JP5018067B2 - Method for producing fluorine-containing alkane esters - Google Patents

Description

  The present invention relates to a method for producing fluorine-containing alkane esters useful as monomers corresponding to functional polymers such as medical lenses or photoresists.

  A fluorine-containing alkane ester obtained by using a fluorine-containing alcohol compound and a carboxylic acid having a polymerization site is useful as a monomer corresponding to a functional polymer such as a medical lens or a photoresist. For example, a polymer containing 1,1,1,3,3,3-hexafluoro-2-methacrylate, which is a fluorine-containing alkane ester, is a compound that is transparent and has a low refractive index. Widely used in the field, it is used as an important functional material.

  As a method for producing this compound, for example, in Patent Document 1, 1,1,1,3,3,3-hexafluoro-2-propanol and methacrylic acid chloride are reacted in the presence of pyridine to produce the compound. An example is disclosed.

On the other hand, Patent Document 2 discloses an example of producing a fluorinated alcohol methacrylate in phosphoric anhydride using methacrylic acid.
U.S. Pat. No. 3,177,185 JP-A-2-295948

  As described above, the generally known methods have some difficulties in industrial production. That is, in the method of Patent Document 1, when 1,1,1,3,3,3-hexafluoro-2-methacrylate is produced, the yield is extremely low at about 20%. Furthermore, since the method of the document produces a salt that is hardly soluble in both water and an organic solvent as a by-product as the reaction proceeds, it can be said that a step of filtering the salt is essential after the reaction is completed. A load is applied.

  On the other hand, the method of Patent Document 2 is a useful method because the target product can be produced in a high yield. However, because the reaction is performed using methacrylic acid in an equivalent amount or more with respect to the raw material fluorinated alcohol. In addition, a process for separating unreacted fluorine-containing alcohol and methacrylic acid which is not involved in the reaction is necessary, and wastes and the like are increased, which causes some problems in productivity and efficiency.

  Therefore, the present inventors strongly demanded a method for producing fluorine-containing methacrylate having a high yield and high purity under conditions that do not cause environmental burden.

  As a result of intensive studies to solve such problems, the present inventors have found that the fluorinated alcohol represented by the formula [1]

（式中、ｎは１〜１０の整数を表し、ａは０又は正の整数、ｂは正の整数であり、かつａ＋ｂ＝２ｎ＋１である。）
と、式［２］で表される酸無水物

(In the formula, n represents an integer of 1 to 10, a is 0 or a positive integer, b is a positive integer, and a + b = 2n + 1.)
And an acid anhydride represented by the formula [2]

（式中、Ｒ₁、Ｒ₂はそれぞれ炭素数１〜６の直鎖、分岐鎖のアルキル基又はアルケニル基を表す。また、Ｒ₁、Ｒ₂はそれぞれ同じか、もしくは別々であっても良い）
を塩基の存在下反応させる際、水を溶媒として共存させることにより、高選択率かつ高収率で当該目的物である、式［３］で表される含フッ素アルカンエステル

(In the formula, R ₁ and R ₂ each represent a linear or branched alkyl group or alkenyl group having 1 to 6 carbon atoms. Also, R ₁ and R ₂ may be the same or different. )
In the presence of a base, by coexisting water as a solvent, the fluorine-containing alkane ester represented by the formula [3], which is the target product with high selectivity and high yield

（式中、ｎ、ａ、ｂは前記と同じであり、Ｒ₃は炭素数１〜６の直鎖、分岐鎖のアルキル基又はアルケニル基である）
を製造する方法を見出した。

(Wherein n, a and b are the same as above, and R ₃ is a linear or branched alkyl group or alkenyl group having 1 to 6 carbon atoms)
The method of manufacturing was found.

  In general, acid anhydrides such as methacrylic anhydride used in the present invention or acid chlorides used in Patent Document 1 readily undergo hydrolysis when reacted with water, and the corresponding acid (carboxylic acid) Etc.) (see, for example, “Chemical Dictionary” (Kyoritsu Shuppan Co., Ltd.), Vol. 3, page 997). For this reason, when carboxylic anhydride is used as a reactant, the reaction is usually carried out under anhydrous conditions.

  When reacting the fluorine-containing alcohol represented by the formula [1] and the acid anhydride represented by the formula [2] as raw materials, the present inventors use the formula [2] It was predicted that the acid anhydride represented would react preferentially with water, not with the fluorinated alcohol, causing hydrolysis.

  However, the present inventors have obtained a surprising finding that hydrolysis does not actually occur and the acid anhydride reacts preferentially with the fluorinated alcohol and the target product is obtained satisfactorily.

  Moreover, although details will be described later, by dissolving the by-product generated with the progress of the reaction to the aqueous layer side, the separation of the target product and the by-product is facilitated. The knowledge which remarkably reduces the purification load after completion | finish of reaction was also acquired.

  Furthermore, since water is allowed to coexist in the system, as a result, a two-layer system (heterogeneous system) is obtained, so that the reaction proceeds in a high yield even when an inorganic base is used as the base.

  The present invention has also been found to show a specific reaction.

  Until now, there has been no known technique for producing a corresponding alkane ester by reacting an acid anhydride with a saturated alkyl alcohol having a linear, branched or cyclic alkyl group having no fluorine atom. . For example, even when methacrylic anhydride is reacted with isopropyl alcohol using water as a solvent, the corresponding isopropyl-2-methacrylate is hardly obtained (see Reference Example 1 described later).

  Furthermore, the fluorinated alcohol represented by the formula [1] has a fluorine atom. Due to the strong electron withdrawing property of the fluorine atom, the reactivity of alcohol was greatly different, and it was expected that it would be difficult to induce the side reaction and obtain the target product with high selectivity.

  However, the present inventors select a fluorine-containing alcohol as a substrate and further allow the above-described water to coexist in the system, whereby the reaction proceeds efficiently without decomposition of the acid anhydride, and is highly selective and The target product was obtained in a high yield.

  In addition, although the details will be described later, the present inventors have also found that when water is used as a solvent, the reaction proceeds sufficiently even when only an organic solvent coexists, that is, only water coexists.

  As described above, the present invention can produce the target compound in a yield higher than that of the prior art under easy reaction conditions that can be carried out industrially, and the reaction proceeds well even under conditions in which no organic solvent coexists. For this reason, the target fluorine-containing alkane ester can be produced with high productivity and no environmental load.

That is, this invention provides the manufacturing method of fluorine-containing alkane ester as described in the following [invention 1]-[invention 11].
[Invention 1]
In the formula [3], when the fluorine-containing alcohol represented by the formula [1] and the acid anhydride represented by the formula [2] are reacted in the presence of a base, water is allowed to coexist as a solvent. The manufacturing method of the fluorine-containing alkane ester represented.
[Invention 2]
The method according to invention 1, wherein the fluorinated alcohol is 1,1,1,3,3,3-hexafluoro-2-propanol.
[Invention 3]
The method according to invention 1, wherein the acid anhydride is methacrylic anhydride or acetic anhydride.
[Invention 4]
4. The method according to any one of Inventions 1 to 3, wherein the reaction is carried out under conditions in which an organic solvent does not coexist in the system.
[Invention 5]
When 1,1,1,3,3,3-hexafluoro-2-propanol and methacrylic anhydride are reacted in the presence of a base, water is used as a solvent, and the reaction is performed under conditions where an organic solvent is not used. A method for producing 1,1,1,3,3,3-hexafluoro-2-methacrylate.
[Invention 6]
Any of the inventions 1 to 5 characterized in that an inorganic base or an organic base is allowed to coexist when the fluorine-containing alcohol represented by the formula [1] is reacted with the acid anhydride represented by the formula [2]. The method of crab.
[Invention 7]
The inorganic base is at least one selected from the group consisting of sodium hydroxide, sodium hydroxide, sodium carbonate, sodium hydrogen carbonate, potassium hydroxide, potassium carbonate, potassium hydrogen carbonate, calcium hydroxide, lithium hydroxide. The method according to claim 6, characterized in.
[Invention 8]
The organic base is at least one selected from the group consisting of methylamine, dimethylamine, trimethylamine, diethylamine, triethylamine, tributylamine, pyridine, piperidine, methylpyridine, dimethylpyridine, and aniline. the method of.
[Invention 9]
The method according to any one of Inventions 1 to 8, wherein the amount of water is 0.2 g to 20 g per 1 g of the fluorinated alcohol.
[Invention 10]
10. The method according to any one of inventions 1 to 9, wherein the temperature during the reaction is -10 ° C to 50 ° C.
[Invention 11]
When 1,1,1,3,3,3-hexafluoro-2-propanol and methacrylic anhydride are reacted, per 1 g of 1,1,1,3,3,3-hexafluoro-2-propanol, 1,1,1,3, characterized in that 0.2 g to 20 g of water coexist as a solvent, no organic solvent coexists, sodium hydroxide is used, and the reaction is performed at −10 ° C. to 50 ° C. A method for producing 3,3-hexafluoro-2-methacrylate.

  In addition, according to the method of the present invention, the purification load after the reaction can be greatly reduced by simplifying the step of removing the by-product because of the reaction of the two-layer system (heterogeneous system) in the presence of water. In addition, since it is not necessary to use an organic solvent, it is useful for producing a target compound on a large scale because of its high productivity.

  Hereinafter, the present invention will be described in more detail. The fluorine-containing alcohol represented by the formula [1], which is a starting material of the present invention, has an alkyl group having 1 to 10 carbon atoms, is a linear, branched or cyclic alkyl group, and at least one is a hydrogen atom. Is a compound substituted with a fluorine atom. Specific examples of the fluorine-containing alcohol represented by the formula [1] include 2,2,2-trifluoroethanol, 3,3,3-trifluoropropanol, 1,1,1,3,3,3. -Hexafluoro-2-propanol, 1,1,1-trifluoro-2-propanol, 2,2,3,3-tetrafluoropropanol, perfluoro-t-butanol, 2,2,3,4,4- Hexafluorobutanol, 1,1,1,3,3,3-hexafluoro-2-methylisopropanol, 2,2,3,3,4,4,5,5-octafluoropentanol, 2,2,3 , 3,4,4,5,5,5-nonafluoropentanol, 3-fluorocyclohexanol, 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoro Heptanol, 1H, 1H 2H, 2H-perfluoro-octanol, IH, IH, 2H, 2H-but perfluoro octadecanol, and the like, without limitation.

  Among these fluorine-containing alcohols, compounds having an alkyl group having 1 to 5 carbon atoms are preferably used because the usefulness of the product and the effect of coexisting water are particularly remarkable. Specific examples include 3,3,3-trifluoropropanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,4,4,5,5-octafluoro Pentanol is preferred, and 3,3,3-trifluoropropanol and 1,1,1,3,3,3-hexafluoro-2-propanol are particularly preferred.

  The acid anhydride represented by the formula [2], which is a starting material of the present invention, is a carboxylic acid anhydride having a linear or branched alkyl group or alkenyl group having 1 to 6 carbon atoms. Specific examples of the acid anhydride represented by the formula [2] include acetic anhydride, propionic anhydride, acrylic anhydride, methacrylic anhydride, butanoic anhydride, isobutyric anhydride, pivalic anhydride. Products, valeric acid anhydride, hexanoic acid anhydride, and the like, but are not limited thereto.

  Of these, acetic anhydride, acrylic anhydride, and methacrylic anhydride are preferred because of the economic viewpoint, the usefulness of the product, and the effect of improving productivity by coexisting water. Acetic anhydride and methacrylic anhydride are particularly preferred.

  There is no particular limitation on the mixing ratio of the fluorinated alcohol represented by the formula [1] and the acid anhydride represented by the formula [2], but the reaction is performed at a molar ratio of 1: 1. It is preferable to mix around a molar ratio (1: 1). However, if one is significantly more expensive than the other, an inexpensive compound may be used in an excessive amount in order to completely consume the expensive reagent, which may be preferable economically. Specifically, the acid anhydride is usually 0.5 to 5 mol, preferably 0.9 to 2 mol, and particularly preferably 1 to 1.2 mol with respect to 1 mol of the fluorinated alcohol compound.

  The reaction temperature (temperature of the internal liquid) can be in the range of −20 ° C. to 90 ° C., but −10 ° C. to 50 ° C. is preferable because it does not take a cooling load and is easy to control the temperature. Among these, it is a particularly preferable embodiment of the present invention to perform the reaction in the range of −5 ° C. to 30 ° C. If it is less than −20 ° C., when a large amount of water is added to the reaction system, the reaction system may solidify and it is difficult to take advantage of the present invention that harsh cooling conditions are not required. On the other hand, when the temperature exceeds 90 ° C., the reaction mixture tends to be colored and the product may be decomposed, which is not preferable.

  In the reaction of the present invention, in order to achieve the promotion of the reactivity, by allowing water to coexist in the reaction system, the by-product carboxylate is dissolved in the aqueous layer as the reaction proceeds, so that it is hardly soluble. Salt precipitation can be avoided and the operability is remarkably improved.

  The amount of water to be present is usually in the range of 0.1 g to 100 g with respect to 1 g of the fluorine-containing alcohol compound. However, in the case of 0 ° C. or lower (particularly lower than −10 ° C.), if a large amount of water is used, water solidification may occur, and productivity is reduced, so usually 0.2 g to 20 g. A range of 1 to 5 g is particularly preferable.

  From the above, the present invention is particularly effective when 0.2 g to 20 g of water is added to 1 g of the fluorinated alcohol represented by the formula [1] at a temperature of −10 ° C. to 50 ° C. It is mentioned as a preferred embodiment.

  Moreover, although this invention uses water as a solvent, it is mentioned as one of the preferable aspects that it reacts on the conditions which an organic solvent does not coexist. Here, the organic solvent means an inert organic compound that does not directly participate in the reaction of the present invention. Specifically, benzene, toluene, xylene, pentane, hexane, heptane, acetonitrile, carbon tetrachloride, chloroform, methylene chloride, 1,2-dichloroethane, ethylbenzene, mesitylene, dioxane, dimethyl ether, diethyl ether, dibutyl ether, tetrahydrofuran, etc. It can be obtained as an organic solvent. In the present specification, “does not coexist with an organic solvent” means that these organic solvents are not substantially present in the system, and specifically, 5% by weight with respect to the fluorinated alcohol compound. Hereinafter, the amount is preferably 1% by weight or less, more preferably 0.1% by weight or less. As long as the reaction is carried out without positively adding these substances into the system, it is easy to achieve the condition that no organic solvent coexists.

  For example, when an organic solvent coexists without using water, the reaction proceeds, but separation and purification of the target 1,1,1,3,3,3-hexafluoro-2-methacrylate and the reaction solvent Is difficult, and the yield is reduced during purification (see Comparative Example 1 described later).

  When considering the industrial production method of the present invention, since the reaction proceeds sufficiently even in the above-described method using water as a solvent, it is easier not to coexist with an organic solvent, because the purification operation is not burdened and the operability is improved. This is one of the preferred embodiments because it is remarkably improved and the target product can be obtained economically with high yield and high selectivity (see Examples below).

As the base used for the reaction, a base having a strength that gives a pH of 8 or more when dissolved in water at a concentration of 1 mol · dm ⁻³ is preferable. Bases include ammonia, sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium carbonate, potassium bicarbonate, potassium hydroxide, inorganic bases such as calcium hydroxide, lithium hydroxide, trimethylamine, triethylamine, tripropylamine, tributylamine Tertiary amines such as dimethylamine, diethylamine, dipropylamine, etc., primary amines such as methylamine, propylamine, butylamine, pyridine, piperidine, methylpyridine, dimethylpyridine, aniline, etc. And organic bases.

  As the base, either an inorganic base or an organic base can be used. When an organic base is used as a base, among the above-mentioned organic bases, tertiary amines such as trimethylamine, triethylamine, tripropylamine, and tributylamine are reacted. Is preferably used also because it proceeds smoothly.

  When an inorganic base is used as the base, sodium hydroxide or potassium hydroxide is preferably used from the above-mentioned inorganic bases because the reaction proceeds smoothly.

  Since one of the characteristics of the present invention is that the burden on the environment is small, it is preferable to use an inorganic base rather than an organic base from the viewpoint of waste.

  Moreover, there is no special restriction | limiting in the quantity of the base used for reaction, It is 0.9-10 mol normally with respect to 1 mol of fluorine-containing alcohol compounds, It is preferable that it is 1-5 mol, 1-2 mol More preferably it is. The fact that the base is less than 0.9 mol does not have a great influence on the selectivity in this reaction, but the conversion rate is low, leading to a decrease in yield, and conversely if the base is more than 10 mol, it is economically disadvantageous. Therefore, neither is preferable.

  The production method of the present invention is simple and advantageous to carry out by a batch reactor. In addition, when either one of acid anhydride or water is sequentially added or continuously added to the reaction system, contact between the acid anhydride and water can be suppressed as much as possible, and acid anhydride, which is an unnecessary side reaction, is performed. Since hydrolysis from a product to a carboxylic acid can be suppressed, it is preferable. As described above, in the reaction system of the present invention, esterification of the fluorinated alcohol compound proceeds preferentially over hydrolysis from an acid anhydride to a carboxylic acid. It is possible to obtain the object without using the method. However, it is more preferable to adopt the sequential or continuous addition method because the reaction can be easily controlled.

  There is no special limitation on the reaction time, and the optimum reaction time varies depending on the conditions. Therefore, the reaction is carried out while measuring the composition of the reaction mixture by a method such as thin layer chromatography or gas chromatography, and the raw fluorinated alcohol is sufficient. It is desirable to complete the reaction after confirming that the amount has decreased. The reaction pressure is not particularly limited, and the reaction can be performed from normal pressure to increased pressure.

  This reaction can be carried out in air or in an inert gas such as nitrogen, helium or argon. Since there is almost no difference in behavior such as reactivity and coloration due to the coexistence of these gases, the reaction may usually be carried out in air.

  When the target fluorine-containing alkane ester is solid, the target compound is precipitated in an aqueous solvent as the reaction proceeds. In the case of a liquid, after completion of the reaction, the target compound layer and the aqueous solvent layer are separated into two layers. Therefore, when the target compound is a solid, it can be easily recovered by filtration, and when it is a liquid, it can be easily recovered by a liquid separation operation.

  The fluorine-containing alkane ester recovered in this manner can usually be used as it is, but can be highly purified by performing purification operations such as flash distillation and recrystallization as necessary.

  The present invention will be described below with reference to examples, but the present invention is not limited to these examples. Here, “%” of the composition analysis value represents “area%” of the composition obtained by directly measuring the reaction mixture by gas chromatography (GC, unless otherwise specified, the detector is FID).

Production of 1,1,1,3,3,3-hexafluoroisopropyl-2-methacrylate 1,1,1,3,3 in a glass 2 L 4-neck flask equipped with a stirring blade, a dropping funnel and a thermometer , 3-hexafluoroisopropyl alcohol 400 g (2.38 mol), sodium hydroxide 105 g (2.62 mol), and water 1000 g (55.6 mol) were charged, and the mixture was cooled to an internal temperature of 0 ° C. with stirring. After cooling, 385 g (2.45 mol) of methacrylic anhydride was added dropwise thereto at an internal temperature of 0-3 ° C. over 1 hour while paying attention to heat generation. After completion of the dropwise addition, the 2 L, 4-necked flask was naturally heated to room temperature over 1 hour, and then the reaction solution was transferred to a separatory funnel and subjected to two-layer separation to obtain crude 1,1,1,3,3. 556 g of 3-hexafluoroisopropyl-2-methacrylate (yield 98.9%, purity 99.8 GC%) was obtained. In order to remove a trace amount of 1,1,1,3,3,3-hexafluoroisopropyl alcohol from the obtained crude 1,1,1,3,3,3-hexafluoroisopropyl-2-methacrylate, Washing was performed using 400 g of 2% caustic water and 400 g of water, respectively. After washing, dehydration with 80 g of calcium chloride, filtration, normal pressure flash distillation (bp; 100 ° C., addition of polymerization inhibitor (0.2 wt%)), 1,1,1,3,3,3 -533 g (yield 94.8%, purity 99.9 GC%) of hexafluoroisopropyl-2-methacrylate was obtained.

Production of 1,1,1,3,3,3-hexafluoroisopropyl-2-methacrylate 1,1,1,3 in a glass 200 ml four-necked flask equipped with a magnetic stirrer, dropping funnel and thermometer 3,3-hexafluoroisopropyl alcohol 50.0 g (0.298 mol), triethylamine 33.2 g (0.328 mol) and water 125 g (6.94 mol) were charged, and the mixture was cooled to an internal temperature of 2 ° C. with stirring. After cooling, 48.1 g (0.313 mol) of methacrylic anhydride was added dropwise thereto at an internal temperature of 2-8 ° C. over 1 hour while paying attention to heat generation. After completion of the dropwise addition, the 200 ml 4-necked flask was naturally heated to room temperature over 1 hour, and then the reaction solution was transferred to a separatory funnel and subjected to two-layer separation to obtain crude 1,1,1,3,3. 67.5 g (96.4% yield) of 3-hexafluoroisopropyl-2-methacrylate was obtained. When this crude product was measured by gas chromatography, it was found that 1,1,1,3,3,3-hexafluoroisopropyl-2-methacrylate was 99.5%, triethylamine was 0.1%, and methacrylic anhydride was 0. 4%.

Preparation of 1,1,1,3,3,3-hexafluoroisopropyl-2-acrylate 1,1,1,3 in a glass 200 ml four-necked flask equipped with a magnetic stirrer, dropping funnel and thermometer 3,3-hexafluoroisopropyl alcohol 50.0 g (0.30 mol), sodium hydroxide 13.1 g (0.327 mol), and water 125 g (6.94 mol) were charged, and the mixture was cooled to an internal temperature of 8 ° C. with stirring. . After cooling, 39.3 g (0.312 mol) of acrylic anhydride was added dropwise thereto at an internal temperature of 8-10 ° C. over 15 minutes while paying attention to heat generation. After completion of the dropwise addition, the 200 ml 4-necked flask was naturally heated to room temperature over 1 hour, and then the reaction solution was transferred to a separatory funnel and subjected to two-layer separation to obtain crude 1,1,1,3,3. 62.7 g of 3-hexafluoroisopropyl-2-acrylate (yield 95.1%, purity 99.9 GC%) was obtained. In order to remove a trace amount of 1,1,1,3,3,3-hexafluoroisopropyl alcohol from the obtained crude 1,1,1,3,3,3-hexafluoroisopropyl-2-acrylate, Washing was performed using 50 g of water. After washing, dehydration with 10 g of calcium chloride, filtration, and normal pressure flash distillation (bp; 74 ° C., addition of a polymerization inhibitor (0.2 wt%)) were performed to obtain 1,1,1,3,3,3 -60.1 g (yield 90.8%, purity 99.9 GC%) of hexafluoroisopropyl-2-acrylate was obtained.

Production of 1,1,1,3,3,3-hexafluoroisopropyl-2-acetate In a 500 ml glass four-necked flask equipped with a magnetic stirrer, dropping funnel and thermometer, 1,1, 100 g (0.595 mol) of 1,3,3,3-hexafluoroisopropyl alcohol, 25.0 g (0.625 mol) of sodium hydroxide, and 250 g (13.9 mol) of water were added to the internal temperature of 5 ° C. with stirring. Cooled down. After cooling, 63.8 g (0.625 mol) of acetic anhydride was added dropwise thereto at an internal temperature of 8-10 ° C. over 15 minutes while paying attention to heat generation. After completion of the dropwise addition, the 500 ml four-necked flask was naturally warmed to room temperature over 1 hour, and then the reaction solution was transferred to a separating funnel and subjected to two-layer separation to obtain crude 1,1,1,3,3. 121 g of 3-hexafluoroisopropyl-2-acetate (yield 96.9%, purity 99.8 GC%) was obtained. In order to remove a trace amount of 1,1,1,3,3,3-hexafluoroisopropyl alcohol from the obtained crude 1,1,1,3,3,3-hexafluoroisopropyl-2-acetate, Washing was performed using 100 g of water. After washing, dehydration with 20 g of calcium chloride, filtration, and normal pressure flash distillation (bp; 72 ° C., addition of a polymerization inhibitor (0.2 wt%)) were performed to obtain 1,1,1,3,3,3 -103 g of hexafluoroisopropyl-2-acetate (yield 82.6%, purity 99.9 GC%) was obtained.

Production of 3,3,3-trifluoropropyl methacrylate 50.0 g (0.439 mol) of 3,3,3-trifluoropropanol in a glass 200 ml four-necked flask equipped with a magnetic stirrer, dropping funnel and thermometer Sodium hydroxide (19.2 g, 0.482 mol) and water (125 g, 6.94 mol) were charged, and the mixture was cooled to an internal temperature of 5 ° C. with stirring. After cooling, 70.9 g (0.460 mol) of methacrylic anhydride was added dropwise thereto at an internal temperature of 5-16 ° C. over 1 hour while paying attention to heat generation. After completion of dropping, the 200 ml four-necked flask was naturally warmed to room temperature over 1 hour, and the reaction solution was transferred to a separatory funnel and separated into two layers to obtain crude 3,3,3-trifluoropropyl methacrylate. 73.9 g (yield 92.5%) was obtained. When this crude product was measured by gas chromatography, the raw material 3,3,3-trifluoropropanol was 5.4%, 3,3,3-trifluoropropyl methacrylate was 79.8%, methacrylic anhydride was It was 14.8%.

Production of 2,2,3,3,4,4,5,5- octafluoropentyl methacrylate 2,2,3,3 in a glass 200 ml four-necked flask equipped with a magnetic stirrer, dropping funnel and thermometer , 4,4,5,5-octafluoropentanol 50.0 g (0.215 mol), sodium hydroxide 9.5 g (0.237 mol) and water 125 g (6.94 mol) were charged, and the internal temperature was stirred. Cooled to 5 ° C. After cooling, 34.8 g (0.226 mol) of methacrylic anhydride was added dropwise thereto at an internal temperature of 5-16 ° C. over 30 minutes while paying attention to heat generation. After completion of the dropwise addition, the 200 ml, 4-necked flask was naturally warmed to room temperature over 1 hour, and then the reaction solution was transferred to a separating funnel and subjected to two-layer separation to obtain crude 2, 2, 3, 3, 4, As a result, 63.3 g (yield 98.0%) of 4,5,5-octafluoropentyl methacrylate was obtained. When this crude product was measured by gas chromatography, the raw material 2,2,3,3,4,4,5,5-octafluoropentanol was 1.1%, 2,2,3,3,4, The amount of 4,5,5-octafluoropentyl methacrylate was 97.0% and methacrylic anhydride was 1.8%.

As described above, in Example 1-6, water was allowed to coexist, and in the case where an inorganic base or an organic base was used under the condition that the inside of the system was a two-layer system (heterogeneous system), Comparative Example 1 described later The target compound was obtained with significantly higher yield and purity.

[Comparative Example 1]
Production of 1,1,1,3,3,3-hexafluoroisopropyl-2-methacrylate In a glass 200 ml four-necked flask equipped with a magnetic stirrer, dropping funnel and thermometer, 1,1, 1,3,3,3-hexafluoroisopropyl alcohol 50.0 g (0.298 mol), triethylamine 33.2 g (0.328 mol), and hexane 125 g (1.45 mol) were charged to the internal temperature of 3 ° C. with stirring. Cooled down. After cooling, 48.1 g (0.315 mol) of methacrylic anhydride was added dropwise at an internal temperature of 6-12 ° C. over 10 minutes while paying attention to heat generation. After completion of the dropwise addition, the reaction solution was measured by gas chromatography. As a result, 1,1,1,3,3,3-hexafluoroisopropyl alcohol was 0.4%, 1,1,1,3,3,3-hexa. 9.3% fluoroisopropyl-2-methacrylate, 10.3% triethylamine, 77.9% hexane, 0.6% methacrylic acid, 0.3% methacrylic anhydride, 1.2% others Met. After completion of the reaction, the reaction solution was subjected to atmospheric distillation as it was in a distillation column having 25 theoretical plates, and fractions around 100 ° C. were collected. As a result, the yield of 1,1,1,3,3,3-hexafluoroisopropyl-2-methacrylate was 42.9%, purity 99.2% (hexane 0.4%, triethylamine 0.1%, other 0.3%).

In the above Comparative Example 1, this reaction proceeds even in a reaction using an organic solvent, and the target product can be obtained satisfactorily. However, during purification, 1,1,1,3,3,3-hexafluoroisopropyl-2-methacrylate (boiling point 100 ° C. at normal pressure) and reaction solvent hexane (boiling point 68 ° C. at normal pressure) As a result, the amount of loss in the distillation operation was large, and the obtained target product having a high purity had a low yield (42.9%). Considering purification, it can be said that it is preferable to carry out only with water because it can reduce the load during purification and is economical.

[Reference Example 1]
Preparation of isopropyl-2-methacrylate 50.0 g (0.832 mol) of isopropyl alcohol and 36.6 g (0.915 mol) of sodium hydroxide in a glass 200 ml four-necked flask equipped with a magnetic stirrer, dropping funnel and thermometer Then, 125 g (6.94 mol) of water was charged, and the mixture was cooled to an internal temperature of 6 ° C. with stirring. After cooling, 134.5 g (0.874 mol) of methacrylic anhydride was added dropwise at an internal temperature of 6-22 ° C. over 15 minutes while paying attention to heat generation. After completion of the dropwise addition, the 200 ml 4-necked flask was naturally warmed to room temperature over 1 hour, and then the reaction solution was transferred to a separatory funnel and separated into two layers to obtain 40.4 g of crude isopropyl-2-methacrylate. It was. When the crude product was measured by gas chromatography, isopropyl alcohol was 79.4%, isopropyl-2-methacrylate was 5.7%, methacrylic acid was 2.2%, and methacrylic anhydride was 12.7%. The raw material was almost recovered.

Even if methacrylic anhydride is reacted with isopropyl alcohol, the corresponding isopropyl-2-methacrylate is hardly obtained, and the decomposition of methacrylic anhydride proceeds almost preferentially.

Claims (11)

Fluorine-containing alcohol represented by the formula [1]

(In the formula, n represents an integer of 1 to 10, a is 0 or a positive integer, b is a positive integer, and a + b = 2n + 1.)
And an acid anhydride represented by the formula [2]

(In the formula, R ₁ and R ₂ each represent a linear or branched alkyl group or alkenyl group having 1 to 6 carbon atoms. Also, R ₁ and R ₂ may be the same or different. .)
Fluorine-containing alkane ester represented by the formula [3], wherein water is allowed to coexist in the presence of a base as a solvent.

(In the formula, n, a and b are the same as described above, and R ₃ represents a linear or branched alkyl group or alkenyl group having 1 to 6 carbon atoms.)
Manufacturing method. The method according to claim 1, wherein the fluorinated alcohol is 1,1,1,3,3,3-hexafluoro-2-propanol. The process according to claim 1, characterized in that the acid anhydride is methacrylic anhydride or acetic anhydride. The method according to any one of claims 1 to 3, wherein the reaction is carried out under conditions in which an organic solvent does not coexist in the system. When 1,1,1,3,3,3-hexafluoro-2-propanol and methacrylic anhydride are reacted in the presence of a base, water is used as a solvent, and the reaction is performed under conditions where an organic solvent is not used. A method for producing 1,1,1,3,3,3-hexafluoro-2-methacrylate. 6. An inorganic base or an organic base is allowed to coexist when reacting the fluorine-containing alcohol represented by the formula [1] and the acid anhydride represented by the formula [2]. The method in any one of. The inorganic base is at least one selected from the group consisting of ammonia, sodium hydroxide, sodium carbonate, sodium hydrogen carbonate, potassium hydroxide, potassium carbonate, potassium hydrogen carbonate, calcium hydroxide, and lithium hydroxide. The method according to claim 6. The organic base is at least one selected from the group consisting of methylamine, dimethylamine, trimethylamine, diethylamine, triethylamine, tributylamine, pyridine, piperidine, methylpyridine, dimethylpyridine, and aniline. The method described. The method according to any one of claims 1 to 8, wherein the amount of water is 0.2 g to 20 g per g of fluorine-containing alcohol. The method according to any one of claims 1 to 9, wherein the temperature during the reaction is -10 ° C to 50 ° C. When 1,1,1,3,3,3-hexafluoro-2-propanol and methacrylic anhydride are reacted, per 1 g of 1,1,1,3,3,3-hexafluoro-2-propanol, 1,1,1,3, characterized in that 0.2 g to 20 g of water coexist as a solvent, no organic solvent coexists, sodium hydroxide is used, and the reaction is performed at −10 ° C. to 50 ° C. A method for producing 3,3-hexafluoro-2-methacrylate.