Allyl flexible ionic liquid and preparation method thereof

Abstract

The invention relates to the technical field of ionic liquid, in particular to allyl flexible ionic liquid and a preparation method thereof. The name of the ionic liquid is 1-ethyl-4-allyl-1, 2, 4-triazolyl bromide, and the ionic liquid has a structural formula as shown in a formula (I) in the specification. The preparation method comprises the following steps: slowly adding 1, 2, 4-triazole and sodium methoxide into methanol, dropwise adding bromoethane, reacting, filtering, washing, carrying out rotary evaporation, and removing impurities; distilling and collecting a middle fraction, enabling the middle fraction to react with bromopropene, and performing rotary evaporation, washing and filtering to obtain 1-ethyl-4-allyl-1, 2, 4-triazolyl bromide; and carrying out vacuum drying to obtain the purified-1-ethyl-4-allyl-1, 2, 4-triazolyl bromine salt, and carrying out vacuum drying on the purified-1-ethyl-4-allyl-1, 2, 4-triazolyl bromine salt. (I)

Description

TECHNICAL FIELD

[0001] The present application relates to the field of functional ionic liquid preparation technology, in particular to an allyl flexible ionic liquid and a preparation method thereof. BACKGROUND

[0002] Ionic liquid is a kind of ionic substance in liquid state at room temperature or near room temperature, which is called room temperature ionic liquid. As an environmentally friendly engineering liquid, it has been widely used in many fields such as electrochemistry, biochemistry, catalysis and functional materials. Ionic liquid has high chemical stability, low saturated vapor pressure at high temperature, high thermal stability, low melting point and non-flammability. At the same time, ionic liquid has good designability. These characteristics have attracted widespread attention from scientists.

[0003] With the in-depth study of ionic liquid and its wide application in many fields, scientists hope to meet different requirements by adjusting the types and quantities of groups on ionic liquid. At the same time, as a "designable solvent", ionic liquid can meet the needs of researchers. The introduction of allyl group into the cation of ionic liquid not only improves the conductivity of ionic liquid and reduces its viscosity, but also improves other properties of ionic liquid. SUMMARY

[0004] The present application aims to provide an allyl flexible ionic liquid with low cost, high stability, simple operation and high purity. The technical scheme adopted by the present application is as follows: an ionic liquid is 1-ethyl-4-allyl-1,2,4-triazolyl bromide, and the structure is shown as formula (I):

[0005]

[0006] (I).

[0007] The preparation method of the above ionic liquid comprises the following steps:

[0008] 1) The reaction container is dehydrated and dried;

[0009] 2) Methanol is added to the reaction container, the container is placed in an ice water bath, and 1,2,4-triazole and sodium methoxide are slowly added to the beaker in sequence to react;

[0010] 3) The reaction container in step 2) is transferred to an oil bath, and bromoethane is added dropwise through a constant pressure dropping funnel. After the addition is completed, the reaction is carried out;

[0011] 4) After the reaction is completed, the product obtained in step 3) is cooled to room temperature, filtered to remove the precipitate, and the obtained filtrate is rotary evaporated to remove methanol;

[0012] 5) The product obtained in step 4) is washed with chloroform, recrystallized, filtered, and rotary evaporated, and the above operation is repeated until the impurities are removed;

[0013] 6) The product obtained in step 5) is transferred to a flask and subjected to normal pressure distillation, and the middle fraction at 186-190°C is collected;

[0014] 7) The product obtained in step 6) is transferred to a three-necked flask, and bromopropylene is added dropwise thereto through a constant pressure dropping funnel, and the reaction vessel is placed in an oil bath to perform the reaction;

[0015] 8) The product obtained in step 7) is rotary evaporated at 70-72°C to remove bromopropylene, and then washed with ethyl acetate, suction filtered until the impurities are completely removed, and vacuum dried to obtain the purified 1-ethyl-4-allyl-1,2,4-triazolyl bromide salt.

[0016] In the above method for preparing the ionic liquid, in step 2), the molar ratio of the 1,2,4-triazole to sodium methoxide is 1:1-1:1.1.

[0017] In the above method for preparing the ionic liquid, in step 2), the reaction temperature is not higher than 40°C.

[0018] In the above method for preparing the ionic liquid, in step 3), the molar ratio of the 1,2,4-triazole to bromoethane is 1:1.2-1:4.

[0019] In the above method for preparing the ionic liquid, in step 3), when the bromoethane is added dropwise, the temperature is not higher than 40°C, and the reaction is stirred at 65-68°C for several hours.

[0020] In the above method for preparing the ionic liquid, in step 7), the molar ratio of the 1-ethyl-1,2,4-triazole to bromopropylene is 1:1.2-1:1.4.

[0021] In the above method for preparing the ionic liquid, in step 7), the reaction is performed at 50-52°C for several hours.

[0022] The present application has the following beneficial effects:

[0023] 1. The allyl flexible ionic liquid synthesized in the present application expands the types of ionic liquids.

[0024] 2. The preparation method of the present application is simple, and the product has high purity.

[0025] 3. The present application introduces an allyl flexible group into the 1,2,4-triazole cation, so as to achieve the modification of the cation structure of the ionic liquid. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is the nuclear magnetic hydrogen spectrum of 1-ethyl-4-allyl-1,2,4-triazolyl bromide salt.

[0027] Figure 2 is the thermogravimetric analysis curve of 1-ethyl-4-allyl-1,2,4-triazolyl bromide salt. DETAILED DESCRIPTION

[0028] Example (1) Synthesis of 1-ethyl-4-allyl-1,2,4-triazolyl bromide salt ionic liquid

[0029] (I) Preparation method is as follows

[0030] 1. Synthesis of 1-ethyl-4-allyl-1,2,4-triazolyl bromide salt crude product

[0031] The reaction container is dehydrated and dried; 48-50 mL of methanol is added to the reaction container, the container is placed in an ice water bath, the thermometer is fixed, and 6.8-7.0 g of 1,2,4-triazole and 5.4-5.5 g of sodium methoxide are slowly added to the beaker in sequence, and the reaction temperature is controlled to be not more than 40°C; the reaction container is transferred into an oil bath, 13.0-13.2 g of bromoethane is added dropwise through a constant pressure dropping funnel, and the reaction temperature is kept not more than 40°C, and the reaction is stirred at 65-68°C for 48-50 hours.

[0032] 2. Purification of 1-ethyl-4-allyl-1,2,4-triazolyl bromide salt

[0033] The 1-ethyl-4-allyl-1,2,4-triazolyl bromide salt crude product obtained in step 1) is purified as follows: after the reaction is completed, it is cooled to room temperature, the obtained product is filtered to remove the precipitate. The obtained filtrate is rotary evaporated to remove methanol; the obtained product after rotary evaporation is washed with chloroform, recrystallized, filtered, rotary evaporated, and the above operation is repeated until the impurities are completely removed; then it is transferred to a flask for atmospheric distillation, and the middle fraction at 186-190°C is collected; the collected middle fraction is transferred to a three-necked flask, 14.4-14.6 g of bromopropylene is added dropwise through a constant pressure dropping funnel, the reaction container is placed in an oil bath, and the temperature is slowly raised to 50-52°C, and the reaction is continued for 48-50 hours; after the reaction is completed, the obtained product is rotary evaporated at 70-72°C to remove bromopropylene, then washed with ethyl acetate, suction filtered until the impurities are completely removed, and vacuum dried to constant weight to obtain purified 1-ethyl-4-allyl-1,2,4-triazolyl bromide salt.

[0034] (II) Property characterization Figure 1 is the nuclear magnetic hydrogen spectrum of 1-ethyl-4-allyl-1,2,4-triazolyl bromide salt 1H NMR characterization (MHz, solvent CDCl3) nuclear magnetic spectrum: δ H = 11.38 (H2C=CH-H2C-N=C H = 11.38 (H2C=CH-H2C-N=C H= = 11.38 (H2C=CH-H2C-N=C H = 11.38 (H2C=CH-H2C-N=C H = 11.38 (H2C=CH-H2C-N=C H = 11.38 (H2C=CH-H2C-N=C H = 11.38 (H2C=CH-H2C-N=C H = 11.38 (H2C=CH-H2C-N=C 1 The chemical shift and resonance peak number of H NMR were analyzed after assignment, and no impurity peak was found, i.e. the target product 1-ethyl-4-allyl-1,2,4-triazolyl bromide salt.

[0035] Figure 2 The full thermal gravimetric TG (TGA / SDTA851e, Mttler) of 1-ethyl-4-allyl-1,2,4-triazolyl bromide salt was performed. It can be seen from the TG spectrum that 1-ethyl-4-allyl-1,2,4-triazolyl bromide salt ionic liquid starts to melt at 43.43°C, and weight loss occurs at 219.19°C, indicating that the initial decomposition temperature of the target product is 219.19°C. Compared with 1-ethyl-4-butyl-1,2,4-triazole acetylglycine ionic liquid [Taz(2,4)][Acgly], the initial decomposition temperature thereof is 180.01°C. Compared with 1-ethyl-4-pentyl-1,2,4-triazole acetylglycine ionic liquid [Taz(2,5)][Acgly], the initial decomposition temperature thereof is 174.04°C. Compared with 1-ethyl-4-hexyl-1,2,4-triazole acetylglycine ionic liquid [Taz(2,6)][Acgly], the initial decomposition temperature thereof is 174.04°C. Compared with 1-ethyl-4-butyl-1,2,4-triazole acetylglycine ionic liquid [Taz(2,4)][Acala], the initial decomposition temperature thereof is 180.52°C. Compared with 1-ethyl-4-pentyl-1,2,4-triazole acetylglycine ionic liquid [Taz(2,5)][Acala], the initial decomposition temperature thereof is 178.49°C. Compared with 1-ethyl-4-hexyl-1,2,4-triazole acetylglycine ionic liquid [Taz(2,6)][Acala], the initial decomposition temperature thereof is 177.56°C. This indicates that 1-ethyl-4-allyl-1,2,4-triazolyl bromide salt ionic liquid has high stability.

Claims

1. An ionic liquid characterized in that, The ionic liquid is 1-ethyl-4-allyl-1,2,4-triazolyl bromide, and the structure is shown as formula (I): （Ⅰ）。 2. The method of claim 1, wherein the ionic liquid is prepared by the steps of: The method comprises the following steps: 1) The reaction container is dehydrated and dried; 2) Methanol is added into the reaction container, and the container is placed in an ice water bath; 1,2,4-triazole and sodium methoxide are slowly added into the beaker in sequence to react; 3) The reaction container in step 2) is transferred into an oil bath, and bromoethane is added dropwise through a constant-pressure dropping funnel; after the addition is completed, the reaction is carried out; 4) After the reaction is completed, the product obtained in step 3) is cooled to room temperature, filtered, and the methanol in the filtrate is removed by rotary evaporation; 5) The product obtained in step 4) is washed with chloroform, recrystallized, filtered, and rotary evaporated; the above operation is repeated until the impurities are removed; 6) The product obtained in step 5) is transferred into a flask for normal pressure distillation, and the middle fraction at 186-190°C is collected; 7) The product obtained in step 6) is transferred into a three-necked flask, and bromopropylene is added dropwise through a constant-pressure dropping funnel; the reaction container is placed in an oil bath, and the reaction is carried out; 8) The product obtained in step 7) is rotary evaporated at 70-72°C to remove bromopropylene, and then washed with ethyl acetate, filtered, until the impurities are completely removed; after vacuum drying, the purified 1-ethyl-4-allyl-1,2,4-triazolyl bromide is obtained.

3. The method of claim 2, wherein: In step 2), the molar ratio of 1,2,4-triazole to sodium methoxide is 1:1-1:1.

1.

4. The method of claim 2, wherein: In step 2), the reaction temperature is not higher than 40°C.

5. The method of claim 2, wherein: In step 3), the molar ratio of 1,2,4-triazole to bromoethane is 1:1.2-1:

4.

6. The method of claim 2, wherein: In step 3), when bromoethane is added, the temperature is not higher than 40°C, and the reaction is stirred at 65-68°C for several hours.

7. The method for preparing ionic liquid according to claim 2, characterized in that: In step 7), the molar ratio of 1-ethyl-1,2,4-triazole to bromopropylene is 1:1.2-1:1.

4.

8. The method of claim 2, wherein: In step 7), the reaction is carried out at 50-52°C for several hours.

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