JP2000086582A - Production of acyloxybenzoic acid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a highly pure acyloxybenzoic acid in high selectivity and high yield without using a specific equipment by reacting a hydroxybenzoic acid with a lower carboxylic anhydride in the presence of a specific carboxylic acid, and subjecting the reaction mixture to the removal of the lower carboxylic acid by distillation in the presence of an acid catalyst. SOLUTION: A hydroxybenzoic acid of formula I [(n) is 1-3] is reacted with a carboxylic acid of formula II (R1 is a 5-21C alkyl or alkenyl, or the like) and a lower carboxylic anhydride of formula III (R2 is a 1-3C alkyl or an alkenyl), (preferably acetic anhydride) to provide a mixture of an acyloxybenzoic acid of formula IV [(h) is 1-3; (i) is 0-3; with the proviso that (h)+(i)=(n)], with a lower acyloxybenzoic acid of formula V [(j) is 1-3; (k) is 0-3; with the proviso that (j)+(k)=1-3]. The mixture is further reacted while removing the lower carboxylic acid by distillation in the presence of an acid catalyst (e.g. sulfuric acid, hydrochloric acid and nitric acid) to provide the objective highly pure acyloxybenzoic acid of formula IV without containing a polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an environmentally benign and cost-effective process for producing acyloxybenzoic acid, which is useful as a bleach activator in oxygen-based bleaches. Further, the present invention relates to a continuous production method for industrially inexpensively and easily obtaining a high-purity acyloxybenzoic acid with a practically reduced amount of carboxylic acid used.

[0002]

2. Description of the Related Art Acyloxybenzoate, like acyloxybenzenesulfonate, is exposed to hydrogen peroxide-generating substrates such as sodium percarbonate and sodium perborate and hydrogen peroxide at low temperatures by contact in water. It is a compound that is particularly useful as a bleach activator because it easily generates an organic peracid and effectively exhibits bleaching performance against stains such as clothing and stain stains (JP-A-6-211746, JP-A-6-11746).
-145697).

[0003] In any of the above publications, this acyloxybenzoic acid is produced by reacting an acid anhydride and hydroxybenzoic acid in a large amount of pyridine, and has problems such as high cost and pyridine odor. Furthermore, these production methods do not produce high-purity products, and purification operations using solvents are indispensable. As a result, the yield is as low as 63 to 90%, and commercial production of acyloxybenzoic acid is difficult. It was unsuitable as a production process.

JP-A-8-188553 describes a method for producing acyloxybenzoic acid by reacting hydroxybenzoic acid with a carboxylic acid halide or carboxylic anhydride in a carboxylic acid.

[0005]

When a carboxylic acid is used as a solvent for reaction, an acyloxybenzoic acid can be obtained in a high yield with few side reactions. JP-A-8-18
JP-A-8553 describes that the presence of this carboxylic acid acts as a foam-removing agent when it is used as a bleaching agent composition, and does not consider it to be a problem. However, it was found that when the carboxylic acid-containing acyloxybenzoic acid obtained by the above production method was blended with a bleaching activator, the odor derived from the carboxylic acid was sharp and the commercial value was lowered.

Accordingly, it has been found that when the amount of the carboxylic acid used in the reaction is reduced and reduced to an odor-acceptable amount, by-products of the multimer become remarkable. A multimer is, for example,
The multimer using p-monohydroxybenzoic acid is represented by the following general formula.

[0007]

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[Wherein, R ¹ is a straight-chain or branched-chain having 5 to 21 carbon atoms, which may be substituted with halogen and may have an ester group, an amide group, an ether group or a phenylene group inserted therein. An alkyl group or an alkenyl group, or a straight-chain or branched-chain alkyl which may be unsubstituted or substituted with a halogen having 1 to 22 carbon atoms, and into which an ester group, an amide group, an ether group or a phenylene group may be inserted. A phenyl group which may be substituted with a group, an alkenyl group or a halogen. 2 when n = 1
Monomer, when n = 2, trimer)

Since the multimer has little solubility in various solvents, when an acyloxybenzoic acid containing a large amount of the multimer is blended with the bleaching activator, a phenomenon such as a precipitate, cloudiness or bleeding occurs, and the blending stability is reduced. Was worse and the product value was lower.

As described above, when the amount of the carboxylic acid used is reduced so that the odor can be tolerated, the amount of the polymer increases, and as a result, the blending stability of the bleaching agent decreases. Conversely, when a large excess of carboxylic acid is used to suppress the by-product of the multimer, odor becomes a problem. Therefore, a production method that simultaneously satisfies both the odor and the blending stability affected by the by-produced multimer has not been known yet.

Further, in the method described in JP-A-8-188553, when a carboxylic acid halide is used as an acylating agent,
It has problems such as bubbling of the reaction solution due to by-produced hydrogen halide gas, detoxification of hydrogen halide gas, and strong corrosion of equipment by hydrogen halide gas.It is not suitable for industrial production and is not suitable for the environment. Problems, the production equipment facilities
Maintenance is costly. When carboxylic anhydride is used as an acylating agent, carboxylic anhydrides having 6 or more carbon atoms are not usually sold on an industrial scale,
It has been difficult to carry out the production of acyloxybenzoic acids on an industrial scale using carboxylic anhydrides as acylating agents.

The problem to be solved by the present invention is to use high-selectivity, high-yield, inexpensive and easily available starting materials for producing high-purity acyloxybenzoic acid.
An object of the present invention is to provide an industrially easy production method capable of producing acyloxybenzoic acid at low cost.

[0013]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have made intensive studies on the reaction between hydroxybenzoic acid and carboxylic anhydride, and as a result, have found that hydroxybenzoic acid has a specific carboxylic acid. When a lower carboxylic acid anhydride is reacted, a mixture of lower acyloxybenzoic acid and lower carboxylic acid as a by-product in addition to the target product, acyloxybenzoic acid, is heated in the presence of an acid catalyst. By distilling off the lower carboxylic acid, the lower acyl group of the lower acyloxybenzoic acid causes an exchange reaction with the acyl group of the carboxylic acid to find that only the desired acyloxybenzoic acid can be obtained. Thus, the present invention has been completed in which a target acyloxybenzoic acid substantially free of a multimer can be obtained without using a compound.

Further, since the acyloxybenzoic acid of the present invention contains a carboxylic acid, the reaction solution is crystallized,
By taking up as crystals, an acyloxybenzoic acid having a low carboxylic acid content is obtained, and when the mother liquor is recovered and used as a carboxylic acid source for the next reaction, and the recycling reaction is repeated, surprisingly, a substantial yield is obtained. It has been found that the present invention is quantitative and that the substantial amount of carboxylic acid used can be reduced, and the present invention has been completed.

That is, the present invention provides a compound represented by the general formula (1):

[0016]

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[In the formula, R ¹ is a straight-chain or branched-chain having 5 to 21 carbon atoms which may be substituted by halogen and may have an ester group, an amide group, an ether group or a phenylene group inserted therein. An alkyl group or an alkenyl group, or a linear or branched unsubstituted or straight-chain or branched-chain which may be substituted with a halogen having 1 to 22 carbon atoms and which may have an ester group, an amide group, an ether group or a phenylene group inserted therein. It represents an alkyl group, an alkenyl group, or a phenyl group optionally substituted with halogen. h indicates a number of 1 to 3, i indicates a number of 0 to 3, and h + i = 1 to 3; When producing the acyloxybenzoic acid represented by the general formula (2)

[0018]

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[Wherein, n represents a number from 1 to 3, and n = h +
i. Here, h and i have the same meaning as described above. A hydroxybenzoic acid represented by the general formula (3):

[0020]

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[Wherein, R ¹ has the same meaning as described above. A carboxylic acid represented by the general formula (4)

[0022]

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[In the formula, R ² represents a linear or branched alkyl or alkenyl group having 1 to 3 carbon atoms, which may be substituted with halogen. With a lower carboxylic acid anhydride represented by the general formula (1) and an acyloxybenzoic acid represented by the general formula (1).

[0024]

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Wherein R ² has the same meaning as described above. j is
Represents a number from 1 to 3, k represents a number from 0 to 3, and j + k = 1
And j + k = n. A mixture of lower acyloxybenzoic acids represented by the general formula (6) in the presence of an acid catalyst.

[0026]

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[Wherein, R ² has the same meaning as described above. Wherein the reaction is carried out while distilling off the lower carboxylic acid represented by the general formula (1).

Further, after completion of the reaction, the acyloxybenzoic acid is filtered off as crystals by crystallization, and the obtained mother liquor is used as a carboxylic acid source represented by the following general formula (3). The present invention relates to a method for continuously producing an acyloxybenzoic acid represented by the general formula (1).

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The hydroxybenzoic acid used as a raw material of the present invention is represented by the above general formula (2). The active site capable of reacting with a carboxylic acid has a substituent number n of 1 to 3, and the water solubility of the desired product is low. It can be selected depending on the case, but is preferably 1.

Specific examples of the hydroxybenzoic acid represented by the general formula (2) include salicylic acid, p-hydroxybenzoic acid, 2,4-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid, 3,4,5 -Trihydroxybenzoic acid. Among them, salicylic acid,
The use of p-hydroxybenzoic acid and 2,4-dihydroxybenzoic acid is preferred and practical. Further, salicylic acid and p-hydroxybenzoic acid are particularly preferred in view of raw material cost.

In the case of monohydroxybenzoic acid, one of the raw materials, salicylic acid, which is an o-isomer, is generally
The reactivity with the acylating agent is lower than that of p-hydroxybenzoic acid. Therefore, when salicylic acid is used as a raw material, it is necessary to take measures such as performing a reaction for a long time.

Specific examples of the carboxylic acid represented by the general formula (3) used in the present invention include n-hexanoic acid and n-hexanoic acid.
Heptanoic acid, i-heptanoic acid, n-octanoic acid, 2-ethylhexanoic acid, n-nonanoic acid, i-nonanoic acid, 3,5
Fatty acids such as 5,5-trimethylhexanoic acid, n-decanoic acid, i-decanoic acid, n-undecanoic acid, i-undecanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, isostearic acid, and behenic acid Aromatic carboxylic acids represented by benzoic acid, methylbenzoic acid, octylbenzoic acid, etc .; halogenated alkyl carboxylic acids represented by chlorocaproic acid, bromocaproic acid, chloroundecanoic acid, etc .; phenylacetic acid; phenylpropionic acid And the like. Among these carboxylic acids, n-hexanoic acid, n-heptanoic acid, i-heptanoic acid, n-octanoic acid, 2-ethylhexanoic acid, n-nonanoic acid, i-nonanoic acid, n-decanoic acid, i-decanoic acid -Decanoic acid, n-undecanoic acid,
Linear or branched fatty acids having 6 to 16 carbon atoms such as i-undecanoic acid, lauric acid, myristic acid, palmitic acid and the like are preferable, especially those having good effects on hydrophilic stains and hydrophobic stains and good water solubility. In order to obtain, a linear or branched fatty acid having 6 to 14 carbon atoms is preferable. For example, especially hydrophilic stains,
Lauric acid is particularly preferred in order to obtain lauroyloxybenzoic acid having a good balance of effects on hydrophobic soil.

The amount of the carboxylic acid represented by the general formula (3) used in the present invention is 1 to 100 equivalents with respect to the hydroxybenzoic acid represented by the general formula (2), and good results can be obtained. Can be If it is less than 1 equivalent, a large amount of unreacted hydroxybenzoic acid remains in the esterification reaction, which is not preferable. 100
If the amount exceeds the equivalent, the productivity decreases, and the odor and stability of the bleaching composition decrease due to the effect of the carboxylic acid contained in a large amount. In order to increase the yield and the reaction selectivity by suppressing the by-product of the polymer formed by the side reaction, the equivalent is more preferably 2 to 20 equivalents. Considering the productivity and the easiness of crystallization in a continuous production method, it is most preferably 3 to 10 equivalents.
In addition, it is preferable to select an appropriate amount of the carboxylic acid according to the method of picking up.In other words, when the reaction solution is directly blended into the bleaching composition, the amount of the carboxylic acid used is preferably reduced, but the When the liquid is crystallized and the acyloxybenzoic acid is taken up by filtration, the amount of the carboxylic acid used may be large.

When a recycling reaction is carried out using the mother liquor obtained by crystallization as a starting material, the carboxylic acid content reacted with the acyloxybenzoic acid in the reaction has already been reduced from the mother liquor used as the raw material. Before the reaction, it is preferable to add an amount of carboxylic acid corresponding to the decrease. Further, at the time of filtration, there is a loss due to the carboxylic acid attached to the crystal, so it is advisable to add it in consideration of the loss. As described above, when the amount of carboxylic acid used relative to hydroxybenzoic acid is kept constant, acyloxybenzoic acid of a constant quality can be easily obtained even when recycling is repeated.

Specific examples of the lower carboxylic acid anhydride represented by the general formula (4) used in the present invention include acetic anhydride,
Propionic anhydride, butyric anhydride, trifluoroacetic anhydride,
Examples thereof include chloroacetic anhydride and trichloroacetic anhydride. Among these acid anhydrides, acetic anhydride is preferred from the viewpoints of cost and low boiling point of the by-produced lower carboxylic acid and easy removal.

The amount of the lower carboxylic acid anhydride to be used is 0.1 to 0.5 parts with respect to the hydroxybenzoic acid represented by the general formula (2). Five ~
Good results are obtained with 5 equivalents. 0. If less than 5 equivalents,
The reaction does not proceed sufficiently and unreacted hydroxybenzoic acid remains, leading to a decrease in the yield of acyloxybenzoic acid. If the amount exceeds 5 equivalents, the production rate of lower acyloxybenzoic acid increases, and the transfer reaction takes time. Further, it is not preferable in terms of production cost. Considering the reaction yield and productivity, 0. 8 to 1. Six equivalents are preferred.

In the present invention, the method of mixing hydroxybenzoic acid represented by the general formula (2), carboxylic acid represented by the general formula (3) and lower carboxylic anhydride represented by the general formula (4) is as follows. , Mix all three components at the same time, add the lower carboxylic anhydride to the slurry of hydroxybenzoic acid and carboxylic acid, add hydroxybenzoic acid to the mixture of carboxylic acid and lower carboxylic anhydride, lower to hydroxybenzoic acid Any method such as adding a mixture of a carboxylic anhydride and a carboxylic acid may be used. Preferably, a lower carboxylic anhydride is added dropwise to a slurry in which hydroxybenzoic acid is well dispersed in carboxylic acid. The dropping temperature can be higher than the melting point of the carboxylic acid, but is preferably 150 ° C. or lower in order to suppress coloring. Below 120 ° C. gives more favorable results. Basically, the dripping time can be set within a range where the above-mentioned temperature can be maintained. Specifically, in the case of a batch type reaction apparatus, the time is 1 minute to 10 hours depending on the reaction scale and the type of stirring in the reaction tank, but there is no particular limitation. A continuous reactor may be used in addition to the batch reactor. In this case, a good result is obtained in that the temperature control of the dropping zone of the lower carboxylic anhydride and the temperature control of the aging zone can be divided into a plurality of zones and arbitrarily controlled. The aging is preferably performed at a temperature not lower than the melting point of the carboxylic acid used and not higher than 150 ° C. The temperature is more preferably from 60 to 120 ° C. in that the reaction is completed in a short time and side reactions are suppressed. The aging time depends on the temperature, for example, about 10 minutes to 1 hour at 150 ° C, and about 10 minutes to 100 ° C.
4 hours, about 10 minutes to 6 hours at 80 ° C are appropriate. In addition,
In this acylation reaction, a lower carboxylic acid derived from the lower carboxylic anhydride is by-produced together with the dropwise addition of the lower carboxylic anhydride.

The acylation reaction proceeds without an acid catalyst. However, when it is desired to carry out the reaction under milder conditions, for example, for suppressing coloration, a small amount of an acid catalyst may be added. As the acid catalyst, an acid or the like used in a transfer reaction described below can be used. The addition amount is effective even if it is smaller than the amount of the subsequent rearrangement reaction. Specifically, with respect to 1 part by weight of hydroxybenzoic acid represented by the general formula (2), 0. 0000
Ten . 05 parts by weight is sufficient.

In this reaction, the hydroxybenzoic acid represented by the general formula (2) is converted into an acyloxybenzoic acid represented by the general formula (1) and a lower acyloxybenzoic acid represented by the general formula (5). Be transformed into The ratio of the two differs depending on conditions such as the type of carboxylic acid and lower carboxylic anhydride used, the reaction temperature, and the type of acid catalyst. When a straight-chain alkyl carboxylic acid is used as the carboxylic acid, the proportion of the acyloxybenzoic acid increases as the amount of the carboxylic acid increases, and when the amount of the lower carboxylic anhydride increases, the lower acyloxycarboxylic acid decreases. The proportion of benzoic acid tends to be high. Therefore, in order to reduce the time required for the subsequent rearrangement reaction and to suppress coloring, it is better to use a large amount of the carboxylic acid if problems such as odor are allowed. The amount of carboxylic acid used can be increased if the mother liquor is recycled after crystallization.

In the present invention, an acid catalyst is used for the transfer reaction of lower acyloxybenzoic acid to acyloxybenzoic acid. This transfer reaction proceeds without an acid catalyst,
High temperatures are required and the reaction takes more time. If the reaction temperature is increased for the purpose of shortening the reaction time, coloring becomes easier, so an acid catalyst is added. The addition of the acid catalyst has an effect of completing the reaction at a lower temperature, and thus has an effect of reducing coloring of the product.

Examples of the acid catalyst used in this reaction include mineral acids such as sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid; organic sulfonic acids such as benzenesulfonic acid and toluenesulfonic acid; and halogenated acetic acids such as trifluoroacetic acid and trichloroacetic acid. And a strongly acidic ion exchange resin. These mixtures may be used. Of these, organic sulfonic acids are preferred because they have high solubility in the reaction solution, have low volatility, and have less coloring of the product. The amount of addition is 0.1 to 1 part by weight of hydroxybenzoic acid represented by the general formula (2). 0001-0.
One part by weight is preferred. 0. If the amount is less than 0001 parts by weight, the transfer reaction is slow, and 0. If added in excess of 1 part by weight, contamination of the product cannot be ignored. In addition, coloring becomes intense.

When an ion exchange resin is used, it is necessary to filter by filtration after the completion of the transfer reaction. In addition, when an acid catalyst with low volatility such as sulfuric acid is used, and when the crystallization mother liquor is used as a starting material for the next reaction and a recycle reaction is performed, most of the initially added acid catalyst escapes into the mother liquor. In a batch reaction, it is not necessary to add, or it is sufficient to make up for the amount of loss attached to the crystal side.

The transfer reaction of lower acyloxybenzoic acid to acyloxybenzoic acid is carried out while distilling off by-product lower carboxylic acid. The removal of the lower carboxylic acid can be carried out by either normal pressure or reduced pressure methods, but the reaction is faster when the solvent is distilled off under reduced pressure. The reaction temperature is preferably from 80 to 150 ° C. If the temperature is lower than 80 ° C, the reaction is slow, and if the temperature is higher than 150 ° C, coloring becomes intense. The reaction time depends on the reaction temperature, but 15
About 1 hour at 0 ° C, 1 to 4 hours at 100 ° C, 1 to 24 at 80 ° C
Time is appropriate. Finally, the lower carboxylic acid is completely distilled off at a decompression degree within a range in which the carboxylic acid is not distilled, specifically, at a reduced pressure of 1 to 40 mmHg. If the lower carboxylic acid remains, the odor peculiar to the lower carboxylic acid becomes a problem when it is incorporated into the bleaching composition. Therefore, it is desirable to remove the lower carboxylic acid as completely as possible.

Although the reaction of the present invention can be carried out basically without using a solvent, if necessary, a hydrocarbon solvent such as hexane, cyclohexane, toluene, xylene, ethylbenzene, mesitylene, cumene or the like may be used. ,
Halogen-based solvents such as chloroform, 1,2-dichloroethane, trichloroethane, tetrachloroethane, trichloroethylene, tetrachloroethylene, and carbon tetrachloride;
Solvents such as aprotic polar solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, 1,3-dimethyl-2-imidazolidinone and ether solvents such as diisopropyl ether and dibutyl ether are represented by the general formula: With respect to the hydroxybenzoic acid represented by (2), 0. 1 to
It may be used 20 times by weight.

The acyloxybenzoic acid thus obtained contains the carboxylic acid used. However, for example, in the case of blending in a detergent for clothing, etc., these carboxylic acids can act as one of the cleaning components and also effectively act as a foam removal during rinsing, due to the alkali agent in the detergent. Therefore, the reaction product in the present invention can be directly supplied to a granulating operation as it is for compounding a detergent or, if necessary, for a granulating operation.

However, the carboxylic acid contained in the bleaching composition may cause a problem in terms of odor and the like. If the amount of the carboxylic acid used is reduced to a point where the odor is acceptable, the rate of production of lower acyloxybenzoic acid increases in the acylation, and the transfer reaction takes time,
Furthermore, by-products of a multimer such as a dimer may become remarkable, which may adversely affect the blending stability.

When the carboxylic acid content is a problem, the carboxylic acid can be removed by the following method.
When a carboxylic acid having a low boiling point is used, the carboxylic acid may be distilled off under reduced pressure. When a carboxylic acid having a high boiling point is used, the reaction solution is crystallized, and then the acyloxybenzoic acid is filtered off as crystals. Although there is no limitation on the method of crystallization, any method such as a cooling crystallization method or a method of adding a solvent to precipitate crystals may be used. When the melting point of the carboxylic acid used is low, a cooling crystallization method for cooling the reaction solution as it is to precipitate crystals is easiest. When the carboxylic acid used has a high melting point, it is advisable to add the solvent as described above and then carry out cooling crystallization.

The method of picking up crystals in the continuous production method can be performed by a known method such as natural filtration, suction filtration, pressure filtration, and centrifugation. Either way,
Although the carboxylic acid is contained in the crystal, the amount thereof is extremely small, and the odor does not become a problem when it is formulated.
In addition, by this filtration operation, a polymer of impurities, unreacted hydroxybenzoic acid, and lower acyloxybenzoic acid are also removed, so that the obtained acyloxybenzoic acid has high purity.

If a slight amount of carboxylic acid in the crystal is disliked, the following operation is performed. That is, when a carboxylic acid having a low boiling point is used, the obtained crystals are dried under reduced pressure to remove the carboxylic acid. When using a high boiling carboxylic acid, after filtration, water, alcohol solvents such as methanol, ethanol, isopropyl alcohol, acetone, ketone solvents such as methyl ethyl ketone, ester solvents such as ethyl acetate, methylene chloride, chloroform, Dichloroethane, halogen solvents such as carbon tetrachloride, ether solvents such as diethyl ether, diisopropyl ether, tetrahydrofuran, dioxane, hexane, benzene,
The carboxylic acid can be easily removed by washing the crystals with a hydrocarbon-based solvent such as toluene, xylene, and mesitylene.

On the other hand, the mother liquor obtained by filtration contains not a small amount of acyloxybenzoic acid. This means that the yield of the pure acyloxybenzoic acid in the crystal is low. The content of acyloxybenzoic acid in the mother liquor varies depending on the concentration of acyloxybenzoic acid in the crystallization liquid, the filtration method, the filtration temperature, and the presence or absence of washing. This carboxylic acid, while containing the acyloxybenzoic acid, can be used as a carboxylic acid source in the next batch of reactions. By this recycling, the acyloxybenzoic acid contained in the mother liquor is recovered in the next reaction.

When the crystals are washed with the above-mentioned solvent after separating the crystals from the crystallized solution, the washing solution obtained by washing also contains carboxylic acid and acyloxybenzoic acid. Therefore, it is preferable to use the first mother liquor in accordance with the mother liquor since loss of the yield is eliminated. However, when such a washing solvent or a solvent is used during the reaction, the mother liquor is preferably subjected to the following treatment and then reacted with hydroxybenzoic acid and a lower carboxylic anhydride.
That is, in the case of washing with water, after water is removed by liquid separation, water is completely removed under reduced pressure. When an organic solvent is used as a reaction solvent or a washing solvent, it may be simply removed under reduced pressure. When water or alcoholic solvents are used, if these solvents remain, they react with the lower carboxylic acid anhydride and wastefully consume the lower carboxylic acid anhydride, so that they must be completely removed before the acid anhydride conversion reaction. It is preferable to keep it.

[0053]

In the reaction of the present invention, the lower carboxylic anhydride apparently acts as a dehydrating agent in the esterification reaction between hydroxybenzoic acid and carboxylic acid as represented by the following reaction formula. .

[0054]

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However, it is generally said that a mixture of a carboxylic acid anhydride and a carboxylic acid forms a mixed acid anhydride and is in an equilibrium state.

[0056]

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It is considered that such an equilibrium is established between the lower carboxylic anhydride and the carboxylic acid in the acylation reaction of the present invention. Considering that a mixture of the acyloxybenzoic acid represented by the general formula (1) and the lower acyloxybenzoic acid represented by the general formula (5) is obtained after the acylation, each acid formed in this equilibrium is obtained. It is reasonable to assume that the anhydride has reacted with the hydroxybenzoic acid. Examples of the acid anhydride include a lower carboxylic acid anhydride represented by the general formula (4) used in the reaction, a mixed acid anhydride of a carboxylic acid represented by the above general formula (7) and a lower carboxylic acid, and It is a carboxylic anhydride represented by the general formula (8).
When lower carboxylic anhydride reacts with hydroxybenzoic acid, lower acyloxybenzoic acid represented by the general formula (5) is generated. Similarly, when a mixed acid anhydride of a carboxylic acid and a lower carboxylic acid reacts with hydroxybenzoic acid,
A mixture of the acyloxybenzoic acid represented by the general formula (1) and the lower acyloxybenzoic acid is formed. When the carboxylic anhydride reacts with hydroxybenzoic acid, acyloxybenzoic acid is produced. As a result, the reaction solution after the acylation is a mixture of acyloxybenzoic acid and lower acyloxybenzoic acid.

To facilitate the subsequent rearrangement reaction, it is preferable to reduce the production of lower acyloxybenzoic acid in the acylation reaction. Generally, when the molar ratio of the lower carboxylic acid anhydride is larger than that of the carboxylic acid, the production of lower acyloxybenzoic acid increases. Therefore, it is desirable to use a lower carboxylic acid anhydride which is almost equivalent to hydroxybenzoic acid, and to use an excess of carboxylic acid which is more than the equivalent to increase the proportion of the target acyloxybenzoic acid.

As described above, in this reaction, by-products such as highly corrosive hydrogen halide are not generated, and only lower carboxylic acids having low corrosiveness are produced as by-products. Therefore, expensive corrosion-resistant materials such as glass lining are used. The reaction can be performed without using the above device. Furthermore, since the acylation reaction and the transfer reaction can be continuously performed using the same reaction apparatus, it has become possible to complete the reaction in one reaction tank.

Next, the operation and effect of recycling the mother liquor will be described. When excess carboxylic acid is used in the method of the present invention, the substantial amount of carboxylic acid can be significantly reduced by recycling the crystallized mother liquor as compared with the case where no recycling is performed. This will be described with a specific example. The following figure shows the reaction formula of the method of the present invention schematically in a simple scheme. Acetic anhydride is used as the lower carboxylic anhydride, and p-hydroxybenzoic acid is used as the hydroxybenzoic acid. The specific molar ratio in the reaction is also shown.

[0061]

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The initial amount of carboxylic acid used is excessive with respect to hydroxybenzoic acid. Eight moles react with hydroxybenzoic acid to form acyloxybenzoic acid. At this time, 0. 2 mol of acetyloxybenzoic acid is by-produced. Next, an acid catalyst is added to these mixtures, and acetic acid is removed, whereby a transfer reaction proceeds. Two moles of carboxylic acid are consumed. At the end of the reaction, the carboxylic acid will be 5 moles since it will be one mole less than the original carboxylic acid. When performing the recycle reaction, when performing the reaction using the same amount of hydroxybenzoic acid in the next batch, to match the initial use amount of the carboxylic acid,
The reaction is performed after adding 1 mol of carboxylic acid newly to make a total of 6 mol. By repeating recycling in this way,
The reaction can always be performed at a constant molar ratio. By the way, comparing the amount of carboxylic acid used between when recycling was not performed and when recycling was performed, as shown in Table 1, recycling was overwhelmingly less. By repeating recycling, the amount of carboxylic acid used per batch can be reduced to 1 without limit.
This is because, in order to increase the production ratio of acyloxybenzoic acid in the acylation reaction, to finish the transfer reaction in a short time, and to further reduce the multimer content extremely, the amount of carboxylic acid used relative to hydroxybenzoic acid is further increased. This is a very effective means. In other words, the method of the present invention can be said to be a production process in which a smaller amount of carboxylic acid is used and by-products of the polymer are reduced.

[0063]

[Table 1]

In practice, the carboxylic acid may adhere to the crystal part of the acyloxybenzoic acid and may be lost. Therefore, it is necessary to further add a carboxylic acid corresponding to the loss. However, the amount of the carboxylic acid attached to the crystal is small compared to the amount of the carboxylic acid charged, and the amount of the carboxylic acid used in the method of the present invention is small even in consideration of the loss due to the attachment. In addition, the carboxylic acid attached to the crystal can be washed off to the mother liquor side by washing the crystal after filtration by the method described above. In particular, when an expensive carboxylic acid is used, the carboxylic acid can be recovered as much as possible by washing treatment, and the amount of carboxylic acid charged in the next reaction can be reduced.

Next, the yield of acyloxybenzoic acid when recycled is described. Although the reaction yields of the acylation and transfer reactions are almost quantitative, a part of the acyloxybenzoic acid generated by the reaction escapes to the mother liquor during filtration. For this reason, the yield of acyloxybenzoic acid contained in the obtained crystals is not quantitative. Normal,
In the first reaction, the pure fraction of acyloxybenzoic acid generated in the transfer reaction is separated into about 80% by crystal filtration and about 20% by mother liquor by filtration. However, the acyloxybenzoic acid taken up by recycling this mother liquor contains:
Acyloxybenzoic acid originally contained in the mother liquor is added. During the recycling reaction, if the raw material hydroxybenzoic acid was used in the same amount in each batch, and the amount of carboxylic acid corresponding to the amount consumed in the reaction was added and reacted,
The yield of picking up the acyloxybenzoic acid crystals with respect to the amount of hydroxybenzoic acid charged increases as the recycle reaction is repeated, and eventually becomes almost quantitative. Typical examples are the first: 78%, the second: 95%, 3
The second time: 102%, the fourth time: 101%, the yield has changed and improved,
Performing 3 to 4 reactions gives a quantitative yield. 100 yield
Exceeding% indicates that the acyloxybenzoic acid and multimers contained in the mother night were gradually recovered. The first or second yield loss increases as the number of recycling increases, and the actual yield of acyloxybenzoic acid becomes quantitative. There is no limit on the number of recycling, and the mother liquor can be collected and re-reacted as many times as necessary.

In the mother liquor, a multimer is in a concentrated form.
When this mother liquor is recycled, the multimer gradually accumulates and the concentration of the multimer increases, but reaches a plateau after three to four recycle reactions (see Table 2). Although the reason for this is not clear, it is probably due to the fact that a part of the homogenization reaction as shown in the following reaction formula occurs between the polymer and the carboxylic acid.

[0067]

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This means that the multimer which has been present as an impurity can be converted into the target product, acyloxybenzoic acid. That is, it can be said that the ratio of the raw material hydroxybenzoic acid consumed for the production of the multimer is smaller than that of the conventional method, and as a result, the yield of acyloxybenzoic acid from hydroxybenzoic acid is high. Thus, the method of the present invention can be said to be an excellent production method that not only reduced the content of the multimer, but also reduced the multimer by-produced by the conventional method to acyloxybenzoic acid.

In some cases, the mother liquor is colored while it is being recovered and used. In this case, the mother liquor is preferably decolorized using activated carbon or activated clay and then reacted with a lower carboxylic anhydride. As described above, particularly in a commercial production process, the more the recycling is repeated, the cheaper the acyloxybenzoic acid can be produced, which is an extremely excellent production process.

[0070]

EXAMPLES Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

Example 1 To a SUS flask equipped with a stir bar, a thermometer, a dropping funnel and a reflux condenser was placed octanoic acid 288. 4 g, p-hydroxybenzoic acid 2 g were weighed and heated with stirring. Upon reaching 85 ° C, acetic anhydride. 1 g was dropped from the dropping funnel over 30 minutes. After completion of the dropwise addition, the temperature was raised to 100 ° C., and the temperature was maintained for 30 minutes to effect acylation. As a result of quantifying the reaction solution by liquid chromatography, the pure content of p-octanoyloxybenzoic acid and p-acetoxybenzoic acid at this time was 148. 0 g (56% yield), 7
It was 7.5 g. Next, concentrated sulfuric acid 0. After adding 2 g, 1
After raising the temperature to 40 ° C, gradually reduce the pressure inside the reaction system,
Acetic acid was distilled off at a reduced pressure of 80 to 120 mmHg. About 0. The distillation of acetic acid was almost completed in 7 hours, but the pressure was further reduced to 20 mmHg, and acetic acid was completely removed at 140 ° C. for 2 hours. The weight of the distillate is 118. 9 g, which was 99% of the theoretical amount calculated from the amount of acetic anhydride used. The result of quantifying the reaction solution after the transfer reaction by liquid chromatography. The pure content of p-octanoyloxybenzoic acid relative to p-hydroxybenzoic acid was 256. With 4 g, the yield was 97%. The pure content of p-acetoxybenzoic acid is 0. It was 5 g. Furthermore, the dimer content for p-octanoyloxybenzoic acid is 4. 2%, trimer content 0. 3%. The fatty acid content is 145. 2 g. Hue is APHA
It was 30. Further, when subjected to a blending stability test and an odor test, the blending stability was Δ and the odor test was ×.

The analysis and color of acyloxybenzoic acid and fatty acid in the reaction product were performed as follows.

1) Analysis of acyloxybenzoic acid Analysis of acyloxybenzoic acid and multimers in the reaction solution, crystals and mother liquor was performed by liquid chromatography.
The following column, elution, and detector were used to carry out an absolute calibration curve method.

Column: Inertsyl manufactured by GL-Science
ODS-2,4. 6 φ × 150mm Eluent: 0. 03M -NaH ₂ PO _3. (Adjusted to pH 2.1 with phosphoric acid) / CH ₃ CN = 3/7 (vol / vol) Detector: UV 254 nm

2) Analysis of fatty acids The fatty acids in the reaction solution, crystals and mother liquor were analyzed by gas chromatography using the following columns and detectors by the internal standard method.

Column: Thermon-3000 manufactured by Shimadzu, loading 5
%, 1m (carrier SHINCARBON A) Carrier gas: helium Carrier flow rate: 40ml / min Initial temperature: 170 ° C Heating rate: 5 ° C / min Final temperature: 280 ° C Inlet temperature: 280 ° C Detector: FID

3) Hue 5% by weight of pure acyloxybenzoic acid was dissolved in a 50/50 (vol / vol) solution of acetonitrile / water and compared with the APHA standard.

4) Formulation stability test In 100 g of a 2% aqueous solution of sodium percarbonate, 1 g equivalent of acyloxybenzoic acid as a pure component was dissolved by heating to 40 ° C.
Stored at 5 ° C for 10 days. The state after 10 days was visually observed.

The evaluation criteria were set as follows. ◎… colorless transparent liquid ○… slightly cloudy △… cloudy ×… precipitation is observed

5) Odor test After adjusting the sample prepared in the formulation stability test to 20 ° C,
Ten odor panelists were smelled, and it was determined whether or not there was an odor derived from fatty acids.

The evaluation criteria were set as follows.

: 10 to 9 persons determined that there was no odor derived from fatty acids. 8: 8 to 7 persons determined that there was no odor derived from fatty acids. 6: 6 to 5 persons determined that there was no odor derived from fatty acids. More than 6 people are judged to have fatty acid-derived odor

Comparative Example 1 Octanoic acid was placed in a glass flask equipped with a stirring rod, a thermometer, a dropping funnel and a reflux condenser. 2 g, p-hydroxybenzoic acid 1 g was weighed and heated with stirring to obtain a uniform slurry. After heating to 80 ° C, octanoyl chloride (Tokyo Kasei) 170. 8 g was added dropwise over 1 hour while maintaining the temperature at 80 ° C. During the period from dropping to ripening, nitrogen gas was passed to promote the discharge of hydrochloric acid gas and prevent coloring. After completion of the dropwise addition, the temperature in the flask was raised to 100 ° C., and the mixture was aged for 4 hours. After the reaction, 100 ℃
While maintaining the pressure, the pressure was reduced to 200 mmHg to remove dissolved hydrochloric acid gas. As a result of quantifying the reaction solution by liquid chromatography, the pure fraction of p-octanoyloxybenzoic acid was
240. In 5 g, the yield based on p-hydroxybenzoic acid is 91
%Met. The dimer content relative to p-octanoyloxybenzoic acid was 15.0%, and the trimer content was 2.5%. 9%. Fatty acid content is 162. At 8 g, the hue of the resulting reaction was APHA100. Further, when subjected to a blending stability test and an odor test, the blending stability was × and the odor test was Δ.

Example 2 865 of octanoic acid was placed in a SUS flask equipped with a stir bar, a thermometer, a dropping funnel and a reflux condenser. 3 g, p-hydroxybenzoic acid 2 g were weighed and heated with stirring. Upon reaching 60 ° C., acetic anhydride. 3 g was dropped from the dropping funnel over 1 hour. After dropping, 1 more
The mixture was stirred at 60 ° C. for an hour to perform acylation. As a result of quantification by liquid chromatography, the content of p-octanoyloxybenzoic acid and p-acetoxybenzoic acid at this time was 216. 7 g (82% yield) and 32.4 g. Next, p-toluenesulfonic acid monohydrate was added. 2g
After the addition, the temperature was raised to 120 ° C., and the pressure inside the reaction system was gradually reduced to 100 mmHg to distill acetic acid. The distillation of acetic acid was almost completed in about 1 hour, but the pressure was further reduced to 10 mmHg, and acetic acid was completely removed at 120 ° C. for 3 hours. The weight of the distillate was 134.7 g, which was 102% of the theoretical amount calculated from the amount of acetic anhydride used. As a result of quantifying the reaction solution by liquid chromatography, the pure content of p-octanoyloxybenzoic acid relative to p-hydroxybenzoic acid was 259. At 0 g, the yield was 98%. Also, p-
The pure content of acetoxybenzoic acid is 0. 4 g. further,
The dimer content for p-octanoyloxybenzoic acid is
1. 1% and the trimer content is 0. 1%.

The reaction solution was cooled in a water bath with stirring to be crystallized. After cooling to 30 ° C., the precipitated crystals of p-octanoyloxybenzoic acid were filtered off by suction filtration. Analysis of the obtained crystals revealed that the target substance, p-octanoyloxybenzoic acid, had a pure content of 207. 2 g.
Therefore, the yield by filtration was 80%, and the total yield based on the charged p-hydroxybenzoic acid was 78%. On the other hand, when the mother liquor was analyzed in the same manner, p
The pure content of octanoyloxybenzoic acid was 51.8 g, which was 20% in terms of yield. When the content of octanoic acid was determined by gas chromatography, 2
0.7 g, 698 in mother liquor. 0g was contained. The hue of the crystal was APHA10. Further, when subjected to a blending stability test and an odor test, the blending stability was ◎ and the odor test was ◎.

Examples 3 to 9 Using the mother liquor obtained in Example 2, a recycle reaction was carried out under the same reaction conditions as in Example 2 with the amounts shown in Table 2.
The amounts of acetic anhydride, octanoic acid and p-hydroxybenzoic acid used in each reaction, and the pure content and yield of the obtained p-octanoyloxybenzoic acid, the polymer content relative to p-octanoyloxybenzoic acid, Table 2 shows the pure and multimeric contents of p-octanoyloxybenzoic acid and octanoic acid in the crystal and the mother liquor, and the results of the hue, formulation stability test and odor test of the obtained crystal.

[0087]

[Table 2]

As is clear from the results in Table 2, the yield of p-octanoyloxybenzoic acid was almost quantitative. The multimer content was very low at 1% or less.
The hue was also good. The formulation stability test and the odor test were also good. The theoretical amount of octanoic acid was 144. Where 2g, 1. 16-1. It is 29 times the amount, and excluding the carboxylic acid necessary for acylation, is 0. 16
~ 0. Recycling was possible with an extremely small amount of 29 times.

Example 10 In a SUS flask equipped with a stirring rod, a thermometer, a dropping funnel and a reflux condenser, lauric acid 801. 3 g, salicylic acid 2 g were weighed and heated with stirring. Upon reaching 80 ° C., acetic anhydride 122. 5 g was dropped from the dropping funnel over 1 hour. After completion of the dropwise addition, the mixture was further stirred at 80 ° C. for 2 hours to perform acylation. As a result of quantification by liquid chromatography, the content of o-lauroyloxybenzoic acid and o-acetoxybenzoic acid at this time was
224. 3 g (70% yield) and 54.0 g. Next, benzenesulfonic acid 0. After adding 4 g, 130 ℃
After the temperature was raised to 100 mmHg, the pressure inside the reaction system was gradually reduced to 100 mmHg, and acetic acid was distilled off. The distillation of acetic acid was almost completed in about 1 hour, but the pressure was further reduced to 10 mmHg, and acetic acid was completely removed at 130 ° C. for 5 hours. The weight of the distillate is 149. 9g
Which was 104% of the theoretical calculated from the amount of acetic anhydride used. As a result of quantifying the reaction solution by liquid chromatography, the pure content of o-lauroyloxybenzoic acid with respect to salicylic acid was 310.8 g, and the yield was 97%. Also, the pure content of o-acetoxybenzoic acid is 0. 4 g. Furthermore, the dimer content for o-lauroyloxybenzoic acid is 2. 7% and a trimer content of 0. 3%.

The reaction solution was cooled in a water bath with stirring to be crystallized. After cooling to 50 ° C., the precipitated crystals of o-lauroyloxybenzoic acid were separated by suction filtration. Analysis of the obtained crystals revealed that the pure content of the target product, o-lauroyloxybenzoic acid, was 269. 2 g. Therefore, the yield by filtration was 84%, and the total yield based on the salicylic acid charged was 81%. On the other hand, when the mother liquor was similarly analyzed, the pure content of o-lauroyloxybenzoic acid in the mother liquor was 41.7 g, which was 13% in terms of yield. The content of lauric acid was determined by gas chromatography and found to be 25.4 g in the crystal and 571 in the mother liquor.
6g was included. The hue of the crystal was APHA10.
Further, when subjected to a blending stability test and an odor test, the blending stability was ◎ and the odor test was ◎.

Examples 11 to 17 Using the mother liquor obtained in Example 10, a recycling reaction was carried out under the same reaction conditions as in Example 10 with the amount of charge shown in FIG.
Pure content and yield of o-lauroyloxybenzoic acid obtained in each recycling reaction, multimer content relative to o-lauroyloxybenzoic acid, o-lauroyloxybenzoic acid in crystals and mother liquor, pure content of lauric acid and Table 3 shows the multimer content, the color of the obtained crystals, the results of the blending stability test and the odor test.

[0092]

[Table 3]

As is clear from the results in Table 3, the yield of o-lauroyloxybenzoic acid was almost quantitative after the fourth recycling. The multimer content was very low at 1% or less. The formulation stability test and odor test were good. The hue was also very good. The theoretical amount of lauric acid was 200. Where 3 g, 1. 1-1. It is twice as much as 0.1% except for the carboxylic acid required for acylation. 1 to
0. Recycling was possible with an extremely small amount of twice as much.

[0094]

According to the present invention, since there is no generation of highly corrosive by-products such as hydrogen chloride gas, a high-yield and high-purity acyloxybenzoate can be obtained without using a corrosion-resistant material such as a glass lining. An acid can be obtained. Furthermore, by recycling the crystallized mother liquor, high-purity acyloxybenzoic acid with a substantially small amount of carboxylic acid, a very small amount of carboxylic acid, and a small amount of by-products of the polymer can be obtained with a quantitative yield. Thus, it has become possible to manufacture easily and inexpensively industrially.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) C07C 67/52 C07C 67/52 69/28 69/28 69/30 69/30 C11D 7/54 C11D 7 / 54 // C07B 61/00 300 C07B 61/00 300 F term (reference) 4H003 DA01 EB09 EE04 EE05 FA43 4H006 AA02 AC48 AD15 BA28 BA32 BA34 BA35 BA36 BA37 BA72 BD20 BD70 BJ50 BN30 BS10 BS30 KA10 KD10 4H039 CA66 CD30 CD40

Claims (7)

[Claims] 1. A compound of the general formula (1) Wherein R ¹ is a straight-chain or branched-chain alkyl group having 5 to 21 carbon atoms, which may be substituted with a halogen and may have an ester group, an amide group, an ether group or a phenylene group inserted. An alkenyl group, or unsubstituted or substituted with a halogen having 1 to 22 carbon atoms,
It represents a linear or branched alkyl or alkenyl group into which an ester group, an amide group, an ether group or a phenylene group may be inserted, or a phenyl group optionally substituted with halogen. h is a number from 1 to 3, and i is
Indicates a number from 0 to 3 and h + i = 1 to 3. In producing the acyloxybenzoic acid represented by the general formula (2): [In the formula, n represents a number of 1 to 3, and n = h + i. Here, h and i have the same meaning as described above. And a hydroxybenzoic acid represented by the general formula (3): [Wherein, R ¹ has the same meaning as described above. And a carboxylic acid represented by the general formula (4): [In the formula, R ² represents a linear or branched alkyl or alkenyl group having 1 to 3 carbon atoms, which may be substituted with halogen. With a lower carboxylic acid anhydride represented by the general formula (1) and an acyloxybenzoic acid represented by the general formula (1). [Wherein, R ² has the same meaning as described above. j indicates a number of 1 to 3, k indicates a number of 0 to 3, j + k = 1 to 3 and j + k = n. After obtaining a mixture of lower acyloxybenzoic acid represented by the following, in the presence of an acid catalyst,
General formula (6) [Wherein, R ² has the same meaning as described above. The method for producing an acyloxybenzoic acid represented by the general formula (1), wherein the reaction is carried out while distilling off the lower carboxylic acid represented by the formula (1). 2. The process for producing acyloxybenzoic acid according to claim 1, wherein the lower carboxylic anhydride represented by the general formula (4) is acetic anhydride. 3. A carboxylic acid represented by the general formula (3):
3. The process for producing an acyloxybenzoic acid according to claim 1, which is a linear or branched fatty acid having 6 to 14 carbon atoms. 4. A lower carboxylic acid anhydride represented by the general formula (4) is added to the hydroxybenzoic acid represented by the general formula (2) in an amount of 0. 8 to 1. The method for producing an acyloxybenzoic acid according to any one of claims 1 to 3, wherein 6 equivalents are used. 5. A carboxylic acid represented by the general formula (3):
1 to 1 for the hydroxybenzoic acid represented by the general formula (2)
The method for producing an acyloxybenzoic acid according to any one of claims 1 to 4, wherein the method is used in an amount of 100 equivalents. 6. An acid catalyst comprising sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid,
6.A method according to claim 1, wherein the compound is one or a mixture of two or more selected from sulfonic acid, trifluoroacetic acid and a strongly acidic ion exchange resin.
The method for producing an acyloxybenzoic acid according to the above item. 7. The mother liquor obtained after crystallization of the acyloxybenzoic acid by crystallization after completion of the reaction according to claim 1 is represented by the following general formula (3). A process for continuously producing acyloxybenzoic acid, characterized in that it is used as a carboxylic acid source.