JPS63243060A - Recovery of esterified product - Google Patents

Abstract

PURPOSE:To recover an esterified product, by esterifying a straight-chain monocarboxylic acid or an alpha,omega-dicarboxylic acid with an aliphatic alcohol in the presence of a mineral acid catalyst, adding an alkali metal or alkaline earth metal hydroxide or carbonate to the product and distilling the mixture. CONSTITUTION:A 9-18C straight-chain monocarboxylic acid or an alpha,omega- dicarboxylic acid is esterified with a lower aliphatic alcohol using a mineral acid catalyst (preferably concentrated sulfuric acid). The obtained reaction product is added with hydroxide or carbonate of an alkali metal or alkaline earth metal (especially preferably sodium carbonate) to neutralize the product preferably to pH 7-8 and is distilled as it is to obtain an esterified product. The monocarboxylic acid and dicarboxylic acid are preferably those produced by fermentation process. The ester can be recovered by this process with simple recovering operation and low recovery loss at a low cost. The ester is useful as a synthetic intermediate for macrocyclic ketone, macrocyclic dioate, etc., or for technical product of musk perfumery.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method for recovering esterified products, and in particular, it relates to a method for recovering esterified products, and in particular, it relates to a method for recovering esterified products, and in particular, it relates to a method for recovering esterified products. The present invention relates to a method for recovering an esterified product from a product of an esterification reaction with a group alcohol using a mineral acid catalyst.

Incidentally, the esterified product is used as a synthetic intermediate for musk-based fragrance materials such as macrocyclic ketones and macrocyclic dioates.

[Prior Art] When an esterified product is isolated and recovered from an esterification reaction product after the completion of the esterification reaction, the mineral acid catalyst contained in the reaction product is usually neutralized with an aqueous solution containing an alkali, and the aqueous phase is After separation, the organic phase containing the esterified product is washed with water and alkali-containing water to remove neutralized salts or unreacted organic acids, and then distilled to recover the esterified product. It's faded.

[Problems to be solved by the invention] However, in the above method, (1) the operation is complicated due to the existence of a washing step, and (2) when lower aliphatic alcohol is used, unreacted alcohol is washed away. (3) In particular, in the case of esterified products using carboxylic acids obtained by fermentation, neutralization, During washing, bacterial cell-derived proteins floated on the interface between the organic phase and the aqueous phase, resulting in loss of esterified products during phase separation.

As a result of intensive studies in view of such problems, the present inventors added an alkali metal or alkaline earth metal hydroxide or a salt with a weak acid to the esterification reaction product, neutralized it, and then carried out phase separation or washing. It has been found that the esterified product can be recovered by distillation without any problems even if it is directly distilled without any problems.

The present invention has been made based on such knowledge, and an object of the present invention is to provide a method for recovering an esterified product that can be performed easily and at low manufacturing costs, and that can reduce loss.

[Means for Solving the Problems] The present invention provides an esterification reaction product of a linear monocarboxylic acid or α,ω-dicarboxylic acid having 9 to 18 carbon atoms and a lower aliphatic alcohol using a mineral acid catalyst. In the method of recovering an esterified product from the esterification reaction product, the mineral acid is neutralized by adding an alkali metal or alkaline earth metal hydroxide or a salt with carbonic acid to the esterification reaction product without phase separation. , which consists of recovering the esterified product by distillation.

The linear monocarboxylic acid or α,ω-dicarboxylic acid having 9 to 18 carbon atoms used in the present invention is obtained by fermenting n-alkanes, fatty acids, linear alcohols, etc. having the corresponding number of carbon atoms using microorganisms. It is particularly preferable to use the
(See ゜-19630 and Japanese Patent Publication No. 57-29994).

On the other hand, as lower aliphatic alcohols which are other raw materials for esterification, aliphatic alcohols having 1 to 4 carbon atoms are preferably used because of ease of separation from esterification products and ease of distillation of esterified products. There is.

The mineral acid used as the catalyst is sulfuric acid, hydrochloric acid, etc., but in the present invention, in order to minimize the amount of water distilled out during distillation, and from the viewpoint of thermal stability of the distillation residue, particularly concentrated acetic acid is used. Preferably, an acid is used.

The esterification reaction is carried out between the carboxylic acid and alcohol in the presence of the mineral acid at a temperature of room temperature to 130°C. In this case, the alcohol is used in an amount equal to or more than the reaction equivalent, 1 to 10 times the weight of the carboxylic acid, and also serves as a reaction solvent;
It is preferable to carry out the distillation under reflux of the alcohol because the subsequent distillation operation becomes simple.

The mineral acid added as a catalyst is 0.0% relative to the carboxylic acid.
The amount is preferably 0.01 to 0.1 part by weight. Although the reaction time cannot be absolutely determined depending on the types of carboxylic acid and alcohol and the reaction temperature, it is appropriately selected within the range of 1 to 24 hours.

After the esterification reaction is completed, a neutralizing agent is added to the esterified raw acid to neutralize the mineral acid added as a catalyst and the unreacted carboxylic acid. In this case, the neutralizing agent must have a thermal decomposition temperature of the salt of the neutralizing agent and the mineral acid after neutralization, which is higher than the temperature at which the esterified product is heated in the distillation operation. or alkaline earth metal hydroxides or salts with carbonates. Any one of these compounds may be used alone, but there will be no problem even if two or more are used in combination.

Examples of these compounds include compounds such as sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, sodium carbonate, sodium hydrogen carbonate, potassium carbonate, potassium hydrogen carbonate, and magnesium carbonate. Among these compounds, sodium carbonate is preferred from the viewpoints of low cost and stability. When these compounds are used as an aqueous solution, it is better to make the aqueous solution as concentrated as possible, but it is particularly preferable to neutralize it by adding it as a solid to the reaction product in order to simplify the distillation operation. .

Neutralization is preferably carried out so that the pH of the reaction product (as measured by diluting with water and measuring the aqueous phase) is 7 to 8.

This can be easily accomplished by adding the above compound in an amount equal to or less than 1.4 times the neutralization equivalent to the mineral acid and stirring.

After neutralization, it is directly distilled without any separation or washing. Distillation is first carried out under normal pressure or a low degree of reduced pressure to distill off unreacted alcohol and water produced or mixed therein, and then the degree of reduced pressure is increased to distill off the esterified product.

The degree of vacuum in the distillation of the esterified product is appropriately selected from an absolute pressure of 10''3 to 20 mm Hg depending on the type of the esterified product.

After distillation of the esterified product, salts of mineral acids and unreacted carboxylic acids remain as residues in the pot, but since these are soluble in lower alcohols or water, they can be easily removed by washing with these.

Next, Examples and Comparative Examples of the present invention will be shown to clarify the effects.

[Example 1 (Example 1) 100 g of α,ω-pentadecanedioic acid produced by fermentation method was added to I with 200 g of methanol and 1.30 g of concentrated sulfuric acid.
The mixture was charged into a Q-volume glass reactor equipped with a reflux device, and an esterification reaction was carried out by heating under reflux (reaction liquid temperature: 72° C.) for 4 hours while stirring with a magnetic stirrer. 4 of the reaction solution
After cooling to 0'C, solid sodium carbonate 1.4], g
(1 equivalent to concentrated sulfuric acid) was added and stirred for 30 minutes to neutralize the sulfuric acid. The entire amount was charged into a 500 mM distillation flask equipped with a capillary, and methanol and water were distilled off while heating.

Next, the degree of reduced pressure was increased using a vacuum pump, and the esterified product was recovered by simple distillation under a N2 stream. Table 1 shows the distillation conditions and the amount of esterified product recovered.

In addition, regarding the obtained esterified product, 5ili-co
ne S E -30 (3%) was used as filler =
7- Gas chromatography analysis was performed using a glass column, and the purity is also listed in Table 1.

(Example 2) Everything was carried out as in Example 1 except that the weight of sodium carbonate used for neutralization in Example 1 was changed to 1.69 g (1.2 equivalents relative to concentrated sulfuric acid). The conditions and results are also shown in Table 1.

(Examples 3 to 9) In Example 1, instead of α, ω-pentadecanedioic acid, a fermentation method α, ω-dicarboxylic acid having 11 to 18 carbon atoms (
The procedure of Example 1 was repeated except that Examples 3 to 9) were used. The conditions and results are shown in Table 1.

(Example 10) In Example 1, a mixture of pentadecanoic acid and α,ω-pentadecanoic acid produced by a fermentation method (weight ratio = 38:62) was used instead of α,ω-pentadecanoic acid. was carried out as in Example 1. The conditions and results are shown in Table 1.

(Example 11) The same procedure as in Example 1 was performed except that ethanol (200 g) was used instead of methanol. The conditions and results are shown in Table 1.

(Comparative example) 100 g of α,ω-pentadecanedioic acid produced by fermentation method was tested with IQ along with 200 g of methanol and 1.30 g of concentrated sulfuric acid.
Pour into a glass reactor equipped with a reflux device, stir with a magnetic stirrer, and heat to reflux for 4 hours (reaction liquid temperature: 72°C).
) to perform the esterification reaction. The reaction solution was transferred to a separatory funnel, washed with 200 mff of 3% saline, and the aqueous phase was discarded.

Next, 200 mff of a 1% aqueous sodium carbonate solution was added, the mixture was shaken, the pH was returned to 6 with acetic acid, and the aqueous phase was discarded.

Finally, it was washed with 200 mQ of water and the aqueous phase was discarded. In the three washings mentioned above, the operation was carried out at a temperature of about 60° C., and during phase separation, efforts were made to include suspended matter at the interface in the organic layer, but a portion of it was discarded along with the aqueous phase by incorporating the ester.

Next, the entire amount of the organic phase was charged into a distillation flask equipped with a capillary, and water was distilled off while heating. Subsequently, the degree of vacuum was increased, and the ester was subjected to simple distillation under a N2 stream, and the esterified product was collected and analyzed in the same manner as in Example 1. The conditions and results are shown in Table 1. (Left below) [Effects of the Invention] The present invention as described above neutralizes the mineral acid added as a catalyst by adding an alkali metal or alkaline earth metal compound to the esterification product, without causing phase separation. Since the esterified product is recovered by distillation, the esterification recovery operation is simple, the manufacturing cost can be reduced, and the recovery loss of the esterified product can be greatly reduced. It is something to play.

Claims (2)

[Claims] (1) Straight chain monocarboxylic acid or α having 9 to 18 carbon atoms
, a method for recovering an esterified product from an esterification reaction product of an ω-dicarboxylic acid and a lower aliphatic alcohol using a mineral acid catalyst, wherein an alkali metal or alkaline earth metal hydroxide is added to the esterification reaction product. Alternatively, a method for recovering an esterified product, which comprises neutralizing the mineral acid by adding a salt with carbonic acid, and recovering the esterified product by distillation without phase separation. (2) Straight chain monocarboxylic acid or α having 9 to 18 carbon atoms
, ω-dicarboxylic acid is obtained by a fermentation method, the method for recovering an esterified product according to claim 1.