JPS59137431A - Production of trimethylolheptane - Google Patents

Abstract

PURPOSE:To obtain the titled compound in high yield and purity, by reacting n-octylaldehyde with formaldehyde in a solvent such as THF in the presence of NaOH, etc. removing the solvent from the reaction mixture, heating the organic phase separated from the residual liquid, and crystallizing and separating the objective compound from the heat-treated phase. CONSTITUTION:Crude trimethylolheptane is prepared by reacting n-octylaldehyde with formaldehyde in tetrahydrofuran or dioxane, in the presence of an alkali metal or alkaline earth metal hydroxide. The obtained reaction mixture is distilled to distill out the solvent, and the distillation bottom is heated at >=60 deg.C to separate the liquid into an organc phase composed mainly of trimethylolheptane and an aqueous phase composed mainly of formic acid. The organic layer is heated at about 100-300 deg.C in the presence of an acid catalyt and water to hydrolyze and remove various formals existing in small amounts, and finally, a 6-9C aromatic hydrocarbon such as benzene is added to the liquid to crystallize and separate trimethylolheptane.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for producing trimethylolhebutane by methylolating 11-octylaldehyde with formaldehyde.

It is already well known that when an aliphatic aldehyde represented by the general formula 1tonzOnO (R: aliphatic hydrocarbon group) is reacted with formaldehyde in the presence of a base, a trimethylolalkane represented by hC(Ck120M)3 is obtained. There is. In particular, the production of trimethylolpropane from n-butyraldehyde is carried out on a large scale industrially, and the trimethylolpropane is produced from alkyd resins,
It is used as a raw material for polyurethane, polyester, etc. Since both n-butyraldehyde' and trimethylolpropane have high solubility in water, the synthesis reaction of trimethylolpronone by methylolation of n-butyraldehyde can be carried out while maintaining a homogeneous system throughout in an aqueous solution. Trimethylolhebutane obtained from n-octylaldehyde has many superior basic physical properties compared to trimethylolpropane, but n-octylaldehyde is expensive and n-
Because octylaldehyde and the product trimethylolhebutane are virtually insoluble in water, their preparation involves a number of problems, and trimethylolhebutane cannot be produced on an industrial scale. This has not yet been achieved.

Conventionally, trimethylolhebutane has been produced using a method of converting n-octylaldehyde into methylol in the presence of an interfacial viscosity agent [J, Amer, Chem, Soc.
76° 1697-9 (1954)), a method of methylolating n-octylaldehyde while keeping the reaction system homogeneous by coexisting ethanol [Acta.

Chern, 8cand, i6. 1062
(1962)] has been proposed, but in either method the yield of trimethylolhebutane is at most 60%.
This was not industrially satisfactory.

The present inventors have previously discovered an advantageous method for producing n-octylaldehyde using butadiene, water and hydrogen as starting materials (Japanese Patent Application No. 56-204997).

From this point of view, the present inventors conducted extensive research to develop an industrially advantageous method for producing butane from n-octylaldehyde to trimethylol, and as a result, they arrived at the present invention. That is, according to the present invention, (1) trimethylolhebutane is prepared by reacting r)-octylaldehyde and formaldehyde in the presence of an alkali metal hydroxide or an alkaline earth metal hydroxide in tetrahydrofuran or dioxane. (2) The reaction mixture obtained in step (1) is distilled to remove tetrahydrofuran or dioxane, and the distillation residue is maintained at a temperature of 60'C or higher to separate the organic layer. (3) The organic layer obtained in step (2) is heat-treated in the presence of an acid catalyst and water, and then an aromatic hydrocarbon having 6 to 9 carbon atoms is added to form trimethylol. By crystallizing and separating hebutane crystals, trimethylolhebutane can be produced in high yield and purity.

In the method of the present invention, an aqueous formaldehyde solution is usually used as the formaldehyde. Industrially available formaldehyde aqueous solution is 5 to 50 wt%.
An aqueous formaldehyde solution can be used as is. The concentration of n-octylaldehyde in the reaction solution is preferably in the range of 2 to 20 wt% relative to the reaction mixture.

The amount of formaldehyde used is 6/1 to 6/1, especially 5.3/1 to 4 in molar ratio to n-octylaldehyde.
, 2/1 is preferable. If the molar ratio is less than 6/1, the amount of unreacted n-octylaldehyde remaining will increase, and the proportion of by-products such as di-trimethylolhebutane will increase, which is not preferable. Also, the molar ratio is 6/
If it exceeds 1, the amount of by-products of various formal numbers will increase, and the cost of recovering unreacted formaldehyde will increase, which is industrially unfavorable.

Specific examples of alkali metal hydroxides and alkaline earth metal hydroxides include lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, etc., but reaction results and prices may vary. In consideration of this, sodium hydroxide is particularly preferred. The amount of these alkali metal or alkaline earth metal hydroxides to be used is 1.0 molar ratio to n-octylaldehyde.
The range of 0/1 to 1.5/1 is preferable. The reaction temperature is in the range of about 5 to 100°C, particularly preferably 60 to 50°C.
A temperature within the range of °C is selected.

The methylolation reaction of n-octylaldehyde according to the method of the invention is carried out in tetrahydrofuran or dioxane, which can increase the reaction rate and the yield of trimethylolhebutane. Conventionally, it has been proposed to use lower alcohols as reaction solvents in the methylolation reaction of n-octylaldehyde, but according to the detailed parsimony of the present inventors, when the reaction is carried out in these lower alcohols, It was found that various formals and hemiformals were formed as by-products, and the yield of trimethylolhebutane was significantly reduced. Furthermore, hydrocarbons, halogenated hydrocarbons, and ethers other than tetrahydrofuran and dioxane were mixed under the reaction conditions. Although they are chemically stable, they are unsuitable as reaction solvents due to the reaction rate, trimethylol to butane yield, and the complexity of the trimethylol to butane separation process.

Tetrahydrofuran or dioxane is used in an amount ranging from 0.05 to 0.9 by weight relative to the reaction mixture. The amount of these solvents used is 0 in terms of weight ratio to the reaction mixture.
．． If the amount is less than 0.05, the reaction rate will be slow, and if the amount exceeds 0.9, the cost of recovering the solvent will increase, which is not preferable.

As a specific method for carrying out the methylolation reaction of n-octylaldehyde, a) n-suctyraldehyde,
Formaldehyde water far (method of reacting while simultaneously adding l and an aqueous solution of an alkali metal or alkaline earth metal hydroxide) n-octylaldehyde and an alkali metal are added to a mixed solution consisting of an aqueous formaldehyde solution and tetrahydrofuran or dioxane. Alternatively, a method of reacting while simultaneously adding a water bath solution of alkaline earth metal hydroxide, ・A method of reacting while simultaneously adding a water bath solution of alkaline metal or alkaline earth metal hydroxide to a mixed solution consisting of a water bath solution of formaldehyde, tetrahydrofuran or dioxane, and n-octylaldehyde. There are three methods that can be considered: a method of reacting while adding a water bath solution of trimethylolhebutane, but according to a study by Akishū Fuko et al. I understand. In the method (2), n-octylaldehyde can also be used after being partially diluted with tetrahydrofuran or dioxane. It goes without saying that the rate of addition of these reaction reagents is determined by the reaction temperature and the cooling capacity of the reactor.

After the methylolation reaction, unreacted formaldehyde remaining in the reaction mixture is usually converted to formate by heat treatment in the presence of an alkali.

After the heat treatment, the reaction mixture is then neutralized with formic acid or mineral acid, and most or all of the solvent is recovered by distillation. When the residual liquid after distilling off the solvent is maintained at a temperature of 60° C. or higher, the residual liquid is separated into an organic layer mainly consisting of trimethylolhebutane and an aqueous layer mainly consisting of formate. In this case, the holding temperature of the residual liquid is 60
If the temperature is lower than .degree. C., some crystals may precipitate, and the liquid separation properties of the organic layer may deteriorate, which is not preferable. The resulting organic layer is heat treated in the presence of an acid catalyst and water, thereby hydrolyzing various formals present in small amounts in the organic layer. This treatment can improve the yield and purity of trimethylol hebutane. Acid catalysts that can be used include mineral acids such as sulfuric acid and hydrochloric acid, formic acid, acetic acid, oxalic acid,
Benzene sulfonic acid, etc.? [Solid acids such as acid, silica-alumina, silica-magnesia, etc. can be mentioned.]

Although the heating temperature varies depending on the type, concentration, etc. of the acid catalyst, a temperature within the range of 100 to 300°C is generally selected.

The organic layer after the heat treatment is neutralized with an alkali if necessary, and then an aromatic hydrocarbon having 6 to 9 carbon atoms is added thereto to crystallize and separate trimethylolhebutane crystals. According to detailed studies by the present inventors, the solubility of trimethylolhebutane in aromatic hydrocarbons strongly depends on temperature, and is substantially insoluble below 50 ° C.
It shows great vulgarity at temperatures above 60°C. Therefore, by utilizing this principle, highly purified trimethylol to butane can be efficiently obtained. The aforementioned Acta
, Cbem, 5cand,, 16. 1062
(1962) describes the precipitation of butane as crystals from chloroform solution to trimethylol, or when using chloroform or esters, butane is precipitated from sodium trimethylol as in the case of aromatic hydrocarbons. No solubility phenomenon was observed, and the acquisition rate and purity of trimethylolhebutane were both low.
Specific examples of aromatic hydrocarbons in No. 9 include benzene, toluene, xylene, ethylbenzene, propylbenzene, and trimethylbenzene. The amount of these aromatic hydrocarbons to be used is in the range of 1 to 50, particularly preferably in the range of 5 to 20, as a weight ratio to the organic layer.

Prior to the crystallization and separation of butane from the organic layer to trimethylol, water and formate mixed in the organic layer can be removed in advance by azeotropic dehydration treatment, filtration, sedimentation, centrifugation, etc.; in this case, It is possible to obtain trimethylol to butane with higher purity. The temperature employed for the crystallization and separation of trimethylolhebutane is selected to be within the range of 20 to 50°C. The aromatic hydrocarbons after the crystallization and separation of trimethylol and butane are recycled and reused in the step of crystallizing and separating trimethylol and butane from the organic layer.

The inventive method will be specifically explained below with reference to Examples.

Example 1 12 wt, % formaldehyde water bath Kl 500 y
(2.0 mol as formaldehyde) and 500 g of tetrahydrofuran were placed in a flask with a content of 21,
While stirring while keeping the internal temperature within the range of 65 to 40°C, n-
Octylaltehyde 70.4 Q (0.55 mol) and 66 g (0.66 mol as sodium hydroxide) of a 40 wt% sodium hydroxide aqueous solution were simultaneously and continuously added over 5 hours. After the addition was complete, stirring was continued for an additional 2 hours at the same temperature. Next, 10 g of a 40 wt% aqueous sodium hydroxide solution was added, and the mixture was further stirred under reflux for 4 hours. After the reaction mixture i& was adjusted to pH 6.8 by adding formic acid, tetrahydrofuran was distilled off under normal pressure. When the residual liquid after tetrahydrofuran was distilled off was heated to 80°C, it was separated into two layers. The organic layer was taken out, and a sulfuric acid aqueous solution (pLL:
1.0) Add 100 g and stir for 8 hours.
It was kept around ℃. After neutralization with sodium hydroxide, an extraction operation was performed at 70° C. using 10,007 nl of toluene.

After water and gold salts were removed from the toluene solution by azeotropic dehydration and filtering, the furnace solution was cooled to room temperature, and white crystals were precipitated. The obtained crystals were collected and dried to obtain 84 g of trimethylolhebutane. The yield of trimethylolhebutane was 8084% based on II-octylaldehyde.

Comparative Example 1 Trimethylolhebutane was synthesized in the same manner and under the same conditions as in Example 1, except that 500 g of ethanol was used instead of 500 g of tetrahydrofuran. The yield of trimethylolhebutane was 55Q, and various ethyl ether derivatives were produced as by-products. The yield of trimethylolhebutane was 52.6% based on n-octylaldehyde.

Example 2 16% formaldehyde aqueous solution 3759 (2.0 mol as formaldehyde) and dioxa 75
00g into a flask with a content of 21 and the same temperature at 65~4
650 g of a dioxane solution containing 70.4 g (0.55 mol) of n-octyl altehyde and 40 wt 0% hydroxide were added under stirring while maintaining the temperature in the range of 0°C.
6 g (0.66 mol as sodium hydroxide) was added simultaneously and continuously over 5 hours. After the addition was complete, stirring was continued for an additional 2 hours at the same temperature. Next, 10 g of 40 wt 0% sodium hydroxide aqueous solution was added, and 40 wt.
Stir for hours. The reaction mixture was adjusted to pH 6 by adding formic acid.
8, dioxane was distilled off under normal pressure. When the residual liquid after dioxane was distilled off was kept at 80°C, it was separated into two layers. The organic layer was taken out and sulfuric acid aqueous solution (phL: 1.0
100 g was added and kept at around 100° C. for 8 hours while stirring. After neutralization with sodium hydroxide, an extraction operation was performed at 70° C. using 1000 rrLl of xylene. Water and salts were removed from the xylene bath liquid by azeotropic dehydration and filtration, and then the liquid was cooled to room temperature, and white crystals were precipitated. The obtained crystals were collected in a furnace and dried to obtain trimethylol hebutane 85Q.

Comparative Example 2 In Example 2, chloroform io was used instead of xylene.
Trimethylolhebutane was synthesized in the same manner and under the same conditions as in Example 2, except that the extraction operation was performed at 50° C. using ooml. The yield of trimethylolhebutane was 64 g. Also, instead of chloroform, vinegar #n-
When a similar reaction was carried out using butyl, the yield of trimethylolhebutane was 62 g.

Claims (2)

[Claims] (1) Synthesizing trimethylolhebutane by reacting n-octylaldehyde and formaldehyde in the presence of an alkali metal hydroxide or alkaline earth metal hydroxide in tetrahydrofuran or dioxane, (2) The reaction mixture obtained in step (1) is subjected to distillation to remove tetrahydrofuran or dioxane, and the distillation residue is then separated into an organic layer and an aqueous layer by maintaining the temperature at a temperature of 60°C or higher. (3) After heat-treating the organic layer obtained in step (2) in the presence of an acid catalyst and water, an aromatic hydrocarbon having a carbon number of 6 to 9 is added to the organic layer to form crystals of trimethylolhebutane. is crystallized and separated. A method for producing trimethylolhebutane, characterized by