Separation and purification method of WS-23 and DIPPN

Abstract

The invention discloses a separation and purification method of WS-23 and DIPPN, which comprises the following steps: putting a WS-23 crude product containing DIPPN into a flask connected with a packed tower, arranging an oil-water separator on the packed tower, adding distilled water into the WS-23 crude product, and stirring; heating at normal pressure until water vapor flows back, and stopping heating when the oil phase at the upper layer in the fraction received in the oil-water separator is not increased any more; cooling, standing and layering the liquid in the flask, sampling and detecting the oil phase liquid which is divided into an upper layer in the flask, and carrying out the next step after detecting that no DIPPN is left in the oil phase liquid; separating to obtain an upper oil phase liquid in the flask, adding a solvent into the oil phase liquid, drying, filtering, cooling and crystallizing to obtain a crystalline powder finished product; by adopting the method, the DIPPN can be removed, the fragrance of the product is not influenced, additional burnt taste is not generated, and the method has the advantages of being simple and convenient to operate, remarkable in treatment effect, capable of being applied to the fields of high-grade flavoring and food additives and the like.

Description

Technical Field

[0001] The invention relates to the technical field of chemical purification, and in particular to a method for separating and purifying WS-23 and DIPPN. Background Art

[0002] WS-23, N, 2, 3-trimethyl-2-isopropylbutanamide, CAS: 51115-67-4, is a food additive that produces a refreshing taste, FEMA: 3804, and is a food-grade flavoring widely used in food and daily chemical fields.

[0003] A paper mentioned the following preparation method: Li Jiayu's paper "Synthesis of a New Cooling Agent N,2,3-Trimethyl-2-isopropylbutyramide (WS-23)" uses propionitrile as the raw material, and synthesizes it in two steps of alkylation and amidation, with a total yield of 73.2%. In production, most of them use DIPPN (2-isopropyl-2,3-dimethylbutyronitrile) and dimethyl carbonate, which reacts with polyphosphoric acid at high temperature to produce a crude product through hydrolysis, but when the reaction is incomplete, there will be DIPPN residue.

[0004] DIPPN (2-isopropyl-2,3-dimethylbutyronitrile) has a special smell. If it cannot be completely separated, it will affect the smell of the product and the quality of the product. Although the existing technology can separate DIPPN from N,2,3-trimethyl-2-isopropylbutyramide by vacuum distillation or vacuum rectification, it requires high temperature and the product is prone to burnt smell, which will also affect the quality and aroma of the product and is not suitable for application in the field of flavors.

[0005] In view of the above-mentioned defects, the inventors of the present invention finally obtained the present invention after a long period of research and practice. Summary of the invention

[0006] In order to solve the above technical defects, the technical solution adopted by the present invention is to provide a method for separating and purifying WS-23 and DIPPN, comprising the steps of:

[0007] S1, placing crude N,2,3-trimethyl-2-isopropylbutanamide containing DIPPN into a flask connected to a packing tower, wherein the packing tower is provided with an oil-water separator, and adding distilled water to the crude N,2,3-trimethyl-2-isopropylbutanamide and stirring;

[0008] S2, heating at normal pressure until water vapor refluxes, and when the oil phase in the upper layer of the fraction received in the oil-water separator no longer increases, stopping heating; cooling and allowing the liquid in the flask to stand and stratify, sampling and testing the oil phase liquid in the upper layer in the flask, and proceeding to the next step after testing that there is no DIPPN residue in the oil phase liquid;

[0009] S3, separating and obtaining the oil phase liquid in the upper layer of the flask, adding a solvent to the oil phase liquid, drying, filtering, cooling and crystallizing, and obtaining a crystalline powder product N,2,3-trimethyl-2-isopropylbutyramide.

[0010] Preferably, the crude N,2,3-trimethyl-2-isopropylbutanamide is post-treated and washed to neutrality before performing step S1 to remove the solvent.

[0011] Preferably, in step S1, the mass ratio of the crude N,2,3-trimethyl-2-isopropylbutyramide to the distilled water is: crude N,2,3-trimethyl-2-isopropylbutyramide: distilled water=1:

[0012] (1~2).

[0013] Preferably, in step S2, the reflux temperature is 90°C to 110°C.

[0014] Preferably, in the step S1, the DIPPN content in the crude N,2,3-trimethyl-2-isopropylbutanamide is 0.1% to 30%.

[0015] Preferably, in step S1, the packing in the packing tower is one of glass Raschig rings, triangular spirals, and stainless steel theta rings.

[0016] Preferably, in step S1, the height of the packing in the packed tower is 15 cm to 50 cm.

[0017] Preferably, in step S3, the added solvent is one of n-hexane, ethyl acetate and acetone.

[0018] Compared with the prior art, the beneficial effect of the present invention is that the present invention can remove DIPPN without affecting the aroma of the product and producing no additional burnt smell, and has the advantages of simple operation, significant treatment effect, and can be applied to the fields of high-end flavoring and food additives. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the process of separation and purification of WS-23 and DIPPN. DETAILED DESCRIPTION

[0020] The above and other technical features and advantages of the present invention are described in more detail below in conjunction with the accompanying drawings.

[0021] like Figure 1 As shown, Figure 1 It is a schematic diagram of the process of separation and purification of WS-23 and DIPPN.

[0022] The separation and purification method of WS-23 and DIPPN of the present invention comprises the steps of:

[0023] S1, placing crude N,2,3-trimethyl-2-isopropylbutanamide containing DIPPN into a flask connected to a packing tower, wherein the packing tower is provided with an oil-water separator, and adding distilled water to the crude N,2,3-trimethyl-2-isopropylbutanamide and stirring;

[0024] S2, heating at normal pressure until water vapor refluxes, and when the oil phase in the upper layer of the fraction received in the oil-water separator no longer increases, stopping heating; cooling and allowing the liquid in the flask to stand and stratify, sampling and testing the oil phase liquid in the upper layer in the flask, and proceeding to the next step after testing that there is no DIPPN residue in the oil phase liquid;

[0025] S3, separating and obtaining the oil phase liquid in the upper layer of the flask, adding a solvent to the oil phase liquid, drying, filtering, cooling and crystallizing, and obtaining a crystalline powder product N,2,3-trimethyl-2-isopropylbutyramide.

[0026] Preferably, the crude N,2,3-trimethyl-2-isopropylbutanamide is post-treated and washed to neutrality before performing step S1 to remove the solvent.

[0027] Preferably, in step S1, the mass ratio of the crude N,2,3-trimethyl-2-isopropylbutyramide to the distilled water is: crude N,2,3-trimethyl-2-isopropylbutyramide: distilled water=1:

[0028] (1~2).

[0029] Preferably, in step S2, the reflux temperature is 90°C to 110°C.

[0030] Preferably, in the step S1, the DIPPN content in the crude N,2,3-trimethyl-2-isopropylbutanamide is 0.1% to 30%.

[0031] Preferably, in step S1, the packing in the packing tower is one of glass Raschig rings, triangular spirals, and stainless steel theta rings.

[0032] Preferably, in step S1, the height of the packing in the packed tower is 15 cm to 50 cm.

[0033] Preferably, in step S3, the added solvent is one of n-hexane, ethyl acetate and acetone.

[0034] The invention provides a crude N,2,3-trimethyl-2-isopropylbutyramide from which a solvent has been removed, puts the crude product into a tower equipped with fillers, adds a proper amount of distilled water, performs normal pressure steam distillation, removes an intermediate DIPPN (2-isopropyl-2,3-dimethylbutyronitrile), obtains a crude N,2,3-trimethyl-2-isopropylbutyramide without an intermediate, then adds a solvent, dries, filters, cools and crystallizes, and obtains a finished N,2,3-trimethyl-2-isopropylbutyramide.

[0035] The present invention can be used to separate trace amounts of DIPPN; the finished product prepared by the present invention has no foreign smell and is particularly suitable for use in the flavor industry for fragrance adjustment; the finished product has a fresh cool feeling without delay and a long-lasting cool feeling; and the present invention is also used to facilitate the secondary crystallization of N,2,3-trimethyl-2-isopropylbutyramide in the mother liquor, thereby improving the yield and utilization rate.

[0036] The present invention can remove DIPPN without affecting the aroma of the product or producing an extra burnt smell, has the advantages of simple operation and significant treatment effect, and can be applied to the fields of high-end flavoring and food additives.

[0037] Embodiment 1

[0038] Take 300 g of crude N,2,3-trimethyl-2-isopropylbutanamide (containing 3% DIPPN, 96% N,2,3-trimethyl-2-isopropylbutanamide, and 1% others) from which the solvent has been removed, put it into a 1L round-bottom flask equipped with a triangular spiral 50 cm high packing tower and an oil-water separator, add 450 g of distilled water, stir, and heat to 110°C at normal pressure. The oil-water separator receives the oil-water mixture until the oil phase no longer increases and the oil phase weighs 15 g. Sample the oil phase in the flask and test it. No DIPPN residue is found.

[0039] Take 285 g of the oil phase in the flask, add 285 g of n-hexane, cool and crystallize, filter and dry to obtain 255 g of product. The product content is detected to be 99.85%.

[0040] Embodiment 2

[0041] Take 200 g of crude N,2,3-trimethyl-2-isopropylbutanamide (containing 30% DIPPN, 69% N,2,3-trimethyl-2-isopropylbutanamide, and 1% others) from which the solvent has been removed, put it into a 1L round-bottom flask equipped with a stainless steel θ-ring 15 cm high packing tower and an oil-water separator, add 400 g of distilled water, stir, and heat to 90°C at normal pressure. The oil-water separator receives the oil-water mixture until the oil phase no longer increases and the oil phase weighs 65 g. Sample the oil phase in the flask and test it, and no DIPPN remains.

[0042] Take 135 g of the oil phase in the flask, add 108 g of ethyl acetate, cool and crystallize, filter and dry to obtain 101 g of product. The product content is detected to be 99.90%.

[0043] Embodiment 3

[0044] Take 200 g of crude N,2,3-trimethyl-2-isopropylbutanamide (containing 0.1% DIPPN, 98.4% N,2,3-trimethyl-2-isopropylbutanamide, and 1.5% others) from which the solvent has been removed, put it into a 1L round-bottom flask equipped with a stainless steel θ-ring 30 cm high packing tower and an oil-water separator, add 200 g of distilled water, stir, and heat to 95°C at normal pressure. The oil-water separator receives the oil-water mixture until the oil phase no longer increases and the oil phase weighs 3.5 g. Sample the oil phase in the flask and test it, and no DIPPN remains.

[0045] Take 196.5 g of the oil phase in the flask, add 142 g of acetone, cool and crystallize, filter and dry to obtain 157 g of product, and the product content is detected to be 99.75%.

[0046] The above description is only a preferred embodiment of the present invention, which is only illustrative and not restrictive of the present invention. Those skilled in the art understand that many changes, modifications, and even equivalences may be made to the present invention within the spirit and scope defined by the claims of the present invention, but all of them will fall within the scope of protection of the present invention.

Claims

1. A method for separating and purifying WS-23 and DIPPN, characterized in that: Includes steps: S1, placing crude N,2,3-trimethyl-2-isopropylbutanamide containing DIPPN into a flask connected to a packing tower, wherein the packing tower is provided with an oil-water separator, and adding distilled water to the crude N,2,3-trimethyl-2-isopropylbutanamide and stirring; S2, heating at normal pressure until water vapor refluxes, and when the oil phase in the upper layer of the fraction received in the oil-water separator no longer increases, stopping heating; cooling and allowing the liquid in the flask to stand and stratify, sampling and testing the oil phase liquid in the upper layer in the flask, and proceeding to the next step after testing that there is no DIPPN residue in the oil phase liquid; S3, separating and obtaining the oil phase liquid in the upper layer of the flask, adding a solvent to the oil phase liquid, drying, filtering, cooling and crystallizing, and obtaining a crystalline powder product.

2. The method for separation and purification of WS-23 and DIPPN as claimed in claim 1, characterized in that: The crude N,2,3-trimethyl-2-isopropylbutanamide is post-treated and washed to neutrality before performing step S1 to remove the solvent.

3. The method for separation and purification of WS-23 and DIPPN as claimed in claim 1, characterized in that: In the step S1, the mass ratio of the crude N,2,3-trimethyl-2-isopropylbutyramide and the distilled water is: crude N,2,3-trimethyl-2-isopropylbutyramide: distilled water = 1: (1-2).

4. The method for separation and purification of WS-23 and DIPPN as claimed in claim 1, characterized in that: In the step S2, the reflux temperature is 90°C to 110°C.

5. The method for separation and purification of WS-23 and DIPPN as claimed in claim 1, characterized in that: In the step S1, the DIPPN content in the crude N,2,3-trimethyl-2-isopropylbutanamide is 0.1% to 30%.

6. The method for separation and purification of WS-23 and DIPPN as claimed in claim 1, characterized in that: In the step S1, the packing in the packing tower is one of glass Raschig rings, triangular spirals, and stainless steel theta rings.

7. The method for separating and purifying WS-23 and DIPPN as claimed in claim 6, characterized in that: In the step S1, the height of the packing in the packed tower is 15 cm to 50 cm.

8. The method for separation and purification of WS-23 and DIPPN as claimed in claim 1, characterized in that: In step S3, the added solvent is one of n-hexane, ethyl acetate and acetone.

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