JP2792883B2 - Purification method of trimethylol compound - Google Patents

Description

The present invention relates to a method for purifying a trimethylol compound.

<Conventional technology and problems to be solved> Trimethylol compounds are used as cosmetic raw materials and surfactants,
It is also important as a raw material for producing alkyd resins, polyurethanes, polyesters and the like and a raw material for various esters and the like.

For the synthesis of this trimethylol compound, the general formula RCH ₂
An aliphatic aldehyde represented by CHO (where R is an alkyl group or an alkenyl group) is converted into a formaldehyde source such as formalin or paraformaldehyde and a base such as an alkali metal hydroxide or an alkaline earth metal oxide. , it is known to produce a trimethylol compound represented by R'C (CH ₂ OH) ₃ by aldol reaction and Cannizzaro reaction (so-called Torrence condensation). In the industrial refining method, a trimethylol compound having a relatively low molecular weight such as trimethylolpropane obtained from a lower aldehyde such as n-butyraldehyde is produced on an industrial scale, and is industrially purified by a distillation method. ing. On the other hand, a trimethylol compound obtained from an aliphatic aldehyde having a relatively high molecular weight of 7 or more carbon atoms such as enanthol has a high boiling point and is difficult to distill. Since it is generally a solid, it is purified by a crystallization method. For example, actor. Chem, Scand, (Acta.Chem.Scan
d.), 16, 1069 (1962), describes that a trimethylol compound such as trimethylol heptane or trimethylol octane is crystallized and separated in chloroform.

The present inventors have obtained a trimethylol compound having very interesting properties by Torens condensation of isostearyl aldehyde obtained by reducing isostearic acid (JP-A-63-113312). Methylol compounds are very excellent as raw materials for cosmetics and as bases for champourin, but they need to be purified to high purity in order to sufficiently bring out their performance. However, this trimethylol compound has a high molecular weight and a very high boiling point, so it is difficult to purify it by distillation.Since it does not crystallize even at a low temperature, it cannot be purified by a crystallization method. There was only a column chromatograph which was hardly advantageous.

On the other hand, a method for purifying a trimethylol-boric acid adduct obtained by a reaction between a trimethylol compound and boric acid includes, for example,
J. Am. Chem. Soc. (HC Brown), Vol. 73,
It is already known on page 2808 (1951) and by JP-B-53-6155. However, there is no description about a method for purifying a trimethylol compound by applying this method.

<Means for Solving the Problems> The inventors of the present invention aimed to find a purification method which can be advantageously carried out on an industrial scale for a trimethylol compound which has a high boiling point and is difficult to carry out a distillation and a crystallization method cannot be carried out. As a result of intensive studies, they have found that a complex of a trimethylol compound and boric acid can be purified as a solvent-insoluble precipitate under basic conditions. Furthermore, they have found that the present invention can be applied to a conventionally known trimethylol compound, and have completed the present invention.

That is, the present invention uses the formula (Wherein R represents a linear or branched alkyl or alkenyl group having 5 to 28 carbon atoms), a method for purifying a trimethylol compound represented by the formula:
The reaction is carried out by adding boric acid to the trimethylol compound containing impurities, dissolving the reaction product in an organic solvent, and then adding an alkali metal or alkaline earth metal hydroxide to isolate an insoluble salt, followed by hydrolysis. A method for purifying trimethylol is provided.

According to the present invention, a trimethylol compound containing impurities is formed into a complex of the trimethylol compound with boric acid, and if necessary, the complex is once isolated by a suitable known crystallization method, and then the complex is separated into an appropriate one. Dissolve in a solvent, add a base to this, filter off as an organic solvent-insoluble salt, remove impurities, and hydrolyze the obtained pure trimethylol compound borate complex salt to regenerate high-purity trimethylol compound. Can be.

The trimethylol compound containing the impurity to be purified may be a refined product of the trimethylolation reaction or may be a product partially purified by an appropriate known method. A high-purity trimethylol compound can be obtained from a low-purity trimethylol compound containing a large amount of impurities.

As the boric acid to be used, any of ordinary boric acid (H ₃ BO ₃ ) or boric anhydride (B ₂ O ₃ ) may be used, and it may be selected from availability, economy and the like.

The formation of the complex between the trimethylol compound and boric acid can be easily achieved only by mixing the trimethylol compound with boric acid. In this case, a solvent may or may not be used. The solvent used is not particularly limited, but dissolves the trimethylol compound and its impurities well,
Boric acid also dissolves relatively well, and the following lower alcohols which can be used as they are in the next step are advantageous. The amount of the solvent to be used is suitably 100 times or less, particularly about 10 times or less by weight with respect to the trimethylol compound. If it is more than 100 times, the recovery of the trimethylol compound will be low, and it will be difficult to economically recover the used solvent, which is not preferable.

If the amount of boric acid used relative to the trimethylol compound is too small, the recovery of the trimethylol compound will be low, and if it is too large, the amount of impurities in the precipitate will increase and this may cause a decrease in the purity of the purified trimethylol. Generally, about 0.2 to 3 times the molar amount of the trimethylol compound is appropriate.

The reaction may be carried out at a temperature from room temperature to the reflux temperature of the solvent when the solvent is used, but the reaction can be carried out at room temperature without any particular heating. The reaction time at this time is one to several hours. Even when a solvent is not used, the reaction temperature may be about room temperature to about 100 ° C, but in the case of a solid trimethylol compound, the reaction time is shortened.
The reaction can be carried out at a temperature equal to or higher than the melting point for one to several hours.

After completion of the complex formation between the trimethylol compound and boric acid, if there is any excess boric acid or impurities of the trimethylol compound which do not dissolve as a solid, they may be removed by a known suitable method, for example, filtration or a gradient method.

The water generated by the reaction may be removed by distilling off under reduced pressure if the presence of the water adversely affects the solubility of the medium in the next step, but is particularly excluded if there is no effect No need. Also, when a solvent other than a lower alcohol is used at the time of complex formation, there is no need to distill off if there is no problem in the solubility in the next step. If there is a problem, it may be removed by means such as distillation. When a lower alcohol is used as a solvent at the time of complex formation, the process may proceed to the next step as long as it is not necessary to remove water generated by the reaction.

The obtained trimethylol compound boric acid complex can be used as it is in the next step when a lower alcohol is used as a solvent at the time of complex formation, otherwise, after the above operation, an organic solvent, particularly a lower solvent Once dissolved in alcohol. At this time, if impurities are present as insolubles, they may be removed by an appropriate known method. The lower alcohol used at this time includes methanol, ethanol, 1-propanol and 2-propanol. The amount of the solvent to be used is preferably about 0.3 to 100 times, particularly about 0.8 to 20 times by weight the trimethylol compound boric acid complex. If it is less than 0.3 times, the amount of impurities contaminating the trimethylol borate complex will increase, and the purity of the obtained trimethylol compound will decrease.If it is more than 100 times, the recovery of the trimethylol compound will decrease, In addition, it is difficult to economically recover the used solvent, which is not preferable.

Next, after dissolving the trimethylol borate complex in an organic solvent, a base is added to form a salt with the trimethylol borate complex to form a solvent-insoluble precipitate. Examples of the base used at this time include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alkaline earth metal hydroxides such as barium hydroxide and calcium hydroxide, and barium oxide and calcium oxide. And sodium hydroxide and potassium hydroxide are particularly preferred. These bases may be added as they are, or when dissolved, may be added in the form of an aqueous solution or an alcohol solution. When added as a solution, the concentration of the solution is usually 5 to 70
%, Preferably 10 to 50%. The amount of base used is
The molar amount is preferably 0.1 to 10 times, more preferably 0.5 to 2 times, the mol of boric acid used. 0.1
If the molar ratio is less than 2 times, the recovery of the trimethylol compound will be low, and if the molar ratio is more than 10 times, the recovery, purity and the like will not be improved.

When a base is added to an alcohol solution of the trimethylol compound boric acid complex, a white precipitate is obtained, and the precipitate is separated from the mother liquor by a known suitable method, for example, filtration or decantation. The purity of the purified trimethylol compound can be further increased by washing the separated precipitate with an appropriate solvent. The washing solvent used at this time is not particularly limited, but it is advantageous to select the same solvent as the previously used organic solvent in consideration of recovery and the like.

The separated precipitate can be hydrolyzed with an aqueous solution of mineral acid or hot water to regenerate the trimethylol compound. The mineral acid to be used can be selected from hydrochloric acid, sulfuric acid, phosphoric acid and the like, and may be selected according to availability, economy, equipment, and the like. The concentration of the aqueous acid solution used is 0.
It is preferably from 1 to 12 and especially from 1 to 6. The amount of the acid used is not particularly limited, but is suitably about 0.5 equivalent to 10 equivalents to the base used. The trimethylol compound regenerated from the complex may be recovered from the aqueous phase by a known appropriate method. For example, extraction may be performed using an aromatic hydrocarbon such as benzene or toluene, a halogenated organic solvent such as chloroform or dichloroethane, or an appropriate organic solvent such as ether or ethyl acetate.

The trimethylol compound purified as described above has sufficient purity as a raw material for cosmetics and the like.

<Effect of the Invention> The method for purifying a trimethylol compound of the present invention is advantageous on an industrial scale, even for a trimethylol compound, particularly for a trimethylol compound whose distillation is difficult at a high boiling point and crystallization cannot be carried out. Can be purified.

Hereinafter, the present invention will be described with reference to typical examples, but these examples are for the purpose of explanation only and do not limit the present invention in any way.

(Example) (Reference Example 1) Synthesis of trimethylolnonane In a 55-necked flask equipped with a mechanical stirrer, a cooling tube, a dropping funnel, and an internal thermometer, 900 g (6 mol) of 20% formalin and 1200 g of 2-propanol were added. Was charged. Internal temperature 40 ℃
While stirring vigorously, 160 g (1 mol) of decanal dissolved in 300 g of 2-propanol and 700 g (3.5 mol) of a 20% aqueous sodium hydroxide solution were simultaneously added dropwise over 4 hours. After completion of the dropwise addition, stirring was further continued at 40 ° C. for 2 hours. As confirmed by a thin layer chromatogram, the raw material decanal had completely disappeared. After completion of the reaction, most of the 2-propanol was distilled off under reduced pressure, 300 g of water and 300 g of ethyl acetate were added to the viscous reaction product obtained, and the mixture was shaken sufficiently to remove water-soluble components into the aqueous layer, and then the oil layer was removed. Was separated. The obtained oil layer was washed with saturated brine and dried over anhydrous magnesium sulfate. After removing the drying agent by filtration, the solvent was distilled off under reduced pressure to obtain 262 g of a waxy crude product. Yield 72%.

(Example 1) Purification of trimethylol nonane 100 g of crude trimethylol nonane obtained in Reference Example 1 and boric acid
19 g (0.31 mol) in a single beaker and 200 g of ethanol
Was added and stirred at room temperature. After stirring was continued for 30 minutes, insolubles were removed by filtration. 12 g (0.26 mol) of sodium hydroxide dissolved in 80 g of ethanol while stirring this homogeneous solution
Was slowly added to form a white precipitate. The white precipitate was separated from the mother liquor by suction filtration, and the filtered white precipitate was dispersed again in 100 g of ethanol, and the precipitate was washed and filtered again. The resulting white precipitate was dispersed in 3N hydrochloric acid (100 ml), ethyl acetate (100 ml) was added, and the mixture was stirred at room temperature until no insolubles were found. The oil layer and the aqueous layer were separated, and the oil layer was washed with 100 ml of water, dried over anhydrous magnesium sulfate, and the solvent was distilled off. As a result, 56 g of pure trimethylolnonane was obtained as a white solid. The melting point of this solid was 74-75 ° C. The purity determined by high performance liquid chromatography was 99%.

(Reference Example 2) Synthesis of trimethylol tridecane Except that the raw material aldehyde was changed from decanal to 212 g of tetradecanal, trimethylol tridecane was synthesized according to the method of Reference Example 1 to obtain 303 g of a waxy crude product. Was. Yield 31%.

(Example 2) Purification of trimethylol tridecane 100 g of the crude trimethylol tridecane obtained in Reference Example 2 and 7 g (0.11 mol) of boric acid were placed in a beaker, and ethanol 20 was added.
0 g was added and the mixture was stirred at room temperature. After stirring was continued for 30 minutes, insolubles were removed by filtration. 5 g (0.1 mol) of sodium hydroxide dissolved in 50 g of ethanol while stirring this homogeneous solution
Was slowly added to form a white precipitate. This white precipitate was separated by suction filtration, and the filtered white precipitate was dispersed again in 100 g of ethanol, and the precipitate was washed and filtered again. The obtained white precipitate was dispersed in 130 ml of 1N sulfuric acid, 100 ml of ethyl acetate was added, and stirring was continued at room temperature until no insoluble matter was found. Separate the oil layer and the aqueous layer, and add 100 ml of the oil layer.
After washing with water and drying over anhydrous magnesium sulfate and evaporating the solvent, 26 g of pure trimethylol tridecane was obtained as a white solid. The melting point of this solid was 86-87 ° C. The purity determined by high performance liquid chromatography was 97%.

Reference Example 3 Synthesis of Trimethylol Isoheptadecane Trimethylol isoheptadecane was prepared according to the method of Reference Example 1 except that the raw material aldehyde was changed from decanal to 268 g of isostearyl aldehyde obtained by Rosenmund reduction of isostearic acid. The synthesis yielded 416 g of a very viscous liquid crude product. 68% yield.

(Example 3) Purification of trimethylol isoheptadecane Crude trimethylol isoheptadecane 10 obtained in Reference Example 3
0 g and 11 g (0.18 mol) of boric acid were placed in a beaker, 200 g of ethanol was added, and the mixture was stirred at room temperature. After stirring was continued for 30 minutes, insolubles were removed by filtration. 7 g (0.17 mol) of sodium hydroxide dissolved in 33 g of water while stirring this homogeneous solution
Was slowly added to form a white precipitate. This white precipitate was separated by suction filtration, and the filtered white precipitate was dispersed again in 100 g of ethanol, and the precipitate was washed and filtered again. The obtained white precipitate was dispersed in 2N hydrochloric acid (100 ml), ethyl acetate (100 ml) was added, and the mixture was stirred at room temperature until insolubles disappeared. Separate the oil layer and the aqueous layer, and add 100 ml of the oil layer.
After washing with water and drying over anhydrous magnesium sulfate and distilling off the solvent, 55 g of pure trimethylol isoheptadecane was obtained as a colorless viscous liquid. The purity determined by high performance liquid chromatography was 98%.

(Example 4) Purification of trimethylol isoheptadecane Crude trimethylol isoheptadecane 10 obtained in Reference Example 3
0 g and boric acid 20 g (0.33 mol) were placed in a single beaker, mixed well, and allowed to stand at room temperature for 24 hours. 200 g of 2-propanol was added, and the mixture was stirred well to remove insolubles by filtration. 13 g (0.31 mol) of sodium hydroxide dissolved in 50 g of water was gradually added to this homogeneous solution with stirring, and a white precipitate was formed. This white precipitate was separated by suction filtration, and the filtered white precipitate was dispersed again in 100 g of 2-propanol, and the precipitate was washed and filtered again. The obtained white precipitate was dispersed in 110 ml of 3N hydrochloric acid, and ethyl acetate 1 was added.
00 ml was added and stirring was continued at room temperature until no insoluble material was found. The oil layer and the aqueous layer were separated, and the oil layer was washed with 100 ml of water, dried over anhydrous magnesium sulfate and the solvent was distilled off. As a result, 54 g of pure trimethylol isoheptadecane was obtained as a colorless viscous liquid. The purity determined by high performance liquid chromatography was 98%.

Claims (1)

(57) [Claims] (1) Expression Wherein R represents a linear or branched alkyl or alkenyl group having 5 to 28 carbon atoms, wherein boric acid is added to the trimethylol compound containing impurities. A method for purifying a trimethylol compound, comprising: dissolving a reaction product in an organic solvent; and adding an alkali metal or alkaline earth metal hydroxide to isolate an insoluble salt, followed by hydrolysis. .