled to room temperature and the pressure is sometimes lowered to atmospheric pressure, the catalyst is separated from the reaction mixture, the solution is fractionated or recrystallized to separate the alkylated product from the unreacted hydroxylated aromatic compound or by-product. do.

When performing a fixed bed continuous process, an appropriate amount of granular porous solid acid catalyst is charged into the reactor, and the reactant hydroxylated aromatic compound and the alkylating reagent are continuously supplied to continuously pass the catalyst layer adjusted to the desired reaction temperature and pressure. Let's do it. Compounds that have passed through the reactor at the appropriate reaction temperature and pressure can be separated / purified and recycled unreacted hydroxylated aromatic compounds.

The hydroxy aromatic alkylated derivatives synthesized by the alkylation process according to the present invention include methylphenol (aka 'cresol'), dimethylphenol (aka 'jaylenol'), ethylphenol, diethylphenol, propylphenol, Dipropylphenol, isopropylphenol, diisopropylphenol, n-butylphenol, n-dibutylphenol, t-butylphenol, pentylphenol, dipentylphenol, methylcatechol, dimethylcatechol, ethylcatechol, diethyl Catechol, propylcatechol, dipropylcatechol, isopropylcatechol, diisopropylcatechol, n-butylcatechol, n-dibutylcatechol, t-butylcatechol, pentylcatechol, dipentylcatechol , Methylhydroquinone, dimethylhydroquinone, ethylhydroquinone, diethylhydroquinone, isopropylhydroquinone, diisopropylhydroquinone, n-butylhydroquinone, n-dibutylhydroquinone, t-butylhydroquinone, pentylhydro Quinone, dipentylhydroquinone, methyl high Doxynaphthalene, dimethyl hydroxy naphthalene, ethyl hydroxy naphthalene, diethyl hydroxy naphthalene, propyl hydroxy naphthalene, dipropyl hydroxy naphthalene, isopropyl hydroxy naphthalene, diisopropyl hydroxy naphthalene, n-butylhydroxy naphthalene , Di-n-butylhydroxynaphthalene, t-butylhydroxynaphthalene, di-t-butylhydroxynaphthalene, pentylhydroxynaphthalene, dipentylhydroxynaphthalene and the like. The alkyl group introduction position in the hydroxy aromatic alkylated derivatives described above results in better selectivity to the p-position than to the o- or m-position. Thus, in the present invention, the alkyl group of the hydroxylated aromatic compound It is useful for highly selective preparation of derivatives substituted at specific positions.

Such a manufacturing method of the present invention will be described in more detail through the following examples, but the present invention is not limited thereto.

That is, the following examples show some alkylation methods of hydroxy aromatic compounds, but alkylation reactions of other compounds included in the scope of the present invention are also readily applicable to those skilled in the art.

Example 1

0.5 g of the catalyst was activated at 400 ° C., cooled to room temperature, charged to a fixed bed reactor, the reactor was maintained at the reaction temperature, and a 2-heptanone solution containing a hydroxylated aromatic compound was used as a catalyst layer at a constant rate of 0.018 mol per hour. The reaction was carried out by simultaneously injecting isobutylene with the same mole of number thereof. The product was collected for 2 hours at a constant reaction temperature and analyzed using GC / MS equipped with SE-30 column.

Example 2

0.3 g of the catalyst was activated at 450 ° C., cooled to room temperature, charged to the reactor, and simultaneously flowed with nitrogen to prevent contact with moisture or air. After the reactor was heated to 170 ° C, the reaction was performed by passing a solution of 0.05 mol of the hydroxylated aromatic compound in 15 ml of t-butanol through a catalyst bed at a constant rate. The product was analyzed using GC / MS equipped with a SE-30 column.

[Effects of the Invention]

According to the results of Tables 1 and 2, H-β or H-ZSM-5 having a three-dimensional structure of zeolite pupils was 67-83% when alkylated catechol or phenol with isobutylene. Conversion and p-isomer selectivity of 55-68%. On the other hand, H-L and H-M zeolites with zeolite pupils having primary or two-dimensional structures show conversions of 22-30% and p-isomer selectivity of 10-25% under similar reaction conditions.

On the other hand, alkylation of catechol or phenol with t-butanol showed better catalytic activity in the case of H-β or H-ZSM-5 than when isobutylene was used as the alkylating reagent. And p-isomer selectivity of 88-95%.

In contrast, catalysts with reduced number of acid sites (eg, NaH-ZSM-5) or γ-alumina that do not have uniformly sized pores by ion exchange of basic sodium ions or the like instead of protons have a large p-isomer selectivity. Although it does not decrease, it shows the selectivity of 68 to 87%, but the conversion rate is much lower, showing 12 to 33%. When t-butanol is used as the alkylating reagent, isobutyl is obtained in high yield, although t-butanol forms stable tertiary carbonium cations on the surface of the solid acid, thereby relatively easily minimizing steric hindrance. When lene is used as an alkylating reagent, isobutylene, which is relatively reactive, not only forms various kinds of isomers but also isobutylene dimers are obtained as alkylated by-products, so that t-butanol is used as p- It is interpreted that the isomer selectivity tends to decrease slightly.

Especially noteworthy is that in the synthesis of pt-butylcatechol by alkylation of the hydroxylated aromatic compound with t-butanol, the conversion rate is 91% and the selectivity is 95%. No bar

Claims (5)

In the alkylation method of a hydroxylated aromatic compound, the alkylation reaction has a molar ratio of silica / alumina (SiO ₂ / Al ₂ O ₃ ) of 1 to 100, a pore size of 2 to 20 kPa, and a pupil having a three-dimensional structure. Process for alkylation of a hydroxylated aromatic compound, characterized in that carried out at 50 to 200 ℃ temperature and atmospheric pressure under a porous solid acid catalyst selected from -β and H-ZSM-5. The alkylation method of a hydroxylated aromatic compound according to claim 1, wherein the hydroxylated aromatic compound is a monohydroxylated aromatic compound or a dihydroxylated aromatic compound. 3. The alkylation method of a hydroxylated aromatic compound according to claim 2, wherein the monohydroxylated aromatic compound is phenol and the dihydroxylated aromatic compound is catechol. The alkylation method of the hydroxylated aromatic compound according to claim 1, wherein the alkylation reagent of the alkylation reaction is an olefin compound having 3 to 6 carbon atoms or an alcohol. 5. The method of claim 4, wherein said alkylating reagent is isobutylene or t-butanol.