High-purity 2-aminoethyl methacrylate hydrochloride, copolymer including said hydrochloride as structural unit, and method for producing 2-aminoethyl methacrylate hydrochloride

Abstract

This method for producing 2-aminoethyl methacrylate hydrochloride comprises a reaction step for reacting aminoethanol hydrochloride and methacrylic acid chloride and a drying step for drying 2-aminoethyl methacrylate hydrochloride obtained in the reaction step at not higher than 45°C.

Description

High-purity 2-aminoethyl methacrylate hydrochloride, copolymer containing said hydrochloride as a constituent unit, and method for producing 2-aminoethyl methacrylate hydrochloride

[0001] The present invention relates to high-purity 2-aminoethyl methacrylate hydrochloride, a copolymer containing said hydrochloride as a constituent unit, and a method for producing 2-aminoethyl methacrylate hydrochloride.

[0002] The compound represented by the following formula (1) is useful as a raw material for polymers for surface treatment of contact lenses and polymers for contact lens treatment solutions, as described in, for example, Patent Documents 1 and 2.

[0003]

[0004] In formula (1), a:b=50:50 to 98:2. １ is a hydrogen atom or a methyl group, and X １ is O or NH.

[0005] The compound represented by the above formula (1) can be obtained, for example, by polymerizing a compound represented by the following formula (2) and 2-aminoethyl methacrylate hydrochloride (AEMA) represented by the following formula (3) by a radical polymerization method or the like.

[0006]

[0007] In formula (2), R ２ is a hydrogen atom or a methyl group, and X ２ is O or NH.

[0008]

[0009] AEMA can be produced, for example, by the method described in Non-Patent Document 1. Specifically, AEMA can be obtained by reacting ethanolamine hydrochloride with methacrylic acid chloride, purifying the reaction mixture with diethyl ether, filtering, and drying.

[0010] Journal of Polymer Science, Part A: Polymer Chemistry (2013), 51(21), 4522-4529.

[0011] International Publication No. 2019 / 111838 International Publication No. 2021 / 070862

[0012] In the conventional production method (the production method described in Non-Patent Document 1), there was a step for which detailed conditions for the production of AEMA were not described. When AEMA was produced based on this production method, a homopolymer of AEMA represented by the following formula (4) was produced as a by-product and was sometimes contained in the AEMA (AEMA composition). It was difficult to remove the homopolymer of AEMA from the AEMA, and there was a need to reduce the amount of by-product. In other words, it was difficult to stably produce high-purity AEMA with the production method described in Non-Patent Document 1.

[0013]

[0014] In formula (4), n is 20 to 30,000.

[0015] If AEMA homopolymers are contained in AEMA (in an AEMA composition), it is difficult to completely remove them by purification. When AEMA contaminated with AEMA homopolymers is used as a structural unit of a compound (copolymer) represented by formula (1), the compound represented by formula (1) is contaminated with the AEMA homopolymer. The inclusion of the AEMA homopolymer in the compound represented by formula (1) may reduce the safety of the compound represented by formula (1). When a compound represented by formula (1) contaminated with the AEMA homopolymer is used for contact lenses, the AEMA homopolymer may inhibit the reaction of the compound represented by formula (1) or the AEMA homopolymer may react, preventing the desired effect from being achieved. In view of the above circumstances, the present invention aims to provide high-purity 2-aminoethyl methacrylate hydrochloride and a copolymer containing or essentially consisting of the hydrochloride as a structural unit, as well as a method for producing 2-aminoethyl methacrylate hydrochloride.

[0016] The present inventors have conducted extensive research to achieve the above object and have found that high-purity AEMA can be obtained by drying AEMA under specific drying conditions in the AEMA production process.

[0017] That is, the present invention is as follows. 1. 2-Aminoethyl methacrylate hydrochloride having a content of a homopolymer of 2-aminoethyl methacrylate hydrochloride of less than 2 mol %. 2. 2-Aminoethyl methacrylate hydrochloride that is substantially free of a homopolymer of 2-aminoethyl methacrylate hydrochloride. 3. 2-Aminoethyl methacrylate hydrochloride according to item 1 or 2 above, wherein, when a solution obtained by dissolving the 2-aminoethyl methacrylate hydrochloride in ethanol at a concentration of 10 wt % is measured for transmittance at a wavelength of 555 nm using a spectrophotometer, the transmittance is 50% or more. 4. A method for producing 2-aminoethyl methacrylate hydrochloride according to item 1 above, comprising the following steps: 1) a reaction step of reacting 2-aminoethanol hydrochloride with methacrylic acid chloride, and 2) a drying step of drying the 2-aminoethyl methacrylate hydrochloride obtained in the reaction step 1) under reduced pressure at 45°C or lower. 5. The production method according to item 4 above, wherein the reduced pressure is 100 hPa or lower. 6. 6. The production method according to item 4 or 5 above, which comprises a crystallization step between step 1) and step 2). 7. The production method according to item 4 or 5 above, wherein the 2-aminoethyl methacrylate hydrochloride contains less than 2 mol % of a homopolymer of 2-aminoethyl methacrylate hydrochloride. 8. The production method according to item 4 or 5 above, wherein the 2-aminoethyl methacrylate hydrochloride is substantially free of a homopolymer of 2-aminoethyl methacrylate hydrochloride. 9. A copolymer comprising the 2-aminoethyl methacrylate hydrochloride according to item 1 or 2 above as a structural unit and a compound represented by formula (2) as a structural unit.

[0018]

[0019] (In formula (2), R ２ is a hydrogen atom or a methyl group, and X ２ is O or NH.) 10. A copolymer represented by formula (1), which contains structural units of 2-aminoethyl methacrylate hydrochloride as described in item 1 or 2 above, and structural units of a compound represented by formula (2).

[0020]

[0021] (In formula (1), a:b=50:50 to 98:2, and R １ is a hydrogen atom or a methyl group, and X １ is O or NH.)

[0022]

[0023] (In formula (2), R ２ is a hydrogen atom or a methyl group, and X ２ is O or NH.)

[0024] The present invention can provide high-purity 2-aminoethyl methacrylate hydrochloride and a method for producing the hydrochloride.

[0025] The method for producing 2-aminoethyl methacrylate hydrochloride of the present invention will be described in more detail below. High-purity 2-aminoethyl methacrylate hydrochloride obtained by the method for producing 2-aminoethyl methacrylate hydrochloride of the present invention is referred to as 2-aminoethyl methacrylate hydrochloride of the present invention. The method for producing 2-aminoethyl methacrylate hydrochloride of the present invention includes at least the following 1) reaction step and 2) drying step, but may also include other steps. The purity of AEMA is １ It can be measured by H NMR and transmittance. １ H NMR can measure the AEMA homopolymer contained in AEMA, while transmittance can evaluate trace amounts of impurities. In this specification, when preferred numerical ranges (e.g., ranges of concentration or weight / number average molecular weight) are described in stages, the lower and upper limits of each numerical range can be freely combined. For example, in the description "preferably 10 or more, more preferably 20 or more, and preferably 100 or less, more preferably 90 or less," the "preferred lower limit: 10" and the "more preferred upper limit: 90" can be combined to obtain "10 or more and 90 or less." Furthermore, for example, in the description "preferably 10 to 100, more preferably 20 to 90," the range can similarly be "10 to 90."

[0026] (Reaction Step) AEMA can be obtained by the reaction of 2-aminoethanol hydrochloride with methacrylic acid chloride. In the reaction of 2-aminoethanol hydrochloride with methacrylic acid chloride, the amount of methacrylic acid chloride used is preferably 1.0 mol or more per mol of 2-aminoethanol hydrochloride. More preferably, it is 1.1 to 5.0 mol, and even more preferably, it is 1.2 to 2.0 mol. Less than 1.0 mol is undesirable because aminoethanol hydrochloride remains, while use of more than 5.0 mol is uneconomical and may make it difficult to remove unreacted methacrylic acid chloride. The above reaction is preferably carried out by melting 2-aminoethanol hydrochloride without using a solvent. Therefore, the reaction temperature is preferably 80°C or higher, more preferably 85°C or higher, and even more preferably 90°C or higher. At temperatures below 80°C, the reaction may not proceed sufficiently. The above reaction is preferably carried out without using a solvent, but a solvent can also be used. When a solvent is used, the solvent is preferably one that does not react with methacrylic acid chloride, such as dimethyl sulfoxide, N,N-dimethylformamide, or acetonitrile. Because hydrogen chloride is generated as the reaction proceeds, it is preferable to conduct the reaction while blowing in an inert gas to remove the hydrogen chloride. Examples of inert gases include nitrogen and argon, with nitrogen being preferred. The reaction is preferably carried out by adding methacrylic acid chloride dropwise. Dropwise addition facilitates control of the heat of reaction and the amount of hydrogen chloride generated by the reaction. A polymerization inhibitor may be added to the reaction as needed. The polymerization inhibitor is not particularly limited as long as it is one that has been conventionally used as a polymerization inhibitor for radical polymerization. Examples include hydroquinone, hydroquinone monomethyl ether, 2-t-butylhydroquinone, 4-methoxyphenol, 2,6-di-t-butyl-4-methylphenol (BHT), and phenothiazine. These polymerization inhibitors may be used alone or in combination of two or more.The amount of polymerization inhibitor is not particularly limited, but is preferably 100 ppm to 50,000 ppm, more preferably 1,000 ppm to 40,000 ppm, and even more preferably 5,000 ppm to 30,000 ppm, relative to the mass of methacrylic acid chloride. The reaction time, including the time for the dropwise addition of methacrylic acid chloride, is preferably 12 hours or less, more preferably 8 hours or less, even more preferably 6 hours or less, particularly preferably 3 hours or less, and most preferably 2 hours or less. If the reaction time is too long, the amount of by-products may increase. If the reaction is cooled after completion of the reaction, the reaction liquid solidifies and becomes difficult to handle; therefore, it is preferable to dilute the reaction liquid with a solvent. Preferred solvents include acetate esters such as methyl acetate, ethyl acetate, and butyl acetate; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; and alcohols such as methanol, ethanol, 1-propanol, 2-propanol, and butanol. Two or more solvents may be used in combination.

[0027] (Crystallization Step) The method for producing 2-aminoethyl methacrylate hydrochloride of the present invention preferably includes a crystallization step between the above-mentioned 1) reaction step and the below-described 2) drying step. The crystallization step refers to a procedure in which 2-aminoethyl methacrylate hydrochloride containing impurities (e.g., AEMA homopolymer) and unreacted raw materials obtained in the above-mentioned 1) reaction step is crystallized by cooling or heating, and is then separated and purified. This procedure is not particularly limited. In addition, this step may include known procedures such as extraction, purification, and filtration. Examples of good solvents used in crystallization include alcohols such as methanol, ethanol, 1-propanol, and 2-propanol, and two or more solvents may be used in combination. Examples of poor solvents include acetate esters such as methyl acetate, ethyl acetate, and butyl acetate; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; hydrocarbons such as hexane and heptane; and aromatic compounds such as toluene. Two or more solvents may be used in combination. To increase the degree of purification, the above crystallization may be performed multiple times, or the crystals may be washed with the above solvent. After crystallization, the precipitated crystals can be recovered by filtration. Examples of the filtration method include hot filtration, gravity filtration, vacuum (suction) filtration, and pressure filtration, with pressure filtration being preferred. The crystallization step is not particularly limited, but examples thereof include the steps of crystallization → pressure filtration → obtaining first crude crystals → redissolution → hot filtration → crystallization → pressure filtration → obtaining second crude crystals → washing with a mixed solvent → obtaining third crude crystals.

[0028] (Drying step) The crystals recovered in the above 1) reaction step or the above crystallization step contain the organic solvent used in the crystallization, and are therefore ultimately dried at a temperature of 45°C or less to obtain powdered AEMA. The drying temperature is preferably 20°C or higher and 45°C or lower, more preferably 30°C or higher and 40°C or lower. Below 20°C, the solvent may not be sufficiently removed, and above 45°C, AEMA homopolymers may be formed. Drying is preferably carried out under reduced pressure. By reducing the pressure, the drying time can be shortened and residual solvent can be reduced. There are no particular restrictions on the pressure, but it is preferably 100 hPa or less, more preferably 50 hPa or less, even more preferably 20 hPa or less, and particularly preferably 10 hPa or less. The drying time is not particularly limited, but is preferably 1 hour or more and 24 hours or less. If it is less than 1 hour, the solvent may not be sufficiently removed, and if it exceeds 24 hours, it is not efficient. For example, it is 1 to 10 hours, or 2 to 8 hours. The loss on drying of AEMA is preferably 2.0 wt% or less, more preferably 1.0 wt%, even more preferably 0.5 wt%, particularly preferably 0.3 wt% or less, and most particularly preferably 0.2 wt% or less. If more than 2.0 wt% of volatile components (solvent and water) remain, the stability and handling properties may be deteriorated.

[0029] (2-Aminoethyl Methacrylate Hydrochloride of the Present Invention) The method for producing 2-aminoethyl methacrylate hydrochloride of the present invention can provide 2-aminoethyl methacrylate hydrochloride (composition) containing less than 2 mol %, 1.5 mol % or less, 1.0 mol % or less, 0.5 mol % or less, 0.3 mol % or less, 0.2 mol % or less, 0.1 mol % or less, 0.05 mol % or less, or 0.01 mol % of the AEMA homopolymer represented by formula (4). In addition, the method for producing 2-aminoethyl methacrylate hydrochloride of the present invention can provide 2-aminoethyl methacrylate hydrochloride (composition) that is substantially free of the AEMA homopolymer represented by formula (4). Note that "substantially free" means that the content is below the detection limit of a known measuring device. Note that the above mol % refers to the molar ratio of the AEMA homopolymer to the total number of moles of 2-aminoethyl methacrylate hydrochloride and impurities (particularly the AEMA homopolymer).

[0030] Furthermore, the 2-aminoethyl methacrylate hydrochloride of the present invention exhibits high solubility in ethanol. When the transmittance of a 10 wt % ethanol solution at a wavelength of 555 nm is measured using a spectrophotometer, the transmittance is 50% or more, preferably 60% or more, more preferably 70% or more, even more preferably 80% or more, still more preferably 90% or more, most preferably 95% or more, and most preferably 97% or more.

[0031] (Compound Represented by Formula (2)) The monomer represented by formula (2) in the present invention can be produced by a known method, for example, a method of reacting a hydroxyl group-containing polymerizable monomer with 2-bromoethylphosphoryl dichloride in the presence of a tertiary base, and then reacting the compound obtained with a tertiary amine. Alternatively, a method of reacting a hydroxyl group-containing polymerizable monomer with a cyclic phosphorus compound to obtain a cyclic compound, and then subjecting the cyclic compound to a ring-opening reaction with a tertiary amine may also be used. X ２ When R is an oxygen atom, from the viewpoint of polymerizability and stability, ２ is preferably a methyl group. ２ If is NH, then R ２ is preferably a hydrogen atom from the viewpoint of polymerizability. ２ 2-(meth)acryloyloxyethyl (2-(trimethylammonio)ethyl)phosphate, where X is an oxygen atom; ２ is NH, and more preferably R ２ is a methyl group and X ２ 2-methacryloyloxyethyl (2-(trimethylammonio)ethyl) phosphate (MPC) where R is an oxygen atom ２ is a hydrogen atom and X ２ is NH, and from the viewpoint of availability, 2-methacryloyloxyethyl (2-(trimethylammonio)ethyl) phosphate is more preferred.

[0032] (Method for Producing a Compound Represented by Formula (1)) The compound represented by formula (1) can be obtained by copolymerizing the structural unit 2-aminoethyl methacrylate hydrochloride of the present invention with the structural unit compound represented by formula (2). For example, the compound represented by formula (1) is a polymerization reaction product (copolymer) of the polymerizable unsaturated groups of each structural unit. The polymerization reaction can be carried out by radical polymerization (for example, known methods such as bulk polymerization, suspension polymerization, emulsion polymerization, and solution polymerization) in the presence of a radical polymerization initiator in an atmosphere substituted with an inert gas such as nitrogen, carbon dioxide, argon, or helium, or in an inert gas atmosphere. From the viewpoint of purification, solution polymerization is preferred. The copolymer can be purified by common purification methods such as reprecipitation, dialysis, and ultrafiltration. Examples of the radical polymerization initiator include azo-based radical polymerization initiators, organic peroxides, and persulfates. Examples of azo radical polymerization initiators include 2,2'-azobis(2-methylpropionamidine) dihydrochloride (V-50), 2,2-azobis(2-diaminopropyl) dihydrochloride, 2,2-azobis(2-(5-methyl-2-imidazolin-2-yl)propane) dihydrochloride, 4,4'-azobis(4-cyanovaleric acid), 2,2-azobisisobutylamide dihydrate, 2,2-azobis(2,4-dimethylvaleronitrile), 2,2-azobisisobutyronitrile (AIBN), etc. It is more preferable to use 2,2'-azobis(2-methylpropionamidine) dihydrochloride (V-50). Examples of organic peroxides include t-butyl peroxyneodecanoate (Perbutyl (registered trademark) ND), benzoyl peroxide, diisopropyl peroxydicarbonate, t-butylperoxy-2-ethylhexanoate, t-butyl peroxypivalate, t-butyl peroxydiisobutyrate, lauroyl peroxide, and succinic acid peroxide (succinyl peroxide). Examples of persulfates include ammonium persulfate, potassium persulfate, and sodium persulfate. These radical polymerization initiators can be used alone or in combination of two or more.The amount of the polymerization initiator used is usually 0.001 to 10 parts by mass, preferably 0.01 to 5.0 parts by mass, per 100 parts by mass of the monomer composition of the copolymer (compound represented by formula (1)).

[0033] The polymerization reaction can be carried out in the presence of a solvent. The solvent can be one that dissolves the monomer composition, which is each structural unit, but does not react with it. Examples of the solvent include water, alcoholic solvents such as methanol, ethanol, n-propanol, and isopropanol; ketone solvents such as acetone, methyl ethyl ketone, and diethyl ketone; ester solvents such as ethyl acetate; linear or cyclic ether solvents such as ethyl cellosolve, tetrahydrofuran, and N-methylpyrrolidone; and nitrogen-containing solvents such as acetonitrile and nitromethane. Water, alcohol, or a mixture thereof is preferred, and water is more preferred. The weight-average molecular weight of the compound represented by formula (1) obtained above is 10,000 to 2,000,000, preferably 100,000 to 1,000,000, more preferably 150,000 to 600,000, and even more preferably 200,000 to 450,000. The molar ratio of a to b in formula (1) can be set arbitrarily, but is preferably a:b=50:50 to 98:2, more preferably a:b=80:20 to 95:5, and even more preferably a:b=88:12 to 94:6.

[0034] The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.

[0035] <Measurement of AEMA homopolymer content> The measurement was carried out according to the following procedure. １ H NMR measurement was carried out. The measurement conditions are described below. １ The peak area value derived from AEMA observed near 6.2 ppm in the H NMR spectrum is A ｍ The area value of the broad peak derived from the homopolymer of AEMA observed in the vicinity of 0.4 to 1.0 ppm was taken as A ｐ The content of the compound represented by formula (4) was calculated using the following calculation formula (1): ｐ / 3) / (A ｍ+ (A ｐ / 3))) × 100 ... Calculation formula (1) 3: Peak area A ｐ Number of protons １ H NMR measurement conditions: Apparatus: ECS400 (manufactured by JEOL Ltd.) Solvent: deuterated dimethyl sulfoxide Sample concentration: 3% Number of accumulations: 32

[0036] <Method for measuring loss on drying (method for measuring residual solvent amount)> Measurement was carried out according to the following procedure. The tared container of the screw tube was weighed, and this weight was recorded as W １ 1 g of AEMA was weighed into this screw tube, and the sum of the weight of the screw tube and the weight of AEMA was W ２ The screw cap was dried in an oven at 125°C for 4 hours. After drying, the screw cap was capped and cooled to room temperature in a desiccator. After cooling, the screw cap was removed from the desiccator, and the cap was removed. The weight was measured. ３ The loss on drying (%) was calculated using the following formula (2): ２ -W ３ ) / (W ２ -W １ )×100...Calculation formula (2)

[0037] <Purity Measurement by Transmittance> Measurement was performed according to the following procedure. Preparation of Measurement Solution: 0.3 g of AEMA and 2.7 g of ethanol (ultra-dehydrated) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were weighed into a screw tube and stirred for 10 minutes to prepare the measurement solution. Transmittance Measurement: The ethanol (ultra-dehydrated) was placed in a cell with an optical path length of 1 cm, and background measurement was performed in the wavelength range of 400 to 750 nm. The measurement solution was then transferred to a cell with an optical path length of 1 cm, and spectral measurement was performed in the wavelength range of 400 to 750 nm to evaluate the transmittance at 555 nm. Other conditions were as follows: Transmittance Measurement Conditions: Apparatus: UV-Visible Spectrophotometer V-650 (manufactured by JASCO Corporation); Response: Medium; Bandwidth: 2.0 nm; Scanning Speed: 200 nm / min. The following scores were assigned to purity by transmittance, with a lower score indicating a higher purity. Transparency 75 or more: Score "1" Transparency 50 or more but less than 75: Score "2" Transparency 0 or more but less than 50: Score "3"

[0038] <Measurement of Weight-Average Molecular Weight> The obtained copolymer was dissolved in ion-exchanged water to a concentration of 0.1 wt %, and the weight-average molecular weight was measured by gel permeation chromatography (GPC). Column: Shodex (GSM-700) Mobile phase: 0.1 mol / L aqueous sodium sulfate Standard substance: Pullulan Measuring instrument: Differential refractive index RI-8020 (manufactured by Tosoh Corporation) Calculation method for weight-average molecular weight: Molecular weight calculation program (GPC program for SC-8020) Flow rate: 1.0 mL per minute Injection volume: 100 μL Column oven temperature: 40°C Measurement time: 30 minutes

[0039] <Cytotoxicity Test Using Rabbit Corneal Epithelial Cells (SIRC Cells)> A cytotoxicity test using SIRC cells was performed with reference to ISO 10993-5:2009 and the reference N. Tani et al., Toxicology in Vitro 13 (1999) 175-187, and the cell viability was measured and evaluated.

[0040] Preparation of SIRC cell culture medium: 5 mL of antibiotic / antimycotic solution (100x) was added to a 500 mL bottle of Dulbecco's Modified Eagle's (DMEM) medium. Next, 50 mL of sterilized fetal bovine serum (inactivated FBS) was thawed at 4°C and added to prepare the cell culture medium. Dulbecco's Modified Eagle's (DMEM) medium was manufactured by Sigma-Aldrich Japan, the antibiotic / antimycotic (100x) was manufactured by Sigma-Aldrich Japan, and the sterilized fetal bovine serum (FBS) was manufactured by Japan Biotest Research Institute.

[0041] Culturing SIRC cells: Add 9 mL of cell culture medium and 1 mL of cell suspension to a sterile dish and incubate in CO ２ The cells were cultured in an incubator for 48 hours or more to grow. The cells in the dish were observed under a microscope to confirm the increase in cell number and their state (whether they had died or were floating without adhering).

[0042] Cell seeding: Cell suspension was seeded at a concentration of 1 x 10 ５ The cell suspension was adjusted to a concentration of 100 μL / well using a cell culture medium to give 100 μL of cell suspension per well of a 96-well plate. ２ The cells were cultured in an incubator for 24 hours.

[0043] Preparation of Test Substances Test substances were prepared by dissolving a 10 w / v% solution of each copolymer and biochemical grade sodium lauryl sulfate (SDS) as a positive control in cell culture medium. The prepared test substances were serially diluted to 100 w / v%, 75 w / v%, 50 w / v%, 25 w / v%, 12.5 w / v%, and 0 w / v% on a 96-well plate and used for evaluation. Biochemical grade sodium lauryl sulfate was manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., and Dulbecco's phosphate buffered saline was manufactured by Sigma-Aldrich Japan.

[0044] Exposure to test substance: The SIRC cell culture medium was removed from the 96-well plate, and the test substance prepared above was added to the 96-well plate in an amount of 200 μL / well after 24 hours of culture.２ The exposure was allowed to continue for 24 hours in an incubator.

[0045] - Cytotoxicity evaluation by neutral red (NR) method NR was dissolved in ion-exchanged water to a concentration of 5 mg / mL to prepare an NR stock solution. The NR stock solution was diluted 100-fold with cell culture medium to prepare an NR medium. The 96-well plate exposed to the test substance was removed, and the medium was removed. Next, 100 μL of NR medium was added to each well, and then the plate was incubated for 1 hour at 20°C for 1 hour. ２ The cells were cultured in an incubator for 3 hours to allow the NR to be incorporated into the cells. ２ The 96-well plate was removed from the incubator and the NR medium was removed. 100 μL / well of PBS was added to the 96-well plate. After removing the PBS, 100 μL / well of NR extract solution, a mixture of 50% ethanol, 49% ion-exchanged water, and 1% acetic acid, was added with a micropipette. The mixture was stirred for 5 minutes on a shaker to extract NR from the cells, and the absorbance at 540 nm was measured using a plate reader. The contact concentration of SDS required for 50% cell viability was confirmed to be approximately 0.01% by mass, and the cell viability and IC after treatment with the test substance were calculated using the following formula: ５０ The value was calculated. Neutral red was manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Formula for calculating cell viability: Cell viability (%) = (absorbance of test substance treatment - absorbance of blank) / (absorbance of medium treatment - absorbance of blank) x 100 IC ５０ Value calculation formula IC ５０ Value = 10 (log10(A / B) × (50-C) / (D-C) + log10(B)) A: High test substance concentration (w / v%) on either side of 50% cell viability B: Low test substance concentration (w / v%) on either side of 50% cell viability C: Cell viability in B D: Cell viability in A The absorbance of the medium treatment is the absorbance when only medium is added to the wells into which cells were seeded.

[0046] The following scores were set as the criteria for judging safety: IC ５０ Value 50 or more: Score "1" (indicates extremely excellent safety) IC ５０Value 25 or more and less than 50: Score "2" (indicates excellent safety) IC ５０ Value 12.5 or more and less than 25: Score "3" (no safety issues) IC ５０ Value 0 or more and less than 12.5: Score "4" (more detailed safety testing required)

[0047] Example 1-1 Synthesis of AEMA by the Production Method of the Present Invention A four-neck flask equipped with a thermometer, a stirring blade, a dropping funnel, and a reflux condenser was charged with 50.0 g (0.51 mol) of 2-aminoethanol hydrochloride and 1.02 g of phenothiazine (approximately 12,800 ppm by mass relative to methacrylic acid chloride), and stirring was initiated. The mixture was heated to 90°C to melt the 2-aminoethanol hydrochloride. 79.8 g (0.76 mol) of methacrylic acid chloride was added dropwise over 3 hours to carry out the reaction. After completion of the reaction, the mixture was cooled to approximately 60°C, and 530 g of ethyl acetate was added. After the addition of ethyl acetate, the mixture was further cooled to room temperature to carry out crystallization, and crude crystals (A) were obtained by pressure filtration using No. 5A filter paper (manufactured by Toyo Roshi Kaisha, Ltd.) at a pressure of 0.02 MPa with nitrogen. To the obtained crude crystals (A), 1.02 g of phenothiazine, 140 g of 2-propanol, and 370 g of ethyl acetate were added, and the mixture was heated to 80 ° C. and dissolved. After confirming dissolution, No. 5A filter paper was used, and insoluble matter was removed by hot filtration under pressure at a pressure of 0.02 MPa with nitrogen, and the filtrate was recovered. The filtrate was cooled to room temperature and then further cooled to -5 ° C. to perform crystallization, and No. 5A filter paper was used, and crude crystals (B) were obtained by pressure filtration under a pressure of 0.02 MPa with nitrogen. The obtained crude crystals (B) were washed with a mixed solvent of 70 g of 2-propanol and 185 g of ethyl acetate, and filtered to obtain crude crystals (C). The obtained crude crystals (C) were dried at 35 ° C. for 5 hours under reduced pressure (20 hPa), and the target AEMA was obtained. The loss on drying was 0.3 wt%. １ As a result of H NMR analysis, it was confirmed that the compound represented by formula (4) was not detectable and was AEMA. Furthermore, transmittance measurement revealed that the transmittance at 555 nm was 81%.

[0048] Example 1-2 A four-neck flask equipped with a thermometer, a stirring blade, a dropping funnel, and a reflux condenser was charged with 100.0 g (1.02 mol) of 2-aminoethanol hydrochloride and 2.04 g of phenothiazine (approximately 12,800 ppm by mass relative to methacrylic acid chloride), and stirring was initiated. The mixture was heated to 92°C to melt the 2-aminoethanol hydrochloride. 159.6 g (1.52 mol) of methacrylic acid chloride was added dropwise over 5 hours to carry out the reaction. After completion of the reaction, the mixture was cooled to approximately 60°C, and 530 g of ethyl acetate was added. After the addition of ethyl acetate, the mixture was further cooled to room temperature to carry out crystallization, and crude crystals (A) were obtained by pressure filtration using No. 5A filter paper at a pressure of 0.02 MPa with nitrogen. To the obtained crude crystals (A), 2.04 g of phenothiazine, 280 g of 2-propanol, and 740 g of ethyl acetate were added, and the mixture was heated to 80 ° C. and dissolved. After confirming dissolution, No. 5A filter paper was used, and insoluble matter was removed by hot filtration under pressure at a pressure of 0.02 MPa with nitrogen, and the filtrate was recovered. The filtrate was cooled to room temperature and then further cooled to -5 ° C. to perform crystallization, and No. 5A filter paper was used, and crude crystals (B) were obtained by pressure filtration under a pressure of 0.02 MPa with nitrogen. The obtained crude crystals (B) were washed with a mixed solvent of 140 g of 2-propanol and 370 g of ethyl acetate, and filtered to obtain crude crystals (C). The obtained crude crystals (C) were dried at 40 ° C. for 8 hours under reduced pressure (80 hPa), and the target AEMA was obtained. The loss on drying was 0.6 wt%. １ As a result of H NMR analysis, it was confirmed that the compound represented by formula (4) was not detectable and was AEMA. Furthermore, transmittance measurement revealed that the transmittance at 555 nm was 70%.

[0049] Example 1-3 A four-neck flask equipped with a thermometer, a stirring blade, a dropping funnel, and a reflux condenser was charged with 50.0 g (0.51 mol) of 2-aminoethanol hydrochloride and 1.02 g of phenothiazine (approximately 12,800 ppm by mass relative to methacrylic acid chloride), and stirring was initiated. The mixture was heated to 90°C to melt the 2-aminoethanol hydrochloride. 79.8 g (0.76 mol) of methacrylic acid chloride was added dropwise over 2 hours to carry out the reaction. After completion of the reaction, the mixture was cooled to approximately 60°C, and 530 g of ethyl acetate was added. After the addition of ethyl acetate, the mixture was further cooled to room temperature to carry out crystallization, and crude crystals (A) were obtained by pressure filtration using No. 5A filter paper at a pressure of 0.02 MPa with nitrogen. To the obtained crude crystals (A), 1.02 g of phenothiazine, 140 g of 2-propanol, and 370 g of ethyl acetate were added, and the mixture was heated to 80 ° C. and dissolved. After confirming dissolution, No. 5A filter paper was used, and insoluble matter was removed by hot filtration under pressure at a pressure of 0.02 MPa with nitrogen, and the filtrate was recovered. The filtrate was cooled to room temperature and then further cooled to -5 ° C. to perform crystallization, and No. 5A filter paper was used, and crude crystals (B) were obtained by pressure filtration under a pressure of 0.02 MPa with nitrogen. The obtained crude crystals (B) were washed with a mixed solvent of 70 g of 2-propanol and 185 g of ethyl acetate, and filtered to obtain crude crystals (C). The obtained crude crystals (C) were dried at 40 ° C. for 2 hours under reduced pressure (10 hPa), and the target AEMA was obtained. The loss on drying was 0.2 wt%. １ As a result of H NMR analysis, it was confirmed that the compound represented by formula (4) was not detectable and was AEMA. Furthermore, transmittance measurement revealed that the transmittance at 555 nm was 90%.

[0050] Example 1-4 A four-neck flask equipped with a thermometer, a stirring blade, a dropping funnel, and a reflux condenser was charged with 50.0 g (0.51 mol) of 2-aminoethanol hydrochloride and 1.02 g of phenothiazine (approximately 12,800 ppm by mass relative to methacrylic acid chloride), and stirring was initiated. The mixture was heated to 90°C to melt the 2-aminoethanol hydrochloride. 79.8 g (0.76 mol) of methacrylic acid chloride was added dropwise over 2 hours to carry out the reaction. After completion of the reaction, the mixture was cooled to approximately 60°C, and 530 g of ethyl acetate was added. After the addition of ethyl acetate, the mixture was further cooled to room temperature to carry out crystallization, and crude crystals (A) were obtained by pressure filtration using No. 5A filter paper at a pressure of 0.02 MPa with nitrogen. To the obtained crude crystals (A), 1.02 g of phenothiazine, 140 g of 2-propanol, and 370 g of ethyl acetate were added, and the mixture was heated to 80 ° C. and dissolved. After confirming dissolution, No. 5A filter paper was used, and insoluble matter was removed by hot pressure filtration at a pressure of 0.02 MPa with nitrogen, and the filtrate was recovered. The filtrate was cooled to room temperature and then further cooled to -5 ° C. to perform crystallization, and No. 5A filter paper was used, and crude crystals (B) were obtained by pressure filtration at a pressure of 0.02 MPa with nitrogen. The obtained crude crystals (B) were washed with a mixed solvent of 70 g of 2-propanol and 185 g of ethyl acetate, and filtered to obtain crude crystals (C). The obtained crude crystals (C) were dried at 25 ° C. for 5 hours under reduced pressure (40 hPa), and the target AEMA was obtained. The loss on drying was 1.0 wt%. １ As a result of H NMR analysis, it was confirmed that the compound represented by formula (4) was not detectable and was AEMA. Furthermore, transmittance measurement revealed that the transmittance at 555 nm was 97%.

[0051] Comparative Example 1-1 Crude AEMA crystals (C) were obtained in the same manner as in Example 1-2. The obtained crude AEMA crystals (C) were dried at 50° C. for 4 hours under reduced pressure (30 hPa). １ As a result of H NMR analysis, it was confirmed that the AEMA homopolymer represented by formula (4) was contained in an amount of 3.2 mol %. Furthermore, when the sample was dissolved in ethanol for transmittance measurement, a precipitate was observed, so the transmittance measurement was not carried out.

[0052] Comparative Example 1-2 Crude AEMA crystals (C) were obtained in the same manner as in Example 1-2. The obtained crude AEMA crystals (C) were dried at 60° C. for 4 hours under reduced pressure (40 hPa). １ As a result of H NMR analysis, it was confirmed that the AEMA homopolymer represented by formula (4) was contained in an amount of 5.5 mol %. Furthermore, when the AEMA homopolymer was dissolved in ethanol for transmittance measurement, a precipitate was observed, so the transmittance measurement was not carried out.

[0053]

[0054] Example 2-1 Synthesis of a compound represented by formula (1) R of a compound represented by formula (2) ２ is a hydrogen atom, X ２ 50.0 g (0.17 mol) of 2-methacryloyloxyethyl (2-(trimethylammonio)ethyl)phosphate (MPC) (manufactured by NOF Corporation), in which ≈ is an oxygen atom, and 3.1 g (0.02 mol) of 2-aminoethyl methacrylate hydrochloride (AEMA) synthesized in Example 1-1 were dissolved in 212.0 g of distilled water. This solution was placed in a four-neck flask equipped with a reflux condenser, a nitrogen inlet tube, a thermometer, and a stirring blade. The solution was heated to 65°C, and 0.36 g of 2,2'-azobis(2-methylpropionamidine) dihydrochloride (V-50) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added, and nitrogen bubbling was initiated at 0.3 L / min. The temperature of this solution was raised to 70°C and maintained for 120 minutes. After completion of the reaction, the solution was cooled to room temperature, purified by dialysis using a dialysis membrane, and freeze-dried to obtain a white powder. The concentration of the obtained compound represented by formula (1) was adjusted to 10 w / v% for ease of handling. The molecular weight was confirmed by GPC and found to be a weight average molecular weight of 330,000. The molar ratio of a to b in the compound represented by formula (1) was 90:10.

[0055] Examples 2-2 to 2-4 Compounds represented by formula (1) were synthesized in the same procedure as in Example 2-1, except that the conditions were changed as shown in Table 2. The molar ratio of a to b in the compound represented by formula (1) synthesized in Example 2-2 was 95:5. The molar ratio of a to b in the compound represented by formula (1) synthesized in Example 2-3 was 92:8. The molar ratio of a to b in the compound represented by formula (1) synthesized in Example 2-4 was 85:15.

[0056] Comparative Examples 2-1 and 2-2 Compounds represented by formula (1) were synthesized in the same manner as in Example 2-1, except that the conditions were changed as shown in Table 2. The molar ratio of a to b in the compound represented by formula (1) synthesized in Comparative Example 2-1 was 90:10. The molar ratio of a to b in the compound represented by formula (1) synthesized in Comparative Example 2-2 was 90:10.

[0057]

[0058] <Example 3 and Comparative Example 3> For the purpose of evaluating the safety of the compound represented by formula (1), cytotoxicity tests using SIRC cells were carried out (Examples 3-1 to 3-4, Comparative Examples 3-1 and 3-2). The results are shown in Table 3.

[0059]

[0060] <Evaluation Results of Examples> In Examples 1-1 to 1-4, as shown in the results in Table 1, AEMA with a homopolymer content of 2% or less (particularly, below the detection limit) could be obtained by drying at 45°C or less in the drying process. In addition, by lowering the pressure in the drying process, it was possible to reduce loss on drying by drying for a short time. Using the AEMA obtained in Examples 1-1 to 1-4 as a raw material, compounds represented by formula (1) were synthesized in Examples 2-1 to 2-4. These were evaluated in Examples 3-1 to 3-4, and IC ５０ It was confirmed that the compound represented by formula (1) had high values ​​and was highly safe.

[0061] <Evaluation Results of Comparative Examples> In Comparative Examples 1-1 and 1-2, as shown in the results in Table 1, the drying temperature in the drying step was set to 50°C or higher, resulting in a content of 3.2% or more of AEMA homopolymer. Using the AEMA obtained in Comparative Examples 1-1 and 1-2 as a raw material, compounds represented by formula (1) were synthesized in Comparative Examples 2-1 and 2-2. When these were evaluated in Comparative Examples 3-1 and 3-2, IC ５０ It was confirmed that the values ​​were low and that further detailed verification of safety was required.

[0062] The production method of the present invention can obtain high-purity 2-aminoethyl methacrylate hydrochloride.

[0063] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. This application is based on a Japanese patent application (Patent Application No. 2024-53758) filed on March 28, 2024, the contents of which are incorporated herein by reference.

Claims

1. 2-aminoethyl methacrylate hydrochloride, having a homopolymer content of 2-aminoethyl methacrylate hydrochloride of less than 2 mol %.

2. 2-aminoethyl methacrylate hydrochloride substantially free of homopolymers of 2-aminoethyl methacrylate hydrochloride.

3. The 2-aminoethyl methacrylate hydrochloride according to claim 1 or 2, wherein when a solution prepared by dissolving the 2-aminoethyl methacrylate hydrochloride in ethanol at a concentration of 10 wt % is measured for transmittance at a wavelength of 555 nm using a spectrophotometer, the transmittance is 50% or more.

4. A method for producing 2-aminoethyl methacrylate hydrochloride according to claim 1, comprising the following steps: 1) a reaction step of reacting 2-aminoethanol hydrochloride with methacrylic acid chloride; and 2) a drying step of drying the 2-aminoethyl methacrylate hydrochloride obtained in the reaction step 1) under reduced pressure at 45°C or lower.

5. The manufacturing method according to claim 4, wherein the reduced pressure is 100 hPa or less.

6. The method according to claim 4 or 5, further comprising a crystallization step between step 1) and step 2).

7. The method of claim 4 or 5, wherein the 2-aminoethyl methacrylate hydrochloride contains less than 2 mole % of a homopolymer of 2-aminoethyl methacrylate hydrochloride.

8. The method according to claim 4 or 5, wherein the 2-aminoethyl methacrylate hydrochloride is substantially free of homopolymers of 2-aminoethyl methacrylate hydrochloride.

9. A copolymer comprising the 2-aminoethyl methacrylate hydrochloride of claim 1 or 2 as a structural unit and a compound represented by formula (2) as a structural unit. (In formula (2), R ２ is a hydrogen atom or a methyl group, and X ２ is O or NH.) 10. A copolymer represented by formula (1), which contains the structural unit of 2-aminoethyl methacrylate hydrochloride according to claim 1 or 2 and the structural unit of a compound represented by formula (2). (In formula (1), a:b=50:50 to 98:2, and R １ is a hydrogen atom or a methyl group, and X １ is O or NH.) (In formula (2), R ２ is a hydrogen atom or a methyl group, and X ２ is O or NH.)

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