3, 5, 5-trimethylhexanoic acid composition and method for improving storage stability of 3, 5, 5-trimethylhexanoic acid composition

Abstract

Provided is a 3, 5, 5-trimethylhexanoic acid composition which contains 3, 5, 5-trimethylhexanoic acid and tertiary butanol, and which has a deuterated toluene-converted concentration of more than 0 to 400 volume ppb (inclusive) as measured by smelling gas chromatography / mass spectrometry after heating in an air atmosphere at 80 DEG C for 4 weeks. The composition has low reproductive toxicity even if stored for a long period of time. (Measurement Condition). The 3, 5, 5-trimethylhexanoic acid composition is concentrated. And measuring the concentrated sample by smelling gas chromatography using a column in which the stationary phase is dimethyl polysiloxane, and analyzing the structure of the measured components by a mass spectrometry detector.

Description

TECHNICAL FIELD

[0001] The technology of the present disclosure relates to a 3,5,5-trimethylhexanoic acid composition and a method for improving storage stability thereof. BACKGROUND

[0002] It is known that 3,5,5-trimethylhexanoic acid can be synthesized by oxidation of 3,5,5-trimethylhexanal, which is an aldehyde as a precursor thereof (for example, see Patent Literature 1). In addition, a method for synthesizing 3,5,5-trimethylhexanoic acid by oxidation of an alcohol is also known (for example, see Patent Literature 2).

[0003] 3,5,5-trimethylhexanoic acid is used as a raw material for cosmetic raw materials, refrigerant oil raw materials, metal working oils, and the like. Cosmetics, refrigerant oils, and metal working oils, although extremely low, have a possibility of exposure in view of their use characteristics, and thus a low toxicity is required for the raw materials.

[0004] 3,5,5-trimethylhexanoic acid generates t-BuOH, which has a reproductive toxicity, as a byproduct in the manufacturing process, but it is considered that it has been sufficiently reduced by the conventional purification method.

[0005] Prior Art Documents

[0006] Patent Literature

[0007] Patent Literature 1: International Publication No. 2022 / 118917

[0008] Patent Literature 2: Specification of Chinese Patent Application Publication No. 112409144 SUMMARY

[0009] Problem to be Solved by the Invention

[0010] However, it has been newly found that t-BuOH increases if 3,5,5-trimethylhexanoic acid is stored for a long period of time.

[0011] The technology of the present disclosure is made in view of the above circumstances, and the problem to be solved by the technology of the present disclosure is to provide a 3,5,5-trimethylhexanoic acid composition having a low reproductive toxicity even if stored for a long period of time and a method for improving storage stability thereof, and to solve the problem.

[0012] Means for Solving the Problem

[0013] <1> A 3,5,5-trimethylhexanoic acid composition comprising 3,5,5-trimethylhexanoic acid and t-butyl alcohol,

[0014] The deuterated toluene-converted concentration of the aforementioned t-butyl alcohol based on gas chromatography / mass spectrometry measured after heating at 80°C for 4 weeks under an air atmosphere is more than 0 volume ppb and 400 volume ppb or less.

[0015] (Measurement conditions)

[0016] • 3,5,5-trimethylhexanoic acid composition 5.0 g was filled in a 500 mL container which can be closed, and left at rest at 30°C for 20 minutes or more. Then, 200 mL of the gas phase portion was suctioned, and the remaining portion from which H2O, N2, O2, and CO2 were removed was concentrated using a concentration device.

[0017] • The concentrated sample was measured by olfactory gas chromatography under the following conditions, and the structure of the measured component was analyzed using a mass spectrometer detector.

[0018] Analysis column: column with dimethylpolysiloxane as stationary phase; length 60 m x inner diameter 320 μm x film thickness 1 μm

[0019] Temperature rising program: 2 minutes at 35°C, then temperature rising at 10°C / minute, 7 minutes and 30 seconds at 240°C.

[0020] Carrier gas: helium

[0021] The measurement conditions of the mass spectrometer detector are as follows.

[0022] Ionization mode: EI

[0023] Measurement type: scan

[0024] Ion source temperature: 250°C

[0025] Temperature of quadrupole rod: 150°C

[0026] Electron energy: 70.0 eV

[0027] Scan start mass: 30

[0028] Scan end mass: 400

[0029] <2> The 3,5,5-trimethylhexanoic acid composition according to <1> for use in cosmetics.

[0030] <3> The 3,5,5-trimethylhexanoic acid composition according to <1> for use in refrigerator oil.

[0031] <4> A method for improving the storage stability of a 3,5,5-trimethylhexanoic acid composition comprising 3,5,5-trimethylhexanoic acid and t-butyl alcohol,

[0032] In the method, the deuterated toluene-converted concentration of the aforementioned t-butyl alcohol based on olfactory gas chromatography / mass spectrometry measured under the following conditions exceeds 0 volume ppb and is 100 volume ppb or less.

[0033] (Measurement conditions)

[0034] • 3,5,5-trimethylhexanoic acid composition 5.0 g was filled in a 500 mL container which can be closed, and left at rest at 30°C for 20 minutes or more. Then, 200 mL of the gas phase portion was sucked, and the remaining portion from which H2O, N2, O2, and CO2 were removed was concentrated using a concentration device.

[0035] • The concentrated sample was measured by olfactory gas chromatography under the following conditions, and the structure of the measured component was analyzed using a mass spectrometer.

[0036] Analysis column: column with dimethylpolysiloxane as stationary phase; length 60 m x inner diameter 320 μm x film thickness 1 μm

[0037] Temperature rising program: 2 minutes at 35°C, then temperature rising at 10°C / minute, 7 minutes and 30 seconds at 240°C.

[0038] Carrier gas: helium

[0039] The measurement conditions of the mass spectrometer are as follows.

[0040] Ionization mode: EI

[0041] Measurement type: scan

[0042] Ion source temperature: 250°C

[0043] Temperature of quadrupole rod: 150°C

[0044] Electron energy: 70.0 eV

[0045] Scan start mass: 30

[0046] Scan end mass: 400

[0047] <5> The method for improving the storage stability of a 3,5,5-trimethylhexanoic acid composition according to <4>, the 3,5,5-trimethylhexanoic acid composition comprising 3,5,5-trimethylhexanoic acid and tert-butyl alcohol,

[0048] The deuterated toluene-converted concentration of the aforementioned tert-butyl alcohol measured by olfactory gas chromatography / mass spectrometry under the aforementioned conditions exceeds 0 volume ppb and is 100 volume ppb or less, and the deuterated toluene-converted concentration of the tert-butyl alcohol measured by olfactory gas chromatography / mass spectrometry under the aforementioned conditions after heating at 80°C for 4 weeks in an air atmosphere exceeds 0 volume ppb and is 400 volume ppb or less.

[0049] Effects of the Invention

[0050] According to the technology of the present disclosure, it is possible to provide a technology related to a 3,5,5-trimethylhexanoic acid composition having low reproductive toxicity even after long-term storage and a method for improving the storage stability thereof. DETAILED DESCRIPTION

[0051] The upper limit value and the lower limit value of the numerical range described in the present specification can be combined arbitrarily. For example, in the case where "A to B" and "C to D" are described as numerical ranges, the numerical ranges of "A to D" and "C to B" are also included in the scope of the present disclosure.

[0052] In addition, unless otherwise specified, the numerical range "lower limit value to upper limit value" described in the present specification means above the lower limit value and below the upper limit value.

[0053] <3,5,5-TRIMETHYLHEXANOIC ACID COMPOSITION>

[0054] The 3,5,5-trimethylhexanoic acid composition according to the present embodiment contains 3,5,5-trimethylhexanoic acid and t-butanol, and the deuterated toluene conversion concentration of t-butanol based on the olfactory gas chromatography / mass spectrometry after heating at 80°C for 4 weeks in an air atmosphere is more than 0 volume ppb and 400 volume ppb or less.

[0055] (Measurement conditions)

[0056] • 5.0 g of the 3,5,5-trimethylhexanoic acid composition was filled in a 500 mL container that can be closed, and left to stand at 30°C for 20 minutes or more. Then, 200 mL of the gas phase portion was suctioned, and the remaining portion from which H2O, N2, O2, and CO2 were removed was concentrated using a concentration device.

[0057] • The concentrated sample was measured using olfactory gas chromatography under the following conditions, and the structure analysis of the measured components was performed using a mass spectrometer.

[0058] Analysis column: column with dimethylpolysiloxane as the stationary phase; length 60 m x inner diameter 320 μm x film thickness 1 μm

[0059] Temperature rising program: 2 minutes at 35°C, then temperature rising at 10°C / minute, and 7 minutes and 30 seconds at 240°C.

[0060] Carrier gas: helium

[0061] The measurement conditions of the mass spectrometer detector are as follows.

[0062] Ionization mode: EI

[0063] Measurement type: scan

[0064] Ion source temperature: 250°C

[0065] Quadrupole temperature: 150°C

[0066] Electron energy: 70.0 eV

[0067] Scan start quality: 30

[0068] Scan end quality: 400

[0069] In the 3,5,5-trimethylhexanoic acid composition according to the present embodiment, “after heating at 80° C. in an air atmosphere for 4 weeks” refers to accelerated conditions for preparing the 3,5,5-trimethylhexanoic acid composition for long-term storage.

[0070] As mentioned above, t-BuOH produced as a by-product during the production of 3,5,5-trimethylhexanoic acid is believed to be sufficiently reduced by conventional purification methods such as distillation. However, in practice, t-BuOH is not detected at the detection level in conventional gas chromatography for impurity detection.

[0071] However, it has been newly discovered that if 3,5,5-trimethylhexanoic acid is stored for a long time, t-BuOH increases.

[0072] As a result of extensive investigations into the increase in t-BuOH, it was found that a trace amount of tert-butyl alcohol (t-BuOH) was present in the 3,5,5-trimethylhexanoic acid composition immediately after production, as determined by olfactory gas chromatography, which has a higher sensitivity.

[0073] The present invention has discovered the novel problem described above, namely, that a trace amount of t-BuOH is present in the 3,5,5-trimethylhexanoic acid composition immediately after production, and that the amount of t-BuOH increases if the 3,5,5-trimethylhexanoic acid composition is stored for a long period of time. This problem has been solved by configuring the 3,5,5-trimethylhexanoic acid composition as described above.

[0074] [Acceleration conditions]

[0075] The 3,5,5-trimethylhexanoic acid composition according to the present embodiment is a 3,5,5-trimethylhexanoic acid composition obtained by heating the 3,5,5-trimethylhexanoic acid composition immediately after production at 80° C. in an air atmosphere for 4 weeks.

[0076] The method for producing the 3,5,5-trimethylhexanoic acid composition will be described later.

[0077] 〔Olfaction gas chromatography / mass spectrometry〕

[0078] The olfactory gas chromatography / mass spectrometry was performed by concentrating the sample by the following method, analyzing the components of the concentrated sample by olfactory gas chromatography, and performing structural analysis of the components by a mass spectrometer.

[0079] (Concentration of sample)

[0080] 3,5,5-trimethylhexanoic acid composition was a liquid at room temperature (25°C) under atmospheric pressure (0.1 MPa). 5.0 g of 3,5,5-trimethylhexanoic acid composition was filled in a 500 mL container which can be closed, and left to stand at 30°C for 20 minutes or more. Then, 200 mL of the gas phase portion was sucked, and the remaining portion from which H2O, N2, O2, and CO2 were removed was concentrated using a concentration device.

[0081] The concentration device can be independent or can be connected to a sniffing gas chromatograph / mass spectrometer detector.

[0082] The concentration device can be, for example, "Entech 7200 automatic concentration device" manufactured by ENTECH INSTRUMENTS Co., Ltd.

[0083] The concentration conditions are described below.

[0084] Internal standard substance: 100 mL (deuterated toluene standard gas: concentration 10 volume ppb, dilution gas is nitrogen, Sumitomo Seika Chemicals Co., Ltd.)

[0085] Concentration method: CTD mode (cold trap dehydration)

[0086] • Temperature conditions of dehydration module 1 (empty trap: ceramic-coated trap without adsorbent filled with hydrazine): trap temperature -40°C, desorption temperature 0°C

[0087] • Temperature conditions of Cold Tenax (registered trademark) module 2 (Tenax TA trap: ceramic-coated trap filled with Tenax TA as an adsorbent): trap temperature -30°C, desorption temperature 200°C

[0088] • Temperature conditions of focusing module 3 (low-temperature focusing): trap temperature -165°C, desorption temperature 100°C

[0089] • Sample flow rate: 50 mL / min

[0090] • Helium purge volume: 75 mL

[0091] • Volume of M1 to M2: 40 mL (100 mL / min)

[0092] • Time of M2 to M3: 3.0 min

[0093] • Injection time: 0.3 min

[0094] Here, Tenax TA refers to a weakly polar porous polymer microsphere with 2,6-diphenyl-p-phenylene ether as a base.

[0095] In addition, M1, M2, M3 respectively correspond to the above-described modules 1, 2, 3, and "M1 to M2" and "M2 to M3" indicate conditions of sample flow between the modules. In each of the modules, the following operations are performed.

[0096] M1: Removal of water, air, or the like

[0097] M2: Removal of VOC by introduction of CO2

[0098] M3: Focusing of sample

[0099] (Odor sniffing gas chromatography)

[0100] The odor sniffing gas chromatography (odor sniffing GC) device can use, for example, "Agilent 7890B Gas Chromatography System" manufactured by Agilent Technologies, Inc.

[0101] The measurement conditions of the odor sniffing GC are described below.

[0102] Analysis column: DB-1 manufactured by Agilent Technologies, Inc. (column in which dimethylpolysiloxane is a stationary phase; length 60 m x inner diameter 320 μm x film thickness 1 μm)

[0103] Temperature rising program: 2 minutes at 35°C, then temperature rising at 10°C / minute, and 7 minutes and 30 seconds at 240°C after reaching 240°C.

[0104] Carrier gas: Helium

[0105] Control mode: Constant pressure (153.09 kPa)

[0106] After the concentrated sample is separated by the capillary column, the sample is sent to ODP3 (odor sniffing port) and a mass spectrometer (for example, MSD5977B described below) at a ratio of 1 / 1.

[0107] (Mass spectrometer)

[0108] The mass spectrometer (MSD) can use, for example, "Agilent 5977B MSD" manufactured by Agilent Technologies, Inc.

[0109] The measurement conditions of the MSD are described below.

[0110] Ionization mode: EI

[0111] Measurement type: Scan

[0112] Ion source temperature: 250°C

[0113] Quadrupole rod temperature: 150°C

[0114] Electron energy: 70.0 eV

[0115] Scan start mass: 30

[0116] Scan end mass: 400

[0117] A standard curve was prepared using a deuterated toluene standard gas (concentration: 10 volume ppb, dilution gas: nitrogen) manufactured by Sumitomo Seika Chemicals Co., Ltd.

[0118] In the data analysis, an extracted ion chromatogram (EIC) was used, and the EIC peak area of the tert-butyl alcohol (EIC: m / z 59.000) appearing at a relative retention time of 0.48 to 0.56 when the relative retention time of the deuterated toluene was set to 1.0 was confirmed.

[0119] In calculating the deuterated toluene conversion concentration of the tert-butyl alcohol in the 3,5,5-trimethylhexanoic acid vapor, the sensitivity of the EIC peak of the tert-butyl alcohol was assumed to be equal to the sensitivity of the EIC peak of the deuterated toluene, and the calculation was performed using the formula derived from the above standard curve, "deuterated toluene conversion concentration (volume ppb) = 3.94 x 10 -6

[0120] [Deuterated toluene conversion concentration of tert-butyl alcohol]

[0121] In the case of the 3,5,5-trimethylhexanoic acid composition according to the present embodiment, the deuterated toluene conversion concentration of the tert-butyl alcohol determined by the above sniffing GC / MSD is preferably 370 volume ppb or less, more preferably 340 volume ppb or less, and further preferably 200 volume ppb or less.

[0122] [Method for producing 3,5,5-trimethylhexanoic acid composition]

[0123] The method for producing the 3,5,5-trimethylhexanoic acid composition according to the present embodiment is not particularly limited, and preferably has a synthesis step of synthesizing crude 3,5,5-trimethylhexanoic acid, and a purification step of purifying the crude 3,5,5-trimethylhexanoic acid.

[0124] The purification step preferably includes a water washing step of water washing the crude 3,5,5-trimethylhexanoic acid, and a bubbling step of bubbling the 3,5,5-trimethylhexanoic acid obtained in the water washing step with a non-active gas.

[0125] [Synthesis step]

[0126] The crude 3,5,5-trimethylhexanoic acid can be synthesized by a known synthesis method.

[0127] ​For example, the crude 3,5,5-trimethylhexanoic acid can be synthesized by the method described in International Publication No. 2022 / 118917. Specifically, for example, 3,5,5-trimethylhexanal is synthesized by a hydroformylation reaction of diisobutene with carbonyl synthesis gas, and then the crude 3,5,5-trimethylhexanoic acid is synthesized by an oxidation reaction.

[0128] 〔purification process〕

[0129] The purification process includes a water washing process of water washing the crude 3,5,5-trimethylhexanoic acid, and a bubbling process of bubbling the 3,5,5-trimethylhexanoic acid obtained in the aforementioned water washing process with a non-active gas.

[0130] The purification process can further include a distillation process or the like. The distillation process is preferably performed before the water washing process.

[0131] (distillation process)

[0132] The distillation process is a process of removing a low-boiling-point component having a boiling point lower than that of 3,5,5-trimethylhexanoic acid (120°C / 13 mmHg).

[0133] Specifically, for example, the high-boiling fraction is added to a three-necked flask equipped with a reflux condenser and a thermometer, and subjected to reduced pressure distillation at 25 kPa, and a fraction having a head temperature of 180 to 200°C is recovered to obtain the low-boiling fraction.

[0134] (water washing process)

[0135] The water washing process is a process of water washing the crude 3,5,5-trimethylhexanoic acid.

[0136] The water washing process is a process of mixing the crude 3,5,5-trimethylhexanoic acid obtained in the synthesis process with water, and phase separating into a water layer and an organic layer to obtain the organic layer containing 3,5,5-trimethylhexanoic acid.

[0137] The water washing process is preferably performed after the distillation process.

[0138] From the viewpoint of extraction efficiency, the amount of water used is preferably 10 to 300 parts by mass, more preferably 20 to 200 parts by mass, relative to 100 parts by mass of the crude 3,5,5-trimethylhexanoic acid. The temperature at which the water is mixed with the crude 3,5,5-trimethylhexanoic acid is not particularly limited, and from the viewpoint of extraction efficiency, the temperature is preferably between 5 and 80°C, more preferably between 10 and 50°C, and further preferably between 10 and 30°C.

[0139] The mixing of the crude 3,5,5-trimethylhexanoic acid with water can be performed, for example, in a batch or continuous manner or the like.

[0140] In the case of performing the process in a batch manner, for example, the following process can be mentioned: the crude 3,5,5-trimethylhexanoic acid and water are added to a mixing tank, and after preferably stirring for 10 seconds to 2 hours, phase separation is performed, preferably after standing for 1 minute to 2 hours, to obtain an organic layer containing 3,5,5-trimethylhexanoic acid. The operation of further adding water to the obtained organic layer containing 3,5,5-trimethylhexanoic acid and performing phase separation to obtain an organic layer containing 3,5,5-trimethylhexanoic acid can also be performed repeatedly, and as the number of repetitions, 1 to 3 times are preferred. In this case, the amount of water used per 1 addition is preferably 10 to 300 parts by mass relative to 100 parts by mass of the crude 3,5,5-trimethylhexanoic acid.

[0141] The mixture of the crude 3,5,5-trimethylhexanoic acid and water can also be subjected to ultrasonic irradiation after stirring and standing. By performing ultrasonic irradiation, the time taken for phase separation can be shortened.

[0142] As the apparatus when performed in a continuous manner, an apparatus generally used for continuous extraction and the like, for example, a combination of a mixer and a settler, a spray tower, a packed column, a plate column, and the like can be used, and a packed column or a plate column having a theoretical plate number of 3 or more is particularly preferred.

[0143] (bubbling step)

[0144] The bubbling step is a step of bubbling the non-active gas to the organic layer containing 3,5,5-trimethylhexanoic acid obtained in the water washing step.

[0145] The non-active gas is bubbled in the organic layer containing 3,5,5-trimethylhexanoic acid obtained in the water washing step, and water and t-BuOH are removed.

[0146] As the non-active gas, for example, nitrogen can be used.

[0147] The amount of the non-active gas introduced at the time of bubbling is preferably 0.5 to 15 1 / min, and more preferably 2.5 to 7.5 1 / min, per 1 kg of the organic layer. The temperature in the bubbling step is 5°C or higher and less than 40°C, and the bubbling time is usually 1 to 30 hours, and preferably 5 to 15 hours.

[0148] <Method for improving storage stability of 3,5,5-trimethylhexanoic acid composition>

[0149] The method for improving the storage stability of the 3,5,5-trimethylhexanoic acid composition according to the present embodiment is a method for improving the storage stability of a 3,5,5-trimethylhexanoic acid composition containing 3,5,5-trimethylhexanoic acid and t-butyl alcohol,

[0150] The method is a method for improving the storage stability of a 3,5,5-trimethylhexanoic acid composition, and the method is characterized by comprising the step of: adjusting the deuterated toluene conversion concentration of t-butyl alcohol in the 3,5,5-trimethylhexanoic acid composition to be 0 volume ppb or more and 100 volume ppb or less.

[0151] Hereinafter, the "method for improving the storage stability of a 3,5,5-trimethylhexanoic acid composition according to the present embodiment" is sometimes referred to as simply "the storage stability improving method according to the present embodiment".

[0152] In the storage stability improving method according to the present embodiment, the deuterated toluene conversion concentration of t-butyl alcohol is preferably 95 volume ppb or less, more preferably 70 volume ppb or less, and further preferably 40 volume ppb or less.

[0153] The storage stability of a 3,5,5-trimethylhexanoic acid composition refers to the property that t-BuOH does not easily increase even if the 3,5,5-trimethylhexanoic acid composition is stored for a long period of time, and the property can be maintained at a low level of reproductive toxicity. The property can be improved by the method for improving the storage stability of a 3,5,5-trimethylhexanoic acid composition according to the present embodiment.

[0154] Specifically, the deuterated toluene conversion concentration of t-butyl alcohol measured by olfactometric gas chromatography / mass spectrometry after heating at 80°C for 4 weeks in an air atmosphere is 400 volume ppb or less.

[0155] "Heating at 80°C for 4 weeks in an air atmosphere" refers to an accelerated condition for producing a state in which a 3,5,5-trimethylhexanoic acid composition is stored for a long period of time.

[0156] The deuterated toluene conversion concentration of t-butyl alcohol measured by olfactometric gas chromatography / mass spectrometry is the same for t-butyl alcohol that has not been heated at 80°C for 4 weeks in an air atmosphere and for t-butyl alcohol that has been heated at 80°C for 4 weeks in an air atmosphere.

[0157] [Deuterated toluene conversion concentration of t-butyl alcohol]

[0158] According to the storage stability improving method according to the present embodiment, the concentration of t-BuOH in a 3,5,5-trimethylhexanoic acid composition after a long period of storage is also 400 volume ppb or less, and the concentration of t-BuOH after heating at 80°C for 4 weeks in an air atmosphere is preferably 370 volume ppb or less, more preferably 340 volume ppb or less, and further preferably 200 volume ppb or less.

[0159] Example

[0160] Next, the technology of the present disclosure is specifically described by examples, but the technology of the present disclosure is not limited by any of these examples.

[0161] [Example 1]

[0162] (Synthesis step)

[0163] Referring to the method described in International Publication WO2022118917A1, crude 3,5,5-trimethylhexanoic acid was synthesized. That is, 3,5,5-trimethylhexanal was synthesized by a hydroformylation reaction of diisobutene with carbonyl synthesis gas, and then crude 3,5,5-trimethylhexanoic acid was obtained by an oxidation reaction.

[0164] (Distillation step)

[0165] Next, 239.50 g of the aforementioned crude 3,5,5-trimethylhexanoic acid was placed in a 300 mL three-necked flask equipped with a reflux condenser and a thermometer, and subjected to reduced pressure distillation at 25 kPa, and a fraction having a head temperature of 184 to 191°C was recovered, and 184.64 g of a low-boiling fraction-removed fraction was obtained at a recovery rate of 77.1%.

[0166] (Water washing step)

[0167] Next, 185 g of 3,5,5-trimethylhexanoic acid after the distillation step and 370 g of water were charged into a 1 L glass sample bottle, and after stirring for 1 minute at room temperature, an ultrasonic cleaner (UT-206H) manufactured by Sharp Manufacturing Systems Co., Ltd. was used to irradiate ultrasonic waves for 1 minute at a temperature of 20°C, and then the mixture was left to stand for 30 minutes, and phase separation was performed into a water layer and an organic layer.

[0168] (Bubbling step)

[0169] Next, the organic layer after the water washing step was charged into a flask, and nitrogen gas was introduced at a flow rate of 800 mL / minute at room temperature using a bubbler, and stirring was performed for 10 hours, and thereby 183 g of a 3,5,5-trimethylhexanoic acid composition was obtained.

[0170] A gas chromatograph mass spectrometer with a concentration device was performed on the obtained 3,5,5-trimethylhexanoic acid composition under the conditions described later, and as a result, the deuterated toluene conversion concentration of tert-butyl alcohol was 93 volume ppb.

[0171] [Storage stability test]

[0172] A 3,5,5-trimethylhexanoic acid composition 10 g was charged into a 20 mL glass container under an air atmosphere, and was subjected to airtight sealing, and was left to stand in a thermostat maintained at 80°C. After 4 weeks from the start of the standing in the thermostat, the 3,5,5-trimethylhexanoic acid composition was taken out.

[0173] The 3,5,5-trimethylhexanoic acid composition after the storage stability test was subjected to gas chromatography mass spectrometry with a concentration device under the conditions described below, and as a result, the deuterated toluene conversion concentration of the t-butanol was 362 volume ppb.

[0174] [Example 2]

[0175] The same procedure as in Example 1 was performed except that the number of water washing steps was 2. The 3,5,5-trimethylhexanoic acid composition obtained was subjected to gas chromatography mass spectrometry with a concentration device under the conditions described below, and as a result, the deuterated toluene conversion concentration of the t-butanol was 35 volume ppb.

[0176] In addition, the 3,5,5-trimethylhexanoic acid composition after the storage stability test was subjected to gas chromatography mass spectrometry with a concentration device under the conditions described below, and as a result, the deuterated toluene conversion concentration of the t-butanol was 337 volume ppb.

[0177] [Example 3]

[0178] The same procedure as in Example 1 was performed except that the number of water washing steps was 3. The 3,5,5-trimethylhexanoic acid composition obtained was subjected to gas chromatography mass spectrometry with a concentration device under the conditions described below, and as a result, the deuterated toluene conversion concentration of the t-butanol was 27 volume ppb.

[0179] In addition, the 3,5,5-trimethylhexanoic acid composition after the storage stability test was subjected to gas chromatography mass spectrometry with a concentration device under the conditions described below, and as a result, the deuterated toluene conversion concentration of the t-butanol was 153 volume ppb.

[0180] [Comparative Example 1]

[0181] The same procedure as in Example 1 was performed except that the water washing step and the bubbling step were not performed. The 3,5,5-trimethylhexanoic acid composition obtained was subjected to gas chromatography mass spectrometry with a concentration device under the conditions described below, and as a result, the deuterated toluene conversion concentration of the t-butanol was 213 volume ppb.

[0182] In addition, the 3,5,5-trimethylhexanoic acid composition after the storage stability test was subjected to gas chromatography mass spectrometry with a concentration device under the conditions described below, and as a result, the deuterated toluene conversion concentration of the t-butanol was 529 volume ppb.

[0183] [Olfactory gas chromatography / mass spectrometry measurement]

[0184] Olfactory gas chromatography / mass spectrometry measurement was performed on each of the 3,5,5-trimethylhexanoic acid compositions before and after the storage stability test in Examples 1 to 3 and Comparative Example 1.

[0185] (Concentration of sample)

[0186] First, the obtained 3,5,5-trimethylhexanoic acid composition was concentrated by the following concentration apparatus and conditions.

[0187] Concentration apparatus: Entech 7200 automatic concentration apparatus manufactured by ENTECH INSTRUMENTS

[0188] Sample amount: 5.0 g

[0189] Container capacity: 500 mL

[0190] Injection amount: 200 mL of gas phase portion in the container which had been left at rest at 30°C for 20 minutes or more

[0191] Internal standard substance: 100 mL (deuterated toluene standard gas: concentration 10 volume ppb, dilution gas: nitrogen, Sumitomo Seika Chemicals Co., Ltd.)

[0192] Concentration method: CTD mode (cold Tenax desorption)

[0193] Temperature conditions of desorption module 1 (empty Tenax: ceramic-coated Tenax without adsorbent): Tenax temperature -40°C, desorption temperature 0°C

[0194] Temperature conditions of Cold Tenax (registered trademark) module 2 (Tenax TA Tenax: ceramic-coated Tenax filled with Tenax TA as adsorbent): Tenax temperature -30°C, desorption temperature 200°C

[0195] Temperature conditions of focusing module 3 (low-temperature focusing): Tenax temperature -165°C, desorption temperature 100°C

[0196] Sample flow rate: 50 mL / min

[0197] Helium purge volume: 75 mL

[0198] Volume of M1 to M2: 40 mL (100 mL / min)

[0199] Time of M2 to M3: 3.0 min

[0200] Injection time: 0.3 min

[0201] Here, Tenax TA refers to a weakly polar porous polymer microsphere with 2,6-diphenyl-p-phenylene ether as a base.

[0202] Next, for the concentrated sample, olfactory gas chromatography / mass spectrometry was performed using the following olfactory gas chromatography (olfactory GC) apparatus and mass spectrometry detector (MSD).

[0203] (Olfactory GC)

[0204] Measuring apparatus: Agilent 7890B Gas Chromatography System manufactured by Agilent Technologies, Inc.

[0205] Analytical column: DB-1 manufactured by Agilent Technologies, Inc. (column with dimethylpolysiloxane as stationary phase; length 60 m x inner diameter 320 μm x film thickness 1 μm)

[0206] Temperature rising program: 2 minutes at 35°C, then rising at 10°C / minute, and 7 minutes and 30 seconds at 240°C after reaching the temperature.

[0207] Carrier gas: Helium

[0208] Control mode: Constant pressure (153.09 kPa)

[0209] After separating the concentrated sample using a capillary column, the sample was sent to ODP3 (olfactory port) and MSD5977B at a ratio of 1 / 1.

[0210] (MSD)

[0211] Detector: Agilent 5977B MSD manufactured by Agilent Technologies, Inc.

[0212] Ionization mode: EI

[0213] Measurement type: Scan

[0214] Ion source temperature: 250°C

[0215] Temperature of quadrupole rod: 150°C

[0216] Electronic energy: 70.0 eV

[0217] Scan start mass: 30

[0218] Scan end mass: 400

[0219] Standard curve: Made using deuterated toluene standard gas (concentration: 10 volume ppb, dilution gas: nitrogen) manufactured by Sumitomo Seika (Co., Ltd.).

[0220] (Data analysis)

[0221] During data analysis, extracted ion chromatography (EIC) was used to confirm the EIC peak area of ​​tert-butyl alcohol (EIC: m / z 59.000), which appeared at relative retention times of 0.48 to 0.56, with the relative retention time of deuterated toluene set to 1.0. When calculating the deuterated toluene equivalent concentration of tert-butyl alcohol in 3,5,5-trimethylhexanoic acid vapor, the sensitivity of the EIC peak for tert-butyl alcohol was assumed to be equal to that of the deuterated toluene EIC peak. The formula derived from the aforementioned calibration curve was used: "Deuterated toluene equivalent concentration (volume ppb) = 3.94 × 10 -6 It was calculated by "×EIC peak area".

[0222] The results are shown in Table 1.

[0223] [Table 1]

[0224] Table 1

[0225]

[0226] After storage stability testing, the 3,5,5-trimethylhexanoic acid compositions obtained in Examples 1 to 3 also showed a deuterated toluene equivalent concentration of tert-butyl alcohol measured by olfactory gas chromatography / mass spectrometry of 400 ppb by volume or less. This demonstrates that the 3,5,5-trimethylhexanoic acid compositions obtained in Examples exhibit excellent suppression of reproductive toxicity even after long-term storage.

[0227] Industrial applicability

[0228] The present invention provides a 3,5,5-trimethylhexanoic acid composition having low reproductive toxicity even during long-term storage, and a method for improving its storage stability. The 3,5,5-trimethylhexanoic acid of this embodiment can be used as a raw material for lubricating oils (e.g., refrigeration oils), metallic soaps, plasticizers, surfactants, alkyd resins, fatty acid chlorides, metalworking oils, cosmetics, and the like.

Claims

1. A 3,5,5-trimethylhexanoic acid composition comprising 3,5,5-trimethylhexanoic acid and tert-butyl alcohol, a deuterated toluene conversion concentration of the tert-butyl alcohol determined based on olfactory gas chromatography / mass spectrometry measured under the following conditions exceeds 0 volume ppb and is 400 volume ppb or less after heating at 80°C for 4 weeks in an air atmosphere, (Measurement conditions) • 3,5,5-trimethylhexanoic acid composition 5.0 g was filled in a 500 mL container which can be closed, and left to stand at 30°C for 20 minutes or more; then, 200 mL of the gas phase portion was sucked, and the remaining portion from which H2O, N2, O2, and CO2 were removed was concentrated using a concentration device; • the concentrated sample was measured using olfactory gas chromatography under the following conditions, and the structure of the measured component was analyzed using a mass spectrometer detector; Analysis column: column with dimethylpolysiloxane as stationary phase; length 60 m x inner diameter 320 μm x film thickness 1 μm Temperature rising program: 2 minutes at 35°C, then temperature rising at 10°C / minute, 7 minutes and 30 seconds at 240°C after reaching; Carrier gas: helium The measurement conditions of the mass spectrometer detector are as follows, Ionization mode: EI Measurement type: scan Ion source temperature: 250°C Quadrupole rod temperature: 150°C Electronic energy: 70.0 eV Scan start mass: 30 Scan end mass:

400.

2. The 3,5,5-trimethylhexanoic acid composition according to claim 1 for use in cosmetics.

3. The 3,5,5-trimethylhexanoic acid composition according to claim 1 for use in refrigerator oils.

4. A method for improving the storage stability of a 3,5,5-trimethylhexanoic acid composition comprising 3,5,5-trimethylhexanoic acid and tert-butyl alcohol, in which method the deuterated toluene conversion concentration of the tert-butyl alcohol determined based on olfactory gas chromatography / mass spectrometry measured under the following conditions exceeds 0 volume ppb and is 100 volume ppb or less; (Measurement conditions) • 3,5,5-trimethylhexanoic acid composition 5.0 g was filled in a 500 mL container which can be closed, and left to stand at 30°C for 20 minutes or more; then, 200 mL of the gas phase portion was sucked, and the remaining portion from which H2O, N2, O2, and CO2 were removed was concentrated using a concentration device; • the concentrated sample was measured using olfactory gas chromatography under the following conditions, and the structure of the measured component was analyzed using a mass spectrometer detector; Analysis column: column with dimethylpolysiloxane as stationary phase; length 60 m x inner diameter 320 μm x film thickness 1 μm Temperature rising program: 2 minutes at 35°C, then temperature rising at 10°C / minute, 7 minutes and 30 seconds at 240°C after reaching; Carrier gas: helium The measurement conditions of the mass spectrometer detector are as follows, Ionization mode: EI Measurement type: scan Ion source temperature: 250°C Quadrupole rod temperature: 150°C Electronic energy: 70.0 eV Scan start mass: 30 Scan end mass:

400.

5. The method of improving storage stability of a 3,5,5-trimethylhexanoic acid composition according to claim 4, the 3,5,5-trimethylhexanoic acid composition comprising 3,5,5-trimethylhexanoic acid and t-butyl alcohol, by making the deuterated toluene-equivalent concentration of the t-butyl alcohol determined based on olfactory gas chromatography / mass spectrometry measured under the conditions exceed 0 volume ppb and be 100 volume ppb or less, thereby making the deuterated toluene-equivalent concentration of the t-butyl alcohol determined based on olfactory gas chromatography / mass spectrometry after heating at 80°C for 4 weeks under an air atmosphere exceed 0 volume ppb and be 400 volume ppb or less.

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