JP2872294B2 - Diacetal manufacturing method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an industrial method for producing a diacetal in which odor and coloring are significantly suppressed.

2. Description of the Related Art Diacetal represented by the general formula (1) has been used as a substance having a unique performance so far as a transparency improving agent such as polypropylene, a fluidity improving agent such as a paint, an ink, an adhesive, an adhesive, and a fragrance. A wide range of uses such as solidifying agents for cosmetics and pharmaceuticals have been developed.

[Wherein X and X ′ are the same or different and represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a thioalkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom. m and n are the same or different and each represents an integer of 1 to 5. p represents 0 or 1. The above-mentioned diacetal is obtained, for example, by condensing an aromatic aldehyde having a specific structure with a polyhydric alcohol in a hydrophobic organic solvent in the presence of an acid catalyst, then neutralizing, collecting the solvent, and drying. (Japanese Patent Publication No. 48-43)
748, JP-B-58-22156, JP-B-58-22157, JP-A-1-149789, etc.).

However, usually 300 to 1000 ppm of aldehyde finally remains in the diacetal obtained by these methods. This is because, in addition to unreacted aldehyde, unneutralized acid catalyst remaining in agglomerates (solids, gel-like blocks) of diacetals generated in the condensation process causes diacetal ( It is considered that hydrolysis of the condensation product is caused, and as a result, an aldehyde derived from the raw material is generated. This hydrolysis of the diacetal is considered to be a cause not only of lowering the state of the target product but also of causing coloring of the product and generating an aldehyde odor.

The development of technology for suppressing the deterioration of the odor and hue of this product is particularly demanded in the field of using resin molded products produced by using diacetal as a nucleating agent for food packaging materials and containers, As a technique capable of solving such a problem, there is known a method in which diacetal is treated with a fluid in a subcritical or supercritical state (JP-A-60-199891). The present inventors have conducted intensive studies to establish a novel production method that can more easily reduce the aldehyde odor and prevent the coloring of products without performing a special purification treatment with a specific fluid. ) In a specific step according to the conventional manufacturing method, the diacetal reaction crude product is swelled and dispersed, and then treated according to the conventional method, whereby aldehyde removal, which has been difficult so far, is relatively easy. And (2) an aldehyde caused by local hydrolysis of diacetal by allowing an aliphatic tertiary amine having a specific structure to coexist with the above-mentioned swelling dispersion in a predetermined amount. Has been found to be able to significantly reduce the amount of generation.

The present invention has been completed on the basis of such findings, and provides a diacetal in which the unpleasant odor and the coloring of the product due to the unreacted aldehyde and the aldehyde generated by hydrolysis of the target diacetal are significantly suppressed. It is an object of the present invention to provide an industrially excellent method for producing efficiently.

Means for Solving the Problems The method for producing a diacetal according to the present invention comprises condensing an aromatic aldehyde and a polyhydric alcohol in a hydrophobic organic solvent in the presence of an acid catalyst, then neutralizing the solvent, and recovering the solvent. In producing the diacetal represented by the general formula (1) by drying, the diacetal crude product may be treated with a polar organic solvent (excluding lower aliphatic ketones) at any stage after the condensation reaction until drying. A swelling step is further introduced. In the above-mentioned production method, an aliphatic tertiary amine represented by the general formula (2) or (3) is added per 100 parts by weight of the diacetal in a stage before drying. It is characterized by adding 0.1 to 20 parts by weight.

[Wherein, 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 has 1 carbon atom
Represents an alkyl group of 4 to 4 or (C ₂ H ₄ O) _n H. n is 1 to
4 is an integer. ] [In the formula, R ⁴ represents an alkyl group having 14 to 22 carbon atoms. R ⁵ ,
R ⁶ is the same or different and represents a hydrogen atom, (C ₂ H ₄ O) _n H. n is an integer of 1 to 4. However, neither R ⁵ nor R ⁶ is a hydrogen atom. Here, “swelling” means that the diacetal crude product according to the present invention is in a slurry state via, for example, a solvent described below, does not undergo solid-liquid separation in a standing state, and maintains a uniform state in a macro sense. State.

The aromatic aldehyde according to the present invention is represented by any of the following general formulas, [In the formula, X and n are the same as those in the general formula (1). ] [Wherein, X ′ and m are the same as those in the general formula (1). Specifically, benzaldehyde, a benzaldehyde-substituted product in which 1 to 5 alkyl groups having 1 to 4 carbon atoms are substituted, a benzaldehyde-substituted product in which 1 to 5 thioalkyl groups having 1 to 4 carbon atoms are substituted, and 1 Substituted with 5 to 5 substituted benzaldehydes, 1 to 4 alkoxy groups
Examples thereof include substituted benzaldehydes having 5 to 5 substituents and mixtures thereof in any ratio.

The polyhydric alcohol is represented by the following general formula, [In the formula, p is the same as in the general formula (1). Specific examples include sugar alcohols such as sorbit and xylit, and mixtures thereof in any proportion.

The obtained diacetal includes not only the asymmetric type or the same symmetric type in which the types and numbers of the aromatic substituents are different from each other, but also any mixtures of sorbit derivatives and xylit derivatives, not to mention mixtures thereof. .

The medium applied to swell the diacetal crude (hereinafter referred to as "swelling medium") is a polar organic solvent (however,
Excludes lower aliphatic ketones. ), The type of which is not particularly limited as long as it can achieve a predetermined purpose, and specific examples include the following polar organic solvents. Among them, a solvent having a relatively low boiling point which is easily recovered together with water is preferable. Specifically, aliphatic lower alcohols such as methanol, ethanol, isopropanol and butanol; alicyclic alcohols such as furfuryl alcohol; tetraethers such as tetrahydrofuran, dioxane and diglyme; ether alcohols such as methyl cellosolve; methylene chloride, tricrene; In addition to halogenated solvents such as perchrene, nitromethane, acetonitrile and the like are exemplified.

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

Specific examples of the nonpolar organic solvent include cyclohexanes such as cyclohexane, methylcyclohexane, ethylcyclohexane, and propylcyclohexane; aromatic solvents such as benzene, toluene, and xylene; naphtha,
6 carbon atoms such as mineral spirit, hexane and heptane
About 20 to about 20 saturated hydrocarbons are exemplified.

The blending amount of the swelling medium according to the present invention is not particularly limited as long as the amount is sufficient to swell the crude diacetal, specifically, 80 to 1,000 ml, preferably, to 100 g of the applied diacetal. About 100-300ml is recommended. When a mixed solvent is used, the amount of the polar organic solvent occupied therein is preferably at least about 5% by volume or more based on the diacetal.
If it is less than 5% by volume, it is difficult to swell the diacetal.

The introduction of the swelling step can be incorporated between any steps from the condensation reaction to drying. For example,
After the neutralization and water washing steps, a swelling treatment is performed by adding a predetermined swelling solvent, followed by a solvent recovery and drying step.
At this time, it is effective to introduce the swelling step again before the drying step. In general, it is efficient to perform the process after the recovery of the solvent and before the drying. Specifically, the diacetal reaction crude product is neutralized with sodium hydroxide, potassium hydroxide or the like as necessary, washed with water (normal temperature to 90 ° C), and then heated with a condensation reaction solvent (40 to 180 ° C). Under normal pressure or reduced pressure (760-1mmH
Collect in g). Thereafter, after applying a predetermined swelling solvent to swell the diacetal crude, water is added as necessary, and steam is blown in or dried under reduced pressure to remove the aldehyde simultaneously with the recovery of the swelling solvent and the like. And dry.

Also, repeating the operation of swelling and drying the diacetal is effective in obtaining a product with a reduced odor.

In addition to performing the above-mentioned swelling treatment and adding an aliphatic tertiary amine represented by the general formula (2) or (3) at any stage from the completion of the condensation reaction to the drying, the above-mentioned swelling dispersion By coexisting with the above, hydrolysis of diacetal can be suppressed, and generation of aldehyde can be greatly reduced.

As the aliphatic tertiary amine represented by the general formula (2), specifically, distearylmethylamine, dihexadecylmethylamine, ditetradecylmethylamine, didodecylmethylamine, dioleylmethylamine, stearyllauryl Examples thereof include methylamine, distearylethylamine, dioleylpropylamine, dilaurylbutylamine, distearylhydroxyethylamine, a 2-mol adduct of ethylene oxide with dioleylamine, and a 4-mol adduct of distearylamine with ethylene oxide.

Specific examples of the aliphatic tertiary amine represented by the general formula (3) include alkyl (or alkenyl) monoalkanolamines such as tetradecylhydroxyethylamine, stearylhydroxyethylamine, and a 2 mol ethylene oxide adduct of stearylamine. Examples thereof include alkyl (or alkenyl) dialkanolamines such as tetradecyldihydroxyethylamine, hexadecyldihydroxyethylamine, stearyldihydroxyethylamine, and oleyldihydroxyethylamine.

The aliphatic tertiary amines are 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.
About 13 parts by weight. If the amount is less than 0.1 part by weight, it is difficult to obtain the desired effect sufficiently.If the amount exceeds 20 parts by weight, no remarkable improvement in the effect is observed. It is not preferable because the diacetal composition tends to be colored.

The compounding time of the aliphatic tertiary amine is not particularly limited as long as it is after the completion of the condensation reaction, and may be any of a neutralization step, a solvent recovery step, and a drying step, which are performed after the reaction step. However, in order to more effectively suppress the hydrolysis of the diacetal, it is preferable to mix the diacetal at an earlier treatment stage.

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

Examples of the acid catalyst here include sulfuric acid, phosphoric acid, p-toluenesulfonic acid, alkyl (C ₂ -C ₁₂ ) benzenesulfonic acid, G acid, R acid, zinc chloride and the like.

The method of adding the aliphatic tertiary amine is not particularly limited as long as it has a predetermined effect. Specifically, a solution containing about 1 to 40% by weight of the aliphatic tertiary amine is added to a predetermined amount of the diacetal. , And uniformly mixed, and then dried.

As a suitable solvent for preparing the above solution, any good solvent for these aliphatic tertiary amines is sufficient, and specifically, benzene, toluene, xylene, n-hexane,
Aliphatic, alicyclic, and aromatic hydrocarbons such as cyclohexane, n-decane, and mineral spirit; lower alcohols such as methanol, isopropanol, ethanol / isopropanol mixed solvent; halogen-based solvents such as methyl chloride, trichlene, and perchrene And the like, and among them, cyclohexane, lower alcohol and the like are preferable.

The treatment according to the present invention is generally carried out according to the recipe exemplified below. (1) A predetermined amount of an aromatic aldehyde (A), a polyhydric alcohol (B) [(A) :( B) = 1: 1 to 4: 1 (molar ratio); Substrate ". ], A homogeneous solution (or suspension) containing a lower alcohol as an auxiliary solvent and an acid catalyst (about 0.05 to 10 parts by weight per 100 parts by weight of the reaction substrate) and a hydrophobic organic solvent as a dispersion medium, Under specified conditions (40-20
(0 ° C, 2 to 15 hours). Here, examples of suitable hydrophobic organic solvents include benzene, toluene, xylene, hexane, heptane, cyclohexane, methylcyclohexane, and ethylcyclohexane.

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

Although the action of the amine is not clear, the amine is more likely to penetrate into agglomerates and gel-like blocks than sodium hydroxide, and as a result, neutralization is promoted and the amount of the remaining acid component is reduced. It is estimated that it does not decrease.

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

An aliphatic tertiary amine may be applied after the water wash.

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

(5) Under heating (40 ~ 180 ℃), under normal pressure or reduced pressure (760 ~ 1m
mHg).

(6) Next, drying is performed under heating and / or reduced pressure.

The diacetal thus obtained is one in which the off-flavor due to the remaining aldehyde is largely suppressed and the hue and thermal stability of the product are greatly improved.

This is not only a nucleating agent for a crystalline resin, but also a gelling agent for a liquid substance, a viscosity adjusting agent, a thixotropic agent, an anti-sagging agent,
Functions as an oil-water separator, flocculant, etc., adhesives, paints, resin modification, fragrances, water treatment, solidification and recovery of spilled oil, fragrances, cosmetics, civil engineering / building materials, lubricants, rust inhibitors, The diacetal according to the present invention is similarly applied to fields in which the diacetal according to the present invention has been conventionally used, such as agrochemicals, pharmaceuticals, non-medical products, fuels, inks, and pastes.

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

The evaluation in each example was performed according to the following method.

-Purity (% by weight): by gas chromatography.

-Aldehyde amount (ppm): After Soxhlet extraction, by gas chromatography.

Hue (APHA): The hue of an N-methyl-2-pyrrolidone solution having a concentration of 10% by weight is evaluated.

Example 1 40 g (0.22 mol) of sorbitol powder, 53 g (0.44 mol) of p-tolualdehyde, 750 ml of cyclohexane, 6 g of p-toluenesulfonic acid and 800 ml of methanol were equipped with a condenser equipped with a decanter, a temperature system, and a nitrogen gas inlet of 2 l. And the reaction was carried out at 75 ° C. for 5 hours while distilling off the produced water / methanol while stirring. Then, neutralize with sodium hydroxide, wash with water and diacetal (69g)
/ Cyclohexane slurry was obtained.

A solution obtained by dissolving 1.5 g of stearyldihydroxyethylamine in 20 ml of cyclohexane was added to the above slurry in its entirety, and mixed for 30 minutes. 150 ml of water was added thereto, and cyclohexane was recovered at 80 to 100 ° C. under normal pressure. Next, at 120 ° C / 1
It was dried for 2 hours under the condition of 0 mmHg to obtain 85 g of 20% by weight hydrous ditruylidene sorbitol (Step I). At this time, the amount of remaining p-tolualdehyde was 4,500 ppm.

To this, add 150 ml of methanol as a swelling medium,
For 30 minutes to obtain a swollen slurry. After adding 150 ml of water, pressurized steam (60 g) was blown in for 1 hour to recover methanol, and further dried at 120 ° C./10 mmHg for 4 hours to dry 68 g of ditoluylidene sorbitol. A powder (purity 99.6% by weight) was obtained (Step I)
I). Table 1 shows the measurement results of the amount of p-tolualdehyde remaining in the product and the hue of the product.

Examples 2 to 6 Ditoluylidene sorbitol was prepared in the same manner as in Example 1 except that the kind and the amount of the aliphatic tertiary amine added and the amount of methanol as the swelling medium were variously selected and applied. Table 1 shows the amount of p-tolualdehyde remaining in Step II and the hue of the product.

Examples 7 to 13 Various kinds of swelling solvents were selected, and ditoluylidene sorbitol was prepared according to Example 1. At this time, Table 1 shows the amount of residual p-tolualdehyde and the hue of the product in Step II. Incidentally, isopropanol is abbreviated as “IPA”.

Example 14 Swelling treatment with methanol was performed in the same manner as in Example 1 except that no aliphatic tertiary amine was added to prepare ditolylidene sorbitol. At this time, the amount of p-tolualdehyde remaining in Step II was 55 ppm, and the color of the product was 50.

Example 15 Instead of p-tolualdehyde, 46.6 g of benzaldehyde
(0.44 mol), except that dibenzylidene sorbitol was prepared in the same manner as in Example 1. At this time, as a result of measuring the amount of benzaldehyde remaining in Step I and Step II, it was as follows.

Step I 5,200 ppm Step II 0 ppm Example 16 Ethylbenzaldehyde in place of p-tolualdehyde
Di (p-ethylbenzylidene) sorbitol was prepared according to Example 1, except that 59.0 g (0.44 mol) was selected. At this time, as a result of measuring the amount of ethylbenzaldehyde remaining in Step I and Step II, it was as follows.

Step I 4,300 ppm Step II 20 ppm Example 17 Di (p-chlorobenzylidene) sorbitol was prepared according to Example 1, except that 61.8 g (0.44 mol) of p-chlorobenzaldehyde was selected instead of p-tolualdehyde. . At this time, as a result of measuring the amount of p-chlorobenzaldehyde remaining during Step I and Step II,
It was as follows.

Step I 4,100 ppm Step II 20 ppm Example 18 Bis (dimethylbenzylidene) sorbitol was prepared according to Example 1, except that 59.0 g (0.44 mol) of dimethylbenzaldehyde was selected instead of p-tolualdehyde. At this time, as a result of measuring the amount of dimethylbenzaldehyde remaining in Step I and Step II, it was as follows.

Step I 2,900 ppm Step II 30 ppm Example 19 60.0 g of anisaldehyde in place of p-tolualdehyde
Di (p-methoxybenzylidene) sorbitol was prepared according to Example 1, except that (0.44 mol) was selected. At this time, as a result of measuring the amount of anisaldehyde remaining in Step I and Step II, it was as follows.

Step I 3,800 ppm Step II 50 ppm Comparative Example 1 The same procedure as in Example 1 was repeated except that the swelling treatment was not performed, and dried again for 6 hours to prepare ditolylidenesorbitol. At this time, the amount of p-tolualdehyde remaining in Step II was 300 ppm, and the hue of the product was 80.

Comparative Example 2 Ditoluylidene sorbitol was prepared by drying again for 6 hours in the same manner as in Example 1 except that the swelling treatment was not performed and stearyl dihydroxyethylamine was not added. At this time, the amount of p-tolualdehyde remaining in Step II was 380 ppm, and the hue of the product was 400.

Comparative Example 3 The procedure of Example 1 was repeated, except that methanol (swelling solvent) was replaced with 300 ml of a non-polar solvent, cyclohexane, and steam was blown therein to re-dry to prepare ditoluylidene sorbitol. At this time, the remaining p in step II
The amount of tolaldehyde was 300 ppm and the color of the product was 280.

Comparative Example 4 Ditoluylidene sorbitol was prepared in the same manner as in Example 1 except that 450 ml of a nonpolar solvent, naphtha, was used instead of methanol (swelling solvent). At this time, the amount of p-tolualdehyde remaining in Step II was 330 ppm, and the hue of the product was 300.

Comparative Example 5 Ditoluylidene sorbitol was prepared in the same manner as in Example 1, except that 250 ml of a nonpolar solvent, toluene, was used instead of methanol (swelling solvent). At this time, Step II
The amount of residual p-tolualdehyde at 330 ppm is
The hue of the product was 300.

Effect of the Invention The diacetal produced by the method according to the present invention is
Since the odor is greatly suppressed and the hue is improved, the production method is industrially extremely useful.

Continuation of front page (56) References JP-A-57-185287 (JP, A) JP-A-61-63686 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C07D 493 / 04 WPIL (Derwent)

Claims (2)

(57) [Claims] 1. An aromatic aldehyde and a polyhydric alcohol,
Condensation in a hydrophobic organic solvent in the presence of an acid catalyst, followed by neutralization, recovery of the solvent, and drying to produce the diacetal represented by the general formula (1), followed by drying after the condensation reaction A process for producing a diacetal, which comprises introducing a step of swelling the crude diacetal with a polar organic solvent (excluding lower aliphatic ketones) at any stage. [Wherein X and X ′ are the same or different and represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a thioalkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom. m and n are the same or different and represent an integer of 1 to 5. p represents 0 or 1. ] 2. After the condensation reaction, in any stage up to drying, per 100 parts by weight of the diacetal, the compound represented by the general formula (2)
Or an aliphatic tertiary amine represented by the general formula (3)
The method for producing a diacetal according to claim 1, wherein 0 parts by weight are added. [Wherein, 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 has 1 to 1 carbon atoms
4 represents an alkyl group or (C ₂ H ₄ O) nH. n is an integer of 1 to 4. ] [In the formula, R ⁴ represents an alkyl group having 14 to 22 carbon atoms. R ⁵ , R ⁶
Is the same or different and represents a hydrogen atom, (C ₂ H ₄ O) nH. n is an integer of 1 to 4. However, neither R ⁵ nor R ⁶ is a hydrogen atom. ]