JPH0971544A - Method for producing 2-hexyl-2-methyl-1,3-propanediol - Google Patents

Abstract

(57) [Problem] To provide a method for industrially and advantageously producing 2-hexyl-2-methyl-1,3-propanediol. SOLUTION: 2-methyloctanal and formaldehyde are reacted in an organic solvent in the presence of an alkaline substance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to 2-hexyl-2
-Methyl-1,3-propanediol. More specifically, alkyd resin, polyurethane,
The present invention relates to a method for producing 2-hexyl-2-methyl-1,3-propanediol, which is useful as a raw material for producing polyesters, plasticizers, lacquers, and the like.

[0002]

2. Description of the Related Art Conventionally, 2-hexyl-2-methyl-1,
As a method for producing 3-propanediol, formula
Chi, H_TwoC = CR-CHO, (wherein R is charcoal
Represents an alkyl group having a prime number of 1 to 20. Acro represented by)
Rhein derivative and formaldehyde are converted to acid catalyst
The product is hydrogenated to the formula_Three
-CR- (CH_Two  OH)_Two, (Where R is charcoal
Represents an alkyl group having a prime number of 1 to 20. ))
(Japanese Patent Laid-Open No. 53-28106)
Reference). In the proposed method, acrolein induction
After reacting the body with formaldehyde,
It is necessary and requires a long reaction step, which is industrially disadvantageous.

Separately from the above method, 2-methylhexenal, 2-methylheptanal, 2-methylnonanal, etc. and formaldehyde are mixed in an aqueous alcoholic solvent.
Using potassium carbonate as a catalyst, 2-butyl-2
-Methyl-1,3-propanediol, 2-pentyl-
A method for synthesizing 2-methyl-1,3-propanediol and 2-heptyl-2-methyl-1,3-propanediol has been proposed {Bull. Soc. Chim. ,
Fr. , 47 , 858 (1930)}. However, this publication does not describe a method for producing 2-hexyl-2-methyl-1,3-propanediol to be provided in the present invention.

[0004]

SUMMARY OF THE INVENTION In view of such circumstances, the present inventors have provided an industrially advantageous and efficient method for synthesizing 2-hexyl-2-methyl-1,3-propanediol. As a result, as a result of intensive studies, the present invention has been completed.

[0005]

According to the present invention, 2-methyloctanal and formaldehyde are reacted in an organic solvent in the presence of an alkaline substance to form 2-hexyl-2. Means for producing -methyl-1,3-propanediol.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
In the method of the present invention, 2-methyloctanal and formaldehyde are used as raw materials. The ratio of the two kinds of raw materials at the time of the reaction can be selected from the molar amount of formaldehyde to 1 mol of 2-methyloctanal in the range of 2 to 8 times the molar amount. If this molar amount is less than twice, a side reaction occurs in which formaldehyde reacts with the alkaline substance, and the yield of the target substance, 2-hexyl-2-methyl-1,3-propanediol, decreases, and the molar amount decreases. Exceeds 8 times,
Any formaldehyde is excessive, and the operation of removing the formaldehyde after the completion of the reaction becomes complicated. A particularly preferred molar amount of the raw material is in the range of 3 to 5 times.

In the method of the present invention, the above raw materials are reacted in an organic solvent. Organic solvents that can be used include tertiary alcohols, cyclic ethers and methyl tert-butyl ether. Specific examples of the tertiary alcohol include t-butyl alcohol, t-amyl alcohol, α-terpineol and the like, and the former two are common. Specific examples of the cyclic ether include ethylene oxide, tetrahydrofuran, dioxane and the like. These may be used alone or as a mixture of two or more.

When the amount of the organic solvent present in the reaction system during the above reaction is too small, the reaction cannot be made homogeneous, and when the amount is too large, the thermal efficiency during the reaction decreases. However, the recovery operation after the completion of the reaction becomes complicated, and neither is preferable. The amount of the organic solvent varies depending on the reaction temperature, the type and amount of the catalyst, and the like, but is preferably 0.1 times or more, more preferably 3 to 5 times the weight ratio of the raw material mixture.

In the method of the present invention, an alkaline substance is present in the reaction system when performing the above reaction. The alkaline substance acts as a catalyst. Examples of the alkaline substance include an alkali metal hydroxide and an alkaline earth metal hydroxide. Specific examples of these include lithium hydroxide, sodium hydroxide, potassium hydroxide, and barium hydroxide. Particularly preferred among these are sodium hydroxide and potassium hydroxide. The amount of the alkali substance to be present in the reaction system varies depending on the type and molar ratio of the raw materials, the type and amount of the organic solvent, the reaction temperature, and the like, but is 1 to 5 times the molar amount of 1 mol of 2-methyloctanal as the raw material. The range is preferably 2 to 3 times the molar amount. The operation of the alkaline substance is usually advantageous in the form of an aqueous solution having a concentration of 50% or less.

The temperature at which the above reaction is carried out depends on the type of raw material,
It varies depending on the molar ratio, the type and amount of the organic solvent, the type and amount of the catalyst, and can be selected within the range of 10 to 100 ° C. If the temperature is lower than 10 ° C, the temperature is too low and the reaction time becomes too long, which is not practical. If the temperature is higher than 100 ° C, the reaction proceeds rapidly or the reaction product is decomposed, and both are preferable. Absent. The preferred temperature range is 1
5-60 ° C. The reaction pressure is preferably normal pressure or slightly increased pressure.

The order of addition of the raw material, the organic solvent and the catalyst during the above-mentioned reaction is not particularly limited, but the organic solvent and the one formaldehyde are charged into the reactor, and the remaining raw material is 2-methyloctanal. It is preferred that the catalyst and the alkali substance of the catalyst are gradually charged at such a rate that the pH of the reaction mixture does not suddenly change.

After the completion of the reaction, the unreacted formaldehyde in the reaction mixture is preferably converted to formate and methyl alcohol. If necessary, an acid such as formic acid may be added to the reaction mixture for neutralization. Next, the solvent is removed from the reaction mixture, and the desired product is isolated and purified. As a method for performing the isolation and purification, (i) a method by distillation under reduced pressure, (ii)
There are a method of azeotropic distillation by adding water, and a method of (iii) solvent extraction by adding a solvent. In the case of the vacuum distillation of (i), the pressure in the distillation system is 10 mmHg or less, preferably 5 mmHg or less, and the temperature is in the range of 100 to 200 ° C.
Preferably, it is good to choose in the range of 120 to 170 ° C.

In the case of the solvent extraction of the above (iii), it is preferable to add a new organic solvent into the system before starting the solvent extraction. Organic solvents that can be added include those having 6 carbon atoms.
To 10 aromatic hydrocarbons or acetates. Specific examples of the aromatic hydrocarbon include benzene,
Examples include toluene and xylene, and specific examples of the acetate include methyl acetate, ethyl acetate, propyl acetate, butyl acetate, isopropyl acetate, and isobutyl acetate. The amount used is 1 to 5 times, preferably 2 to 3 times the weight of the reaction product containing the target product. An organic solvent is added to the reaction mixture, and the mixture is shaken and allowed to stand. Then, the mixture is separated into an organic layer (oil layer) containing a reaction product and an aqueous layer not containing the organic layer. Discard the water layer as it is,
The organic layer is subjected to an operation of isolating and purifying the target substance.

In order to isolate and purify the target compound from the reaction mixture, the organic solvent is removed from the system by azeotropic distillation, steam distillation or the like, and the residue after the removal is subjected to a temperature of -20 to 20 ° C.
At a temperature of, preferably, -5 to 5 ° C. while cooling with ice water to crystallize the desired product. The crystallized target product is obtained by filtration, separation and drying. The target substance, 2-hexyl-2-methyl-1,3-propanediol, is a solid and is useful as a raw material for producing alkyd resins, polyesters, plasticizers, lacquers, and the like.

[0015]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following description unless it exceeds the gist.

[Example] Stirrer, reflux condenser, thermometer,
In a 2-liter capacity reactor equipped with a jacket, raw material charging ports, etc., 956 g of t-butyl alcohol and 280 g of paraformaldehyde were charged, and the internal temperature was adjusted to 20 to 25.
The temperature was raised to ° C. While stirring the reactor contents, 284 g of 2-methyloctanal was required for 1.5 hours,
392 g of a 48% aqueous sodium hydroxide solution was continuously dropped into each of the reactors over 2.5 hours, and reacted. The reaction is an exothermic reaction, and the internal temperature gradually increases during the continuous dropping of the 2-methyloctanal and the aqueous solution of sodium hydroxide. Was adjusted within the range. After the end of the continuous dropping, the internal temperature decreased. Therefore, the reaction was continued for another hour in this temperature range while maintaining the internal temperature at 40 to 45 ° C. to terminate the reaction.

The pH was adjusted to 7 by adding formic acid to the reaction product, and the mixture was allowed to stand to separate an aqueous layer and an oil layer, and the aqueous layer was removed. Next, after the oil layer was washed with 300 g of water, the solvent was distilled off under reduced pressure to obtain a reaction mixture. 500 g of ethyl acetate was added to the reaction mixture, and the reaction mixture was dissolved, washed twice with 300 g of water, water was removed by azeotropic distillation, the residue was cooled to 5 ° C., and the crystallized crystals were filtered. -Separated and vacuum dried. The yield of the crystals was 72%, and the melting point was 62 to 63 ° C. Analysis by gas chromatography revealed a purity of 99%.

The hydroxyl group contained in the molecule of the product is converted into chlorotrimethylsilane in a pyridine medium, and
The reaction with 1,1,1,3,3,3-hexamethyldisilazane was converted to trimethylsilyl ether, and the mass spectrum was measured using a mass spectrometer (manufactured by Shimadzu Corporation, model: ECMS-QP1000A). Had a molecular ion peak of 319 (M ++ 1). In addition, an infrared spectrometer (manufactured by JASCO Corporation, model: JIR-
5500) was consistent with the absorption spectrum of the standard substance, confirming that the product was the desired 2-hexyl-2-methyl-1,3-propanediol. Further, when the NMR spectrum of the product was measured by an NMR spectrometer (manufactured by Varian, model: Gemini200), a resonance line specific to the target substance was observed, and the product was 2-hexyl-2-methyl-.
It was confirmed to be 1,3-propanediol.

[0019]

According to the method of the present invention, 2-hexyl-2-methyl-1,3-propanediol can be synthesized very efficiently in a short process, and its industrial utility value is extremely high. Is big.

Claims (3)

[Claims] 1. A method of reacting 2-methyloctanal and formaldehyde in an organic solvent in the presence of an alkaline substance, comprising the steps of:
A method for producing 1,3-propanediol. 2. The organic solvent according to claim 1, wherein the organic solvent is selected from the group consisting of tertiary alcohols, cyclic ethers and methyl tertiary butyl ether.
A method for producing hexyl-2-methyl-1,3-propanediol. 3. The process for producing 2-hexyl-2-methyl-1,3-propanediol according to claim 1, wherein the molar ratio of formaldehyde to 2-methyloctanal is in the range of 2 to 8.