Product 1,3-butylene glycol

Abstract

Provided is a 1,3-butylene glycol product such that, when the relative retention time of n-dodecane is taken to be 1.00 in gas chromatography analysis carried out using a splitless injection method under specific conditions, the sum of concentrations in terms of n-dodecane of peaks excluding a peak of an acetal product of methyl ethyl ketone and 1,3-butylene glycol is 25 ppm or less, among peaks that appear within a relative retention time of 0.80-0.99.

Description

[Technical Field]

[0001] The present invention relates to 1,3-butylene glycol, a product useful as a raw material for synthetic resins, surfactants, solvents, antifreezes, cosmetic ingredients, etc. [Background technology]

[0002] 1,3-butylene glycol is a viscous, colorless, transparent, low-odor liquid with a boiling point of 208°C and excellent chemical stability. For this reason, 1,3-butylene glycol is used as a raw material for various synthetic resins and surfactants. Taking advantage of its excellent moisture absorption properties, low volatility, and low toxicity, 1,3-butylene glycol is also used as a material for cosmetics, moisture absorbents, high-boiling point solvents, and antifreeze. In particular, in recent years, demand for 1,3-butylene glycol has grown significantly in the cosmetics industry due to its low toxicity and irritation properties and excellent properties as a moisturizer.

[0003] Patent Document 1 discloses 1,3-butylene glycol with a low odor, and as a method for obtaining 1,3-butylene glycol with a low odor, it discloses a method for producing 1,3-butylene glycol in which crude 1,3-butylene glycol is purified by a hydrogenation treatment. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2020-512351 Summary of the Invention [Problem to be solved by the invention]

[0005] Here, for example, when 1,3-butylene glycol is used in the field of cosmetics, it is applied directly to the skin, but there is a problem in that the skin sensitization is not sufficiently reduced in the 1,3-butylene glycol obtained by the method described in Patent Document 1. Furthermore, when 1,3-butylene glycol is used in the field of cosmetics, it is sometimes blended by heating under basic conditions, but there is also a problem in that the 1,3-butylene glycol becomes discolored when mixed and prepared under basic conditions.

[0006] In view of the above circumstances, an object of the present invention is to provide a 1,3-butylene glycol product that has reduced skin sensitization and is less likely to discolor under basic conditions. [Means for solving the problem]

[0007] As a result of extensive research, the present inventors have found that the above-mentioned problems can be solved by suppressing the concentration of specific impurities contained in 1,3-butylene glycol to a certain level or less, and have completed the present invention.

[0008] That is, the present invention is as follows: In this specification, ppm indicates ppm by mass unless otherwise specified. [1] In gas chromatography analysis by splitless injection under the following conditions, when the relative retention time of n-dodecane is taken as 1.00, the sum of the concentrations of peaks appearing in the relative retention time range of 0.80 to 0.99, excluding the peaks of the acetal product of methyl ethyl ketone and 1,3-butylene glycol, converted into n-dodecane, is 25 ppm or less. [Gas chromatographic analysis conditions] Analytical column: Column (length 30 m × inner diameter 0.25 mm × film thickness 0.25 μm) whose stationary phase is (50% cyanopropyl-phenyl)dimethylpolysiloxane Temperature rise conditions: After holding at 50°C for 5 minutes, the temperature was raised from 50°C to 135°C at 10°C / min, held at 135°C for 9 minutes, then raised from 135°C to 220°C at 15°C / min, and held at 220°C for 12 minutes. Sample introduction temperature: 220℃ Carrier gas: Nitrogen Column gas flow rate: 0.5 mL / min Detector and detection temperature: Hydrogen flame ionization detector (FID), 220°C Control Mode: Constant Flow Split ratio: Splitless Injection port vent purge: 60 mL / min Purge start time: 1 minute Sample injection conditions: 0.6 μL Sample preparation: The internal standard substance n-dodecane is diluted with 2-propanol to 24 ppm to prepare an internal standard solution, and then 0.5 g of the product 1,3-butylene glycol is mixed with 0.1 g of the internal standard solution to prepare a sample. Calculation of the sum of n-dodecane-equivalent concentrations: When the relative retention time of n-dodecane detected under the gas chromatography analysis conditions is set to 1.00, the total area value (detected peak area value) of peaks detected in the range of relative retention times of 0.80 to 0.99, excluding the peak of the acetal of methyl ethyl ketone and 1,3-butylene glycol, is converted into the sum of n-dodecane-equivalent concentrations using the following formula (1). Sum of n-dodecane converted concentration (ppm) = n-dodecane concentration (ppm) × detected peak area value / n-dodecane area value (1) Here, the n-dodecane concentration (ppm) is a value calculated using the following formula (2). n-Dodecane concentration (ppm) = (mass of n-dodecane in sample / mass of product 1,3-butylene glycol in sample) × 10 6 (2) [2] In gas chromatography analysis using the splitless injection method under the following conditions, the sum of the n-dodecane-equivalent concentrations of the 2-ethylcrotonaldehyde peak and the peak of the acetal of n-butylaldehyde and 1,3-butylene glycol is 20 ppm or less. [Gas chromatographic analysis conditions] Analytical column: Column (length 30 m × inner diameter 0.25 mm × film thickness 0.25 μm) whose stationary phase is (50% cyanopropyl-phenyl)dimethylpolysiloxane Temperature rise conditions: After holding at 50°C for 5 minutes, the temperature was raised from 50°C to 135°C at 10°C / min, held at 135°C for 9 minutes, then raised from 135°C to 220°C at 15°C / min, and held at 220°C for 12 minutes. Sample introduction temperature: 220℃ Carrier gas: Nitrogen Column gas flow rate: 0.5 mL / min Detector and detection temperature: Hydrogen flame ionization detector (FID), 220°C Control Mode: Constant Flow Split ratio: Splitless Injection port vent purge: 60 mL / min Purge start time: 1 minute Sample injection conditions: 0.6 μL Sample preparation: The internal standard substance n-dodecane is diluted with 2-propanol to 24 ppm to prepare an internal standard solution, and then 0.5 g of the product 1,3-butylene glycol is mixed with 0.1 g of the internal standard solution to prepare a sample. Calculation of the sum of n-dodecane-equivalent concentrations: The total area value (detected peak area value) of the 2-ethylcrotonaldehyde peak and the peak of the acetal of n-butylaldehyde and 1,3-butylene glycol detected under the gas chromatography analysis conditions is converted into the sum of n-dodecane-equivalent concentrations using the following formula (1). Sum of n-dodecane converted concentration (ppm) = n-dodecane concentration (ppm) × detected peak area value / n-dodecane area value (1) Here, the n-dodecane concentration (ppm) is a value calculated using the following formula (2). n-Dodecane concentration (ppm) = (mass of n-dodecane in sample / mass of product 1,3-butylene glycol in sample) × 10 6 (2) [3] The 1,3-butylene glycol product according to [1] or [2] above, in which the area ratio of the 1,3-butylene glycol peak is 99.5% or more in gas chromatography analysis under the following conditions: [Gas chromatographic analysis conditions] Analytical column: Column with polyethylene glycol stationary phase (length 30 m × inner diameter 0.25 mm × film thickness 0.25 μm) Heating conditions: Heat from 80°C to 230°C at 5°C / min, then hold at 230°C for 10 minutes Sample introduction temperature: 250℃ Carrier gas: Nitrogen Column gas flow rate: 0.5 mL / min Detector and detection temperature: Hydrogen flame ionization detector (FID), 250°C Control Mode: Constant Flow Split ratio: 50:1 Sample injection conditions: 1 μL [Effects of the Invention]

[0009] The present invention can provide a 1,3-butylene glycol product that has reduced skin sensitization and is less likely to discolor under basic conditions. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail. The present invention is not limited to the following description, and can be practiced in various modifications within the scope of the gist thereof. In this embodiment, the final product 1,3-butylene glycol is also referred to as "product 1,3-butylene glycol," and 1,3-butylene glycol as a raw material or an intermediate on the way to the final product is also referred to as "crude 1,3-butylene glycol."

[0011] [Production method of 1,3-butylene glycol] (raw materials) The crude 1,3-butylene glycol used as a raw material when producing the product 1,3-butylene glycol in this embodiment is not particularly limited, but examples include 1,3-butylene glycol that is skin sensitizing and 1,3-butylene glycol that discolors under basic conditions.

[0012] From the viewpoint of reducing the amount of impurities contained in the 1,3-butylene glycol product, the area ratio of the peak of 1,3-butylene glycol in gas chromatography analysis 2 under specific conditions described below for crude 1,3-butylene glycol as a raw material is preferably 99.5% or more, more preferably 99.6% or more, and even more preferably 99.7% or more.

[0013] The method for producing crude 1,3-butylene glycol as a raw material is not particularly limited. For example, crude 1,3-butylene glycol can be produced by known methods (see, for example, Japanese Patent Publication No. 3-80139 and Japanese Patent Application Laid-Open No. 7-258129). Furthermore, any of those produced by the liquid-phase hydrogen reduction of acetaldol, the hydrolysis of 1,3-butylene oxide, or the fermentation method using microorganisms or fungi, or a mixture thereof, may be used. Among these, the use of a reaction product obtained by the liquid-phase hydrogen reduction of acetaldol is preferred because the effects of the present invention tend to be more pronounced. In the liquid-phase hydrogen reduction of acetaldol, low-boiling compounds such as acetaldehyde, n-butylaldehyde, crotonaldehyde, and methyl vinyl ketone, as well as condensates thereof, which are considered to be odor-causing substances, are produced as by-products, such as acetaldehyde, n-butylaldehyde, crotonaldehyde, and methyl vinyl ketone, as well as acetals of these compounds with 1,3-butylene glycol and acetals of these compounds with ethanol, which are difficult to sufficiently remove even by distillation. Furthermore, in heating processes such as distillation, there is also the problem that acetaldehyde and n-butylaldehyde undergo a condensation reaction, resulting in the by-production of 2-ethylcrotonaldehyde, or an acetal compound of n-butylaldehyde and 1,3-butylene glycol.The odor-causing substances mentioned above include substances that are odor sources themselves, as well as substances that become odorous due to changes over time, heat treatment, chemical treatment, etc.

[0014] Alternatively, the crude 1,3-butylene glycol may be obtained by removing by-products such as alcohols (e.g., ethanol), salts, and water from the reaction product obtained by the liquid-phase hydrogen reduction of acetaldol. The method for removing these components is not limited, and methods such as distillation and adsorption can be used.

[0015] Alternatively, the fraction obtained by removing ethanol and the like may be further subjected to one or more known purification steps, such as a step of adding an alkali metal compound (e.g., sodium hydroxide, potassium hydroxide, etc.) and subjecting it to heat treatment (see Japanese Patent No. 4559625, etc.), and the like, before being used as crude 1,3-butylene glycol. Crude 1,3-butylene glycol is also available as a commercially available product.

[0016] (hydrogenation process) The method for producing the 1,3-butylene glycol product in this embodiment includes a step of hydrogenating crude 1,3-butylene glycol using a catalyst (hydrogenation step). More specifically, the hydrogenation step is a treatment step in which crude 1,3-butylene glycol is reduced by hydrogen by passing crude 1,3-butylene glycol and hydrogen gas through a catalyst layer filled with a catalyst. It is presumed that by subjecting crude 1,3-butylene glycol to hydrogenation treatment using a catalyst, 2-ethylcrotonaldehyde, which is a substance that causes coloration and skin sensitization under basic conditions, and an acetal compound of n-butylaldehyde and 1,3-butylene glycol are hydrogenated or hydrolyzed. However, the mechanism of the present invention is not limited to the above.

[0017] The hydrogenation step can be carried out in either the gas phase or the liquid phase, and is preferably carried out in the liquid phase. When carried out in the liquid phase, the reaction temperature can be lowered compared to when carried out in the gas phase, thereby suppressing the thermal decomposition reaction of 1,3-butylene glycol. In the hydrogenation step, a Pd / C catalyst is preferably used as the catalyst. The Pd / C catalyst refers to a catalyst in which palladium is dispersed and supported on activated carbon as a support. The loading rate of palladium dispersed and supported on activated carbon is not particularly limited, but is preferably 0.1 to 30%, more preferably 0.2 to 10%, and particularly preferably 0.4 to 1%. The shape of the Pd / C catalyst is also not particularly limited, and may be in the form of powder, pellets, or the like.

[0018] The reaction temperature in the hydrogenation treatment step is not particularly limited, and when the heat treatment step described below is carried out, it is preferably 100 to 150°C, more preferably 110 to 145°C, and even more preferably 125 to 135°C. When the heat treatment step described below is not carried out, it is preferably above 120°C and up to 150°C, more preferably 125 to 135°C. If the reaction temperature in the hydrogenation treatment step is 150°C or lower, the thermal decomposition reaction of 1,3-butylene glycol will not proceed and an increase in high-boiling components will tend to be suppressed, whereas if the temperature is 100°C or higher (over 120°C if the heat treatment step is not performed), the hydrogenation or hydrocracking of 2-ethylcrotonaldehyde and the acetal of n-butylaldehyde with 1,3-butylene glycol will tend to proceed.

[0019] The hydrogen pressure in the hydrogenation step is not particularly limited and is preferably 0.4 to 1.0 MPa, more preferably 0.5 to 0.9 MPa, and even more preferably 0.6 to 0.8 MPa. If the hydrogen pressure in the hydrogenation step is 1.0 MPa or less, there is a tendency for equipment costs to be reduced because a thick-walled device with sufficient strength as a high-pressure gas facility is not required, while if it is 0.4 MPa or more, there is a tendency for the progress of hydrogenation or hydrogenolysis of 2-ethylcrotonaldehyde and the acetal compound of n-butylaldehyde and 1,3-butylene glycol to be promoted.

[0020] The method for producing the product 1,3-butylene glycol in this embodiment is not particularly limited as long as it includes a step of hydrogenating crude 1,3-butylene glycol using a catalyst (hydrogenation step), and may further include one or more steps of a step of heat-treating crude 1,3-butylene glycol (heat treatment step) and a step of distilling off low-boiling components from crude 1,3-butylene glycol (low-boiling point distillation step). The order of these steps is not particularly limited, but from the viewpoint of more pronounced effects of the present invention, it is preferable to carry out the heat treatment step, hydrogenation step, and low-boiling point distillation step in that order. Each step will be described below.

[0021] (heat treatment process) The heat treatment step in the method for producing the 1,3-butylene glycol product of this embodiment is a step of heat treating crude 1,3-butylene glycol. By heat treating crude 1,3-butylene glycol, acetaldehyde and n-butylaldehyde, which are substances that cause the by-production of 2-ethylcrotonaldehyde, are consumed by a condensation reaction or the like, or n-butylaldehyde, which is the substance that causes the by-production of an acetal of n-butylaldehyde and 1,3-butylene glycol, is consumed. Therefore, in subsequent steps involving heating, such as a distillation step, the amount of 2-ethylcrotonaldehyde and acetals of n-butylaldehyde and 1,3-butylene glycol produced is reduced. Furthermore, by first producing 2-ethylcrotonaldehyde or an acetal of n-butylaldehyde and 1,3-butylene glycol in the heat treatment step and then performing a hydrogenation treatment, the causative substances tend to be efficiently decomposed by hydrogenation or hydrocracking. However, the mechanism of the present invention is not limited to the above.

[0022] The heating time in the heat treatment step is not particularly limited, but is preferably 20 minutes to 9 hours, more preferably 1 to 6 hours, and even more preferably 1 to 3 hours. If the heating time is 20 minutes or more, the consumption of acetaldehyde and n-butylaldehyde by the condensation reaction tends to proceed sufficiently, while if it is 9 hours or less, an increase in the cost required for the heat treatment tends to be suppressed.

[0023] The heating temperature in the heat treatment step is not particularly limited, but is preferably 80 to 200° C., more preferably 90 to 120° C., and even more preferably 100 to 110° C. If the heating temperature is 80° C. or higher, the condensation reaction of acetaldehyde and n-butylaldehyde tends to proceed, while if the heating temperature is 200° C. or lower, the thermal decomposition reaction of 1,3-butylene glycol is inhibited, and impurities tend to be reduced.

[0024] The heat treatment device used in the heat treatment step is not particularly limited, and examples thereof include continuous tubular, batch tank, and continuous tank types, with the batch tank type being particularly preferred from the viewpoint of stirring efficiency.

[0025] (low boiling point distillation process) The low-boiling point removal distillation step in the method for producing the 1,3-butylene glycol product of this embodiment is, for example, a step of distilling off low-boiling point components from a fraction containing a large amount of 1,3-butylene glycol obtained in the hydrogenation treatment step. Examples of distillation apparatuses used in the low-boiling point removal distillation step include perforated plate columns, bubble cap columns, and packed columns. Among these, a packed column having 7 to 40 theoretical plates is preferred. One or more distillation columns may be used. Regarding distillation conditions, the pressure at the top of the distillation column is preferably 1 to 20 kPa, and the temperature at the bottom of the distillation column is preferably 100 to 160°C, more preferably 110 to 140°C. A specific embodiment of the low-boiling point removal distillation step may be a continuous method or a batch method. For example, a continuous method may include a method in which a fraction containing a large amount of 1,3-butylene glycol is continuously supplied to the top of a distillation column, and a fraction containing a large amount of low-boiling point components is continuously withdrawn from the top of the column, while a fraction containing a larger amount of 1,3-butylene glycol is continuously withdrawn from the bottom of the column.

[0026] [Product: 1,3-butylene glycol] As one embodiment of the present invention, there is provided a product, 1,3-butylene glycol, in which, when the relative retention time of n-dodecane is taken as 1.00 in gas chromatography analysis by a splitless injection method under the following conditions, the sum of the concentrations of peaks, calculated as n-dodecane, that appear in the relative retention time range of 0.80 to 0.99, excluding peaks of acetals of methyl ethyl ketone and 1,3-butylene glycol, is 25 ppm or less. [Gas chromatographic analysis conditions] Analytical column: Column (length 30 m × inner diameter 0.25 mm × film thickness 0.25 μm) whose stationary phase is (50% cyanopropyl-phenyl)dimethylpolysiloxane Temperature rise conditions: After holding at 50°C for 5 minutes, the temperature was raised from 50°C to 135°C at 10°C / min, held at 135°C for 9 minutes, then raised from 135°C to 220°C at 15°C / min, and held at 220°C for 12 minutes. Sample introduction temperature: 220℃ Carrier gas: Nitrogen Column gas flow rate: 0.5 mL / min Detector and detection temperature: Hydrogen flame ionization detector (FID), 220°C Control Mode: Constant Flow Split ratio: Splitless Injection port vent purge: 60 mL / min Purge start time: 1 minute Sample injection conditions: 0.6 μL Sample preparation: The internal standard substance n-dodecane is diluted with 2-propanol to 24 ppm to prepare an internal standard solution, and then 0.5 g of the product 1,3-butylene glycol is mixed with 0.1 g of the internal standard solution to prepare a sample. Calculation of the sum of n-dodecane-equivalent concentrations: When the relative retention time of n-dodecane detected under the gas chromatography analysis conditions is set to 1.00, the total area value (detected peak area value) of peaks detected in the range of relative retention times of 0.80 to 0.99, excluding the peak of the acetal of methyl ethyl ketone and 1,3-butylene glycol, is converted into the sum of n-dodecane-equivalent concentrations using the following formula (1). Sum of n-dodecane converted concentration (ppm) = n-dodecane concentration (ppm) × detected peak area value / n-dodecane area value (1) Here, the n-dodecane concentration (ppm) is a value calculated using the following formula (2). n-Dodecane concentration (ppm) = (mass of n-dodecane in sample / mass of product 1,3-butylene glycol in sample) × 10 6 (2) Here, as the analytical column, for example, DB-225 (length 30 m×inner diameter 0.25 mm×film thickness 0.25 μm, stationary phase: (50% cyanopropyl-phenyl)dimethylpolysiloxane) manufactured by Agilent Technologies can be used.

[0027] In the case of the product 1,3-butylene glycol, which is one of the present embodiments, the effects of the present invention tend to be more pronounced, so that the sum of the n-dodecane-equivalent concentrations of peaks appearing in the relative retention time range of 0.80 to 0.99, excluding the peaks of the acetal of methyl ethyl ketone and 1,3-butylene glycol, is 25 ppm or less, preferably 23 ppm or less, and more preferably 21 ppm or less.

[0028] Furthermore, as one of the present embodiments, there is provided a product, 1,3-butylene glycol, in which, in gas chromatography analysis by a splitless injection method under the following conditions, the sum of the concentrations, calculated as n-dodecane, of the peaks of 2-ethylcrotonaldehyde and the peaks of an acetal of n-butylaldehyde and 1,3-butylene glycol is 20 ppm or less. [Gas chromatographic analysis conditions] Analytical column: Column (length 30 m × inner diameter 0.25 mm × film thickness 0.25 μm) whose stationary phase is (50% cyanopropyl-phenyl)dimethylpolysiloxane Temperature rise conditions: After holding at 50°C for 5 minutes, the temperature was raised from 50°C to 135°C at 10°C / min, held at 135°C for 9 minutes, then raised from 135°C to 220°C at 15°C / min, and held at 220°C for 12 minutes. Sample introduction temperature: 220℃ Carrier gas: Nitrogen Column gas flow rate: 0.5 mL / min Detector and detection temperature: Hydrogen flame ionization detector (FID), 220°C Control Mode: Constant Flow Split ratio: Splitless Injection port vent purge: 60 mL / min Purge start time: 1 minute Sample injection conditions: 0.6 μL Sample preparation: The internal standard substance n-dodecane is diluted with 2-propanol to 24 ppm to prepare an internal standard solution, and then 0.5 g of the product 1,3-butylene glycol is mixed with 0.1 g of the internal standard solution to prepare a sample. Calculation of the sum of n-dodecane-equivalent concentrations: The total area value (detected peak area value) of the 2-ethylcrotonaldehyde peak and the peak of the acetal of n-butylaldehyde and 1,3-butylene glycol detected under the gas chromatography analysis conditions is converted into the sum of n-dodecane-equivalent concentrations using the following formula (1). Sum of n-dodecane converted concentration (ppm) = n-dodecane concentration (ppm) × detected peak area value / n-dodecane area value (1) Here, the n-dodecane concentration (ppm) is a value calculated using the following formula (2). n-Dodecane concentration (ppm) = (mass of n-dodecane in sample / mass of product 1,3-butylene glycol in sample) × 10 6 (2) Here, as the analytical column, for example, DB-225 (length 30 m×inner diameter 0.25 mm×film thickness 0.25 μm, stationary phase: (50% cyanopropyl-phenyl)dimethylpolysiloxane) manufactured by Agilent Technologies can be used.

[0029] In the case of the product 1,3-butylene glycol, which is one of the present embodiments, the effects of the present invention tend to be more pronounced, so the sum of the n-dodecane-equivalent concentrations of the peak of 2-ethylcrotonaldehyde and the peak of the acetal of n-butylaldehyde and 1,3-butylene glycol is 20 ppm or less, preferably 16 ppm or less, and more preferably 12 ppm or less.

[0030] In the product 1,3-butylene glycol of this embodiment, the area ratio of the 1,3-butylene glycol peak in gas chromatography analysis under the following conditions is preferably 99.5% or more, more preferably 99.7% or more, even more preferably 99.8% or more, and particularly preferably 99.9% or more, depending on the required product quality. The "area ratio" of a peak refers to the ratio of the area of ​​a specific peak to the sum of the areas of all peaks appearing in the chart. Furthermore, "all peaks" refers to all peaks that appear when the analysis is continued until the relative retention time reaches 2.2, assuming that the relative retention time of the 1,3-butylene glycol peak is 1.0, and then stopped. Having the area ratio of the peaks within the above range tends to further reduce odor generation and skin sensitization. [Gas chromatographic analysis conditions] Analytical column: Column with polyethylene glycol stationary phase (length 30 m × inner diameter 0.25 mm × film thickness 0.25 μm) Heating conditions: Heat from 80°C to 230°C at 5°C / min, then hold at 230°C for 10 minutes Sample introduction temperature: 250℃ Carrier gas: Nitrogen Column gas flow rate: 0.5 mL / min Detector and detection temperature: Hydrogen flame ionization detector (FID), 250°C Control Mode: Constant Flow Split ratio: 50:1 Sample injection conditions: 1 μL Here, as the analytical column, for example, DB-WAX manufactured by Agilent Technologies (a column whose stationary phase is polyethylene glycol; length 30 m × inner diameter 0.25 mm × film thickness 0.25 μm) can be used.

[0031] [Skin sensitization test] The product 1,3-butylene glycol in this embodiment has reduced skin sensitization. Skin sensitization here refers to the induction of an allergic reaction after skin contact. While laboratory animals have typically been used to evaluate skin sensitization, in 2015 the OECD guideline TG442C adopted the peptide binding assay (DPRA), an in chemistry test, as an alternative test from the perspective of animal welfare. In this embodiment, skin sensitization is evaluated using a test that mutatis mutandis applies the DPRA. More specifically, skin sensitization is evaluated according to the method described in the practical examples below.

[0032] [Coloration under basic conditions] The 1,3-butylene glycol product of this embodiment has the advantage of being less likely to discolor under basic conditions. Discoloration under basic conditions can be evaluated by the method (basic discoloration test) described in the Examples below. When the 1,3-butylene glycol product of this embodiment is evaluated by this method, the color saturation (b*) of the Beastar color system (JIS Z 8729) is not particularly limited, but is preferably 4.0 or less, more preferably 3.8 or less, and particularly preferably 3.5 or less, as an average value of three measurements. [Example]

[0033] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples. The crude 1,3-butylene glycol used as the raw material was obtained by hydrogenating and reducing acetaldol, followed by removing low-boiling components and high-boiling components (distillation to remove high-boiling components contained in the crude 1,3-butylene glycol). Various analyses and evaluations were carried out as follows. In gas chromatography analysis 2 under the following conditions, the peak area ratio of the crude 1,3-butylene glycol used as the raw material was 99.6%.

[0034] [Gas Chromatography Analysis 1] The 1,3-butylene glycol products obtained in Examples 1 to 3 and Comparative Example 1 were subjected to gas chromatography analysis 1 according to the following method. (Gas Chromatography Analysis 1 Conditions) Analytical equipment: Agilent Technologies 7890A Gas Chromatography System Analytical column: Agilent Technologies DB-225 (length 30 m × inner diameter 0.25 mm × film thickness 0.25 μm, stationary phase: (50% cyanopropyl-phenyl)dimethylpolysiloxane) Temperature rise conditions: After holding at 50°C for 5 minutes, the temperature was raised from 50°C to 135°C at 10°C / min, held at 135°C for 9 minutes, then raised from 135°C to 220°C at 15°C / min, and held at 220°C for 12 minutes. Sample introduction temperature: 220℃ Carrier gas: Nitrogen Column gas flow rate: 0.5 mL / min Detector and detection temperature: Hydrogen flame ionization detector (FID), 220°C Control Mode: Constant Flow Split ratio: Splitless Injection port vent purge: 60 mL / min Purge start time: 1 minute Sample injection conditions: 0.6 μL Sample preparation: An internal standard solution was prepared by diluting n-dodecane (GL Sciences) to 24 ppm with 2-propanol (Fujifilm Wako Pure Chemical Industries, Ltd.). A sample was prepared by mixing 0.5 g of 1,3-butylene glycol and 0.1 g of the internal standard solution. Calculation of the sum of n-dodecane-equivalent concentrations: When the relative retention time of n-dodecane detected under the above measurement conditions was taken as 1.00, the total area value (detected peak area value) of peaks detected at relative retention times of 0.80 to 0.99, excluding the peak of the acetal of methyl ethyl ketone and 1,3-butylene glycol, was converted into the sum of n-dodecane-equivalent concentrations using the following formula (1), and this was defined as impurity concentration A. In addition, the total area value (detected peak area value) of the peak of 2-ethylcrotonaldehyde and the peak of the acetal of n-butylaldehyde and 1,3-butylene glycol was converted into the sum of n-dodecane-equivalent concentrations using the following formula (1), and this was defined as impurity concentration B. Sum of n-dodecane converted concentration (ppm) = n-dodecane concentration (ppm) × detected peak area value / n-dodecane area value (1) Here, the n-dodecane concentration (ppm) is a value calculated using the following formula (2). n-Dodecane concentration (ppm) = (mass of n-dodecane in sample / mass of product 1,3-butylene glycol in sample) × 10 6 (2)

[0035] [Gas Chromatography Analysis 2] The crude 1,3-butylene glycol used as the raw material in Examples 1 to 3 and Comparative Example 1 and the product 1,3-butylene glycol obtained in Examples 1 to 3 and Comparative Example 1 were subjected to gas chromatography analysis 2 according to the following method. (Gas Chromatography Analysis 2 Conditions) Analytical equipment: Agilent Technologies 7890B Gas Chromatography System Analytical column: Agilent Technologies DB-WAX (column with polyethylene glycol as the stationary phase; length 30 m × inner diameter 0.25 mm × film thickness 0.25 μm) Heating conditions: Heat from 80°C to 230°C at 5°C / min, then hold at 230°C for 10 minutes Sample introduction temperature: 250℃ Carrier gas: Nitrogen Column gas flow rate: 0.5 mL / min Detector and detection temperature: Hydrogen flame ionization detector (FID), 250°C Control Mode: Constant Flow Split ratio: 50:1 Sample injection conditions: 1 μL

[0036] [Skin sensitization test] The 1,3-butylene glycol products obtained in Examples 1 to 3 and Comparative Example 1 were evaluated for skin sensitization according to the following method. (Conditions for skin sensitization testing) A 0.05M phosphate buffer solution containing 0.667 mM of the peptide (hereafter referred to as the peptide solution) was prepared by mixing 15 mg of a cysteine-containing peptide for DPRA (Scrum) with 30 mL of 0.05M phosphate buffer. One hour after the peptide solution was prepared, 750 μL of the peptide solution and 250 μL of acetonitrile were added to three amber HPLC sample bottles to prepare three reference solutions. Two hours after the reference solution was prepared, a sample solution was prepared by adding 750 μL of the peptide solution, 200 μL of acetonitrile, and 50 μL of 1,3-butylene glycol to another amber HPLC sample bottle (sample solution 1). Four and six hours after the preparation of the reference solution, sample solutions were prepared in the same manner (sample solution 2 and sample solution 3). The three standard solutions and the sample solutions (sample solution 1, sample solution 2, and sample solution 3) were each measured by HPLC analysis 72±2 hours after preparation, and the average peak heights of the peptides in the standard and sample solutions were calculated three times. The peptide reduction rate was calculated from the calculated three average values ​​using the following formula (3), and this was used as the evaluation result. Peptide reduction rate (%) = (average of three peptide peak heights in the sample solution / average of three peptide peak heights in the reference solution) × 100 (3) From the viewpoint of reproducibility, the test was carried out on the same day for the sample solution of the 1,3-butylene glycol product of Comparative Example 1, which was used as the reference, and for each sample solution of the 1,3-butylene glycol products of Examples 1 to 3. (HPLC analysis conditions for skin sensitization testing) Analytical equipment: Agilent Technologies Agilent 1260 Infinity II Detector: Agilent Technologies Agilent 1260 InfinityII UV-Vis Detector G7114A Detection wavelength: 220 nm Analytical column: Zorbax SB-C-18 (particle diameter 3.5 μm, inner diameter × length = 2.1 mm × 10 mm) manufactured by Agilent Technologies Column temperature: 30℃ Measurement time: 20 min Mobile phase: A 0.1% by volume aqueous solution of trifluoroacetic acid B 0.085% by volume trifluoroacetic acid solution in acetonitrile Gradient: A / B=90 / 10~75 / 25(10min) A / B=75 / 25~10 / 90(1min) A / B=10 / 90(2min) A / B=10 / 90~90 / 10(0.5min) A / B=90 / 10 (6.5 min) Mobile phase flow rate: 0.35mL / min Sample injection conditions: 5 μL

[0037] [Basic coloration test] The 1,3-butylene glycol products obtained in Examples 1 to 3 and Comparative Example 1 were evaluated for coloration under basic conditions according to the following method. (Conditions for basic coloration test) 13g of water and 2g of potassium hydroxide were mixed in a 100mL heat-resistant medium bottle, and then 6g of the target product, 1,3-butylene glycol, was added. The heat-resistant medium bottle was then immersed in a water bath and heated at 90°C for 1 hour. After cooling to room temperature, the color saturation (b*) of the heated solution was measured using a Nippon Denshoku SE2000 spectrophotometer and scored.

[0038] [Example 1] (hydrogenation process) Crude 1,3-butylene glycol was added to a catalyst bed packed with 10 mL of 0.5% Pd / C catalyst manufactured by N.E. Chemcat Corporation at an LHSV of 8.0 h. -1 , hydrogen gas GHSV420h -1 The hydrogen pressure during the reaction was 0.7 MPa, and the reaction temperature was set to 135°C.

[0039] Gas chromatography analysis 1 was performed on the resulting product, 1,3-butylene glycol. As a result, when the relative retention time of n-dodecane was taken as 1.00, it was detected at a relative retention time of 0.80 to 0.99, and the sum of the n-dodecane-equivalent concentrations of the peaks excluding the peaks of the acetal of methyl ethyl ketone and 1,3-butylene glycol was 21 ppm (impurity concentration A). In addition, the sum of the n-dodecane-equivalent concentrations of the peaks of 2-ethylcrotonaldehyde and the acetal of n-butylaldehyde and 1,3-butylene glycol was 12 ppm (impurity concentration B). As a result of gas chromatography analysis 2 performed on the product 1,3-butylene glycol, the area ratio of the peak of the product 1,3-butylene glycol was 99.6%. When a skin sensitization test was conducted on the product 1,3-butylene glycol, the peptide reduction rate was 45 relative to the result of Comparative Example 1, which was set at 100. In addition, when a basic coloring test was conducted, the color saturation (b*) was 2.8. These results for the product 1,3-butylene glycol are shown in Table 1.

[0040] [Example 2] The same procedure as in Example 1 was carried out except that the reaction temperature in the hydrogenation treatment step was 125°C.

[0041] Gas chromatography analysis 1 was performed on the resulting product, 1,3-butylene glycol. As a result, when the relative retention time of n-dodecane was taken as 1.00, it was detected at a relative retention time of 0.80 to 0.99, and the sum of the n-dodecane-equivalent concentrations of the peaks excluding the peaks of the acetal of methyl ethyl ketone and 1,3-butylene glycol was 18 ppm (impurity concentration A). In addition, the sum of the n-dodecane-equivalent concentrations of the peaks of 2-ethylcrotonaldehyde and the acetal of n-butylaldehyde and 1,3-butylene glycol was 10 ppm (impurity concentration B). As a result of gas chromatography analysis 2 performed on the product 1,3-butylene glycol, the area ratio of the peak of the product 1,3-butylene glycol was 99.6%. When a skin sensitization test was conducted on the product 1,3-butylene glycol, the peptide reduction rate was 43 relative to the result of Comparative Example 1, which was set at 100. In addition, when a basic coloring test was conducted, the color saturation (b*) was 3.2.

[0042] [Example 3] (heat treatment process) Crude 1,3-butylene glycol was passed through a tank heated to 100°C so that the residence time was 1 hour, and heat treatment was carried out.

[0043] (hydrogenation process) The same procedure as in Example 1 was carried out except that the 1,3-butylene glycol obtained in the heat treatment step was used as the raw material for the hydrogenation step, and the reaction temperature in the hydrogenation step was set to 100°C.

[0044] (low boiling point distillation process) The 1,3-butylene glycol obtained in the above hydrogenation treatment step was subjected to low-boiling point distillation at an oil bath temperature of 126°C and a pressure of 1.6 kPa in a distillation apparatus equipped with a 500 mm high packed column (internal diameter 22 mm) packed with 3 mm Dixon packings to a packed height of 415 mm, and a distillate at a weight ratio of 10% of the charged liquid amount was distilled off from the top of the distillation apparatus, and the product 1,3-butylene glycol was obtained from the bottom of the distillation apparatus. Gas chromatography analysis 1 was performed on the resulting product, 1,3-butylene glycol. As a result, when the relative retention time of n-dodecane was taken as 1.00, it was detected at a relative retention time of 0.80 to 0.99, and the sum of the n-dodecane-equivalent concentrations of the peaks excluding the peaks of the acetal of methyl ethyl ketone and 1,3-butylene glycol was 0 ppm (impurity concentration A). In addition, the sum of the n-dodecane-equivalent concentrations of the peaks of 2-ethylcrotonaldehyde and the acetal of n-butylaldehyde and 1,3-butylene glycol was 0 ppm (impurity concentration B). Gas chromatography analysis 2 was performed on the product 1,3-butylene glycol, and the area ratio of the peak of the product 1,3-butylene glycol was 99.7%. When a skin sensitization test was conducted on the product 1,3-butylene glycol, the peptide reduction rate was 22 relative to the result of Comparative Example 1, which was set at 100. In addition, when a basic coloring test was conducted, the color saturation (b*) was 0.7.

[0045] [Comparative Example 1] The same procedure as in Example 1 was carried out except that the catalyst used in the hydrogen reduction was NiSAT340 (composition: NiO, SiO2, Al2O3, etc.) manufactured by Clariant.

[0046] Gas chromatography analysis 1 was performed on the resulting product, 1,3-butylene glycol. As a result, when the relative retention time of n-dodecane was taken as 1.00, it was detected at a relative retention time of 0.80 to 0.99, and the sum of the n-dodecane-equivalent concentrations of the peaks excluding the peaks of the acetal of methyl ethyl ketone and 1,3-butylene glycol was 28 ppm (impurity concentration A). In addition, the sum of the n-dodecane-equivalent concentrations of the peaks of 2-ethylcrotonaldehyde and the acetal of n-butylaldehyde and 1,3-butylene glycol was 27 ppm (impurity concentration B). As a result of gas chromatography analysis 2 performed on the product 1,3-butylene glycol, the area ratio of the peak of the product 1,3-butylene glycol was 99.6%. A skin sensitization test was conducted on the product 1,3-butylene glycol, and the peptide reduction rate obtained was set at 100, which serves as the standard for relative comparison with the examples. In addition, a basic coloring test was conducted, and the color saturation (b*) was 19.6.

[0047] [Table 1]

[0048] This application is based on a Japanese patent application (Patent Application No. 2022-083950) filed with the Japan Patent Office on May 23, 2022, the contents of which are incorporated herein by reference. [Industrial Applicability]

[0049] The 1,3-butylene glycol of the present invention has industrial applicability as a raw material for synthetic resins, a raw material for surfactants, a solvent, an antifreeze, a raw material for cosmetics, etc.

Claims

1. In gas chromatography analysis by a splitless injection method under the following conditions, when the relative retention time of n-dodecane is taken as 1.00, the sum of the concentrations of peaks, calculated as n-dodecane, excluding the peak of an acetal compound of methyl ethyl ketone and 1,3-butylene glycol, among peaks appearing in the relative retention time range of 0.80 to 0.99 is more than 0 ppm by mass and 25 ppm by mass or less; [Gas Chromatography Analysis Conditions] Analytical column: a column (length 30 m x inner diameter 0.25 mm x film thickness 0.25 μm) whose stationary phase is (50% cyanopropyl-phenyl)dimethylpolysiloxane Temperature increase conditions: After holding at 50°C for 5 minutes, the temperature was increased from 50°C to 135°C at 10°C / min, held at 135°C for 9 minutes, then increased from 135°C to 220°C at 15°C / min, and held at 220°C for 12 minutes. Sample introduction temperature: 220°C Carrier gas: Nitrogen Column gas flow rate: 0.5 mL / min Detector and detection temperature: Hydrogen flame ionization detector (FID), 220°C Control Mode: Constant Flow Split ratio: Splitless Injection port vent purge: 60 mL / min Purge start time: 1 minute Sample injection conditions: 0.6 μL Sample preparation: The internal standard substance n-dodecane is diluted with 2-propanol to 24 mass ppm to prepare an internal standard solution, and then 0.5 g of the product 1,3-butylene glycol and 0.1 g of the internal standard solution are mixed to prepare a sample. Calculation of the sum of n-dodecane-equivalent concentrations: When the relative retention time of n-dodecane detected under the gas chromatography analysis conditions is set to 1.00, the total area value (detected peak area value) of peaks detected in the range of relative retention times of 0.80 to 0.99, excluding the peak of the acetal compound of methyl ethyl ketone and 1,3-butylene glycol, is converted into the sum of n-dodecane-equivalent concentrations using the following formula (1): Sum of n-dodecane-equivalent concentrations (ppm by mass) = n-dodecane concentration (ppm by mass) × detected peak area value / n-dodecane area value (1) Here, the n-dodecane concentration (ppm by mass) is a value calculated using the following formula (2). n-Dodecane concentration (ppm by mass) = (mass of n-dodecane in sample / mass of product 1,3-butylene glycol in sample) × 10 (2) A 1,3-butylene glycol product composition, in which the area ratio of the 1,3-butylene glycol peak is 99.5% or more in gas chromatography analysis under the following conditions: [Gas Chromatography Analysis Conditions] Analytical column: a column with a stationary phase of polyethylene glycol (length 30 m x inner diameter 0.25 mm x film thickness 0.25 μm) Temperature increase conditions: Increase temperature from 80°C to 230°C at 5°C / min, then hold at 230°C for 10 minutes Sample introduction temperature: 250°C Carrier gas: Nitrogen Column gas flow rate: 0.5 mL / min Detector and detection temperature: Flame ionization detector (FID), 250°C Control Mode: Constant Flow Split ratio: 50:1 Sample injection conditions: 1 μL

2. In gas chromatography analysis by a splitless injection method under the following conditions, the sum of the concentrations of the peak of 2-ethylcrotonaldehyde and the peak of an acetal of n-butylaldehyde with 1,3-butylene glycol, converted into n-dodecane, is more than 0 ppm by mass and 20 ppm by mass or less, [Gas Chromatography Analysis Conditions] Analytical column: a column (length 30 m x inner diameter 0.25 mm x film thickness 0.25 μm) whose stationary phase is (50% cyanopropyl-phenyl)dimethylpolysiloxane Temperature increase conditions: After holding at 50°C for 5 minutes, the temperature was increased from 50°C to 135°C at 10°C / min, held at 135°C for 9 minutes, then increased from 135°C to 220°C at 15°C / min, and held at 220°C for 12 minutes. Sample introduction temperature: 220°C Carrier gas: Nitrogen Column gas flow rate: 0.5 mL / min Detector and detection temperature: Hydrogen flame ionization detector (FID), 220°C Control Mode: Constant Flow Split ratio: Splitless Injection port vent purge: 60 mL / min Purge start time: 1 minute Sample injection conditions: 0.6 μL Sample preparation: The internal standard substance n-dodecane is diluted with 2-propanol to 24 mass ppm to prepare an internal standard solution, and then 0.5 g of the product 1,3-butylene glycol and 0.1 g of the internal standard solution are mixed to prepare a sample. Calculation of the sum of concentrations converted into n-dodecane: The total area value (detected peak area value) of the peak of 2-ethylcrotonaldehyde and the peak of the acetal of n-butylaldehyde and 1,3-butylene glycol detected under the gas chromatography analysis conditions described above is converted into the sum of concentrations converted into n-dodecane using the following formula (1): Sum of n-dodecane-equivalent concentrations (ppm by mass) = n-dodecane concentration (ppm by mass) × detected peak area value / n-dodecane area value (1) Here, the n-dodecane concentration (ppm by mass) is a value calculated using the following formula (2). n-Dodecane concentration (ppm by mass) = (mass of n-dodecane in sample / mass of product 1,3-butylene glycol in sample) × 10 (2) A 1,3-butylene glycol product composition, in which the area ratio of the 1,3-butylene glycol peak is 99.5% or more in gas chromatography analysis under the following conditions: [Gas Chromatography Analysis Conditions] Analytical column: a column with a stationary phase of polyethylene glycol (length 30 m x inner diameter 0.25 mm x film thickness 0.25 μm) Temperature increase conditions: Increase temperature from 80°C to 230°C at 5°C / min, then hold at 230°C for 10 minutes Sample introduction temperature: 250°C Carrier gas: Nitrogen Column gas flow rate: 0.5 mL / min Detector and detection temperature: Flame ionization detector (FID), 250°C Control Mode: Constant Flow Split ratio: 50:1 Sample injection conditions: 1 μL

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