JP2008037852A - METHOD FOR PRODUCING omega-BROMO LONG-CHAIN CARBOXYLIC ACID - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for readily and efficiently producing an ω-bromo long-chain carboxylic acid by using an inexpensive and easily available raw material. <P>SOLUTION: The method for producing the ω-bromo long-chain carboxylic acid represented by formula (2) (wherein, n is an integer of 12-16) involves reacting a macrocyclic ester represented by general formula (1) (wherein, n is the same as the above) with hydrogen bromide in acetic acid solvent in a closed system. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing an ω-bromo long chain carboxylic acid.

Omega-bromo long chain carboxylic acid is a useful raw material for the production of surfactants and the like in the cosmetics and cosmetics fields. Conventionally, ω-bromo long chain carboxylic acid is produced by, for example, a method of producing 15-bromopentadecanoic acid from azelaic acid by Kolbe electrolysis, half Ag chlorination and bromination (Non-patent Document 1), 15-methoxypentadecanoic acid. A method for producing 15-bromopentadecanoic acid by allowing boron tribromide to act on (Non-patent Document 2) has been reported.
However, these methods have problems such as requiring a multi-stage production, and are not easy production methods.

In recent years, a method for obtaining 15-bromopentadecanoic acid in high yield from cyclopentadecanolide (trade name Pentalide) using concentrated sulfuric acid-hydrobromic acid has been reported (Non-patent Document 3). .
However, this method has problems such as blackening of the reaction system, insoluble matter, etc., which makes it difficult to separate from the aqueous layer, and it is necessary to reflux for a long time such as 3.5 days. It was difficult.
Synthetic fragrance, Chemical Industry Daily Bull. Chem. Soc. Jap., 54 (3), 945, 1981 Aust. J. Chem. 51., 581-586,1998

  The present invention relates to providing a method for easily and efficiently obtaining a ω-bromo long-chain carboxylic acid using inexpensive and readily available raw materials.

  As a result of studying the production method of ω-bromo long chain carboxylic acid using macrocyclic esters, the present inventors have caused hydrogen bromide to act under sealing without producing a by-product, It was found that ω-halogenated long chain carboxylic acid can be obtained quantitatively.

  That is, as shown in the following reaction formula, the present invention comprises reacting a macrocyclic ester represented by formula (1) with hydrogen bromide in an acetic acid solvent in a closed system ( The present invention provides a process for producing a ω-bromo long chain carboxylic acid represented by 2).

[In formula, n shows the integer of 12-16. ]

  According to the present invention, ω-bromo long chain carboxylic acid can be quantitatively produced using macrocyclic esters that are easily available at low cost. Further, the method of the present invention can be carried out in a short time, and the post-treatment is easy without blackening the reaction system or generating insoluble matter or by-products. Therefore, it is useful as an industrial production method of ω-bromo long chain carboxylic acid which is a raw material for producing a surfactant and the like.

  In the present invention, n in the general formulas (1) and (2) represents an integer of 12 to 16, of which 15 or 16 is preferable.

The reaction of the present invention is carried out in the presence of acetic acid, and acetic acid can be used as a solvent. As disclosed in Non-Patent Document 2 described above, when a concentrated sulfuric acid-hydrobromic acid system is used and, for example, pentalide is reacted, it is difficult to separate from the target 15-bromopentadecanoic acid 15 -(15-Bromopentadecyloxy) pentadecanoic acid is by-produced and it is difficult to obtain high-purity 15-bromopentadecanoic acid.
Here, the usage-amount of acetic acid is 0.1-10 times amount with respect to macrocyclic esters, Preferably it is 1-5 times amount.
As a reaction solvent, a non-aqueous solvent such as toluene, hexane or xylene can be used together with acetic acid, but it is particularly preferable to use only acetic acid as a solvent.

  As for the usage-amount of hydrogen bromide, it is preferable to use 1-3 times mole with respect to 1 mol of macrocyclic esters, and use of 1.0-2.0 times mole is still more preferable.

The reaction of the present invention is carried out in a closed system. By conducting the reaction in a closed system, loss of hydrogen bromide can be prevented and the reaction is considered to proceed efficiently. However, in an open system, this reaction was performed using a device equipped with a cooling pipe. In this case, even if hydrogen bromide is used in excess, the yield of the target product is only about 50% (see Comparative Example).
The closed reactor used in the production method of the present invention may be a heat and pressure resistant device such as an autoclave, and preferably has a stirring device inside.

The reaction temperature is preferably 10 ° C to 150 ° C, particularly preferably in the range of 50 ° C to 130 ° C.
The reaction time is preferably 1 to 30 hours, more preferably 5 to 20 hours.

  The ω-bromo long chain carboxylic acid thus obtained is purified and isolated, if necessary, by a purification method commonly used in organic synthetic chemistry, for example, filtration, washing, drying, recrystallization, various chromatography, etc. be able to.

The details of the reaction will be described below using examples.
The product of this reaction was confirmed by comparing a separately synthesized sample with gas chromatography and ¹ H-NMR by a method known in the literature.

Example 1 Synthesis of 15-bromopentadecanoic acid (1)
14.3 g (59.5 mmol) of cyclopentadecanolide and 24.8 g (98.0 mmol, 1.6 eq) of a 32% hydrogen bromide / acetic acid solution were placed in a 100 ml autoclave protected with Teflon. After substituting with nitrogen, it was sealed, placed in an oil bath at 120 ° C., and stirred for 16 hours. A magnetic stirrer was used for stirring. After cooling, 14 ml of water was added and transferred to a separatory funnel using 200 ml of ethyl acetate. As a result of analyzing this ethyl acetate layer with capillary GC, the raw material disappeared and a peak of only the target product 15-bromopentadecanoic acid was observed. The extract was washed with saturated brine, dried over magnesium sulfate, filtered, concentrated under reduced pressure, and crystallized from a mixed solvent of ethyl acetate-n-hexane to obtain 17.1 g (yield 90%) of the desired product.

Example 2 Synthesis of 15-bromopentadecanoic acid (2)
14.3 g (59.5 mmol) of cyclopentadecanolide and 24.8 g (98.0 mmol, 1.6 eq) of a 32% hydrogen bromide / acetic acid solution were placed in a 100 ml autoclave protected with Teflon. After substituting with nitrogen, it was sealed, placed in an oil bath at 60 ° C., and stirred for 16 hours. A magnetic stirrer was used for stirring. After cooling, 14 ml of water was added and transferred to a separatory funnel using 200 ml of hot hexane. After washing with ion-exchanged water, drying with magnesium sulfate, filtration and crystallization with n-hexane gave 17.4 g (yield 91%) of the desired product.

Comparative Example 15 Synthesis of bromopentadecanoic acid (open system)
1.0 g (4.2 mmol) of cyclopentadecanolide and 3.3 g (13.1 mmol, 3.1 eq) of a 32% hydrogen bromide / acetic acid solution were placed in a 50 ml two-necked flask equipped with a reflux condenser and a magnetic stirrer. The mixture was placed in a 60 ° C. oil bath and stirred for 16 hours under a nitrogen atmosphere. As a result of sampling and GC analysis, the area percentage was 10% of the target product 15-bromopentadecanoic acid, 89% of raw material cyclopentadecanolide, and 1% of by-product 15-acetoxypentadecanoic acid. Furthermore, as a result of heating and stirring in an oil bath at 80 ° C. for 8 hours, the area percentage was 31% of the target product, 65% of the raw material, and 4% of the by-product. Furthermore, as a result of heating and stirring in an oil bath at 100 ° C. for 20 hours, the area percentage was 42% for the target product, 52% for the raw material, and 6% for the by-product. After adding 3 g (11.9 mmol, 2.8 eq) of 32% hydrogen bromide / acetic acid solution and heating and stirring in an oil bath at 100 ° C. for 2 hours, the area percentage was 47% of the target product, 47% and 6% by-product.

Claims (2)

Following formula (1)

[In formula, n shows the integer of 12-16. ]
Wherein the macrocyclic ester represented by formula (2) is reacted with hydrogen bromide in an acetic acid solvent in a closed system (2)

[Wherein n is the same as above]
The manufacturing method of the omega-bromo long-chain carboxylic acid represented by these.   The process according to claim 1, wherein the reaction is carried out at 50 to 130 ° C.