Poly (4-vinylbenzyl-N-isopropylacrylamide) ionic liquid catalyst as well as preparation and application thereof
By preparing poly4-vinylbenzyl N-isopropylacrylamide ionic liquid catalyst, the problem of existing catalysts requiring strict conditions and difficulty in separation is solved, and the synthesis of 1-hydroxy-4-aminodiphenylphosphine oxide is achieved efficiently, with the advantages of high yield and easy separation.
Patent Information
- Application Number
- CN202510455112.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-11
- Publication Date
- 2025-08-29
AI Technical Summary
The existing catalysts require strict reaction conditions and poor circulation when preparing 1-hydroxy-4-aminodiphenylphosphine oxide, and the ionic liquid homogeneous catalysts are difficult to separate, resulting in the formation of by-products.
The in-situ polymerization strategy of amide-based monomers was adopted to prepare a poly4-vinylbenzyl N-isopropylacrylamide ionic liquid catalyst. By copolymerizing benzyl chloride ionic liquid with N-isopropylacrylamide, a binary copolymerized ionic liquid rich in strong acidic metals and amide groups was formed, achieving high activity and easy separation of the catalyst.
It provides a simple operation and environmentally friendly catalyst preparation method, high catalytic activity, and is easy to produce large-scale through centrifugation, which improves the yield of 1-hydroxy-4-aminodiphenylphosphine oxide.
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Abstract
Description
Technical Field
[0001] The present invention relates to an ionic liquid catalyst, its preparation and application, and in particular to a poly (4-vinylbenzyl N-isopropylacrylamide) ionic liquid catalyst, its preparation method and its application in catalyzing the synthesis of phosphine oxides from disubstituted benzene and phosphorus trichloride. Background Art
[0002] Phosphinous oxides (R2P(O)H) are a class of phosphorus-containing organic compounds. The phosphorus atom exists in the +3 oxidation state. It has the chemical properties of Lewis acidity and weak reducibility through the stable P=O bond and organic substituents. It can be hydrolyzed under acidic / alkaline conditions to generate phosphinous acid (R2P(O)OH) and can react with Sn to form phosphine oxides. 4+ 、Pd 2+ The metal ions are coordinated to form efficient catalytic active centers. In the application field, this compound is not only used as a phosphine ligand precursor for palladium-catalyzed coupling reactions (such as Suzuki and Negishi reactions), significantly improving the catalytic selectivity by regulating the electronic effect of the ligand, but also as a key intermediate for anti-tumor drugs (such as indiprolon) and anti-epileptic drugs, supporting the functional modification of drug molecules; at the same time, its derivatives improve the stability of devices by inhibiting electrode side reactions in lithium-ion battery electrolyte additives, showing application potential in the field of materials science. To date, many catalysts have been developed for the preparation of 1-hydroxy-4-aminodiphenylphosphine oxide from 1-hydroxy-4-aminobenzene and phosphorus trichloride, such as ionic liquids, solid-supported catalysts, traditional Lewis acid catalysts, etc. However, most of the reported catalysts require harsh reaction conditions and have poor recyclability.
[0003] Ionic liquids (ILs) are molten salt compounds composed of organic cations and organic or inorganic anions, typically existing in liquid form at temperatures below 100°C. These substances are considered "green solvents" due to their unique physicochemical properties. Their advantages include: structural tunability, allowing their solubility, polarity, and catalytic activity to be customized by adjusting the anion and cation combinations; low volatility and high stability, combining low vapor pressure, a wide liquid range, and excellent chemical and thermal stability, reducing environmental pollution risks; and outstanding solubility, dissolving a wide range of polar and non-polar substances, adapting to the needs of complex reaction systems. Currently, ionic liquids have demonstrated significant application value in areas such as surface engineering (e.g., metal plating), microelectronic device manufacturing (e.g., electrolyte materials), fine chemical synthesis (e.g., biomass extraction), and functional material development (e.g., rare earth element separation). They also demonstrate significant advantages in Friedel-Crafts reactions and the preparation of phosphine oxides in organic synthesis. However, ILs, as homogeneous catalysts, are difficult to separate in reaction systems, leading to catalyst decomposition or the formation of byproducts. Therefore, easy catalyst separation is a significant advantage in reaction systems. N-isopropylacrylamide (NIPAAm) is an acrylamide derivative monomer with a molecular structure containing both a hydrophilic amide group (-CONH-) and a hydrophobic isopropyl group (-CH(CH3)2). N-isopropylacrylamide has become a core raw material for the development of smart materials due to its unique amphiphilic molecular structure, precise temperature-sensitive response characteristics, and wide controllability. It has irreplaceable technical advantages, especially in the fields of biomedicine and industrial separation. The copolymerization of N-isopropylacrylamide and ionic liquids as monomers to form a catalyst not only has high catalytic activity but also effectively solves problems such as difficult catalyst separation. In addition, the significant difference between the hydrophilicity of N-isopropylacrylamide and the hydrophobicity of ionic liquids leads to easy phase separation during the copolymerization of the two. The high polarity of ionic liquids may inhibit the activity of free radical polymerization, and a balance needs to be struck between the interaction between the catalytic system and the monomers. Therefore, the preparation of PNIPAAm-co-R catalysts remains a great challenge. To this end, a simple method was used to develop PNIPAAm-co-R catalysts with good catalytic activity and stability. Summary of the Invention
[0004] One object of the present invention is to provide a method for preparing a poly (4-vinylbenzyl N-isopropylacrylamide) ionic liquid catalyst by overcoming the problems and deficiencies of the prior art. Another object of the present invention is to provide a catalyst prepared by the above method. A further object of the present invention is to provide the use of the above catalyst in catalyzing the synthesis of phosphine oxides from disubstituted benzene and phosphorus trichloride.
[0005] The technical solution of the present invention is characterized by adopting an in-situ polymerization strategy of amide monomers to copolymerize benzyl chloride ionic liquid and N-isopropylacrylamide free radicals to prepare a binary copolymerized ionic liquid rich in strongly acidic metals and amide groups, with a degree of polymerization generally ranging from 80 to 160. The benzyl chloride ionic liquid provides a rigid skeleton structure containing a benzene ring and a Lewis acid-active group. The N-isopropylacrylamide unit contains a hydrophilic amide group and a hydrophobic isopropyl group. By adjusting the degree of polymerization of NIPAM, the temperature range of the material's "heat deformation" can be precisely controlled, achieving more precise temperature-sensitive regulation.
[0006] The specific technical solution of the present invention is: a method for preparing a poly (4-vinylbenzyl N-isopropylacrylamide) ionic liquid catalyst, characterized in that 4-vinylbenzyl chloride is first reacted with a nitrogen-containing organic base to generate a benzyl chloride salt, which is then reacted with a strongly acidic metal chloride salt to generate a benzyl chloride ionic liquid R, and N-isopropylacrylamide (NIPAAm) and the benzyl chloride ionic liquid R are copolymerized as monomers to generate the poly (4-vinylbenzyl N-isopropylacrylamide) ionic liquid catalyst (PNIPAAm-co-R). The specific steps are as follows:
[0007] (1) Synthesis of benzyl chloride ionic liquid R: 4-vinylbenzyl chloride and a nitrogen-containing organic base are sequentially poured into a container containing an organic solvent, and heated to react under a protective gas atmosphere; then distilled, washed, and dried to obtain benzyl chloride; benzyl chloride and a strongly acidic metal chloride are weighed and placed in a container, and heated and stirred under a protective atmosphere to obtain benzyl chloride ionic liquid R;
[0008] (2) Synthesis of PNIPAAm-co-R: N-isopropylacrylamide (NIPAAm), benzyl chloride ionic liquid (R), and initiator were dissolved in an organic solvent and stirred until completely dissolved. Protective gas was introduced to replace the air, and the reaction was heated. The solid was filtered, washed, and dried to obtain a PNIPAAm-co-R copolymer.
[0009] The catalyst structure is shown in Formula 1 below:
[0010]
[0011] Preferably, the nitrogen-containing organic base described in step (1) is any one of imidazole, pyridine, triethylenediamine or 4-methylguanidine; the organic solvent is any one of ethanol, ethyl acetate or acetone; the protective gas is any one of nitrogen, argon or helium; and the strongly acidic metal chloride is any one of FeCl3, ZnCl2, AlCl3 or SnCl4.
[0012] Preferably, the heating reaction temperature in step (1) is 70-100° C., and the heating reaction time is 12-36 hours; the stirring temperature is 80-100° C., and the stirring time is 2-4 hours; the molar ratio of 4-vinylbenzyl chloride to the nitrogen-containing organic base is 1:(1-2), the molar ratio of 4-vinylbenzyl chloride to the organic solvent is 1:(4-6), and the molar ratio of benzyl chloride to the strongly acidic metal chloride is 1:(2-3).
[0013] Preferably, the initiator in step (2) is any one of azobisisobutyronitrile, methyl ethyl ketone peroxide or azobisisoheptanenitrile; the organic solvent is any one of methanol, ethyl acetate or ethanol; the protective gas is any one of nitrogen, argon or helium; the molar ratio of N-isopropylacrylamide and benzyl chloride ionic liquid R is 1:(1-2), and the molar ratio of N-isopropylacrylamide to initiator is 1:(0.10-0.25); the reaction temperature is 70-100°C, and the reaction time is 24-36h.
[0014] The present invention also provides a poly 4-vinylbenzyl N-isopropylacrylamide ionic liquid catalyst PNIPAAm-co-R prepared by the above method.
[0015] The present invention also provides the use of the aforementioned poly (4-vinylbenzyl N-isopropylacrylamide) ionic liquid catalyst, PNIPAAm-co-R, in catalyzing the synthesis of phosphinous oxides from disubstituted benzene and phosphorus trichloride. The specific steps are as follows: sequentially adding the reaction raw materials, p-disubstituted benzene, phosphorus trichloride, and the PNIPAAm-co-R catalyst, to a container equipped with a reflux device and a magnetic stirrer; purging and displacing the air in the container with protective gas, heating, and stirring to react; after the reaction is completed, cooling, separating the catalyst by centrifugation, and then dripping the resulting solution into ice water; collecting the supernatant, stirring, and extracting, washing the extracted organic phase with an alkaline aqueous solution, and drying to obtain the phosphinous oxide.
[0016] The chemical reaction is as follows:
[0017]
[0018] Preferably, the mass ratio of disubstituted benzene, phosphorus trichloride and PNIPAAm-co-R catalyst is 1:(1.5-3):(0.2-0.5); the reaction temperature is 100-150°C, the reaction time is 7-12 hours, and the stirring rate is 100-300 rpm; the protective gas is any one of nitrogen, argon or helium; the extractant is any one of n-hexane, carbon tetrachloride, ether or cyclohexane; the alkaline aqueous solution is any one of sodium hydroxide, potassium hydroxide or calcium hydroxide solution; and the concentration of the alkaline aqueous solution is 0.01-0.10 mol / L.
[0019] The invention adopts a harmless and green free radical polymerization method to obtain a poly 4-vinylbenzyl N-isopropylacrylamide ionic liquid catalyst with high catalytic activity.
[0020] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in:
[0021] (1) The PNIPAAm-co-R catalyst synthesis method provided by the present invention has the advantages of simple equipment, convenient operation, mild conditions, etc. The process is environmentally friendly and conducive to large-scale production.
[0022] (2) The PNIPAAm-co-R catalyst provided by the present invention can be separated from the reactants by centrifugation during the production process. Compared with existing catalysts, this reduces post-processing energy and material consumption, facilitating large-scale production.
[0023] (3) The PNIPAAm-co-R catalyst provided by the present invention is used to synthesize 1-hydroxy-4-aminodiphenylphosphine oxide from 1-hydroxy-4-aminobenzene and phosphorus trichloride, with a high yield, which is higher than the 80% yield of 1-hydroxy-4-aminodiphenylphosphine oxide reported in existing literature. DETAILED DESCRIPTION
[0024] The present invention is described in more detail below using examples. These examples are merely descriptions of the best mode of carrying out the present invention and do not limit the scope of protection of the present invention in any way.
[0025] Example 1
[0026] Step 1: 4-Vinylbenzyl chloride (40 mmol) and imidazole (40 mmol) were sequentially added to a flask containing ethanol (160 mmol) and reacted at 70°C under a nitrogen atmosphere for 24 h. The mixture was distilled, washed, and vacuum-dried to obtain 1-(4-vinylbenzyl)-1H-imidazolium chloride (VBzImCl). VBzImCl (40 mmol) and FeCl3 (80 mmol) were added to a flask and stirred at 80°C under a nitrogen atmosphere for 4 h to obtain [VBzIm][Fe2Cl7].
[0027] Step 2: Dissolve N-isopropylacrylamide (5 mmol), [VBzIm][Al2Cl7] (10 mmol) and azobisisobutyronitrile (1.25 mmol) in methanol, introduce nitrogen to replace the air, stir until the mixture is uniform, react at 100°C for 24 h, filter to obtain a solid, wash, and dry to obtain a PNIPAAm-co-[VBzIm][Fe2Cl7] copolymer.
[0028] Example 2
[0029] Step 1: 4-Vinylbenzyl chloride (60 mmol) and pyridine (60 mmol) were sequentially added to a flask containing ethyl acetate (360 mmol) under an argon atmosphere at 70°C for 12 h. The mixture was distilled, washed, and dried to obtain 1-(4-vinylbenzyl)pyridinium chloride (VBzPyCl). VBzPyCl (50 mmol) and SnCl4 (100 mmol) were added to a flask and stirred at 100°C under an argon atmosphere for 2 h to obtain [VBzPyCl][Sn2Cl8].
[0030] Step 2: Dissolve N-isopropylacrylamide (5 mmol), [VBzPyCl][Sn2Cl8] (5 mmol) and methyl ethyl ketone peroxide (0.50 mmol) in ethyl acetate, introduce argon to replace the air, stir until the mixture is uniform, react at 70°C for 24 h, filter the solid, wash, and dry to obtain PNIPAAm-co-[VBzPyCl][Sn2Cl8] copolymer.
[0031] Example 3
[0032] Step 1: 4-Vinylbenzyl chloride (40 mmol) and triethylenediamine (80 mmol) were sequentially added to a flask containing acetone (240 mmol) and reacted at 100°C under a nitrogen atmosphere for 36 h. The mixture was distilled, washed, and dried to obtain 1-(4-vinylbenzyl)-1,4-diazabicyclo-2.2.2-octane chloride ([VBz-DABCO]Cl). [VBz-DABCO]Cl (40 mmol) and AlCl₃ (120 mmol) were placed in a flask and stirred at 80°C under a nitrogen atmosphere for 4 h to obtain [VBz-DABCO][Al₂Clₐ].
[0033] Step 2: Dissolve N-isopropylacrylamide (5 mmol), [VBz-DABCO][Al2Cl7] (10 mmol) and azobisisoheptanenitrile (1.25 mmol) in ethanol, introduce nitrogen to replace the air, stir until the mixture is uniform, react at 100°C for 36 h, filter to obtain a solid, wash, and dry to obtain a PNIPAAm-co-[VBz-DABCO][Al2Cl7] copolymer.
[0034] Example 4
[0035] Step 1: 4-Vinylbenzyl chloride (60 mmol) and 4-methylguanidine (120 mmol) were sequentially added to a flask containing ethyl acetate (240 mmol) under a helium atmosphere at 100°C for 12 h. The mixture was distilled, washed, and dried to obtain 1-(4-vinylbenzyl)-4-methylguanidine chloride (VBzGuCl). VBzGuCl (50 mmol) and ZnCl2 (100 mmol) were added to a flask and stirred at 100°C under a helium atmosphere for 2 h to obtain [VBzGu][ZnCl4].
[0036] Step 2: Dissolve N-isopropylacrylamide (5 mmol), [VBzGu][ZnCl4] (5 mmol) and azobisisobutyronitrile (0.50 mmol) in methanol, introduce helium to replace the air, stir until the mixture is uniform, react at 100°C for 24 h, filter to obtain a solid, wash, and dry to obtain a PNIPAAm-co-[VBzGu][ZnCl4] copolymer.
[0037] Application Example 1
[0038] To a container equipped with a reflux system and a magnetic stirrer, the reaction materials (0.50 g 1-hydroxy-4-aminobenzene), 1.50 g phosphorus trichloride, and 0.10 g of the catalyst from Example 1, PNIPAAm-co-[VBzIm][Fe2Cl7), were added sequentially. The air in the container was purged with nitrogen three times, and the reaction temperature was set at 100°C and the stirring rate at 200 rpm for 7 hours. After the reaction was completed and cooled to room temperature, the catalyst was separated by centrifugation. The resulting solution was then dropped into ice water, the supernatant liquid was stirred, and extracted with n-hexane. The organic phase was washed with 0.01 mol / L potassium hydroxide solution and dried to obtain 1-hydroxy-4-aminodiphenylphosphine oxide. Liquid chromatography analysis revealed a 97% conversion of 1-hydroxy-4-aminobenzene and an 85% yield of 1-hydroxy-4-aminodiphenylphosphine oxide.
[0039] Application Example 2
[0040] To a container equipped with a reflux system and a magnetic stirrer, the reaction materials (0.50 g 1-hydroxy-4-aminobenzene), 1.0 g phosphorus trichloride, and 0.20 g of the catalyst from Example 2, PNIPAAm-co-[VBzPyCl][Sn2Cl8) were added in sequence. The air in the container was displaced three times by purging with argon, followed by a protective gas flow. The reaction temperature was set at 150°C and the stirring rate at 300 rpm for 12 hours. After the reaction was completed and cooled to room temperature, the catalyst was separated by centrifugation. The resulting solution was then dropped into ice water, the supernatant liquid was stirred, and carbon tetrachloride was added for extraction. The organic phase was washed with a 0.10 mol / L aqueous sodium hydroxide solution and dried to obtain 1-hydroxy-4-aminodiphenylphosphine oxide. Liquid chromatographic analysis revealed a 98% conversion of 1-hydroxy-4-aminobenzene and an 86% yield of 1-hydroxy-4-aminodiphenylphosphine oxide.
[0041] Application Example 3
[0042] To a container equipped with a reflux system and a magnetic stirrer, the reaction materials (0.50 g 1-hydroxy-4-aminobenzene), 0.75 g phosphorus trichloride, and 0.25 g of the catalyst from Example 3, PNIPAAm-co-[VBz-DABCO][Al2Cl7) were added in sequence. The air in the container was displaced three times with helium purge, and helium was introduced as a protective gas. The reaction temperature was set at 120°C and the stirring rate was 100 rpm for 12 hours. After the reaction was completed and cooled to room temperature, the catalyst was separated by centrifugation. The resulting solution was then dropped into ice water, the supernatant liquid was stirred, and ether was added for extraction. The organic phase was washed with a 0.05 mol / L aqueous solution of calcium hydroxide and dried to obtain 1-hydroxy-4-aminodiphenylphosphine oxide. Liquid chromatography analysis revealed a 98% conversion of 1-hydroxy-4-aminobenzene and a 91% yield of 1-hydroxy-4-aminodiphenylphosphine oxide.
[0043] Application Example 4
[0044] To a container equipped with a reflux system and a magnetic stirrer, the reaction materials (0.50 g 1-hydroxy-4-aminobenzene), 0.75 g phosphorus trichloride, and 0.25 g of the catalyst from Example 4, PNIPAAm-co-[VBzGu][ZnCl4), were added sequentially. The air in the container was displaced three times with nitrogen purge, followed by nitrogen as a protective gas. The reaction temperature was set at 120°C and the stirring rate at 200 rpm for 12 hours. After the reaction was completed and cooled to room temperature, the catalyst was separated by centrifugation. The resulting solution was then dropped into ice water, the supernatant liquid was stirred, and cyclohexane was added for extraction. The resulting organic phase was washed with 0.10 mol / L sodium hydroxide solution and dried to obtain 1-hydroxy-4-aminodiphenylphosphine oxide. Liquid chromatography analysis revealed a 99% conversion of 1-hydroxy-4-aminobenzene and a 90% yield of 1-hydroxy-4-aminodiphenylphosphine oxide.
[0045] The experimental results of the application example are shown in Table 1
[0046] Table 1 Application example experimental results
[0047]
[0048] The raw material 1 is 1-hydroxy-4-aminobenzene, and the raw material 2 is phosphorus trichloride.
Claims
1. A method for preparing poly (4-vinylbenzyl N-isopropylacrylamide) ionic liquid catalyst, characterized in that: First, 4-vinylbenzyl chloride reacts with a nitrogen-containing organic base to generate a benzyl chloride salt, which then reacts with a strongly acidic metal chloride salt to generate a benzyl chloride ionic liquid R. N-isopropylacrylamide (NIPAAm) and the benzyl chloride ionic liquid R are copolymerized as monomers to generate a poly (4-vinylbenzyl N-isopropylacrylamide) ionic liquid catalyst (PNIPAAm-co-R). The specific steps are as follows: (1) Synthesis of benzyl chloride ionic liquid R: 4-vinylbenzyl chloride and a nitrogen-containing organic base are sequentially poured into a container containing an organic solvent, and heated to react under a protective gas atmosphere; then distilled, washed, and dried to obtain benzyl chloride; benzyl chloride and a strongly acidic metal chloride are weighed and placed in a container, and heated and stirred under a protective atmosphere to obtain benzyl chloride ionic liquid R; (2) Synthesis of PNIPAAm-co-R: N-isopropylacrylamide (NIPAAm), benzyl chloride ionic liquid (R), and initiator were dissolved in an organic solvent and stirred until completely dissolved. Protective gas was introduced to replace the air, and the reaction was heated. The solid was filtered, washed, and dried to obtain a PNIPAAm-co-R copolymer.
2. The method according to claim 1, characterized in that The nitrogen-containing organic base described in step (1) is any one of imidazole, pyridine, triethylenediamine or 4-methylguanidine; the organic solvent is any one of ethanol, ethyl acetate or acetone; the protective gas is any one of nitrogen, argon or helium; and the strongly acidic metal chloride is any one of FeCl3, ZnCl2, AlCl3 or SnCl4.
3. The method according to claim 1, characterized in that The heating reaction temperature in step (1) is 70-100° C., and the heating reaction time is 12-36 hours; the stirring temperature is 80-100° C., and the stirring time is 2-4 hours; the molar ratio of 4-vinylbenzyl chloride to the nitrogen-containing organic base is 1:(1-2), the molar ratio of 4-vinylbenzyl chloride to the organic solvent is 1:(4-6), and the molar ratio of benzyl chloride to the strongly acidic metal chloride is 1:(2-3).
4. The method according to claim 1, characterized in that The initiator in step (2) is any one of azobisisobutyronitrile, methyl ethyl ketone peroxide or azobisisoheptanenitrile; the organic solvent is any one of methanol, ethyl acetate or ethanol; the protective gas is any one of nitrogen, argon or helium; the molar ratio of N-isopropylacrylamide and benzyl chloride ionic liquid R is 1:(1-2), and the molar ratio of N-isopropylacrylamide to initiator is 1:(0.10-0.25); the reaction temperature is 70-100°C, and the reaction time is 24-36h.
5. A poly (4-vinylbenzyl N-isopropylacrylamide) ionic liquid catalyst PNIPAAm-co-R prepared as claimed in claims 1 to 4.
6. Use of the poly (4-vinylbenzyl N-isopropylacrylamide) ionic liquid catalyst PNIPAAm-co-R as claimed in claim 5 in catalyzing the synthesis of phosphine oxides from disubstituted benzene and phosphorus trichloride.
7. The use according to claim 6, comprising the following specific steps: sequentially adding p-disubstituted benzene and phosphorus trichloride as reaction raw materials and a PNIPAAm-co-R catalyst to a container equipped with a reflux device and a magnetic stirrer; purging and displacing the air in the container with protective gas, heating and stirring to react; cooling after completion of the reaction, separating the catalyst by centrifugation, and then dropping the resulting solution into ice water; taking the upper layer of liquid, stirring it uniformly, extracting it, and washing the extracted organic phase with an alkaline aqueous solution, and drying it to obtain the phosphine oxide.
8. The use according to claim 7, characterized in that: The mass ratio of disubstituted benzene, phosphorus trichloride and PNIPAAm-co-R catalyst is 1:(1.5-3):(0.2-0.5); the reaction temperature is 100-150°C, the reaction time is 7-12 hours, and the stirring rate is 100-300 rpm; the protective gas is any one of nitrogen, argon or helium; the extractant is any one of n-hexane, carbon tetrachloride, ether or cyclohexane; the alkaline aqueous solution is any one of sodium hydroxide, potassium hydroxide or calcium hydroxide solution; and the concentration of the alkaline aqueous solution is 0.01-0.10 mol / L.