Cooling agent N, 2, 3-trimethyl-2-isopropyl butyramide as well as synthesis method and application of cooling agent N, 2, 3-trimethyl-2-isopropyl butyramide

Abstract

The invention belongs to the technical field of chemical engineering, and discloses a cooling agent N, 2, 3-trimethyl-2-isopropyl butyramide and a synthesis method and application thereof, and the synthesis method comprises the following steps: adding propionitrile and isopropyl bromide into a reaction kettle, and reacting under the low-temperature liquid ammonia condition of-30-50 DEG C to obtain an intermediate DIPPN; carrying out purification and distillation on the intermediate DIPPN; reacting the purified and distilled intermediate DIPPN with dimethyl polyphosphate at the temperature of 100-140 DEG C, neutralizing with acid, separating, and filtering to obtain a crude product; the crude product is crystallized and dried, and the cooling agent N, 2, 3-trimethyl-2-isopropyl butyramide is obtained; the problem of low yield in the prior art is solved, and the problem of high acid value of amidation of methanol and concentrated sulfuric acid as a catalyst in the prior art is also solved.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical industry, and in particular relates to a cooling agent N,2,3.trimethyl-2-isopropylbutanamide and a synthesis method and application thereof. Background Art

[0002] Cooling agent N,2,3.trimethyl-2-isopropylbutyramide is also known as WS23, molecular formula: C10H21NO, molecular weight: 171.29. Due to its refreshing, lasting, fresh, non-irritating spicy taste, no bitterness, and low dosage, it has been widely used in food, medicine, daily chemicals, tobacco and other industries.

[0003] In the prior art, propionitrile and 2-bromopropane are often used to generate an intermediate under the conditions of sodium amide and liquid ammonia, and the intermediate is synthesized in two steps by amidation with methanol using concentrated sulfuric acid as a catalyst. However, the conversion rate of this method is low, which is 84%-87%, the content of the finished product is low, which is 85-90%, and the reaction time is long, which is 30 hours. Therefore, a method for synthesizing a cooling agent N,2,3.trimethyl-2-isopropylbutanamide is needed to improve the conversion rate and the content of the finished product. Summary of the invention

[0004] The purpose of the present invention is to solve the deficiencies in the prior art and to provide a cooling agent N,2,3.trimethyl-2-isopropylbutanamide and a synthesis method and application thereof.

[0005] In order to achieve the above object, the present invention is achieved through the following technical solutions:

[0006] In a first aspect, the present invention provides a method for synthesizing a cooling agent N,2,3.trimethyl-2-isopropylbutanamide, the method comprising the following steps:

[0007] Step S1, adding propionitrile and isopropyl bromide into a reaction kettle, reacting under low temperature liquid ammonia conditions of -30-50°C to obtain an intermediate DIPPN (2-isopropyl-2,3-dimethylbutyronitrile);

[0008] Step S2, purifying and distilling the intermediate DIPPN;

[0009] Step S3, reacting the purified and distilled intermediate DIPPN with dimethyl polyphosphate at 100-140° C., neutralizing with an acid, separating, filtering, and obtaining a crude product;

[0010] Step S4, crystallizing and drying the crude product to obtain the cooling agent N,2,3.trimethyl-2-isopropylbutanamide.

[0011] Preferably, in step S1, the molar ratio of propionitrile to isopropyl bromide is 1:3.

[0012] Preferably, step S2 specifically comprises: extracting the intermediate DIPPN with ether, and finally drying and distilling under reduced pressure.

[0013] Preferably, the acid in step S3 is concentrated sulfuric acid.

[0014] Preferably, step S3 is specifically to react the purified and distilled intermediate DIPPN with dimethyl polyphosphate at 100-140° C., neutralize the reaction solution with concentrated sulfuric acid, separate the organic phase, extract with ether, wash with water and saturated NaCl solution respectively, filter and dry to obtain a crude product.

[0015] Preferably, the molar ratio of the intermediate DIPPN after purification and distillation to dimethyl polyphosphate is 1:5-10.

[0016] In a second aspect, the present invention provides a cooling agent N,2,3.trimethyl-2-isopropylbutyramide, and the cooling agent N,2,3.trimethyl-2-isopropylbutyramide is prepared by the method.

[0017] In a third aspect, the present invention provides an application of the cooling agent N,2,3.trimethyl-2-isopropylbutyramide, wherein the cooling agent N,2,3.trimethyl-2-isopropylbutyramide is used in daily chemical products.

[0018] The invention has the following beneficial effects: according to the invention, propionitrile and isopropyl bromide are reacted in a low-temperature liquid ammonia environment to obtain an intermediate, the treated intermediate DIPPN is reacted with dimethyl polyphosphate, concentrated sulfuric acid is used to neutralize the reaction liquid, dimethyl polyphosphate replaces traditional concentrated sulfuric acid and methanol, the problem of low yield in the prior art is solved, and the problem of high acid value in the amidation of methanol with concentrated sulfuric acid as a catalyst is solved in the prior art, and the reaction is simple, short in time and low in cost. DETAILED DESCRIPTION

[0019] The present invention will be further described below in conjunction with the embodiments, but they are not intended to limit the present invention.

[0020] Example 1

[0021] Add liquid ammonia into the reaction kettle, add a mixture of propionitrile and isopropyl bromide into the reaction kettle at a molar ratio of 1:3, react for 15 hours under low temperature liquid ammonia conditions at -30°C to obtain DIPPN, and recycle the liquid ammonia;

[0022] The intermediate DIPPN is extracted with ether, dried, and distilled under reduced pressure;

[0023] The treated intermediate DIPPN was reacted with dimethyl polyphosphate at a molar ratio of 1:5 at 100°C, and then the reaction solution was neutralized with concentrated sulfuric acid, the organic phase was separated, extracted with ethanol, washed with water and saturated NaCl solution, filtered and dried to obtain a crude product;

[0024] The crude product is crystallized and dried to obtain the cooling agent N,2,3.trimethyl-2-isopropylbutanamide.

[0025] Example 2

[0026] Add liquid ammonia into the reaction kettle, add a mixture of propionitrile and isopropyl bromide into the reaction kettle at a molar ratio of 1:3, react for 18 hours under low temperature liquid ammonia conditions at 10°C to obtain DIPPN, and recycle the liquid ammonia;

[0027] The intermediate DIPPN is extracted with ether, dried, and distilled under reduced pressure;

[0028] The treated intermediate DIPPN was reacted with dimethyl polyphosphate at a molar ratio of 1:8 at 120°C, and then the reaction solution was neutralized with concentrated sulfuric acid, the organic phase was separated, extracted with ethanol, washed with water and saturated NaCl solution, filtered and dried to obtain a crude product;

[0029] The crude product is crystallized and dried to obtain the cooling agent N,2,3.trimethyl-2-isopropylbutanamide.

[0030] Example 3

[0031] Add liquid ammonia into the reaction kettle, add a mixture of propionitrile and isopropyl bromide into the reaction kettle at a molar ratio of 1:3, react for 20 hours under low temperature liquid ammonia conditions at 50°C to obtain DIPPN, and recycle the liquid ammonia;

[0032] The intermediate DIPPN is extracted with ether, dried, and distilled under reduced pressure;

[0033] The treated intermediate DIPPN was reacted with dimethyl polyphosphate at a molar ratio of 1:10 at 140°C, and then the reaction solution was neutralized with concentrated sulfuric acid, the organic phase was separated, extracted with ethanol, washed with water and saturated NaCl solution, filtered and dried to obtain a crude product;

[0034] The crude product is crystallized and dried to obtain the cooling agent N,2,3.trimethyl-2-isopropylbutanamide.

[0035] Comparative Example 1

[0036] Sodium amide and liquid ammonia are added to the reaction kettle, and a mixed solution of propionitrile and isopropyl bromide is added to the reaction kettle at a molar ratio of 1:3. The mixture is reacted under low-temperature liquid ammonia conditions for 30 hours. After the reaction is completed, a small amount of water is added to quench the reaction, and then an appropriate amount of water is added, and then extracted with ether; the mixture is washed with water and a saturated NaCl solution, filtered and dried to obtain an intermediate; concentrated sulfuric acid is added and then methanol is slowly added, the reaction solution is neutralized with sodium hydroxide, extracted with ether, washed with water and a saturated NaCl solution, filtered and dried to obtain a crude product, and the crude product is crystallized to obtain a cooling agent N,2,3.trimethyl-2-isopropylbutanamide.

[0037] Comparative Example 2

[0038] Add liquid ammonia into the reaction kettle, add a mixture of propionitrile and isopropyl bromide into the reaction kettle at a molar ratio of 1:3, react for 15 hours under low temperature liquid ammonia conditions at -30°C to obtain DIPPN, and recycle the liquid ammonia;

[0039] The intermediate DIPPN is extracted with ether, dried, and distilled under reduced pressure;

[0040] Concentrated sulfuric acid was added and then methanol was slowly added. The reaction solution was neutralized with sodium hydroxide, extracted with ether, washed with water and saturated NaCl solution respectively, filtered and dried to obtain a crude product. The crude product was crystallized to obtain a cooling agent N,2,3.trimethyl-2-isopropylbutanamide.

[0041] The quality of the N,2,3,trimethyl-2-isopropylbutanamide products obtained in Example 1-3 and Comparative Example 1-2 was tested, and the results are shown in Table 1.

[0042] Table 1 Comparison of the quality of the products of the embodiments and comparative examples

[0043] Color Organization Status Aroma, fragrance WS-23 content% Melting point Acid value mg / g Example 1 White Crystalline solid Mint-like cool taste 99.96 63 0.5 Example 2 White Crystalline solid Mint-like cool taste 99.5 62 0.7 Example 3 White Crystalline solid Mint-like cool taste 99.0 61 0.8 Comparative Example 1 White White needles Mint-like cool taste 90 60 1.2 Comparative Example 2 White Crystalline solid Mint-like cool taste 89 59 1

[0044] As can be seen from Table 1, in Comparative Example 1, an intermediate is obtained under the conditions of sodium amide and liquid ammonia, and concentrated sulfuric acid is used as a catalyst for amidation with methanol. The reaction time is long, and the product WS-23 content is low, the acid value is high, and the preparation process of raw materials is complicated. In Comparative Example 2, an intermediate is obtained under low-temperature liquid ammonia conditions, and concentrated sulfuric acid is used as a catalyst for amidation with methanol. Although the reaction time is shorter than that of Comparative Example 2 and the acid value is low, compared with Examples 1-3 using concentrated sulfuric acid as a neutralizing agent, the product content is still lower and the acid value is higher.

[0045] The above shows and describes the basic principles, main features and advantages of the present invention. However, the above is only a specific embodiment of the present invention, and the technical features of the present invention are not limited thereto. Any other implementation methods derived by any technician in the field without departing from the technical solution of the present invention should be included in the patent scope of the present invention.

Claims

1. A method for synthesizing a cooling agent N,2,3-trimethyl-2-isopropylbutyramide, characterized in that: The method comprises the following steps: Step S1, adding propionitrile and isopropyl bromide into a reaction kettle, reacting under low temperature liquid ammonia conditions of -30-50°C to obtain the intermediate DIPPN; Step S2, purifying and distilling the intermediate DIPPN; Step S3, reacting the purified and distilled intermediate DIPPN with dimethyl polyphosphate at 100-140° C., neutralizing with an acid, separating, filtering, and obtaining a crude product; Step S4, crystallizing and drying the crude product to obtain the cooling agent N,2,3.trimethyl-2-isopropylbutanamide.

2. The method for synthesizing the cooling agent N,2,3-trimethyl-2-isopropylbutyramide according to claim 1, characterized in that: In step S1, the molar ratio of propionitrile to isopropyl bromide is 1:

3.

3. The method for synthesizing the cooling agent N,2,3-trimethyl-2-isopropylbutyramide according to claim 1, characterized in that: Step S2 specifically comprises: extracting the intermediate DIPPN with ether, and finally drying and distilling under reduced pressure.

4. The method for synthesizing the cooling agent N,2,3-trimethyl-2-isopropylbutyramide according to claim 1, characterized in that: The acid in step S3 is concentrated sulfuric acid.

5. The method for synthesizing the cooling agent N,2,3-trimethyl-2-isopropylbutyramide according to claim 4, characterized in that: Step S3 specifically comprises reacting the purified and distilled intermediate DIPPN with dimethyl polyphosphate at 100-140° C., neutralizing the reaction solution with concentrated sulfuric acid, separating the organic phase, extracting with ether, washing with water and saturated NaCl solution, filtering and drying to obtain a crude product.

6. The method for synthesizing the cooling agent N,2,3-trimethyl-2-isopropylbutyramide according to claim 1, characterized in that: The molar ratio of the intermediate DIPPN to dimethyl polyphosphate after purification and distillation is 1:5-10.

7. A cooling agent N,2,3.trimethyl-2-isopropylbutyramide, characterized in that: The cooling agent N,2,3.trimethyl-2-isopropylbutyramide is prepared by the method according to any one of claims 1-8.

8. An application of the cooling agent N,2,3-trimethyl-2-isopropylbutyramide according to claim 7, characterized in that: The cooling agent N,2,3.trimethyl-2-isopropylbutyramide is used in daily chemical products.