JPH03120285A - Production of diacetal - Google Patents

Abstract

PURPOSE:To obtain the subject compound having suppressed odor and improved hue on an industrial scale at a low cost by condensing an aromatic aldehyde and a polyhydric alcohol in a hydrophobic organic solvent in the presence of an acid catalyst, swelling the crude product and subjecting to neutralization, solvent recovery and drying. CONSTITUTION:The objective compound of formula (X and X' are H, 1-4C alkyl, thioalkyl, alkoxy or halogen atom; m and n are 1-5; p is 0 or 1) can be produced by condensing an aromatic aldehyde and a polyhydric alcohol in a hydrophobic organic solvent (e.g. benzene) in the presence of an acid catalyst (e.g. sulfuric acid), swelling 100g of the resultant crude acetal with 80-1,000ml (>=5vol.% based on the diacetal) of a polar organic solvent (e.g. ethanol), neutralizing the swollen material, adding 0.1-20 pts.wt. (based on 100 pts.wt. of diacetal) of an aliphatic tertiary amine (e.g. distearylmethylamine), recovering the solvent and drying the product.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an industrial method for producing diacetals with significantly reduced odor and coloration.

Diacetal, represented by the general formula (1) at the beginning of the sentence, has been used as a substance with unique properties, as a transparency improver for polypropylene, a fluidity improver for paints, inks, adhesives, etc.
It has been developed for a wide range of uses, including as a solidifying agent for adhesives, cosmetics, and pharmaceuticals.

H20H [wherein, represent. m and n are the same or different and represent integers of 1 to 5. p represents O or 1. ] The above diacetal is produced, for example, by condensing an aromatic aldehyde with a specific structure and a polyhydric alcohol in a hydrophobic organic solvent in the presence of an acid catalyst, then neutralizing it, recovering the solvent, and drying it. (Tokuko Sho 48 = 4)
No. 3748, Special Publication No. 58-22156, Special Publication No. 58-
22157@, JP-A No. 1-149789, etc.).

However, in the diacetal obtained by these methods, usually 300 to 1000 ppm of aldehyde ultimately remains. This, in addition to unreacted aldehyde,
The unneutralized acid catalyst remaining in the diacetal aggregates (solid matter, gel-like blocks) generated during the condensation process causes hydrolysis of the diacetal (condensation product) during heating processes such as solvent recovery and drying. This is thought to be because aldehydes derived from the raw materials are produced as a result. This hydrolysis of diacetal is thought to be the cause of not only a decrease in the yield of the target product, but also coloring of the product and generation of aldehyde odor.

The development of technology to suppress deterioration of the odor and color of this product is particularly desired in the field where resin molded products manufactured by applying diacetal as a nucleating agent are used for food packaging materials, containers, etc. As a technique that can solve this problem, there is a method of purifying diacetal by treating it with a fluid in a subcritical or supercritical state (Japanese Patent Application Laid-open No. 199891/1989).
It has been known.

Problems to be Solved by the Invention The present inventors have established a new manufacturing method that more easily reduces aldehyde odor and prevents coloring of products without performing special purification treatment using specific fluids. (1) In a specific process related to the conventional production method, the diacetal reaction phase is swollen and dispersed, and then processed according to the conventional method to produce aldehyde, which has been difficult until now. (2) By coexisting a predetermined amount of aliphatic tertiary amine having a specific structure with the above swelling dispersion, local diacetal removal can be carried out relatively easily and to a high degree. We have found the advantage that the amount of aldehyde generated due to the hydrolysis of

The present invention was completed based on this knowledge, and it is possible to obtain diacetal in which the off-odor and product coloring caused by unreacted aldehyde and aldehyde generated by hydrolysis of the target diacetal are significantly suppressed. The purpose is to provide an industrially superior method for efficient production.

Means for Solving the Problems The method for producing diacetal according to the present invention involves condensing an aromatic aldehyde and a polyhydric alcohol in a hydrophobic organic solvent in the presence of an acid catalyst, followed by neutralization and recovering the solvent. , when drying to produce a diacetal represented by general formula (1), a step of swelling the crude acetal is introduced in the step leading to drying after the condensation reaction; In the method, in the stage before drying, 0.1 to 0.1 to 100 parts of aliphatic tertiary amine represented by general formula (2) or general formula (3) is added per 100 parts by weight of diacetal.
It is characterized by adding 20 parts by weight.

2/ [wherein R1 and R2 are the same or different and have 10 carbon atoms
~26 alkyl or alkenyl group. R3 is an alkyl group having 1 to 4 carbon atoms or (02H40), H
represents. n is an integer from 1 to 4. Co\R6 [Wherein, R4 represents an alkyl group having 14 to 22 carbon atoms. R5 and R6 are the same or different, a hydrogen atom, (C2
H40). represents the eyes. n is an integer of 1Q-4. However, neither R5 nor R6 is a hydrogen atom. ] Here, "swelling J" means that the crude diacetal according to the present invention becomes a slurry state through the use of a solvent as described later, does not undergo solid-liquid separation in a stationary state, and maintains a homogeneous state in a macroscopic sense. It refers to the state of being.

The aromatic aldehyde according to the present invention is represented by any of the following general formulas, where X and n are the same as in general formula (1). ] [wherein, X
' and m are the same as in general formula (1). Specifically, benzaldehyde, a benzaldehyde substituted product substituted with 1 to 5 alkyl groups having 1 to 4 carbon atoms, a benzaldehyde substituted product substituted with 1 to 5 thioalkyl groups having 1 to 4 carbon atoms, and a benzaldehyde substituted product substituted with 1 to 5 thioalkyl groups having 1 to 4 carbon atoms; Examples include a benzaldehyde substituted product having ~5 substitutions, a benzaldehyde substitution product substituted with 1 to 5 alkoxy groups having 1 to 4 carbon atoms, and a mixture thereof in an arbitrary ratio.

Further, the polyhydric alcohol is represented by the following general formula, where p is the same as in general formula (1). ] Specifically, sugar alcohols such as sorbitol and xylit, and mixtures thereof in arbitrary proportions are exemplified.

The diacetals obtained include not only asymmetric types having different types and numbers of aromatic substituents, symmetric types having the same aromatic substituents, and mixtures thereof, but also any mixtures of nruvit derivatives and xylite derivatives.

The medium applied to swell the diacetal crude (
Hereinafter referred to as "swelling medium". ) is not particularly limited as long as it can achieve the predetermined purpose, but specific examples include the following polar organic solvents. Among these, a relatively low boiling point solvent that can be easily recovered together with water is preferred. Specifically, aliphatic lower alcohols such as methanol, ethanol, isopropanol, and butanol; alicyclic alcohols such as furfuryl alcohol; ethers such as tetrahydrofuran, dioxane, and diglyme; ether alcohols such as methyl cellosolve; acetone. , methyl ethyl ketone, methyl isobutyl ketone, and other ketones; halogenated solvents such as methylene chloride, trichrene, perchlorene, and the like, as well as nitromethane, acetonitrile, and the like.

This polar organic solvent can also be used in combination with water or a non-polar organic solvent.

Specifically, the above non-polar organic solvents include cyclohexane, methylcyclohexane, ethylcyclohexane,
Cyclohexane such as propylcyclohexane; Aromatic solvent such as benzene, toluene, xylene, etc. Carbon number 6-2 such as naphtha, mineral spirit, hexane, heptane, etc.
Examples include saturated hydrocarbons with a concentration of about 0.

The amount of the swelling medium according to the present invention is not particularly limited as long as the amount is sufficient to swell the diacetal. Specifically, the amount of the swelling medium used is 80-1. 000m1, preferably 100-30
Approximately 0m1 is recommended.

When a mixed solvent is used, the amount of polar organic solvent in the mixed solvent is at least 5% relative to the diacetal.
It is preferable that the content is about % by volume or more. 5% by volume
If it is less than that, it is difficult to swell the diacetal.

The swelling treatment step can be incorporated between any steps after the condensation reaction and up to drying. for example,
After the neutralization and water washing steps, a predetermined swelling solvent is added to carry out swelling treatment, followed by solvent recovery and drying steps.

At this time, it is effective to reintroduce a swelling process before the drying process. - For boat fishing, it is effective to do this after recovering the solvent and before drying. Specifically, the diacetal reaction crude product is neutralized with sodium hydroxide, potassium hydroxide, etc. as necessary, and after washing with water (room temperature to 90'C), the condensation reaction solvent etc. is heated (40 to 180'C). C) Under normal pressure or reduced pressure (
760~1mH! Collect at J). After that, after applying a specified swelling solvent to swell the diacetal, aldehyde is removed at the same time as the swelling solvent is recovered by adding water as necessary, blowing in steam, or drying under reduced pressure. , it dries.

Furthermore, repeating the operations of swelling and drying diacetal is effective in obtaining a product with further reduced odor.

In addition to carrying out the above swelling treatment, an aliphatic tertiary amine represented by the general formula (2> or general formula (3)) is added at any stage of the condensation reaction solvent removal and drying, and the above swelling dispersion is By coexisting with diacetal, it is possible to suppress the hydrolysis of diacetal and significantly reduce the generation of aldehyde.

As an aliphatic tertiary amine represented by general formula (2),
Specifically, distearylmethylamine, distearylmethylamine, distearylmethylamine, didodecylmethylamine, dioleylmethylamine, stearyllaurylmethylamine, distearylethylamine, dioleylpropylamine, dilaurylbutylamine, distearyl Examples include hydroxyethylamine, an adduct of dioleylamine with 2 moles of ethylene oxide, and an adduct of distearylamine with 4 moles of ethylene oxide.

As an aliphatic tertiary amine represented by general formula (3),
Specifically, alkyl (or alkenyl) monoalkanolamines such as tetradecylhydroxyethylamine, stearylhydroxyethylamine, and a 2-mole ethylene oxide adduct of stearylamine; tetradecyldihydroxyethylamine, hexadecyldihydroxydiethylamine, stearyldihydroxydiethylamine, Examples include alkyl (or alkenyl) dialkanolamines such as oleyldihydroxydiethylamine.

The aliphatic tertiary amine may be used alone or in combination of two or more, and the effective amount thereof is 0.1 to 20 parts by weight, preferably 0.3 to 20 parts by weight, based on 100 parts by weight of diacetal. The amount is approximately 13 parts by weight. If the amount is less than 0.1 part by weight, it is difficult to obtain the desired effect;
Even if it is blended beyond the double-marked area, no significant improvement in effect is observed, and on the contrary, the amine itself tends to be colored upon heating, which is not preferable because the diacetal composition tends to be colored as a result.

The timing of blending the aliphatic tertiary amine is not particularly limited as long as it is after the completion of the condensation reaction, and it can be added during any of the neutralization, solvent recovery, and drying steps that follow the reaction step. Although it is possible to obtain the desired effect,
In order to more effectively suppress the hydrolysis of diacetal, it is preferable to incorporate it at an earlier treatment stage.

When an aliphatic tertiary amine is applied in the neutralization step, it functions as a neutralizing agent for the acid catalyst, either alone or in combination with the alkali metal hydroxides mentioned above.

Examples of the acid catalyst here include sulfuric acid, phosphoric acid, p-toluenesulfonic acid, alkyl(02-Cl2)benzenesulfonic acid, GM, R acid, and zinc chloride.

The method of adding the aliphatic tertiary amine is not particularly limited as long as it achieves the desired effect, but specifically, a predetermined amount of a 1 to 40% by weight solution of the aliphatic tertiary amine is added. It may be added to diacetal, mixed uniformly, and then dried.

Suitable solvents for preparing the above solution include any good solvent for these aliphatic tertiary amines, specifically benzene, toluene, xylene, n-hexane, cyclobequinane, n- Aliphatic, alicyclic, and aromatic hydrocarbons such as decane and mineral spirits; Lower alcohols such as methanol, isopropanol, and mixed ethanol/isopropanol solvents; Halogen solvents such as methyl chloride, trichrene, and perchrene. Among them, cyclohexane, lower alcohols and the like are preferred.

The treatment according to the present invention is generally carried out according to the recipe exemplified below. That is, (1) Predetermined amounts of aromatic aldehyde (A) and polyhydric alcohol (B) [(A): (B) = 1: 1
~4:1 (molar ratio), hereinafter both are collectively referred to as "reaction substrate"
That's what it means. ], a homogeneous solution (or suspension) containing a lower alcohol and an acid catalyst (approximately 0.05 to 10 parts by weight per 100 parts by weight of the reaction substrate) as an auxiliary solvent, and a hydrophobic organic solvent as a dispersion medium. Under specified conditions (40-200'C12-1
5 hours) to carry out the condensation reaction.

Here, examples of suitable hydrophobic organic solvents include benzene, toluene, xylene, hexane, heptane, cyclohexane, methylcyclohexane, and ethylcyclohexane.

(2) The resulting reaction mixture in the form of a slurry or wet powder is optionally filtered and neutralized by adding a predetermined amount of base thereto. At this time, an aliphatic tertiary amine or a separately prepared amine solution may be added together with a strong base solution such as a sodium hydroxide solution.

Although the action of the above amine is not clear, the amine penetrates into aggregates and gel blocks more easily than sodium hydroxide, and as a result, neutralization is promoted and the amount of residual acid components is reduced. It is presumed that they will.

(3) Unreacted raw materials (polyhydric alcohol and aromatic aldehyde) and reaction intermediates (monobenzal, etc.) are washed and removed with water (room temperature to 90°C). At this time, since the aliphatic tertiary amine added in the previous step is a hydrophobic substance, most of it remains in the system except for being removed as a neutralized salt.

Aliphatic tertiary amines may be applied after the water washing.

(4) A predetermined amount of a swelling solvent is added to the obtained diacetal slurry, and the mixture is mixed and stirred for usually 10 minutes to 3 hours to swell the diacetal.

(5) Under heating (40 to 180°C), under normal pressure or reduced pressure (7
60-1 sHg).

(6) Next, dry under heat and/or reduced pressure.

The diacetal thus obtained has significantly suppressed off-odor caused by residual aldehyde, and the color and thermal stability of the product are greatly improved.

This product functions not only as a nucleating agent for crystalline resins, but also as a gelling agent, viscosity modifier, thixotropic agent, anti-sagging agent, oil/water separator, flocculant, etc. for liquid substances, and is used in adhesives, paints, Resin modification, fragrances, water treatment, assimilation and recovery of spilled oil, fragrances,
The diacetal according to the present invention can be similarly applied to fields in which the diacetal according to the present invention has been conventionally used, such as cosmetics, civil engineering/building materials, lubricants, rust preventives, agricultural chemicals, medicines, medical exterior products, fuels, inks, and glues.

EXAMPLES Hereinafter, the present invention will be explained in detail with reference to Examples and Comparative Examples.

Note that the evaluation on each side was performed according to the following method.

・Toughness (weight %): Gas chromatography (depending on the weight).

・Aldehyde ffi (ppm): After Soxhlet extraction,
By gas chromatography.

・Hue (APHA): N-methyl-2 at a concentration of 10% by weight
- Evaluate the hue of the pyrrolidone solution.

Example 1 Sorbitol powder 40g (0.22 mol), p-tolualdehyde 539 (0.44 mol), cyclohexane 7
50th! , 63 parts of p-toluenesulfonic acid and 800 parts of methanol were charged into a 21 twin-screw kneader equipped with a condenser with a decanter, a temperature system, and a nitrogen gas inlet. The reaction was continued for 5 hours while methanol was distilled off. Next, it was neutralized with sodium hydroxide and washed with water to obtain diacetal (6'l)/cyclohexane free.

A solution prepared by dissolving 1,57 g of stearyldihydroxydiethylamine in 20 d of cyclohexane was added in its entirety to the above slurry and mixed for 30 minutes. 150 d of water was added to this, and cyclohexane was recovered at 80 to 100°C under normal pressure. Next, under the conditions of 120'C/10mm Hg,
After drying for several hours, 857 of 20% by weight water-containing super-ruiliden sorbitol was obtained (Step D). At this time, the amount of p-tolualdehyde remaining was 4,500 ppm T:''.

Add to this 150ml of methanol as a swelling medium! ! Add
The mixture was mixed and stirred at 55°C for 30 minutes to form a swollen slurry. After adding 15M of water to this, pressurized steam (60!
J) for 1 hour to recover methanol, and further dried under the conditions of 120°C/110ml for 4 hours to obtain dry powder of ditolylidene sorbitol (purity 99.6% by weight) of 61. The results of measurements regarding the amount of p-tolualdehyde remaining in this product and the hue of the product are shown in Table 1.

Examples 2 to 6 Ditolylidene sorbitol was prepared in the same manner as in Example 1, except that the type and amount of aliphatic tertiary amine added and the amount of methanol in the swelling medium were selected and applied. Table 1 shows the amount of p-tolualdehyde remaining in step (2) and the hue of the product.

Examples 7 to 14 Ditolylidene rubitol was prepared according to Example 1 by selecting various types of swelling solvents. At this time, Table 1 shows the amount of p-tolualdehyde remaining and the hue of the product in step (2).

Example 15 Ditolylidene sorbitol was prepared in the same manner as in Example 1 except that no aliphatic tertiary amine was added. At this time, the amount of p-tolualdehyde remaining in step (2) was 55 pl)m, and the hue of the product was 50.

Example 16 Benzaldehyde instead of p-tolualdehyde 46.6
Dibenzylidene sorbitol was prepared according to Example 1, except that g (0.44 mol) was selected. At this time,
As a result of measuring m of benzaldehyde remaining in step T and step (2), it was found to be as follows.

Step D 5,200pf) m step■
○ppm Example 17 Ethylbenzaldehyde 5 instead of p-tolualdehyde
9. Example 1 except that (1 (0.44 mol) was selected)
Di(p-ethylbenzi-1nodene)sorbitol was prepared according to . At this time, as a result of measuring the amount of ethylbenzaldehyde remaining in step ■ and step ■,
It was as follows.

Step T 4.300ppm Step II
20ppm Example 18 p-chlorobenzaldehyde instead of p-tolualdehyde 61. Di(p-chlorobenzylidene)turdotol was prepared according to Example 1 except that i (0.44 mol) was selected. At this time, the amount of p-chlorobenzaldehyde remaining in step A and step II was measured, and the results were as follows. Step I 4.1 ooppm Step n
2oppm Example 19 Bis(dimethylbenzylidene) sorbitol was prepared according to Example 1, except that 59.0 g (0.44 mol) of dimethylbenzaldehyde was selected in place of p-+rualdehyde. At this time, the dimethylbenzaldehyde remaining in the seedlings in step (2) and step (2) was measured, and the results were as follows.

Step I 2.900ppm Step I [3
0 ppm Example 20 Anisaldehyde 60.0 instead of p-tolualdehyde
! Example 1 except that 17 (0.44 mol) was selected.
Di(p-methoxybenzylidene)sorbitol was prepared according to . At the time of separation, the amount of anisaldehyde remaining in Step A and Step II was measured, and the results were as follows.

Stella 7I 3. aooppm step n
50 pl)m Comparative Example 1 Ditolylidene sorbitol was prepared by re-drying for 6 hours in the same manner as in Example 1 except that the swelling treatment was not performed. At this time, the amount of p-tolualdehyde remaining in step (2) was 300C1m, and the hue of the product was 80.

Comparative Example 2 Ditolylidene rubitol was prepared by re-drying for 6 hours in the same manner as in Example 1, except that no swelling treatment was performed and stearyldihydroxydiethylamine was not added. At this time,
The amount of p-tolualdehyde remaining in step ① is 3
At 80 pDm, the product had a hue of 400.

Comparative Example 3 Ditolylidene sorbitol was prepared in the same manner as in Example 1 except that 300 m of cyclohexane, a non-polar solvent, was used instead of methanol (swelling solvent), by blowing in steam and redrying. At this time, p remaining in step ■
-The amount of tolualdehyde is 300 ppm, and the color of the product is 280.

Comparative Example 4 Ditolylidene sorbitol was prepared according to Example 1, except that naphtha 450%, which is a nonpolar solvent, was used instead of methanol (swelling solvent). At this time, the amount of p-tolualdehyde remaining in step ① was 330 ppm.
The hue of the product was 300.

Comparative Example 5 Ditolylidene rubitol was prepared according to Example 1, except that 250ml of toluene, a nonpolar solvent, was used in place of methanol (swelling solvent).

At this time, the amount of p-tolualdehyde remaining in step a3 was 330 ppm, and the hue of the product was 300.

Effects of the Invention The diacetal produced by the method according to the present invention has significantly suppressed odor and improved hue.
The production method is extremely useful industrially.

Claims (1)

[Claims] 1. An aromatic aldehyde and a polyhydric alcohol are condensed in a hydrophobic organic solvent in the presence of an acid catalyst, then neutralized, the solvent is recovered, and dried to obtain the general formula (1 ) A method for producing diacetal, which comprises introducing a step of swelling the crude acetal in the step leading to drying after the condensation reaction. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (1) [In the formula, X and X' are the same or different, hydrogen atom, alkyl group having 1 to 4 carbon atoms, thioalkyl group having 1 to 4 carbon atoms, carbon Represents an alkoxy group of numbers 1 to 4 and a halogen atom. m and n are the same or different and represent integers of 1 to 5. p represents 0 or 1. ] 2. In the stage before the drying step, 0.1 to 20 parts by weight of an aliphatic tertiary amine represented by general formula (2) or general formula (3) is added per 100 parts by weight of diacetal. The method for producing diacetal according to claim 1. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (2) [In the formula, R^1 and R^2 are the same or different and represent an alkyl group or an alkenyl group having 10 to 26 carbon atoms. R
^3 is an alkyl group having 1 to 4 carbon atoms or (C_2H_4
O)_nH. n is an integer from 1 to 4. ] ▲There are mathematical formulas, chemical formulas, tables, etc.▼(3) [In the formula, R^4 represents an alkyl group having 14 to 22 carbon atoms. R^5 and R^6 are the same or different, and are hydrogen atoms,
(C_2H_4O)_nH. n is an integer from 1 to 4. However, neither R^5 nor R^6 is a hydrogen atom. ]