CN118186152A - Multifunctional high-absorption chrome tanning auxiliary agent containing barbituric acid structure and preparation method thereof - Google Patents

Multifunctional high-absorption chrome tanning auxiliary agent containing barbituric acid structure and preparation method thereof Download PDF

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CN118186152A
CN118186152A CN202410464747.6A CN202410464747A CN118186152A CN 118186152 A CN118186152 A CN 118186152A CN 202410464747 A CN202410464747 A CN 202410464747A CN 118186152 A CN118186152 A CN 118186152A
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ethyl
chrome tanning
diethyl
dimethyl
barbituric acid
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王国伟
王颖
赵慧敏
朱昱
庄玲华
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Nanjing Tech University
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Nanjing Tech University
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Abstract

The invention discloses a multi-functional group high-absorption chrome tanning auxiliary agent containing barbituric acid structure, which is a polycarboxylic acid compound containing barbituric acid structure; the invention discloses a preparation method of a high-absorption chrome tanning auxiliary agent, which comprises the following four steps of reaction: c-alkylation, cyclization, N-alkylation and hydrolysis; the high-absorption chrome tanning auxiliary agent comprises 2-3 ketocarbonyl groups and 2-4 carboxyl groups, wherein the ortho-ketocarbonyl groups and the carboxyl groups can be subjected to cyclization reaction with arginine in collagen protein, so that collagen modification is realized, the carboxyl groups are introduced, the number of the carboxyl groups on a side chain of collagen is increased, the coordination point of chrome is increased, the absorption of trivalent chrome can be obviously improved, the concentration of trivalent chrome in chrome tanning wastewater is reduced, the high-absorption chrome tanning target is realized, and the clean production of leather industry is promoted; the invention provides a new idea for the design and preparation of the high-absorption chrome tanning auxiliary agent.

Description

Multifunctional high-absorption chrome tanning auxiliary agent containing barbituric acid structure and preparation method thereof
Technical Field
The invention belongs to the technical field of chrome tanning auxiliary agents, and particularly relates to a multifunctional group high-absorption chrome tanning auxiliary agent containing barbituric acid structure and a preparation method thereof.
Background
Chrome tanning, which is by far the most important and most widely used tanning process in leather manufacture, imparts higher thermal stability, comfortable hand feel and excellent leather formation properties to leather, is currently absolutely dominant in the leather industry (China c.r. et al chemosphere,2020, 254:126804). However, in conventional tanning processes, the absorption rate of chrome tanning agents is generally only about 70%, resulting in high-concentration chrome-containing wastewater. This not only increases the environmental pollution load and the wastewater treatment cost, but also causes great resource waste. Tanning has been classified as one of the highly polluting industries due to the adverse environmental impact of chromium contaminants. Therefore, how to improve the absorption of chromium and the utilization rate of chrome tanning agent as much as possible in the tanning process, realizing high-absorption chrome tanning is a problem which is widely focused in the leather-making academia and industry in recent years, and is also a key technological problem which is urgently needed to be solved in order to ensure the sustainable development of the leather-making industry (Ouyang Mai, etc.. Research of high-absorption chrome tanning and high-absorption chrome tanning auxiliary agent [ J ]. Western leather, 2022, 44 (07): 13-20; chen Bo, zhang Hui, jiang Xi, etc.. Research progress of high-absorption chrome tanning auxiliary agent [ J ]. Chinese leather, 2019, 48 (04): 41-46).
The high absorption chrome tanning technology is based on the existing chrome tanning method, improves the absorption rate of the chrome tanning agent in the skin collagen to 80-98% by optimizing the tanning process or adding chemical auxiliary agents and the like, reduces the discharge amount of chrome in waste liquid, and effectively improves the environmental problem caused by the tanning industry. Wherein the added chemical auxiliary agent is called a high-absorption chrome tanning auxiliary agent.
High absorption chrome tanning aids are of great interest to tanneries and researchers. Tanning workers have developed numerous high-absorbency chrome tanning aids, such as hyperbranched polymers, nanocomposites, waterborne epoxy resins, dicarboxylic acid compounds, hydroxy acid compounds, aromatic sulfonic acids, aldehyde acid compounds, keto acid compounds, and the like. However, the existing high-absorption chrome tanning auxiliary agents have various defects. The synthesis steps of the polymer auxiliary agent are complicated, and the commercialization cost is high; too large molecular weight, poor permeability in skin collagen, resulting in lower binding to collagen; the active groups are too many, the combination of the collagen fibers and Cr (III) is diversified, and the production control is difficult. The small molecular auxiliary agent has small molecular weight, single functional group type and most of the action modes of the small molecular auxiliary agent and the collagen fiber are electrostatic action, ionic bond, hydrogen bond and the like. Aldehyde acid compounds such as glyoxylic acid can form covalent bond with collagen side chains, but the bonding stability is low, and the quantity of introduced carboxyl groups is insufficient, so that the quantity of coordination sites is limited. The ketonic acid high-absorption chrome tanning auxiliary agent contains ketocarbonyl and carboxyl, and the purpose of introducing the carboxyl to coordinate with Cr (III) is achieved by combining the ketocarbonyl on a molecular structure with alkaline groups such as amino, guanidine group and the like on a collagen chain.
Ouyang Mai and the like take acetylacetone and acrylic ester as raw materials, prepare a keto acid high-absorption chrome tanning auxiliary agent 4-acetyl pimelic acid (AHA) containing one ketocarbonyl group and two carboxyl groups through Michael addition reaction, and apply the keto acid high-absorption chrome tanning auxiliary agent to a chrome retanning procedure. When the dosage of the chromium retanning agent is 4%, the chromium content in leather is obviously increased (82.43%), the chromium content in retanning waste liquid is obviously reduced, the Chemical Oxygen Demand (COD) of the waste liquid is reduced by 43.82%, and the total dissolved solids content (TDS) is reduced by 31.46%. In addition, the wet heat stability and mechanical properties of the leather are also improved (Ouyang M.et al. Journal of Cleaner Production,2022, 367:133125).
The King's name in China patent No. ZL202011536195.3 reports a polycarboxylic acid high-absorption chrome tanning auxiliary agent containing ketocarbonyl (King's name, ouyang Mai, hu Kehui, zhuang Linghua. A multifunctional high-absorption chrome tanning auxiliary agent, a preparation method and application thereof [ P ] ZL202011536195.3, 20220617). Active methylene-containing compounds (such as 3-ketone-glutarate diester, 2-ketone-glutarate diester, dibenzoyl methyl ester acetone and the like) and alpha, beta-unsaturated compounds (such as methyl acrylate, ethyl acrylate or acrylonitrile and the like) are used as raw materials, the polycarboxylic acid esters are prepared through Michael addition reaction, the polycarboxylic acid compounds containing ketocarbonyl groups are obtained through continuous hydrolysis, six carboxyl groups are introduced into leather collagen through collagen modification, the coordination point of chromium is obviously increased, the absorption of trivalent chromium can be obviously improved, the concentration of trivalent chromium in chrome tanning wastewater is reduced, the environmental pollution of leather industry is reduced, and the clean production of the leather industry is promoted.
The King's great et al report in Chinese patent application ZL202011431991.0 a high-absorption chrome tanning aid containing ketocarboxylic acid structure (Wang Guowei, hu Kehui, ouyang Mai, zhuang Linghua. Preparation and application of a high-absorption chrome tanning aid containing ketocarboxylic acid structure [ P ]. ZL202011431991.0, 20230519). Active methylene compound (acetylacetone, dibenzoyl methane, benzoyl acetone or 3, 5-diheptone) and compound containing alpha, beta-unsaturated nitrile or compound containing alpha, beta-unsaturated carboxylic ester or compound containing alpha, beta-unsaturated amide (methyl acrylate, ethyl acrylate, acrylonitrile, acrylamide and the like) are used as raw materials, and the multi-carboxylic ester is prepared by a double Michael addition reaction, and the hydrolysis is continued to prepare the high-absorption chrome tanning auxiliary containing ketocarboxylic acid structure. According to the auxiliary agent, through collagen modification, a plurality of carboxyl groups are introduced into leather collagen, so that coordination sites of trivalent chromium are remarkably improved, the concentration of trivalent chromium in chrome tanning wastewater is reduced, high-absorption chrome tanning is realized, and clean production of leather industry is promoted.
With the continuous and intensive research of the high-absorption chrome tanning technology, the high-absorption chrome tanning auxiliary agent containing the ketocarboxylic acid structure cannot meet the requirements of the high-absorption chrome tanning technology. The absorptivity of the chrome tanning agent in the leather collagen is maintained at 85-92%, the wet-heat resistance stability and mechanical property of the leather cannot be further improved, and the requirements of the current high-grade leather cannot be met. It is desirable to further optimize the structure and application properties of the high absorption chrome tanning agents containing ketocarboxylic acid structures.
Disclosure of Invention
The invention aims to: the first object of the invention is to provide a multi-functional group high-absorption chrome tanning auxiliary agent containing barbituric acid structure, and the second object of the invention is to provide a preparation method of the multi-functional group high-absorption chrome tanning auxiliary agent containing barbituric acid structure.
The technical scheme is as follows: the multifunctional high-absorption chrome tanning auxiliary agent containing barbituric acid structure has the following molecular structure:
Wherein X is O or S,R1＝H,CH3,C2H5,R2＝H,CH3,C2H5,C3H5,C3H7,C4H9,C5H9,C6H5,C6H11,C7H7,Cl,Br.
The preparation method of the multi-functional group high-absorption chrome tanning auxiliary agent containing barbituric acid structure comprises the following steps:
(1) C-alkylation reaction
Taking a malonic acid diester compound and a halogenated carboxylic acid ester compound as raw materials, taking inorganic alkali as an alkaline agent, and reacting in an organic solvent at 60-100 ℃ for 6-12 hours under the condition of a phase transfer catalyst to obtain a carboxylic acid ester compound A; the molar ratio of the malonic acid diester compound to the halogenated carboxylic acid ester compound is 1:1.0-2.05, and the molar ratio of the malonic acid diester compound to the alkaline agent to the phase transfer catalyst is 1:0.2-0.4:0.02-0.06;
(2) Cyclization reaction
Taking carboxylic ester compound A and urea or thiourea as raw materials, catalyzing by inorganic alkali or organic alkali, and reacting in an organic solvent at 80-100 ℃ for 4-6 hours to obtain barbituric acid derivative or 2-thiobarbituric acid derivative B; the mol ratio of the carboxylic ester compound A to the urea or the thiourea is 1: (0.95-1.05), and the mol ratio of the carboxylic ester compound A to the organic base or the inorganic base is 1: (0.1-0.3);
(3) N-alkylation reaction
Barbituric acid derivative or 2-thiobarbituric acid derivative B and halogenated carboxylic ester are used as raw materials, inorganic alkali is used as an alkaline agent, and the barbituric acid derivative containing polybasic carboxylic ester or 2-thiobarbituric acid derivative C containing polybasic carboxylic ester is prepared by reacting in an organic solvent at 60-100 ℃ for 4-8h under the catalysis of a phase transfer catalyst; the molar ratio of the barbituric acid derivative or the 2-thiobarbituric acid derivative B to the halogenated carboxylic ester is 1: (1.0-2.05), and the molar ratio of the barbituric acid derivative or the 2-thiobarbituric acid derivative B to the alkaline agent and the phase transfer catalyst is 1: (0.2-0.4): (0.02-0.06);
(4) Hydrolysis reaction
The barbituric acid derivative containing polybasic carboxylic acid ester or the 2-thiobarbituric acid derivative C containing polybasic carboxylic acid ester is hydrolyzed for 4 to 12 hours at 70 to 100 ℃ under alkaline condition, cooled to normal temperature, and is regulated to pH 4 to 5 by acid, solid is separated out, and suction filtration is carried out to obtain the high-absorption chrome tanning auxiliary agent; the alkali liquor used in the alkaline condition is sodium hydroxide or potassium hydroxide solution with the mass fraction of 10-20%; the acid is one of hydrochloric acid solution, sulfuric acid solution or phosphoric acid solution with the mass fraction of 5-15%.
Further, in the step (1), the malonic acid diester compound is dimethyl malonate, dimethyl 2-methylmalonate, dimethyl 2-ethylmalonate, dimethyl 2-propylmalonate, dimethyl 2-butylmalonate, dimethyl 2-isobutylmalonate, dimethyl 2-allylmalonate, dimethyl 2-cyclopentylmalonate, dimethyl 2-phenylmalonate, dimethyl 2-cyclohexylmalonate, dimethyl 2-benzylmalonate, dimethyl 2-chloromalonate, dimethyl 2-bromomalonate, diethyl malonate, diethyl 2-methylmalonate, diethyl 2-propylmalonate, diethyl 2-butylmalonate, diethyl 2-isobutylmalonate, diethyl 2-allylmalonate, diethyl 2-cyclopentylmalonate, diethyl 2-phenylmalonate, diethyl 2-cyclohexylmalonate, diethyl 2-benzylmalonate, diethyl 2-chloromalonate, diethyl 2-bromomalonate, dipropyl malonate, diisopropyl malonate, dibutyl malonate, di-tert-butyl malonate, or one of diethyl malonate.
Further, in the step (1), the halogenated carboxylic acid ester is one of methyl chloroacetate, ethyl chloroacetate, butyl chloroacetate, tert-butyl chloroacetate, ethyl bromoacetate, butyl bromoacetate, tert-butyl bromoacetate, methyl 2-chloropropionate, ethyl 2-chloropropionate, methyl 2-bromopropionate, ethyl 2-bromopropionate, methyl 2-chlorobutyrate, ethyl 2-chlorobutyrate, methyl 2-bromobutyrate and ethyl 2-bromobutyrate; the inorganic base is one of anhydrous potassium carbonate, anhydrous sodium carbonate, potassium phosphate and sodium phosphate; the phase transfer catalyst is one of tetrabutylammonium bromide, tetrabutylammonium chloride, dodecyl trimethyl ammonium chloride, tetradecyl trimethyl ammonium chloride, dodecyl trimethyl ammonium bromide and tetradecyl trimethyl ammonium bromide; the organic solvent is one of petroleum ether, cyclohexane, n-hexane, ethyl acetate and1, 4-dioxane.
Further, in the step (2), the inorganic base is one of sodium hydroxide and potassium hydroxide; the organic base is one of sodium ethoxide, sodium methoxide, sodium tert-butoxide and potassium tert-butoxide; the organic solvent is one of methanol, ethanol, isopropanol, n-butanol and tert-butanol.
Further, in the step (3), the halogenated carboxylic acid ester is one of methyl chloroacetate, ethyl chloroacetate, butyl chloroacetate, tert-butyl chloroacetate, ethyl bromoacetate, butyl bromoacetate, tert-butyl bromoacetate, methyl 2-chloropropionate, ethyl 2-chloropropionate, methyl 2-bromopropionate, ethyl 2-bromopropionate, methyl 2-chlorobutyrate, ethyl 2-chlorobutyrate, methyl 2-bromobutyrate and ethyl 2-bromobutyrate; the inorganic base is one of anhydrous potassium carbonate, anhydrous sodium carbonate, potassium phosphate and sodium phosphate; the phase transfer catalyst is one of tetrabutylammonium bromide, tetrabutylammonium chloride, dodecyl trimethyl ammonium chloride, tetradecyl trimethyl ammonium chloride, dodecyl trimethyl ammonium bromide and tetradecyl trimethyl ammonium bromide; the organic solvent is one of 1, 4-dioxane, methanol, ethanol and n-butanol.
The invention provides a multi-functional group high-absorption chrome tanning auxiliary agent containing barbituric acid structure, which comprises the following four steps of reaction: c-alkylation, cyclization, N-alkylation, and hydrolysis. The method comprises the steps of preparing a carboxylic ester compound A by C-alkylation reaction of an active methylene-containing compound (such as dimethyl malonate, diethyl malonate and the like) and halogenated carboxylic ester (such as ethyl chloroacetate, ethyl 2-chloropropionate and the like), preparing a barbituric acid derivative or a 2-thiobarbituric acid derivative B by cyclization reaction of the carboxylic ester compound A and urea (or thiourea), preparing a barbituric acid derivative or a 2-thiobarbituric acid derivative C containing a polybasic carboxylic ester by N-alkylation reaction of the barbituric acid derivative or the 2-thiobarbituric acid derivative B and halogenated carboxylic ester (such as ethyl chloroacetate, ethyl 2-chloropropionate and the like), and continuously hydrolyzing to prepare the high-absorption chrome tanning auxiliary containing a barbituric acid structure. The high-absorption chrome tanning auxiliary agent comprises 2-3 ketocarbonyl groups and 2-4 carboxyl groups, wherein the ortho-ketocarbonyl groups and the carboxyl groups can be subjected to cyclization reaction with lysine or arginine in collagen protein, collagen modification is realized, the carboxyl groups are introduced, the number of the carboxyl groups of a side chain of the collagen is increased, the coordination point of the chrome is increased, the absorption of trivalent chrome can be obviously improved, the concentration of the trivalent chrome in chrome tanning wastewater is reduced, the high-absorption chrome tanning target is realized, and the clean production of the tanning industry is promoted.
The beneficial effects are that: compared with the prior art, the invention has the following remarkable advantages:
(1) The preparation method of the high-absorption chrome tanning auxiliary agent has simple steps, and the auxiliary agent contains 2-3 ketocarbonyl groups and 2-4 carboxyl groups and has high functionality;
(2) The high-absorption chrome tanning auxiliary agent disclosed by the invention is characterized in that ortho-ketone carbonyl and carboxyl can be subjected to cyclization reaction with lysine or arginine in collagen protein, so that collagen modification is realized;
(3) The high-absorption chrome tanning auxiliary agent contains multi-carboxyl, can form stable coordination with chrome, remarkably improves the absorption rate of trivalent chrome, and achieves the aim of high-absorption chrome tanning;
(4) The steps of the traditional tanning process are not changed, and only the auxiliary agent is needed to be added in the pickling process.
Drawings
FIG. 1 shows the general structural formula of a multifunctional high-absorption chrome tanning auxiliary containing barbituric acid structure
Detailed Description
The present invention will be described in further detail with reference to examples, but embodiments of the invention are not limited thereto.
Example 1
Synthesis of (one) tetracarboxylic esters
Into a 250mL four-necked flask equipped with a stirrer, a thermometer and a reflux condenser were added 0.1mol of dimethyl malonate, anhydrous K 2CO3 (0.1 mol), 1g of tetrabutylammonium bromide and 80mL of n-hexane, 0.2mol of ethyl chloroacetate was added dropwise, the reflux reaction was carried out for 4 hours, stirring was stopped, and post-treatment was carried out to obtain dimethyl 3, 3-phthalate-1, 5-diethyl glutarate (C 13H20O8, mr= 304.12 g/mol), the mass was 28.3g, the yield was 93.2%, the structural formula of the product was as follows:
Nuclear magnetism hydrogen spectrum (C 13H20O8,CDCl3)
4.01ppm(q,4H,-CCH2COOCH2CH3),3.66ppm(s,6H,-CCOOCH3),2.93ppm(s,4H,-CCH2COOC2H5),1.07ppm(t,6H,-CCH2COOCH2CH3).
Nuclear magnetism carbon spectrum (C 13H20O8,CDCl3)
172.2ppm，170.4ppm，61.3ppm，52.2ppm，43.1ppm，37.2ppm，14.1ppm.
Elemental analysis (C 13H20O8)
Theoretical value (%): c:51.31, H:6.63. measured value (%): c:51.33, H:6.65.
Synthesis of barbituric acid
In a 250mL four-necked flask equipped with a stirrer, a thermometer and a reflux condenser, 80mL of ethanol was added, 0.1mol of sodium ethoxide (6.8 g) was added, 0.11mol of urea (6.6 g), 0.1mol of dimethyl 3, 3-glutarate-1, 5-glutarate (30.4 g) was added, the reaction was carried out at 80℃for 6 hours, cooled to room temperature, quenched with a saturated aqueous sodium bicarbonate solution, extracted with ethyl acetate, combined with an organic phase, washed with saturated brine, dried over anhydrous sodium sulfate, filtered and distilled off with water to give a product of 5, 5-diethyl diacetate-2, 4, 6-trioxyhexahydropyrimidine (C 12H16N2O7) having a mass of 28.4g and a yield of 94.6% and having the following structural formula.
Nuclear magnetism hydrogen spectrum (C 12H16N2O7 DMSO-d 6)
11.13ppm(s,2H,-NHC(O)NH-),4.01ppm(q,4H,-CCH2COOCH2CH3),2.71ppm(s,4H,-CCH2COOC2H5),1.07ppm(t,6H,-CCH2COOCH2CH3).
Nuclear magnetic carbon spectrum (C 12H16N2O7 DMSO-d 6)
174.0ppm，170.4ppm，150.4ppm，61.3ppm，46.8ppm，37.8ppm，14.1ppm.
Elemental analysis (C 12H16N2O7)
Theoretical value (%): c:48.00, H:5.37, N:9.33. measured value (%): c:48.02, H:5.36, N:9.34.
Synthesis of (III) carboxylic acid ester-containing barbituric acid derivatives
To a 250mL four-necked flask equipped with a stirrer, a thermometer and a reflux condenser were added 0.1mol of diethyl 5, 5-diacetate-2, 4, 6-trioxohexahydropyrimidine, anhydrous K 2CO3 (0.1 mol), 1g of tetrabutylammonium bromide and 80mL of n-hexane, 0.2mol of ethyl chloroacetate was added dropwise, the reflux reaction was carried out for 4 hours, stirring was stopped, and post-treatment was carried out to obtain 1,3, 5-tetraethyl-2, 4, 6-trioxopyrimidine (C 20H28N2O11) having a mass of 43.8g and a yield of 92.8%, the product had the following structural formula:
nuclear magnetism hydrogen spectrum (C 20H28N2O11 DMSO-d 6)
4.48ppm(s,4H,-NCH2COOC2H5),4.15ppm(q,4H,-NCH2COOCH2CH3),4.01ppm(q,4H,-CCH2COOCH2CH3),2.71ppm(s,4H,-CCH2COO-),1.21ppm(t,6H,-NCH2COOCH2CH3),1.07ppm(t,6H,-CCH2COOCH2CH3).
Nuclear magnetic carbon spectrum (C 20H28N2O11 DMSO-d 6)
178.2ppm，170.4ppm，167.5ppm，150.7ppm，61.3ppm，61.0ppm，45.7ppm，41.8ppm，38.4ppm，14.1ppm·
Elemental analysis (C 20H28N2O11)
Theoretical value (%): c:50.85, H:5.97, N:5.93. measured value (%): c:50.86, H:5.95, N:5.95.
Hydrolysis of carboxylic acid ester-containing barbituric acid derivatives
To a 250mL four-necked flask equipped with a stirrer, a thermometer and a reflux condenser was added 0.1mol of tetraethyl-1, 3, 5-tetraacetate-2, 4, 6-trioxypyrimidine, 150mL of 20% by mass sodium hydroxide solution was added, stirring was carried out at 60℃for 5 hours, pH was adjusted to 4-5 with an acid, filtration was carried out to obtain a product, which was dried in a vacuum oven at 65℃for 4 hours to obtain 1,3, 5-tetraacetic acid-2, 4, 6-trioxypyrimidine (C 12H12N2O11) having a mass of 32.3g and a yield of 89.6% and having the following structural formula:
nuclear magnetism hydrogen spectrum (C 12H12N2O11 DMSO-d 6)
13.51ppm(s，2H，-CCH2COOH)，13.03ppm(s，2H，-NCH2COOH)，4.46ppm(s，4H，-NCH2COOH)，2.69ppm(s，4H，-CCH2COOH).
Nuclear magnetic carbon spectrum (C 12H12N2O11 DMSO-d 6)
178.2ppm，177.3ppm，169.0ppm，150.7ppm，45.1ppm，41.2ppm，40.6ppm.
Elemental analysis (C 12H2N2O11)
Theoretical value (%): c:40.01, H:3.36, N:7.78. measured value (%): c:40.02, H:3.37, n:7.76.
Example 2
Synthesis of (one) tetracarboxylic esters
Into a 250mL four-necked flask equipped with a stirrer, a thermometer and a reflux condenser were added 0.1mol of dimethyl malonate, anhydrous K 2CO2 (0.1 mol), 1g of tetrabutylammonium bromide and 80mL of n-hexane, 0.2mol of ethyl chloroacetate was added dropwise, the reflux reaction was carried out for 4 hours, stirring was stopped, and post-treatment was carried out to obtain dimethyl 3, 3-phthalate-1, 5-diethyl glutarate (C 13H20O8, mr= 304.12 g/mol), the mass was 27.8g, the yield was 91.5%, the structural formula of the product was as follows:
Synthesis of (di) 2-thiobarbituric acid derivatives
In a 250mL four-necked flask equipped with a stirrer, a thermometer and a reflux condenser, 80mL of ethanol, 0.1mol of sodium ethoxide (6.8 g) and 0.11mol of thiourea (8.4 g) were added, and 0.1mol of dimethyl 3, 3-glutarate-1, 5-glutarate was reacted at 80℃for 3 hours, cooled to room temperature, quenched with saturated aqueous sodium hydrogencarbonate solution, extracted with ethyl acetate, combined with an organic phase, washed with saturated brine, dried over anhydrous sodium sulfate, filtered and rotary distilled to give a product of 5, 5-diethyl diacetate-2-thio-4, 6-dioxohexahydropyrimidine (C 12H16N2O6 S) having a mass of 29.7g and a yield of 93.8%, the product had the following structural formula:
Nuclear magnetism hydrogen spectrum (C 12H16N2O6 S, DMSO-d 6)
13.89ppm(s,2H,-NHC(S)NH-),4.01ppm(q,4H,-CCH2COOCH2CH3),2.71ppm(s,4H,-CCH2COOC2H5),1.07ppm(t,6H,-CCH2COOCH2CH3).
Nuclear magnetic carbon spectrum (C 12H16N2O6 S, DMSO-d 6)
177.9ppm，176.0ppm，170.4ppm，61.3ppm，46.5ppm，37.8ppm，14.1ppm.
Elemental analysis (C 12H16N2O6 S)
Theoretical value (%): c:45.56, H:5.10, N:8.86, S:10.14. measured value (%): c:45.55, H:5.12, N:8.87, S:10.12.
Synthesis of (III) carboxylate-containing 2-thiobarbituric acid derivatives
To a 250mL four-necked flask equipped with a stirrer, a thermometer and a reflux condenser were added 0.1mol of diethyl 5, 5-diacetate-2-thio-4, 6-dioxohexahydropyrimidine, anhydrous K 2CO3 (0.1 mol), 1g of tetrabutylammonium bromide and 80mL of N-hexane, 0.2mol of ethyl chloroacetate was added dropwise, the reflux reaction was carried out for 4 hours, stirring was stopped, and post-treatment was carried out to obtain 1,3, 5-tetraethyl-diacetate-2-thio-4, 6-dioxopyrimidine (C20H 28N 2010S), the mass was 44.7g, the yield was 91.6%, and the structural formula of the product was as follows:
nuclear magnetism hydrogen Spectrometry (C20H 28N2O10S, DMSO-d 6)
4.77ppm(s,4H,-NCH2COOC2H5),4.15ppm(q,4H,-NCH2COOCH2CH3),4.01ppm(q,4H,-CCH2COOCH2CH3),2.71ppm(s,4H,-CCH2COOCH2CH3),1.21ppm(t,6H,-NCH2COOCH2CH3),1.07ppm(t,6H,-CCH2COOCH2CH3).
Nuclear magnetic carbon spectrum (C20H 28N2O10S, DMSO-d 6)
180.2ppm，172.5ppm，170.4ppm，167.5ppm，61.3ppm，61.0ppm，50.8ppm，41.5ppm，38.4ppm，14.1ppm.
Elemental analysis (C20H 28N2O 10S)
Theoretical value (%): c:49.17, H:5.78, N:5.73, S:6.56. measured value (%): c:49.16, H:5.79, N:5.71, S:6.57.
Hydrolysis of (IV) carboxylate-containing 2-thiobarbituric acid derivatives
To a 250mL four-necked flask equipped with a stirrer, a thermometer and a reflux condenser was added 0.1mol of tetraethyl-1, 3, 5-tetraacetate-2-thio-4, 6-dioxopyrimidine, 150mL of 20% by mass sodium hydroxide solution was added, stirring was carried out at 60℃for 5 hours, pH was adjusted to 4-5 with an acid, and filtration was carried out to obtain 1,3, 5-tetraacetic acid-2-thio-4, 6-dioxopyrimidine (C12H 12N2O 10S) 34.2g in mass, yield 90.9%, the structural formula of the product was as follows:
nuclear magnetism hydrogen spectrum (C12H 12N2O10S, DMSO-d 6)
13.51ppm(s，2H，-CCH2COOH)，13.03ppm(s，2H，-NCH2COOH)，4.75ppm(s，4H，-NCH2COOH)，2.69ppm(s，4H，-CCH2COOH).
Nuclear magnetic carbon spectrum (C12H 12N2O10S, DMSO-d 6)
180.2ppm，177.3ppm，172.5ppm，169.0ppm，53.0ppm，40.9ppm，40.6ppm.
Elemental analysis (C12H 12N 2010S)
Theoretical value (%): c:38.30, h:3.21, n:7.44, S:8.52. measured value (%): c:38.32, h:3.20, N:7.43, S:8.55.
Example 3
Synthesis of (one) tricarboxylic acid esters
To a 250mL four-necked flask equipped with a stirrer, a thermometer and a reflux condenser were added 0.1mol of dimethyl 2-ethylmalonate, anhydrous K 2CO3 (0.1 mol), 1g of tetrabutylammonium bromide and 80mL of n-hexane, 0.105mol of ethyl chloroacetate was added dropwise, the reflux reaction was carried out for 3 hours, stirring was stopped, and post-treatment was carried out to obtain ethyl 3, 3-dimethyl-1-valerate (C 11H18O6), 23.0g in mass, yield 92.7%, and the structural formula of the product was as follows:
Nuclear magnetism hydrogen spectrum (C 11H18O6)
4.01ppm(q,2H,-CCH2COOCH2CH3),3.66ppm(s,6H,-CCOOCH3),2.93ppm(s,2H,-CCH2COOC2H5),2.25ppm(q,2H,-CCH2CH3),1.07ppm(t,3H,-CCH2COOCH2CH3),0.71ppm(t,3H,-CCH2CH3).
Nuclear magnetism carbon spectrum (C 11H18O6)
171.1ppm，170.4ppm，61.3ppm，52.2ppm，50.2ppm，37.5ppm，28.2ppm，14.1ppm，8.2ppm.
Elemental analysis (C 11H18O6)
Theoretical value (%): c:53.65, H:7.37. measured value (%): c:53.63, H:7.38.
Synthesis of barbituric acid
In a 250mL four-necked flask equipped with a stirrer, a thermometer and a reflux condenser, 80mL of ethanol, 0.1mol of sodium ethoxide (6.8 g), 0.11mol of urea (6.6 g), 0.1mol of methyl 3, 3-diformate-1-pentanoate ethyl ester, reaction at 80℃for 6 hours, cooling to room temperature, quenching the reaction with saturated aqueous sodium bicarbonate solution, extraction with ethyl acetate, merging the organic phases, washing with saturated saline solution, drying with anhydrous sodium sulfate, filtering, and rotary evaporation to remove ethyl acetate, thereby obtaining a product of 5-ethyl-5-ethyl acetate-2, 4, 6-trioxohexahydropyrimidine (C 10H14N2O5), 22.4g in mass, yield 92.5%, the structural formula of the product is as follows:
nuclear magnetism hydrogen spectrum (C 10H14N2O5, DMSO-d 6)
11.13ppm(s,2H,-NHC(O)NH-),4.01ppm(q,2H,-CCH2COOCH2CH3),2.71ppm(s,2H,-CCH2COOC2H5),2.03ppm(q,2H,-CCH2CH3),1.07ppm(t,3H,-CCH2COOCH2CH3),0.71ppm(t,3H,-CCH2CH3).
Nuclear magnetic carbon spectrum (C 10H14N2O5, DMSO-d 6)
174.0ppm，170.4ppm，150.4ppm，61.3ppm，53.9ppm，38.1ppm，28.8ppm，14.1ppm，7.4ppm.
Elemental analysis (C 10H14N2O5)
Theoretical value (%): c:49.58, h:5.83, N:11.56. measured value (%): c:49.57, H:5.84, N:11.57.
Synthesis of (III) carboxylic acid ester-containing barbituric acid derivatives
To a 250mL four-necked flask equipped with a stirrer, a thermometer and a reflux condenser were added 0.1mol of 5-ethyl-5-ethyl acetate-2, 4, 6-trioxohexahydropyrimidine, anhydrous K 2CO3 (0.1 mol), 1g of tetrabutylammonium bromide and 80mL of n-hexane, and 0.2mol of ethyl chloroacetate was added dropwise to carry out reflux reaction for 4 hours, stirring was stopped, and post-treatment was carried out to obtain 5-ethyl-1, 3, 5-triethyl triacetate-2, 4, 6-trioxopyrimidine (C 18H26N2O9), 37.7g in mass, 91.2% in yield, and the product had the following structural formula:
Nuclear magnetism hydrogen spectrum (C 18H26N2O9, DMSO-d 6)
4.48ppm(s,4H,-NCH2COO-),4.15ppm(q,4H,-NCH2COOCH2CH3),4.01ppm(q,2H,-CCH2COOCH2CH3),2.71ppm(s,2H,-CCH2COOC2H5),2.03ppm(q,2H,-CCH2CH3),1.21ppm(t,6H,-NCH2COOCH2CH3),1.07ppm(t,3H,-CCH2COOCH2CH3),0.71ppm(t,3H,-CCH2CH3).
Nuclear magnetic carbon spectrum (C 18H26N2O9, DMSO-d 6)
178.2ppm，170.4ppm，167.5ppm，150.7ppm，61.3ppm，61.Oppm，48.9ppm，45.7ppm，38.7ppm，29.4ppm，14.1ppm，7.4ppm.
Elemental analysis (C 18H26N2O9)
Theoretical value (%): c:52.17, h:6.32, N:6.76. measured value (%): c:52.18, h:6.30, N:6.77.
Hydrolysis of carboxylic acid ester-containing barbituric acid derivatives
Into a 250mL four-necked flask equipped with a stirrer, a thermometer and a reflux condenser, 0.1mol of 5-ethyl-1, 3, 5-triethyl triacetate-2, 4, 6-trioxypyrimidine is added, 150mL of 20% by mass sodium hydroxide solution is added, stirring is carried out at 80 ℃ for 5 hours, pH is regulated to 4-5 by acid, filtering is carried out, 5-ethyl-1, 3, 5-triacetate-2, 4, 6-trioxypyrimidine (C 12H14N2O9) is obtained, the mass is 30.1g, the yield is 91.3%, and the structural formula of the product is as follows
Nuclear magnetism hydrogen spectrum (C 12H14N2O9, DMSO-d 6)
13.51ppm(s,1H,-CCH2COOH),13.03ppm(s,2H,-NCH2COOH),4.46ppm(s,4H,-NCH2COOH),2.69ppm(s,2H,-CCH2COOH),2.03ppm(q,2H,-CCH2CH3),0.71ppm(t,3H,-CCH2COOH).
Nuclear magnetic carbon spectrum (C 12H14N2O9, DMSO-d 6)
178.2ppm，177.3ppm，169.0ppm，150.7ppm，48.6ppm，45.1ppm，40.9ppm，29.4ppm，7.4ppm.
Elemental analysis (C 12H14N2O9)
Theoretical value (%): c:43.64, H:4.27, n:8.48. measured value (%): c:43.62, H:4.28, n:8.50.
Example 4
Synthesis of (one) tricarboxylic acid esters
To a 250mL four-necked flask equipped with a stirrer, a thermometer and a reflux condenser were added 0.1mol of dimethyl 2-cyclohexylmalonate, anhydrous K 2CO3 (0.1 mol), 1g of tetrabutylammonium bromide and 60mL of n-hexane, 0.1mol of methyl chloroacetate was added dropwise, the reflux reaction was carried out for 3 hours, stirring was stopped, and the post-treatment was carried out to obtain dimethyl 2-cyclohexyl-2-carboxylate-succinate (C 14H22O6), the mass of the product was 26.6g, the yield was 92.9%, and the reaction equation was as follows:
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Nuclear magnetism hydrogen spectrum (C 14H22O6,CDCl3)
3.66ppm(s,6H,-CCOOCH3),3.61ppm(s,3H,-CCH2COOCH3),2.93ppm(s,2H,-CCH2COOCH3),2.60ppm(m,1H, Cyclohexane), 1.62ppm (m, 2H, cyclohexane), 1.53ppm (m, 2H, cyclohexane), 1.46ppm (m, 1H, cyclohexane), 1.44ppm (m, 1H, cyclohexane), 1.43ppm (m, 2H, cyclohexane), 1.38ppm (m, 2H, cyclohexane).
Nuclear magnetism carbon spectrum (C 14H22O6,CDCl3)
171.1ppm，170.4ppm，61.3ppm，52.9ppm，52.2ppm，36.6ppm，35.6ppm，26.0ppm，25.8ppm，14.1ppm.
Elemental analysis (C 14H22O6)
Theoretical value (%): c:58.73, h:7.74. measured value (%): c:58.75, h:7.76.
Synthesis of barbituric acid
In a 250mL four-necked flask equipped with a stirrer, a thermometer and a reflux condenser, 80mL of t-butanol was added, 0.1mol of potassium t-butoxide (11.2 g) was added, 0.11mol of urea (6.6 g), 0.1mol of methyl-2-cyclohexyl-2-carboxylate-dimethyl succinate was added, the reaction was allowed to react at 80℃for 3 hours, cooled to room temperature, quenched with saturated aqueous sodium bicarbonate solution, extracted with ethyl acetate, the organic phases were combined, washed with saturated brine, dried over anhydrous sodium sulfate, filtered and distilled off with water to give the product, 5-cyclohexyl-5-methyl acetate-2, 4, 6-trioxohexahydropyrimidine (C 11H18N2O5), 25.9g in mass, yield 91.7%, the structural formula of the product was as follows:
nuclear magnetism hydrogen spectrum (C 13H18N2O5, DMSO-d 6)
11.13ppm(s,2H,-NHC(O)NH-),3.63ppm(s,3H,-CCH2COOCH3),2.71ppm(s,2H,-CCH2COOCH3),1.94ppm(m,1H, Cyclohexane), 1.62ppm (m, 2H, cyclohexane), 1.53ppm (m, 2H, cyclohexane), 1.46ppm (m, 1H, cyclohexane), 1.44ppm (m, 1H, cyclohexane), 1.43ppm (m, 2H, cyclohexane), 1.38ppm (m, 2H, cyclohexane).
Nuclear magnetic carbon spectrum (C 13H18N2O5, DMSO-d 6)
174.0ppm，170.4ppm，150.4ppm，61.3ppm，56.6ppm，37.2ppm，36.2ppm，26.Oppm，24.6ppm，14.1ppm.
Elemental analysis (C 13H18N2O5)
Theoretical value (%): c:55.31, H:6.43, n:9.92. measured value (%): c:55.33, H:6.42, n:9.94.
Synthesis of (III) carboxylic acid ester-containing barbituric acid derivatives
To a 250mL four-necked flask equipped with a stirrer, a thermometer and a reflux condenser were added 0.1mol of methyl 5-cyclohexyl-5-acetate-2, 4, 6-trioxohexahydropyrimidine, anhydrous K 2CO3 (0.1 mol), 1g of tetrabutylammonium bromide and 80mL of n-hexane, 0.205mol of methyl chloroacetate was added dropwise, the reflux reaction was carried out for 4 hours, stirring was stopped, and the post-treatment was carried out to obtain 5-cyclohexyl-1, 3, 5-trimethyl triacetate-2, 4, 6-trioxohexahydropyrimidine (C 19H26N2O9), 39.4g in mass, 92.4% in yield, and the product had the following structural formula:
Nuclear magnetism hydrogen spectrum (C 19H26N2O9, DMSO-d 6)
4.15ppm(s,4H,-NCH2COOCH3),3.95ppm(s,2H,-CCH2COOCH3),3.67ppm(s,6H,-NCH2COOCH3),3.61ppm(s,3H,-CCH2COOCH3),1.94ppm(m,1H, Cyclohexane), 1.62ppm (m, 2H, cyclohexane), 1.53ppm (m, 2H, cyclohexane), 1.46ppm (m, 1H, cyclohexane), 1.44ppm (m, 1H, cyclohexane), 1.43ppm (m, 2H, cyclohexane), 1.38ppm (m, 2H, cyclohexane).
Nuclear magnetic carbon spectrum (C 19H26N2O9, DMSO-d 6)
178.2ppm,170.4ppm,167.5ppm,150.7ppm,61.3ppm,61.0ppm,51.6ppm,45.7ppm,37.8ppm,36.8ppm,25.0ppm,24.6ppm,14.1ppm.
Elemental analysis (C 19H26N2O9)
Theoretical value (%): c:53.52, H:6.15, N:6.57. measured value (%): c:53.55, H:6.13, N:6.59.
Hydrolysis of carboxylic acid ester-containing barbituric acid derivatives
To a 250mL four-necked flask equipped with a stirrer, a thermometer and a reflux condenser was added 0.1mol of 5-cyclohexyl-1, 3, 5-trimethyl-2, 4, 6-trioxohexahydropyrimidine, 150mL of 20% by mass sodium hydroxide solution was added, stirring was carried out at 85℃for 5 hours, pH was adjusted to 4-5 with an acid, and filtration was carried out to obtain 5-cyclohexyl-1, 3, 5-triacetate-2, 4, 6-trioxopyrimidine (C 16H20N2O9), the mass of the product was 35.3g, the yield was 91.9%, and the structural formula of the product was as follows:
Nuclear magnetism hydrogen spectrum (C 16H20N2O9, DMSO-d 6)
13.51ppm(s,1H,-CCH2COOH),13.03ppm(s,2H,-NCH2COOH),4.46ppm(s,4H,-NCH2COOH),2.69ppm(s,2H,-CCH2COOH),1.94ppm(m,1H, Cyclohexane), 1.62ppm (m, 2H, cyclohexane), 1.53ppm (m, 2H, cyclohexane), 1.46ppm (m, 1H, cyclohexane), 1.44ppm (m, 1H, cyclohexane), 1.43ppm (m, 2H, cyclohexane), 1.38ppm (m, 2H, cyclohexane).
Nuclear magnetic carbon spectrum (C 16H20N2O9, DMSO-d 6)
178.2ppm，177.3ppm，169.0ppm，150.7ppm，51.3ppm，45.1ppm，39.0ppm，37.8ppm，26.0ppm，25.0ppm，24.6ppm.
Elemental analysis (C 16H20N2O9)
Theoretical value (%): c:50.00, H:5.25, N:7.29. measured value (%): c:50.02, H:5.28, N:7.27.
Examples 1-4 of the preparation of multi-functional highly absorptive chrome tanning agents containing barbituric acid structure using different raw materials are summarized in table 1.
TABLE 1 multifunctional high absorption chrome tanning aid containing barbituric acid structure
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Claims (6)

1. The multifunctional high-absorption chrome tanning auxiliary agent containing barbituric acid structure is characterized by comprising the following molecular structure:
Wherein X is O or S,R1＝H,CH3,C2H5,R2＝H,CH3,C2H5,C3H5,C3H7,C4H9,C5H9,C6H5,C6H11,C7H7,Cl,Br.
2. A process for preparing a multi-functional high-absorption chrome tanning assistant containing barbituric acid structure according to claim 1, which is characterized by comprising the following steps:
(1) C-alkylation reaction
Taking a malonic acid diester compound and a halogenated carboxylic acid ester compound as raw materials, taking inorganic alkali as an alkaline agent, and reacting in an organic solvent at 60-100 ℃ for 6-12 hours under the condition of a phase transfer catalyst to obtain a carboxylic acid ester compound A; the molar ratio of the malonic acid diester compound to the halogenated carboxylic acid ester compound is 1:1.0-2.05, and the molar ratio of the malonic acid diester compound to the alkaline agent to the phase transfer catalyst is 1:0.2-0.4:0.02-0.06;
(2) Cyclization reaction
Taking carboxylic ester compound A and urea or thiourea as raw materials, catalyzing by inorganic alkali or organic alkali, and reacting in an organic solvent at 80-100 ℃ for 4-6 hours to obtain barbituric acid derivative or 2-thiobarbituric acid derivative B; the mol ratio of the carboxylic ester compound A to the urea or the thiourea is 1: (0.95-1.05), and the mol ratio of the carboxylic ester compound A to the organic base or the inorganic base is 1: (0.1-0.3);
(3) N-alkylation reaction
The barbituric acid derivative or the 2-thiobarbituric acid derivative B and halogenated carboxylic ester are used as raw materials, inorganic alkali is used as an alkaline agent, and the barbituric acid derivative or the 2-thiobarbituric acid derivative C containing polybasic carboxylic ester is prepared by reacting in an organic solvent at 60-100 ℃ under the catalysis of a phase transfer catalyst; the molar ratio of the barbituric acid derivative or the 2-thiobarbituric acid derivative B to the halogenated carboxylic ester is 1: (1.0-2.05), and the molar ratio of the barbituric acid derivative or the 2-thiobarbituric acid derivative B to the alkaline agent and the phase transfer catalyst is 1: (0.5-1.2): (0.02-0.06);
(4) Hydrolysis reaction
The barbituric acid derivative containing polybasic carboxylic acid ester or the 2-thiobarbituric acid derivative C containing polybasic carboxylic acid ester is hydrolyzed for 4 to 12 hours at 70 to 100 ℃ under alkaline condition, cooled to normal temperature, and is regulated to pH 4 to 5 by acid, solid is separated out, and suction filtration is carried out to obtain the high-absorption chrome tanning auxiliary agent; the alkali liquor used in the alkaline condition is sodium hydroxide or potassium hydroxide solution with the mass fraction of 10-20%; the acid is one of hydrochloric acid solution, sulfuric acid solution or phosphoric acid solution with the mass fraction of 5-15%.
3. The method for preparing the multi-functional group high-absorption chrome tanning auxiliary containing barbituric acid structure, which is characterized in that: in the step (1), the malonic acid diester compound is one of dimethyl malonate, dimethyl 2-methylmalonate, dimethyl 2-propylmalonate, dimethyl 2-butylmalonate, dimethyl 2-isobutylmalonate, dimethyl 2-allylmalonate, dimethyl 2-cyclopentylmalonate, dimethyl 2-fluoromalonate, dimethyl 2-chloromalonate, dimethyl 2-bromomalonate, diethyl malonate, diethyl 2-methylmalonate, diethyl 2-propylmalonate, diethyl 2-butylmalonate, diethyl 2-isobutylmalonate, diethyl 2-allylmalonate, diethyl 2-cyclopentylmalonate, diethyl 2-fluoromalonate, diethyl 2-chloromalonate, diethyl 2-bromomalonate, dipropyl malonate, diisopropyl malonate, dibutyl malonate, di-tert-butyl malonate, dihexyl malonate, diethyl phenylmalonate and diethyl benzylmalonate.
4. The method for preparing the multi-functional group high-absorption chrome tanning auxiliary containing barbituric acid structure, which is characterized in that: in the step (1), the halogenated carboxylic acid ester is one of methyl chloroacetate, ethyl chloroacetate, butyl chloroacetate, tert-butyl chloroacetate, ethyl bromoacetate, butyl bromoacetate, tert-butyl bromoacetate, methyl 2-chloropropionate, ethyl 2-chloropropionate, methyl 2-bromopropionate, ethyl 2-bromopropionate, methyl 2-chlorobutyrate, ethyl 2-chlorobutyrate, methyl 2-bromobutyrate and ethyl 2-bromobutyrate; the inorganic base is one of anhydrous potassium carbonate, anhydrous sodium carbonate, potassium phosphate and sodium phosphate; the phase transfer catalyst is one of tetrabutylammonium bromide, tetrabutylammonium chloride, dodecyl trimethyl ammonium chloride, tetradecyl trimethyl ammonium chloride, dodecyl trimethyl ammonium bromide and tetradecyl trimethyl ammonium bromide; the organic solvent is one of petroleum ether, cyclohexane, n-hexane, ethyl acetate and 1, 4-dioxane.
5. The method for preparing the multi-functional group high-absorption chrome tanning auxiliary containing barbituric acid structure, which is characterized in that: in the step (2), the inorganic base is one of sodium hydroxide and potassium hydroxide; the organic base is one of sodium ethoxide, sodium methoxide, sodium tert-butoxide and potassium tert-butoxide; the organic solvent is one of methanol, ethanol, isopropanol, n-butanol and tert-butanol.
6. The method for preparing the multi-functional group high-absorption chrome tanning auxiliary containing barbituric acid structure, which is characterized in that: in the step (3), the halogenated carboxylic acid ester is one of methyl chloroacetate, ethyl chloroacetate, butyl chloroacetate, tert-butyl chloroacetate, ethyl bromoacetate, butyl bromoacetate, tert-butyl bromoacetate, methyl 2-chloropropionate, ethyl 2-chloropropionate, methyl 2-bromopropionate, ethyl 2-bromopropionate, methyl 2-chlorobutyrate, ethyl 2-chlorobutyrate, methyl 2-bromobutyrate and ethyl 2-bromobutyrate; the inorganic base is one of anhydrous potassium carbonate, anhydrous sodium carbonate, potassium phosphate and sodium phosphate; the phase transfer catalyst is one of tetrabutylammonium bromide, tetrabutylammonium chloride, dodecyl trimethyl ammonium chloride, tetradecyl trimethyl ammonium chloride, dodecyl trimethyl ammonium bromide and tetradecyl trimethyl ammonium bromide; the organic solvent is one of ethyl acetate, 1, 4-dioxane, methanol, ethanol and n-butanol.
CN202410464747.6A 2024-04-17 2024-04-17 Multifunctional high-absorption chrome tanning auxiliary agent containing barbituric acid structure and preparation method thereof Pending CN118186152A (en)

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