Method for producing glycerin acetal and / or glycerin ketal, and composition containing glycerin acetal and / or glycerin ketal

Abstract

The present invention provides a manufacturing method that suppresses thermal decomposition during distillation and purification, enabling the efficient production of high-purity five-membered ring glycerin acetal (ketal) with a high recovery rate, and a glycerin acetal (ketal)-containing composition. [Solution] A method for producing glycerin acetal and / or glycerin ketal, comprising a reaction step of reacting glycerin with a specific ketone compound to obtain a crude reaction solution containing glycerin acetal and / or glycerin ketal, and a distillation step of distilling and purifying the crude reaction solution to obtain glycerin acetal and / or glycerin ketal, wherein the distillation step includes distilling and purifying the bottom liquid obtained in the distillation step at a distillation temperature such that the molar ratio of compound (3) represented by the following general formula (3) to glycerin acetal and / or glycerin ketal is less than or equal to a predetermined value. JPEG2026136946000022.jpg3232

Description

Technical Field

[0001] The present invention relates to a method for producing glycerin acetal and / or glycerin ketal (hereinafter also referred to as "glycerin acetal (ketal)"), and a composition containing glycerin acetal and / or glycerin ketal.

Background Art

[0002] Glycerin acetal (ketal) such as solketal is used not only as an additive for gasoline and diesel fuel or a plasticizer for polymers due to its unique properties, but also because of its non-toxicity, it is used in many applications such as a raw material for pharmaceutical intermediates and a solvent for perfumes. However, in applications such as a raw material for pharmaceutical intermediates and a perfume solvent, glycerin acetal (ketal) with a reduced impurity content as much as possible, that is, high-purity glycerin acetal (ketal) is required from the viewpoint of toxicity to the human body.

[0003] [[ID=…]] As an industrial production method of glycerin acetal (ketal) such as 5-membered ring glycerin acetal (ketal), for example, in Patent Documents 1 to 3, glycerin and a carbonyl compound such as acetone are subjected to an acetalization reaction to obtain a crude reaction solution containing glycerin acetal (ketal), and then the crude reaction solution is purified by distillation to obtain glycerin acetal (ketal).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present inventors investigated glycerin acetals (ketals) having a five-membered ring structure represented by the following general formula (1) (hereinafter referred to as "five-membered ring glycerin acetals (ketals)") and found that the five-membered ring glycerin acetals (ketals) can be heated and thermally decomposed during distillation purification, and a small amount of glycerin acetals (ketals) having a six-membered ring structure represented by the following general formula (3) (hereinafter referred to as "six-membered ring glycerin acetals (ketals)") are produced as by-products.

[0006] [ka]

[0007] [ka]

[0008] (In formulas (1) and (3), R1 and R2 may be the same or different, and represent a hydrogen atom, a linear or branched alkyl or alkenyl group having 1 to 22 carbon atoms, or an aryl group having 6 to 30 carbon atoms that may be substituted with an alkyl group, and R1 and R2 may be bonded together to form a ring.)

[0009] However, because the boiling points of the five-membered ring glycerin acetal (ketal) and the six-membered ring glycerin acetal (ketal) mentioned above are very close, effective separation using distillation purification is difficult, and obtaining high-purity five-membered ring glycerin acetal (ketal) is challenging. Specifically, increasing the number of distillation stages or reflux ratio to improve the purity of five-membered ring glycerin acetal (ketal) using distillation increases the consumption of equipment and energy used for distillation. Furthermore, the decomposition of the five-membered ring glycerin acetal (ketal) progresses due to the influence of thermal history, resulting in a decrease in the recovery rate of the five-membered ring glycerin acetal (ketal) obtained after distillation. In contrast, Patent Documents 1 to 3 do not mention anything about the thermal decomposition of 5-membered ring glycerol acetals (ketals) during distillation purification, nor do they mention any method for separating 6-membered ring glycerol acetals (ketals) during distillation purification.

[0010] The present invention aims to solve the above-mentioned problems. Specifically, the present invention solves the problems of the above-mentioned prior art and aims to provide a method for producing a five-membered ring glycerin acetal (ketal) that suppresses the thermal decomposition of the five-membered ring glycerin acetal (ketal) during distillation purification and enables the efficient production of high-purity five-membered ring glycerin acetal (ketal) with a high recovery rate. [Means for solving the problem]

[0011] The inventors of the present invention have conducted extensive research to solve the above problems and have found that the above technical problems can be solved by setting the distillation temperature in the distillation process within a predetermined range so that the molar ratio of 6-membered ring glycerin acetal (ketal) to 5-membered ring glycerin acetal (ketal) in the bottom liquid obtained in the distillation process is within a predetermined range. This led to the present invention.

[0012] This invention was achieved based on the above findings, and its gist is as follows. [1] A method for producing glycerin acetal and / or glycerin ketal, comprising a reaction step of reacting glycerin with a carbonyl compound represented by the following general formula (2) to obtain a crude reaction solution containing glycerin acetal and / or glycerin ketal (1) represented by the following general formula (1), and a distillation step of distilling and purifying the crude reaction solution to obtain glycerin acetal and / or glycerin ketal (1), wherein the distillation and purification is carried out at a distillation temperature such that the molar ratio of compound (3) represented by the following general formula (3) to glycerin acetal and / or glycerin ketal (1) in the bottom liquid obtained in the distillation step is less than or equal to a predetermined value.

[0013] [Chemical formula]

[0014] [In formula (2), R1 and R2 may be the same or different and each represents a hydrogen atom, a linear or branched alkyl or alkenyl group having 1 to 22 carbon atoms, or an aryl group having 6 to 30 carbon atoms which may be substituted with an alkyl group, and R1 and R2 may combine to form a ring. ]

[0015] [Chemical formula]

[0016] [In formula (1), R1 and R2 are respectively synonymous with R1 and R2 in formula (2). ]

[0017] [Chemical formula]

[0018] [In formula (3), R1 and R2 are respectively synonymous with R1 and R2 in formula (2). ] [2] The method for producing glycerin acetal and / or glycerin ketal according to [1] above, wherein in the distillation step, the crude reaction solution is distilled and purified to distill off unreacted carbonyl compounds, and a bottom liquid containing glycerin acetal and / or glycerin ketal (1) is obtained. [3] The method for producing glycerin acetal and / or glycerin ketal according to [1] or [2] above, wherein in the bottom liquid obtained in the distillation step, the molar ratio of the compound (3) represented by the general formula (3) to glycerin acetal and / or glycerin ketal (1) is within the range of 0 or more and 0.03 or less, and the distillation temperature is within the range of a predetermined numerical value. [4] The method for producing glycerin acetal and / or glycerin ketal according to any one of [1] to [3] above, wherein the distillation temperature in the distillation step is within the range of 115°C or more and 170°C or less. [5] A method for producing glycerin acetal and / or glycerin ketal according to any one of [1] to [4] above, wherein the distillation temperature in the distillation step is within the range of 120°C to 160°C. [6] A method for producing glycerin acetal and / or glycerin ketal according to any one of [1] to [5] above, wherein the reaction step involves carrying out the reaction of glycerin with a carbonyl compound (2) in the presence of an acid. [7] A glycerin acetal-containing composition comprising a glycerin acetal and / or glycerin ketal (1) represented by the following general formula (1) and a compound (3) represented by the following general formula (3), wherein the molar ratio of the compound (3) to the glycerin acetal and / or glycerin ketal (1) is in the range of 0 to 0.03.

[0019] [ka]

[0020] [In formula (1), R1 and R2 may be the same or different, and represent a hydrogen atom, a linear or branched alkyl or alkenyl group having 1 to 22 carbon atoms, or an aryl group having 6 to 30 carbon atoms that may be substituted with an alkyl group, and R1 and R2 may be bonded together to form a ring.]

[0021] [ka]

[0022] [In equation (3), R1 and R2 are equivalent to R1 and R2 in equation (2), respectively.] [8] The glycerin acetal and / or glycerin ketal-containing composition according to [7] above, wherein the content of the glycerin acetal and / or glycerin ketal (1) is 70% by mass or more based on 100% of the total mass of the glycerin acetal and / or glycerin ketal-containing composition. [Effects of the Invention]

[0023] According to the present invention, it is possible to provide a method for producing a five-membered ring glycerin acetal (ketal) that can efficiently produce a high-purity five-membered ring glycerin acetal (ketal) with a high recovery rate by suppressing the thermal decomposition of the five-membered ring glycerin acetal (ketal) during distillation purification. Furthermore, the five-membered ring glycerin acetal (ketal) obtained by the manufacturing method of the present invention has a low content of six-membered ring glycerin acetal (ketal), which is produced as a by-product in the reaction process. Therefore, it can be suitably used as a raw material for pharmaceutical intermediates and as a solvent for perfumes. [Brief explanation of the drawing]

[0024] [Figure 1] This is a schematic diagram illustrating an example of the process for producing glycerin acetal (ketal) from glycerin and a carbonyl compound such as acetone, according to the present invention. [Figure 2] The graphs in Experimental Examples 1-5 show the relationship between distillation temperature, the molar ratio of compound (3) to glycerol acetal (ketal) (1) in the bottom liquid after distillation (●), and the decomposition rate of glycerol acetal (ketal) (〇). [Modes for carrying out the invention]

[0025] The embodiments of the present invention will be described in detail below, but the present invention is not limited to the following description and can be modified and implemented as appropriate without departing from the spirit of the invention. Furthermore, unless otherwise specified, numerical ranges represented using "~" in this specification mean a range that includes the numbers written before and after "~" as the lower and upper limits, respectively. "A~B" means A or greater and B or less.

[0026] In this specification, "including A or B" means "including A," "including B," and "including A and B," unless otherwise specified. Furthermore, in this specification, "mass%" indicates the percentage of a given component contained in 100% of the total amount. Also, "mass%" and "weight%" are synonymous.

[0027] In this specification, “optional” or “optionally” means that the circumstances described below may or may not occur, and therefore the description includes both the cases in which the circumstances occur and the cases in which they do not occur. Furthermore, all steps described herein may be carried out in any preferred order, unless otherwise specified herein or unless the context clearly contradicts it. The embodiments of the present invention will be described in detail below, but the description of the constituent elements described below is merely one example of an embodiment of the present invention and is not limited to these.

[0028] [Method for producing glycerin acetal (ketal)] The present invention provides a method for producing glycerin acetal (ketal), which involves reacting glycerin with a carbonyl compound represented by the following general formula (2) (hereinafter referred to as "carbonyl compound (2)") in a reaction step described later to obtain a crude reaction solution containing glycerin acetal (ketal) represented by the following general formula (1) (hereinafter referred to as "glycerin acetal (ketal) of the present invention" or "glycerin acetal (ketal) (1)"), and further purifying the crude reaction solution by distillation in a distillation step described later to obtain glycerin acetal (ketal).

[0029] [ka]

[0030] [In formula (2), R1 and R2 may be the same or different, and represent a hydrogen atom, a linear or branched alkyl or alkenyl group having 1 to 22 carbon atoms, or an aryl group having 6 to 30 carbon atoms that may be substituted with an alkyl group, and R1 and R2 may be bonded together to form a ring.]

[0031] [ka]

[0032] [In equation (1), R1 and R2 are equivalent to R1 and R2 in equation (2), respectively.]

[0033] The present invention provides a method for producing glycerin acetal (ketal), characterized in that the distillation temperature is set within a predetermined range so that the molar ratio of the compound represented by the following general formula (3) (hereinafter referred to as "compound (3)") to the glycerin acetal (ketal) (1) in the bottom liquid obtained in the distillation step is within a predetermined range. By keeping the molar ratio within a predetermined range, the decomposition of the 6-membered ring glycerin acetal (ketal) can be selectively performed in the bottom liquid of the column, while suppressing the thermal decomposition of the 5-membered ring glycerin acetal (ketal) during distillation purification. As a result, it becomes possible to efficiently produce high-purity 5-membered ring glycerin acetal (ketal) with a high recovery rate using distillation conditions with minimal thermal history.

[0034] [ka]

[0035] [In equation (3), R1 and R2 are equivalent to R1 and R2 in equation (2), respectively.]

[0036] The aforementioned five-membered ring glycerin acetal (ketal) corresponds to the aforementioned glycerin acetal (ketal) (1), and the aforementioned six-membered ring glycerin acetal (ketal) corresponds to compound (3). Details of the glycerin acetal (ketal) (1) and the compound (3) will be described later.

[0037] In the method for producing glycerin acetal (ketal) of the present invention, the distillation temperature refers to the temperature of the bottom liquid in the distillation column when distillation purification is performed using a distillation column in the distillation step.

[0038] <Distillation Process> The present invention provides a method for producing glycerin acetal (ketal), which includes a distillation step to obtain glycerin acetal (ketal) by distilling and purifying the crude reaction solution obtained in the reaction step.

[0039] The specific embodiments of the distillation process in the present invention are not particularly limited, and known distillation methods can be used. Specifically, examples include atmospheric pressure distillation, reduced pressure distillation, and the use of an evaporator. Among these, atmospheric pressure distillation is preferred. Furthermore, these distillation methods can be used in combination, and for example, a method of further reducing pressure distillation of the bottom liquid obtained by atmospheric pressure distillation is also a preferred embodiment.

[0040] A more specific embodiment of the distillation process is, for example, to separate and recover the glycerin acetal (ketal) by using atmospheric pressure distillation to distill off the unreacted carbonyl compound and by-product water from the crude reaction solution obtained in the reaction process, and then using vacuum distillation to distill off the glycerin acetal (ketal) from the bottom liquid, thereby obtaining a distillation residue containing high-boiling point by-products and unreacted glycerin. This distillation residue can be further used by vacuum distillation to obtain a distillate containing high-purity glycerin acetal.

[0041] In the method for producing glycerin acetal (ketal) of the present invention, in the distillation step, the crude reaction solution is purified by distillation to distill off unreacted carbonyl compounds, and a bottom liquor containing glycerin acetal (ketal) can be obtained. More specifically, in a method for producing glycerin acetal (ketal) (1), such as solketal, by an acetalization reaction between glycerin and a carbonyl compound such as acetone, when distilling and purifying the crude reaction solution after the acetalization reaction to obtain glycerin acetal (ketal) (1), the distillation temperature can be set within a predetermined range so that the molar ratio of compound (3) to glycerin acetal (ketal) (1) in the bottom liquid obtained in the distillation step is within a predetermined range, thereby obtaining a bottom liquid containing glycerin acetal (ketal) (1).

[0042] The "predetermined range of values" in the aforementioned molar ratio refers to a range of values ​​in which the resulting glycerin acetal (ketal) (1) has practically acceptable characteristics or performance. For example, these values ​​may be empirically determined using the manufacturing equipment used, or they may be theoretically determined using simulations or the like. In the experimental examples of the present invention, the values ​​used are empirically determined based on the results of a reasonable number of trials using the manufacturing equipment.

[0043] The "predetermined range of values" at the distillation temperature refers to a range of values ​​in which the molar ratio of compound (3) to glycerin acetal (ketal) (1) falls within the aforementioned predetermined range. This range may be, for example, a value determined empirically using the manufacturing equipment used, or a value determined theoretically using simulations. In the experimental examples of the present invention, the values ​​used are those determined empirically based on the results of a suitable number of trials using the manufacturing equipment.

[0044] In the method for producing glycerin acetal (ketal) of the present invention, the distillation step may be carried out in a single distillation operation, or it may be carried out in combination of multiple distillation operations. When multiple distillation operations are carried out in combination, a method of carrying out multiple distillation operations under the same conditions, or a method of carrying out multiple distillation operations under different conditions, can be employed. When performing multiple distillation operations, the molar ratio of compound (3) to glycerin acetal (ketal) (1) can be kept within a predetermined range in any of the distillation operations. In particular, it is preferable to keep the molar ratio within the predetermined range in the final distillation operation.

[0045] In the bottom liquid obtained in the distillation process, there is no particular upper limit to the molar ratio of compound (3) to glycerin acetal (ketal) (1), but from the viewpoint of economics, such as the manufacturing costs required to purify glycerin acetal (ketal) (1), it is preferably 0.03 or less. The molar ratio is more preferably 0.025 or less, even more preferably 0.020 or less, and particularly preferably 0.015 or less. On the other hand, the lower limit of the molar ratio of compound (3) to glycerin acetal (ketal) (1) is not particularly limited. Compound (3) may not be included (molar ratio = 0), or it may be 0.0001 or higher from the viewpoint of economics, such as the manufacturing costs required for the separation and removal of compound (3). The molar ratio is more preferably 0.0003 or higher, even more preferably 0.001 or higher, and particularly preferably 0.003 or higher. The preferred upper and lower limits of the above molar ratios can be combined arbitrarily. For example, the molar ratio of compound (3) to glycerin acetal (ketal) (1) is not particularly limited, and compound (3) may not be included (molar ratio = 0), or it is preferably 0.0001 to 0.03, more preferably 0.0003 to 0.025, even more preferably 0.001 to 0.020, and particularly preferably 0.003 to 0.015.

[0046] In this specification, the details of the method for measuring the molar ratio of compound (3) to glycerin acetal (ketal) (1) (hereinafter sometimes simply referred to as "molar ratio") will be described later.

[0047] The lower limit of the distillation temperature is not particularly limited, but a lower distillation temperature is preferable as it reduces the molar ratio of compound (3) to glycerin acetal (ketal) (1). From a similar viewpoint, a temperature of 120°C or higher is more preferable, 125°C or higher is even preferable, 130°C or higher is particularly preferable, and 135°C or higher is most preferable. On the other hand, the upper limit of the distillation temperature is not particularly limited, but a higher distillation temperature increases the decomposition rate of glycerin acetal (ketal) (1), so a temperature of 170°C or lower is preferred. From a similar viewpoint, a temperature of 160°C or lower is more preferred, 155°C or lower is even more preferred, 150°C or lower is particularly preferred, and 145°C or lower is most preferred. The preferred upper and lower limits of the distillation temperature can be combined in any way. For example, the distillation temperature in the distillation process is not particularly limited, but is preferably 115°C to 170°C, more preferably 120°C to 160°C, even more preferably 125°C to 155°C, particularly preferably 130°C to 150°C, and most preferably 135°C to 145°C.

[0048] <Reaction Process> The present invention provides a method for producing glycerin acetal (ketal), which includes a reaction step of reacting glycerin with a carbonyl compound represented by the following general formula (2) to obtain a crude reaction solution containing glycerin acetal (ketal) represented by the following general formula (1).

[0049] The specific embodiments of the reaction in the present invention, in which glycerin is reacted with a carbonyl compound represented by the following general formula (2) to obtain a crude reaction solution containing a glycerin acetal (ketal) represented by general formula (1), are not particularly limited, and known reaction methods can be used. Specifically, methods using the batch reaction format described in Japanese Patent Application Publication No. 2006-273750 or the flow reaction format described in Japanese Patent Application Publication No. 60-87282 can be used. Among these, the method using the flow reaction format is preferred from the viewpoint of superior productivity.

[0050] A specific method for obtaining a crude reaction solution containing the glycerin acetal (ketal) is to fill a reaction tube with a strongly acidic cation exchange resin and react glycerin with a carbonyl compound represented by the following general formula (2).

[0051] Furthermore, in the reaction step of the present invention, the reaction between glycerin and the carbonyl compound can be carried out in the presence of an acid. The type of acid is not particularly limited, and examples include homogeneous catalysts such as p-toluenesulfonic acid, methanesulfonic acid, sulfuric acid, hydrochloric acid, phosphoric acid, and nitric acid, as well as heterogeneous catalysts such as porous silica, ion exchange resins, and zeolites. Examples of ion exchange resins include strongly acidic cation exchange resins whose ionic form is H+. Among these acids, a strongly acidic cation exchange resin with an ionic form of H+ is preferred from the viewpoint of easily separating the catalyst from the obtained crude reaction solution.

[0052] <Other processes> In the method for producing glycerin acetal (ketal) of the present invention, the crude reaction solution obtained in the reaction step may be supplied directly to the distillation step. Alternatively, if necessary, another step may be added between the reaction step and the distillation step, and the crude reaction solution may be subjected to other treatments before being supplied to the distillation step. Other processes mentioned above are not limited to those described above and may include, for example, adding additives, adjusting the pH to a predetermined range, or purifying the product using purification methods other than distillation, such as ion exchange resins or crystallization.

[0053] The "predetermined range of values" in the pH mentioned above refers to a range of values ​​in which the molar ratio of compound (3) to glycerin acetal (ketal) (1) falls within the aforementioned predetermined range. For example, this range may be a value empirically determined using the manufacturing equipment used, or a value theoretically determined using simulations, etc. In the experimental examples of the present invention, the values ​​used are those empirically determined based on the results of a suitable number of trials using the manufacturing equipment.

[0054] In the aforementioned other steps, when the pH of the crude reaction solution is to be brought within a predetermined range, the method is not particularly limited, but from the viewpoint of suppressing the reverse reaction of glycerin acetal (ketal), it is preferable to add a basic substance, as described later, to the crude reaction solution to bring the pH of the crude reaction solution within a predetermined range. The method for adding the basic substance described later to the crude reaction solution is not particularly limited, and those skilled in the art can use well-known techniques by appropriately optimizing them. Details will be described later.

[0055] The upper limit of the pH of the crude reaction solution subjected to the distillation step is not particularly limited, but since the effect remains constant even when an excess amount of base is added, a pH of 9.00 or less is preferred. From the above viewpoint, a pH of 8.95 or less is more preferred, 8.90 or less is even more preferred, 8.85 or less is particularly preferred, and 8.80 or less is most preferred. On the other hand, the lower limit of the pH of the crude reaction solution subjected to the distillation step is not particularly limited, but since heating in an acidic region to remove the carbonyl compound causes the reverse reaction of general formula (1) to proceed and the yield decreases, a pH of 7.60 or higher is preferred. From the above viewpoint, a pH of 7.65 or higher is more preferred, 7.70 or higher is even more preferred, 7.75 or higher is particularly preferred, and 7.80 or higher is most preferred. The preferred upper and lower limits of pH mentioned above can be combined in any way. For example, the pH of the crude reaction solution subjected to the distillation step is not particularly limited, but is preferably 7.60 to 9.00, more preferably 7.65 to 8.95, even more preferably 7.70 to 8.90, particularly preferably 7.75 to 8.85, and most preferably 7.80 to 8.80.

[0056] The method of adding the basic substance described later to the crude reaction solution is not particularly limited, and for example, an alkaline solution prepared by dissolving a basic compound in water or an organic solvent can be added. A method using a solid base from a basic ion exchange resin is preferred because the added solvent or basic compound can be easily removed. Details of the aforementioned basic substance will be described later.

[0057] <Basic substances> When the pH of the crude reaction solution is set within a predetermined range, the basic substance is not particularly limited and examples include anion exchange resins and alkali metal salts such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, and sodium acetate. Among the basic substances mentioned above, anion exchange resins are preferred because they have the effect of reducing the molar ratio of compound (3) to glycerol acetal (ketal) (1). The anion exchange resin in the present invention is not particularly limited, and examples include a quaternary ammonium type strongly basic anion exchange resin and a tertiary amine type weakly basic anion exchange resin. A tertiary amine type ion exchange resin is preferred because it allows for easy pH adjustment of the crude reaction solution and regeneration after use. Commercially available anion exchange resins include Mitsubishi Chemical's DION series such as WA10, WA20, and WA30 (product names), Organo Corporation's Amberlight series such as IRA400JCl and IRA402BLCl (product names), and Sumika Chemtex Corporation's Duolite. TM A113LF and Duolight TM The A116 (product name) Duolite series and similar products can be used.

[0058] <Carbonyl compound (2) represented by general formula (2)> The carbonyl compound (2) represented by the following general formula (2) is a compound that serves as a starting material when synthesizing glycerin acetal (ketal) in the method for producing glycerin acetal (ketal) of the present invention.

[0059] [ka]

[0060] [In formula (2), R1 and R2 may be the same or different, and represent a hydrogen atom, a linear or branched alkyl or alkenyl group having 1 to 22 carbon atoms, or an aryl group having 6 to 30 carbon atoms that may be substituted with an alkyl group, and R1 and R2 may be bonded together to form a ring.]

[0061] Examples of the carbonyl compound include aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, and butyraldehyde, and ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, 3-pentanone, diethyl ketone, cyclopentanone, and cyclohexanone. Acetone is preferred because it is easy to remove unreacted carbonyl compound (2) when distillation is performed after the reaction.

[0062] <Glycerin acetal (ketal) represented by general formula (1) (1)> According to the method for producing glycerin acetal (ketal) of the present invention, glycerin acetal (ketal) (1) represented by the following general formula (1) can be produced.

[0063] [ka]

[0064] [In formula (1), R1 and R2 may be the same or different, and represent a hydrogen atom, a linear or branched alkyl or alkenyl group having 1 to 22 carbon atoms, or an aryl group having 6 to 30 carbon atoms that may be substituted with an alkyl group, and R1 and R2 may be bonded together to form a ring.] In equation (1), R1 and R2 can be treated as equivalent to R1 and R2 in equation (2), respectively.

[0065] Specifically, as the glycerin acetal (ketal) (1), if the carbonyl compound (2) is acetone, examples include 2,2-dimethyl-1,3-dioxolane-4-methanol; if the carbonyl compound (2) is methyl ethyl ketone, examples include 2-ethyl-2-methyl-1,3-dioxolane-4-methanol; if the carbonyl compound (2) is methyl butyl ketone, examples include 2-butyl-2-methyl-1,3-dioxolane-4-methanol; and if the carbonyl compound (2) is methyl isobutyl ketone, examples include 2-isobutyl-2-methyl-1,3-dioxolane-4-methanol.

[0066] <Compound (3) represented by general formula (3)> The present invention provides a method for producing glycerin acetal (ketal), which focuses on compound (3) represented by the following general formula (3), and includes ensuring that the molar ratio of compound (3) to glycerin acetal (ketal) (1) in the bottom liquid obtained in the distillation step is within a predetermined range.

[0067] [ka]

[0068] [In formula (3), R1 and R2 may be the same or different, and represent a hydrogen atom, a linear or branched alkyl or alkenyl group having 1 to 22 carbon atoms, or an aryl group having 6 to 30 carbon atoms that may be substituted with an alkyl group, and R1 and R2 may be bonded together to form a ring.] In equation (3), R1 and R2 can be treated as equivalent to R1 and R2 in equation (2), respectively.

[0069] When the glycerin acetal (ketal) of the present invention is used as a solvent for pharmaceuticals or perfumes, compound (3) contained as an impurity in the glycerin acetal (ketal) degrades the quality of the final glycerin acetal (ketal). Therefore, by setting the distillation temperature within a predetermined range so that the molar ratio of compound (3) represented by the following general formula (3) to glycerin acetal (ketal) (1) is within a predetermined range, the content of compound (3) can be reduced to a desired value.

[0070] One specific embodiment of compound (3) is 1,3-dioxan-5-ol. For example, if the carbonyl compound (2) is acetone, the corresponding compound (3) is 2,2-dimethyl-1,3-dioxan-5-ol. According to the inventors' investigations, it is presumed that when acetone and glycerin react in the presence of an acid, a certain amount of compound (3), which is a structural isomer of compound (1), is produced in addition to compound (1).

[0071] <Compositions containing glycerin acetal and / or glycerin ketal> The glycerin acetal and / or glycerin ketal-containing composition of the present invention (hereinafter also referred to as "glycerin acetal (ketal)-containing composition") is a glycerin acetal (ketal)-containing composition comprising a glycerin acetal (ketal) (1) represented by the following general formula (1) and a compound (3) represented by the following general formula (3), wherein the molar ratio of compound (3) to glycerin acetal (ketal) (1) is in the range of 0 to 0.03.

[0072] [ka]

[0073] [In formula (1), R1 and R2 may be the same or different, and represent a hydrogen atom, a linear or branched alkyl or alkenyl group having 1 to 22 carbon atoms, or an aryl group having 6 to 30 carbon atoms that may be substituted with an alkyl group, and R1 and R2 may be bonded together to form a ring.]

[0074] [ka]

[0075] [In formula (3), R1 and R2 may be the same or different, and represent a hydrogen atom, a linear or branched alkyl or alkenyl group having 1 to 22 carbon atoms, or an aryl group having 6 to 30 carbon atoms that may be substituted with an alkyl group, and R1 and R2 may be bonded together to form a ring.]

[0076] In the glycerin acetal (ketal)-containing composition of the present invention, the glycerin acetal (ketal) represented by the general formula (1) is synonymous with glycerin acetal (ketal) (1) in the method for producing glycerin acetal (ketal) of the present invention.

[0077] In the glycerin acetal (ketal)-containing composition of the present invention, the compound represented by the general formula (3) is synonymous with compound (3) in the method for producing glycerin acetal (ketal) of the present invention.

[0078] In the glycerin acetal (ketal)-containing composition of the present invention, the upper limit of the molar ratio of compound (3) to glycerin acetal (ketal) (1) is preferably 0.03 or less from the viewpoint of increasing the purity of glycerin acetal (ketal) (1). The molar ratio is more preferably 0.025 or less, even more preferably 0.020 or less, and particularly preferably 0.015 or less. On the other hand, the lower limit of the molar ratio of compound (3) to glycerin acetal (ketal) (1) is either that compound (3) is not included (molar ratio = 0), or, from the viewpoint of economics such as the manufacturing cost required for the separation and removal of compound (3), it is preferably 0.0001 or higher. The molar ratio is more preferably 0.0003 or higher, even more preferably 0.001 or higher, and particularly preferably 0.003 or higher. The preferred upper and lower limits of the above molar ratios can be combined arbitrarily. For example, the molar ratio of compound (3) to glycerin acetal (ketal) (1) is not particularly limited, and compound (3) may not be included (molar ratio = 0), or it is preferably 0.0001 to 0.03, more preferably 0.0003 to 0.025, even more preferably 0.001 to 0.020, and particularly preferably 0.003 to 0.015.

[0079] The method for producing the glycerin acetal (ketal)-containing composition of the present invention is not particularly limited, and one specific embodiment is the method for producing the glycerin acetal (ketal) of the present invention described above.

[0080] In the glycerin acetal (ketal)-containing composition of the present invention, the lower limit of the glycerin acetal (ketal) content is not particularly limited. From the viewpoint of obtaining sufficient effects from glycerin acetal (ketal) (1) in the obtained glycerin acetal (ketal)-containing composition, the content can be 70.0% by mass or more, based on 100% of the total mass of the glycerin acetal (ketal)-containing composition. More preferably 80.0% by mass or more, even more preferably 90.0% by mass or more, particularly preferably 95.0% by mass or less, and most preferably 98.0% by mass or more. On the other hand, the upper limit of the glycerin acetal (ketal) content is not particularly limited. From the viewpoint of economics, such as the manufacturing costs required to purify glycerin acetal (ketal) (1), the content can usually be 99.9% by mass or less, based on 100% of the total mass of the glycerin acetal (ketal)-containing composition. A percentage of 99.5% by mass or less is more preferable, 99.2% by mass or less is even more preferable, 99.8% by mass or less is particularly preferable, and 98.5% by mass or less is most preferable. The upper and lower limits for the glycerin acetal (ketal) content percentage mentioned above can be combined arbitrarily.

[0081] The method for adjusting the glycerin acetal (ketal) content in the glycerin acetal (ketal)-containing composition of the present invention to within the above numerical range is not particularly limited. For example, when producing the composition using the glycerin acetal (ketal) production method of the present invention described above, the glycerin acetal (ketal) content can be adjusted to a desired range by appropriately optimizing the reaction conditions in the reaction step and the distillation conditions in the distillation step based on well-known technology by those skilled in the art.

[0082] The method for producing glycerin acetal (ketal) according to the present invention will be described in detail for each step with reference to Figure 1. Figure 1 is a schematic diagram showing an example of a manufacturing process in which, according to the present invention, glycerin and a carbonyl compound are reacted to obtain a crude reaction solution containing glycerin acetal (ketal), and then the crude reaction solution is purified by distillation to separate and recover the glycerin acetal (ketal).

[0083] The raw materials, acetone and glycerin, are introduced into reactor 1. A cation exchange resin is introduced into reactor 1, and a crude reaction solution containing glycerin acetal (ketal) is obtained by the condensation reaction of acetone and glycerin. Water is produced as a reaction byproduct at this time.

[0084] In filter 2, the cation exchange resin is filtered and separated from the reaction solution obtained in reactor 1. In the pH adjustment reactor 3, the reaction solution filtered and separated in the filter 2 is brought into contact with an anion exchange resin to adjust the pH to a predetermined range. In filter 4, the anion exchange resin is separated from the reaction solution after its pH has been adjusted in pH adjustment reactor 3.

[0085] In the first distillation column 5, unreacted acetone and water, a reaction by-product, are separated and removed from the top of the column by distillation from the crude reaction solution, which has been adjusted to a pH within a predetermined range by the filter 4, to obtain a bottom liquid containing glycerin and glycerin acetal (ketal). The acetone recovered in the distillation column 5 may be used again as a reaction raw material by supplying it to the reactor 1 after removing the water.

[0086] In the second distillation column 6, the bottom liquid containing glycerin and glycerin acetal (ketal) obtained in distillation column 5 is separated by distillation, and the desired glycerin acetal (ketal) is obtained from the distillate. In this process, the distillation temperature is set to a predetermined range so that the molar ratio of compound (3) to glycerin acetal (ketal) (1) in the bottom liquid of the distillation column 6 falls within a predetermined range. [Examples]

[0087] The present invention will be described more specifically below with reference to alternative and comparative experimental examples, but the present invention is not limited to the following experimental examples unless it exceeds the essence of the invention.

[0088] In this experimental example and comparative experimental example, 2,2-dimethyl-1,3-dioxolane-4-methanol corresponds to glycerin acetal (ketal) (1) in the present invention, and 2,2-dimethyl-1,3-dioxan-5-ol corresponds to compound (3) in the present invention.

[0089] [raw materials] The abbreviations for the compounds used in the following experimental and comparative experiments are as follows: Acetone (manufactured by Mitsubishi Chemical Corporation) Glycerin (manufactured by Sakamoto Pharmaceutical Co., Ltd.) UBK08H: Acidic cation exchange resin (product name: DIAION) TM (UBK08H, manufactured by Mitsubishi Chemical Corporation) WA30: Basic anion exchange resin (product name: DIAION) TM WA30 (manufactured by Mitsubishi Chemical Corporation) Dodecylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) NaOH: Sodium hydroxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

[0090] [Evaluation Method] The measurement and evaluation methods used in this experiment are as follows: <Yield of glycerin acetal (ketal) (1) and compound (3)> For the crude reaction solution obtained in Synthesis Example 1, using a gas chromatograph (GC) measuring device and the gas chromatography internal standard method, it was analyzed under the following GC measurement conditions, and glycerin, glycerin acetal (ketal) (1), 2,2-dimethyl-1,3-dioxolan-4-methanol, and compound (3), 2,2-dimethyl-1,3-dioxan-5-ol in the crude reaction solution were quantified, and the yields of glycerin acetal (ketal) (1) and compound (3) were calculated.

[0091] <GC Measurement Conditions> GC device: GC-2014 (high-performance general-purpose gas chromatograph, manufactured by Shimadzu Corporation) Detector: Flame ionization detector (FID) Carrier gas: Helium (column flow rate 3.71 ml / min) Column: Capillary column InterCap Pure-WAX (manufactured by GL Sciences Inc., size: length 60 m × inner diameter 0.32 mm, film thickness 0.50 μm) Column temperature: 50 °C (holding time 5 minutes) → temperature increase at 10 °C / min → 230 °C (holding time 17 minutes) Inlet temperature: 250 °C Detector temperature: 250 °C Sample volume: 0.2 μL (split ratio: 1 / 10) Quantification method: Internal standard method (internal standard: acetonitrile)

[0092] Next, from the amount of glycerin charged and the contents of glycerin, glycerin acetal (ketal) (1), 2-dimethyl-1,3-dioxolan-4-methanol, and compound (3), 2,2-dimethyl-1,3-dioxan-5-ol in the crude reaction solution, the yields of glycerin acetal (ketal) (1) and compound (3) were calculated using the following calculation formula. The evaluation results are shown in Table 1. (Calculation formula) Yield (%) of glycerin acetal (ketal) (1) and compound (3) = [amount of glycerin acetal (ketal) (1) produced (mol) + amount of compound (3) produced (mol)] / [amount of glycerin charged (mol)] × 100

[0093] <Molar ratio of compound (3) to glycerol acetal (ketal) (1)> The concentrations (in mass%) of glycerin acetal (ketal) (1), which is 2,2-dimethyl-1,3-dioxolane-4-methanol, and compound (3), which is 2,2-dimethyl-1,3-dioxan-5-ol, in the crude reaction solution supplied to the distillation apparatus and the bottom liquid in the distillation apparatus were determined using a gas chromatograph (GC) under the aforementioned GC measurement conditions. After converting these concentrations to moles, the molar ratio of compound (3) to glycerin acetal (ketal) (1) ("molar ratio of compound (3) / glycerin acetal (ketal) (1)") was calculated using the following formula.

[0094] The molar ratio of compound (3) to glycerol acetal (ketal) (1) = {amount of compound (3) contained in the bottom liquid (unit: moles)} / {amount of glycerol acetal (ketal) (1) contained in the bottom liquid (unit: moles)}

[0095] For GC measurement, the crude reaction solution and the bottom liquid from the distillation apparatus were used as samples without any pretreatment.

[0096] <Decomposition rate of glycerin acetal (ketal) (1)> The crude reaction solution supplied to the distillation apparatus, as well as the bottom liquid and distillate in the distillation apparatus after distillation, were analyzed using a gas chromatograph (GC) under the aforementioned GC measurement conditions to determine the concentration (in mass%) of 2,2-dimethyl-1,3-dioxolane-4-methanol as glycerol acetal (ketal) (1). After converting this to the amount of substance (in moles), the decomposition rate of glycerol acetal (ketal) (1) was calculated using the following formula.

[0097] Decomposition rate of glycerol acetal (ketal) (1) = 100 - {Amount of substance (in moles) of glycerol acetal (ketal) (1) contained in the bottom liquid and distillate after distillation} / {Amount of substance (in moles) of glycerol acetal (ketal) (1) contained in the crude reaction solution supplied to the distillation apparatus} × 100

[0098] For GC measurement, the bottom liquid from the simple distillation apparatus was used directly without any pretreatment.

[0099] [Synthesis Example 1] 50 mL of acetone-substituted acidic ion exchange resin UBK08H (Mitsubishi Chemical Corporation) was packed into a SUS316 reaction tube with a diameter of 10 / 300 mm. Acetone was passed through the reaction tube at a flow rate of 4 mL / min and glycerin at a flow rate of 1 mL / min, and the reaction tube was heated until the measured temperature reached 50°C, and a stabilization treatment was performed for 1 hour. Next, while maintaining the measured temperature in the reaction tube at 50°C, the acetalization reaction was carried out by passing acetone and glycerin through for 4 hours, and a crude reaction solution containing 2,2-dimethyl-1,3-dioxolane-4-methanol corresponding to glycerin acetal (ketal) (1), 2,2-dimethyl-1,3-dioxan-5-ol corresponding to compound (3), unreacted acetone, unreacted glycerin, and water was obtained from the outlet of the reaction tube. The yield of glycerol acetal (ketal) (1) (1), calculated according to the measurement method described above, was 75% and the pH was 6.91 for the crude reaction solution obtained.

[0100] [Synthesis Example 2] In a 1L flask, 418g of acetone, 166g of glycerin, and 23g of acidic ion exchange resin UBK08H (manufactured by Mitsubishi Chemical Corporation) were added. The reaction solution in the flask was heated to 50°C and then reacted for 2 hours. Next, UBK08H was filtered off to obtain a crude reaction solution containing 2,2-dimethyl-1,3-dioxolane-4-methanol corresponding to glycerin acetal (ketal) (1), 2,2-dimethyl-1,3-dioxan-5-ol corresponding to compound (3), unreacted acetone and unreacted glycerin, and water. The yield of glycerin acetal (ketal) (1) (1), calculated according to the measurement method described above, was 56% and the pH was 6.77 for the crude reaction solution obtained.

[0101] [Experimental Example 1] To the crude reaction solution obtained in Synthesis Example 1, basic ion exchange resin WA30 was added as a basic substance so that its content in the crude reaction solution was 0.5% by mass, and the mixture was stirred with a stirring bar for 30 minutes. After stirring, the anion exchange resin was filtered off, and the pH of the filtered crude reaction solution was measured to be 8.71. Next, 100 g of the filtered crude reaction solution was placed in a simple distillation apparatus equipped with a thermometer, electromagnetic stirrer, reflux tubing, and condenser, and set in an oil bath. The crude reaction solution in the simple distillation apparatus was then heated at atmospheric pressure until its temperature reached 120°C while distilling off acetone and water, which are light-boiling components. The molar concentrations of glycerin acetal (ketal) (1) and compound (3) were determined in the bottom liquid of the simple distillation apparatus. The molar ratio of compound (1) to the total of glycerin acetal (1) and compound (3) before and after distillation (hereinafter referred to as "molar ratio (1) / [(1)+(3)]"), the molar ratio of compound (3) to glycerin acetal (ketal) (1) before and after distillation (hereinafter referred to as "molar ratio (3) / (1)"), the decomposition rate (%) of glycerin acetal (ketal) (1), and the decomposition rate (%) of compound (3) were calculated. The obtained evaluation results are shown in Table 1.

[0102] [Experimental Examples 2-5] In Experimental Example 1, the bottom liquid was obtained from a simple distillation apparatus using the same procedure as in Experimental Example 1, except that the distillation temperature was changed to 120°C as shown in Table 1. The evaluation results of the obtained bottom liquid are shown in Table 1.

[0103] [Table 1]

[0104] Table 1 and Figure 2 show the following trends in the bottom liquor of the simple distillation apparatus in Experimental Examples 1-5. The higher the distillation temperature, the lower the molar ratio (3) / (1) becomes, and the higher the decomposition rate (%) of compound (3), indicating that compound (3) is decomposed during distillation purification. • The higher the distillation temperature, the higher the molar ratio (1) / [(1)+(3)], which improves the purity of glycerin acetal (ketal) (1).

[0105] Therefore, it is expected that high-purity glycerin acetal (ketal) (1) can be obtained by adjusting the distillation temperature so that the molar ratio (3) / (1) is less than or equal to a predetermined value.

[0106] On the other hand, since the decomposition rate of glycerin acetal (ketal) (1) tends to increase with higher distillation temperatures, it is expected that high-purity glycerin acetal (ketal) (1) can be obtained while maintaining a good yield of glycerin acetal (ketal) (1) by using a distillation temperature in the range of 120°C to 160°C, preferably in the range of 130°C to 150°C.

[0107] [Experimental Example 6] To the crude reaction solution obtained in Synthesis Example 2, basic ion exchange resin WA30 was added as a basic substance so that its content ratio in the crude reaction solution was 6% by mass, and the mixture was stirred with a stirring bar for 30 minutes. After stirring, the pH of the filtered crude reaction solution obtained by filtering off the anion exchange resin was measured to be 8.71. Next, the crude reaction mixture was placed in a multi-stage distillation apparatus equipped with a thermometer, electromagnetic stirrer, vacuum pump, Aldershaw distillation column with 20 theoretical stages, condenser, and distillation receiver. The crude reaction mixture was distilled at 130-146°C until the distillation of acetone decreased, and the bottom liquid was obtained. Subsequently, the pressure inside the distillation apparatus was reduced to 8 kPa at the top of the column, and heating was restarted in an oil bath. The distillate was collected while heating the liquid temperature to 130-147°C. GC analysis revealed that the molar ratios (3) / (1) before and after distillation were 0.026 and 0.010, respectively, the decomposition rate of glycerin acetal (ketal) (1) was 26%, and the decomposition rate of compound (3) was 71%.

[0108] Although the present invention has been described above with reference to specific embodiments, each embodiment is presented as an example and does not limit the scope of the present invention. Each embodiment described herein can be modified in various ways without departing from the spirit of the invention and can be combined with features described in other embodiments to the extent that is feasible. [Industrial applicability]

[0109] The present invention's method for producing glycerin acetal (ketal) offers a significant industrial advantage: it allows for the production of high-purity glycerin acetal (ketal) with lower impurity levels compared to conventional purification techniques. [Explanation of Symbols]

[0110] 1 Reactor 2. Filter 3 pH adjustment reactor 4. Filter 5. First distillation column 6. Second distillation column 7. Acetone 8. Glycerin 9. Acetone 10 water 11. Glycerin acetal (ketal)

Claims

1. A reaction step in which glycerin is reacted with a carbonyl compound represented by the following general formula (2) to obtain a crude reaction solution containing glycerin acetal and / or glycerin ketal (1) represented by the following general formula (1), The process includes a distillation step in which the crude reaction solution is purified by distillation to obtain glycerin acetal and / or glycerin ketal (1). A method for producing glycerin acetal and / or glycerin ketal, A method for producing glycerin acetal and / or glycerin ketal, comprising distilling and purifying the bottom liquid obtained in the distillation step at a distillation temperature such that the molar ratio of compound (3) represented by the following general formula (3) to glycerin acetal and / or glycerin ketal (1) is less than or equal to a predetermined value. 【Chemistry 1】 [In formula (2), R １ and R ２ R represents a hydrogen atom, a linear or branched alkyl or alkenyl group having 1 to 22 carbon atoms, or an aryl group having 6 to 30 carbon atoms that may be substituted with an alkyl group, and R may be the same or different. １ and R ２ They may be joined together to form a ring. 【Chemistry 2】 [In formula (1), R １ and R ２ These are R in equation (2), respectively. １ and R ２ This is synonymous with [the above]. 【Transformation 3】 〔In formula (3), R １ and R ２ are synonymous with R １ and R ２ in formula (2), respectively.〕

2. The method for producing glycerin acetal and / or glycerin ketal according to claim 1, wherein in the distillation step, the crude reaction solution is distilled and purified to distill off unreacted carbonyl compounds to obtain a bottom liquor containing glycerin acetal and / or glycerin ketal (1).

3. A method for producing glycerin acetal and / or glycerin ketal according to claim 1, wherein the distillation temperature is within a predetermined range such that the molar ratio of compound (3) represented by the general formula (3) to glycerin acetal and / or glycerin ketal (1) in the bottom liquid obtained in the distillation step is within a range of 0 to 0.

03.

4. A method for producing glycerin acetal and / or glycerin ketal according to claim 1, wherein the distillation temperature in the distillation step is within the range of 115°C to 170°C.

5. A method for producing glycerin acetal and / or glycerin ketal according to claim 1, wherein the distillation temperature in the distillation step is within the range of 120°C to 160°C.

6. The method for producing glycerin acetal and / or glycerin ketal according to claim 1, wherein the reaction step involves carrying out the reaction between glycerin and the carbonyl compound (2) in the presence of an acid.

7. A glycerin acetal and / or glycerin ketal-containing composition comprising a glycerin acetal and / or glycerin ketal (1) represented by the following general formula (1) and a compound (3) represented by the following general formula (3), A glycerin acetal and / or glycerin ketal-containing composition in which the molar ratio of compound (3) to glycerin acetal and / or glycerin ketal (1) is in the range of 0 to 0.

03. 【Chemistry 4】 [In formula (1), R １ and R ２ R represents a hydrogen atom, a linear or branched alkyl or alkenyl group having 1 to 22 carbon atoms, or an aryl group having 6 to 30 carbon atoms that may be substituted with an alkyl group, and these may be the same or different. １ and R ２ They may be joined together to form a ring. 【Transformation 5】 [In formula (3), R １ and R ２ These are R in equation (2), respectively. １ and R ２ This is synonymous with [the above].

8. The glycerin acetal and / or glycerin ketal-containing composition according to claim 7, wherein the content of the glycerin acetal and / or glycerin ketal (1) is 70% by mass or more based on 100% of the total mass of the glycerin acetal and / or glycerin ketal-containing composition.

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