CN1305555C - Water-soluble ion liquid synthesizing method - Google Patents

Abstract

The present invention discloses a method for synthesizing water-soluble ionic liquid. The present invention carries out ultrasonic treatment to mixed liquid of methylimidazole and bromohydrocarbon with the molar ratio of 1: 1.0 to 1: 1.1 by an ultrasonic cell pulverization instrument under the condition of 740W to 760W, the whole reaction is carried out in a water bath of 20 DGE C to 80 DGE C, the mixed liquid is cooled after treated for 0.5 to 1 hour, extraction is carried out 2 to 3 times by cooled ethyl acetate with the same volume with the reactant, and product water-soluble ionic liquid is obtained after vacuum drying for 6 to 8 hours under 60 DGE C to 80 DGE C. The molecular formula of the obtained water-soluble ionic liquid is (RCH3IM)X, the structural formula is disclosed in a chemical formula, wherein R represents the alkane base of C4, and X<-> represents Br<->. The method of the present invention has the advantages of simple operation, short required time, low cost and few toxic substance in production, impurities in products are effectively controlled, and produced ionic liquid can be used as a medium for enzyme catalysis reaction.

Description

A kind of synthetic method of water-soluble ionic liquid

technical field

The invention relates to a method for synthesizing a water-soluble ionic liquid. In the method, the ionic liquid is synthesized by means of ultrasonic heating, and the required ionic liquid is purified by dichloromethane and water extraction and reverse phase extraction.

Background technique

In recent years, ionic liquids have attracted widespread attention as green solvents. In addition to being able to replace conventional organic solvents as reaction media in chemical reactions, many enzymes have recently been found to have good catalytic properties in ionic liquids. The steps of the traditional two-step synthesis of ionic liquids are: mixing the raw materials methylimidazole or alkylpyridine with haloalkanes, and heating under reflux to generate ionic liquids such as alkylimidazolium salts or alkylpyridinium salts with halide ions as anions. Then add the metal salt to carry out the displacement reaction to obtain the ionic liquid containing the desired anion. The traditional two-step synthesis method has the following disadvantages:

(1) The reaction time is longer. The first step reaction often needs to be heated under reflux for more than 24 hours, and the reaction is often incomplete. In the second step reaction, if the sodium salt or potassium salt containing the required anion is used to carry out the displacement reaction in acetone, it also needs to be reacted at room temperature for more than 48 hours;

(2) process cost is high if second step reaction carries out displacement reaction with silver salt in alcoholic water, and reaction time is short, and residual halide ion removal effect is good, but expense is higher;

(3) Poor process safety If the second step reaction carries out displacement reaction with lead salt in alcoholic water, or directly carries out displacement reaction with acid, also can make reaction time shorten, but technology is difficult to control to the poisonous harm of environment.

(4) Product quality control is difficult If select sodium salt or potassium salt to carry out displacement reaction in acetone in the second step reaction, product often remains a small amount of impurity, influences the activity of enzyme catalysis in ionic liquid.

Contents of the invention

The purpose of this invention is to provide a kind of synthetic method of water-soluble ionic liquid.

A method for synthesizing a water-soluble ionic liquid: use an ultrasonic cell pulverizer under the condition of 740W to 760W to ultrasonically treat the mixture of methylimidazole and brominated hydrocarbon with a molar ratio of 1:0 to 1:1.1, and the whole The reaction is carried out in a water bath at 20°C to 80°C. After treatment for 0.5 to 1 hour, cool down. After cooling, the above reaction product is extracted with the same volume of ethyl acetate for 2 to 3 times, and dried in vacuum at 60°C to 80°C for 6 to 8 hours. The molecular formula and the structural formula of the gained water-soluble ionic liquid are respectively [RCH ₃ IM]X and

Wherein, R represents a C ₄ alkane group, and X ^- represents Br ^- .

Another method for synthesizing water-soluble ionic liquids: use an ultrasonic cell pulverizer under the condition of 740W to 760W to ultrasonicate the mixture of methylimidazole and brominated or chlorinated hydrocarbons with a molar ratio of 1.0 to 1:1.1 Treatment, the whole reaction is carried out in a water bath at 20°C to 80°C, and cooled after 0.5 to 1 hour of treatment, the above cooled reaction product is extracted 2 to 3 times with the same volume of ethyl acetate, and vacuum dried at 60°C to 80°C for 6 ~ 8 hours, the obtained water-soluble ionic liquid with halide ions as anions was dissolved in the same volume of deionized water, and then mixed with sodium tetrafluoroborate or potassium tetrafluoroborate in equimolar ratios, and the mixture was stirred at room temperature for 2 to 3 hours. Two hours later, extract twice with the same volume of dichloromethane, combine the extracts, reverse phase extraction with 1/6 to 1/5 volume of deionized water of the extract for 5 to 7 times, and use a rotary evaporator for the dichloromethane phase Concentrate and vacuum dry at 60°C to 80°C for 6 to 8 hours, and the molecular formula and structural formula of the water-soluble ionic liquid obtained are [RCH ₃ IM]X and

Wherein, R represents a C ₄ alkane group, and X ^- represents BF ₄ ^- .

Compared with the prior art, the present invention has the following remarkable effects:

(1) Short reaction time Ultrasonic heating shortens the reaction time, reducing the tens of hours required for reflux heating to about one hour; replacing acetone with water as the reaction medium for the anion replacement reaction of the ionic liquid, making the original out-of-phase The reaction became a homogeneous reaction, and the reaction time was reduced from tens of hours to several hours;

(2) Low process cost Under the condition of ensuring the purity of the ionic liquid, no silver salt is used as the reaction raw material, which reduces the cost;

(3) The product quality is under control The ionic liquid is purified by means of dichloromethane and water extraction and reverse phase extraction, so that the impurity content of the product is controlled, which provides the possibility for the enzyme to catalyze in the ionic liquid.

Detailed ways

Example 1 1-butyl 3-methylimidazolium bromide

Take 1mol each of methylimidazole and bromo-n-butane and add it to a 250ml beaker. The 250ml beaker is covered with a 500ml beaker, and an appropriate amount of water is added inside to make a water bath. The temperature of the water bath is not higher than 80°C. Ultrasonic treatment was performed under the ultrasonic condition of 750W, 99 times per round, each working time was 4 seconds, and the rest time was 5 seconds. After 5 rounds, the liquid in the beaker became clear and transparent, slightly pale yellow. After the liquid was cooled, 200 ml of ethyl acetate was added to extract twice to remove unreacted products. The reaction product was vacuum-dried at 80° C. for 6 hours to obtain about 180 ml of product.

Example two 1-butyl 3-methylimidazolium bromide

Take 0.2 mol of methylimidazole and 0.2 mol of n-bromobutane and put them into a 100ml beaker. The 100ml beaker is covered with a 250ml large beaker, and an appropriate amount of water is added inside as a water bath. The temperature of the water bath is controlled at 20°C to 60°C. Ultrasonic treatment was performed under the ultrasonic condition of 750W, 99 times per round, each working time was 4 seconds, and the rest time was 5 seconds. After 4 rounds, the liquid in the beaker became clear and transparent. After the liquid was cooled, 70 ml of ethyl acetate was added to extract twice to remove unreacted products. The reaction product was vacuum-dried at 80° C. for 6 hours to obtain about 35 ml of product.

Example 3 1-butyl 3-methylimidazolium bromide

Take 0.3 mol of methylimidazole and 0.33 mol of n-bromobutane and put them into a 100ml beaker. The 100ml beaker is covered with a 250ml large beaker, and an appropriate amount of water is added inside as a water bath. The temperature of the water bath is controlled at 30°C to 80°C. Ultrasonic treatment was performed under the ultrasonic condition of 750W, 99 times per round, each working time was 4 seconds, and the rest time was 5 seconds. After 4 rounds, the liquid in the beaker became clear and transparent. After the liquid was cooled, 100 ml of ethyl acetate was added for extraction three times to remove unreacted products. The reaction product was vacuum-dried at 80° C. for 8 hours to obtain about 50 ml of product.

Example four 1-butyl 3-methylimidazolium tetrafluoroborate

Take 0.5 mol of 1-butyl 3-methylimidazolium bromide synthesized according to the method of Example 1, dissolve it in 100 ml of deionized water, then add 0.5 mol of sodium tetrafluoroborate, stir magnetically at room temperature for 3 hours, and the liquid after reaction Extracted twice with 200ml of dichloromethane, combined the extracts, and reverse-phase-extracted with 80ml of deionized water for five times. The dichloromethane phase was concentrated with a rotary evaporator, dried in vacuo at 80° C. for 6 hours, and about 60 ml of a nearly colorless transparent liquid was obtained.

¹ H NMR (500MHz, CDCl ₃ ): δ=8.83(s, 1H, H ₂ ), 7.33 and 7.29(2s, 2H, H ₄ , H ₅ ), 4.19(t, 2H, J=7.45Hz, H ₆ ), 3.96 (s, 3H, H ₁₀ ), 1.85 (m, 2H, H ₇ ), 1.37 (m, 2H, H ₈ ), 0.96 (t, 3H, J=7.38Hz, H ₉ ) ppm;

¹³ C NMR (500MHz, CDCl ₃ ):

δ = 13.57, 19.67, 32.15, 36.65, 50.21, 122.13, 123.71, 137.05 ppm.

Titrate the transparent liquid with saturated AgNO3 aqueous solution without precipitation.

Example five 1-butyl 3-methylimidazolium tetrafluoroborate

Take 0.5 mol of 1-butyl 3-methylimidazolium bromide synthesized according to the method in Example 1, dissolve it in 100 ml of deionized water, then add 0.5 mol of potassium tetrafluoroborate, stir magnetically at room temperature for 2 hours, and the liquid after reaction Extracted twice with 200ml of dichloromethane, combined the extracts, and reversed-phase extracted with 80ml of deionized water for seven times. The dichloromethane phase was concentrated with a rotary evaporator, dried in vacuo at 60°C for 8 hours, and about 60 ml of a nearly colorless transparent liquid was obtained.

Example six 1-butyl 3-methylimidazolium tetrafluoroborate

Take 0.3 mol of 1-butyl 3-methylimidazolium bromide synthesized according to the method in Example 1, dissolve it in 60 ml of deionized water, then add 0.3 mol of sodium tetrafluoroborate, stir magnetically at room temperature for 2.5 hours, and the liquid after reaction Extract twice with 120ml of dichloromethane, combine the extracts, and reverse-phase extract with 50ml of deionized water for 6 times. The dichloromethane phase was concentrated with a rotary evaporator, dried in vacuo at 60° C. for 8 hours, and about 35 ml of a nearly colorless transparent liquid was obtained.

Claims (4)

1. ion liquid method of synthesizing water-solubility, it is characterized in that: use the supersonic cell crusher under the condition of 740W～760W, to mol ratio is that 1: 1.0～1: 1.1 the methylimidazole and the mixed liquor of bromo-hydrocarbons carry out ultrasonic processing, entire reaction is carried out in 20 ℃～80 ℃ water-bath, handle cooling after 0.5～1 hour, the ethyl acetate extraction of cooled above-mentioned product usefulness equal volume 2～3 times, the molecular formula and the structural formula of 60 ℃～80 ℃ vacuum drying gained water soluble ion liquid after 6～8 hours are respectively [RCH ₃IM] X and

Wherein, R represents C ₄Alkyl, X ^-Expression Br ^-

2. the ion liquid method of a kind of synthesizing water-solubility according to claim 1 is characterized in that said ultrasonic processing: be to carry out 4～5 to take turns processing, whenever take turns work 99 times, each 4 seconds working times, 5 seconds intermittent times.

3. ion liquid method of synthesizing water-solubility, it is characterized in that: use the supersonic cell crusher under the condition of 740W～760W, to mol ratio is that 1: 1.0～1: 1.1 the methylimidazole and the mixed liquor of bromo-hydrocarbons carry out ultrasonic processing, entire reaction is carried out in 20 ℃～80 ℃ water-bath, handle cooling after 0.5～1 hour, the ethyl acetate extraction of above-mentioned cooled product usefulness equal volume 2～3 times, 60 ℃～80 ℃ vacuum drying obtain with bromide ion after 6～8 hours be anionic water soluble ion liquid, it is dissolved in the deionized water with volume, mix with moles such as sodium tetrafluoroborate or potassium tetrafluoroborates again, mixed liquor is magnetic agitation 2～3 hours at room temperature, with with twice of the dichloromethane extraction of volume, combining extraction liquid, with the deionized water reversed phase extraction of 1/6～1/5 volume of extract 5～7 times, carrene concentrates with Rotary Evaporators, 60 ℃～80 ℃ vacuum drying after 6～8 hours gained water soluble ion fluid molecule formula and structural formula be respectively [RCH ₃IM] X and

Wherein, R represents C ₄Alkyl, X ^-Expression BF ₄ ^--

4. the ion liquid method of a kind of synthesizing water-solubility according to claim 3 is characterized in that said ultrasonic processing: be to carry out 4～5 to take turns processing, whenever take turns work 99 times, each 4 seconds working times, 5 seconds intermittent times.