A kind of preparation method of alkanolamide

Abstract

The present application proposes a method for preparing alkanolamide, which comprises the following steps: (1) adding an excess of alkanolamine and an organic tertiary amine catalyst into a distillation reactor, heating the reactor to a reaction temperature, dripping a fatty acid ester, and reacting at a set reaction pressure; the distillation reactor is a reactor with a distillation tower; (2) after the reaction is completed, the materials in the reactor are allowed to stand for stratification, and the lower layer of liquid is separated from the distillation reactor; (3) the lower layer of liquid is distilled to separate the organic tertiary amine catalyst and the unreacted alkanolamine to obtain an alkanolamine product; the upper layer of liquid is used as a reaction raw material and continues to react in the reactor. By using the present invention, the chromaticity of the alkanolamide product prepared by using a mono-fatty acid ester is lower than 303HAPA, and the amine value is maintained below 20mgKOH / g. The chromaticity of the alkanolamide product prepared by using a diester fatty acid ester is lower than 103HAPA, and the product purity is maintained above 95.5%.

Description

Technical Field

[0001] The invention relates to a method for preparing alkanolamide. Background Art

[0002] Alkanolamides are a type of widely used fine chemical product, widely used in metal cleaning and metal processing formulations, personal care, secondary oil recovery in oil fields, fuel additives, solid powder coatings and other fields. They are often used as foaming agents and viscosity increasers in detergents, and as curing agents in powder coatings. They are a low-toxic powder coating curing agent with broad application prospects.

[0003] At present, the preparation of alkanolamide products mostly uses alkali metal hydroxides as reaction catalysts, all of which are strong alkaline catalysts. This type of catalyst has high catalytic activity and high catalytic efficiency. However, since this type of catalyst itself can produce saponification reaction with fatty acid ester raw materials, the reaction activity is often quenched by the raw materials. Therefore, a large amount of catalyst is required to achieve the expected catalytic effect. At the same time, this type of catalyst is difficult to separate from the product after the reaction is completed. These residual catalysts will also affect the application performance of the product. In addition, due to its high catalytic activity, it will also bring more esterification side reactions in the catalytic reaction of alkyl alcoholamine and fatty acid ester; in terms of color, the strong alkaline alkali metal hydroxide catalyst also has a great influence on the color of the product, especially under the condition of higher reaction temperature, its influence on the color is more obvious. Summary of the invention

[0004] In order to improve the product performance of alkanolamide, the present application proposes a method for preparing alkanolamide.

[0005] In the preparation method, an organic tertiary amine base is used as a catalyst, and fatty acid alkyl ester or dialkyl ester and excess alkyl alcohol amine are used as raw materials. After the low-carbon alcohol by-product is separated by distillation, a crude product is prepared, and the residual organic tertiary amine catalyst is separated by distillation to obtain an alkanolamide product. The preparation method specifically comprises the following steps:

[0006] (1) adding an excess of alkyl alcohol amine and an organic tertiary amine catalyst into a distillation reactor, raising the temperature to the reaction temperature, adding a fatty acid ester dropwise, and reacting under a set reaction pressure; the distillation reactor is a reactor with a distillation tower;

[0007] (2) After the reaction is completed, the materials in the reactor are allowed to stand and separate into layers, and the lower layer of liquid is separated from the distillation reactor;

[0008] (3) distilling the lower layer liquid to separate the organic tertiary amine catalyst and unreacted alkyl alcoholamine to obtain an alkyl alcoholamine product;

[0009] The upper layer of liquid is used as the reaction raw material and continues to react in the reactor.

[0010] Preferably, in step (3), the distillation equipment is a film evaporator or an ultra-gravity rectifier.

[0011] By using the present invention, the chromaticity of the alkanolamide product prepared by using mono-fatty acid ester is lower than 303HAPA, and the amine value is kept below 20mgKOH / g. The chromaticity of the alkanolamide product prepared by using diester fatty acid ester is lower than 103HAPA, and the product purity is kept above 95.5%.

[0012] Specifically, in step (1), the alkyl alcoholamine is ethanolamine, diethanolamine, N-methylethanolamine, N-methylisopropanolamine, monoisopropanolamine, and diisopropanolamine; the fatty acid ester can be at least one of fatty acid methyl ester, fatty acid ethyl ester, dimethyl adipate, dimethyl phthalate, methyl benzoate, and dimethyl succinate, that is, the alkyl alcoholamine can be any one of the above materials or a mixture of two or more thereof.

[0013] Specifically, in step (1), the organic tertiary amine catalyst is any one of triethylamine, tripropylamine, triisopropylamine, N,N-dimethylisopropylamine, N,N-diethylisopropylamine, N-methyldiethylamine, N-ethyldiisopropylamine, and N-methyldiisopropylamine.

[0014] In the present application, no alkali metal catalyst is used.

[0015] In the present invention, a relatively large amount of organic tertiary amine is used as a catalyst, and the low-carbon alcohol produced by the reaction is separated by rectification. The low-carbon alcohol produced during the reaction is discharged from the distillation tower of the reactor. The alkanolamide product has a low solubility in the organic tertiary amine, which is beneficial to promote the synthesis reaction. After static stratification, the generated alkanolamide will enter the lower layer liquid, and the lower layer liquid is distilled to separate the residual catalyst and a small amount of alkyl alcohol amine raw material to obtain a high-purity alkanolamide product. The remaining upper layer liquid containing the tertiary amine catalyst can be added to the alkyl alcohol amine raw material to continue the reaction to prepare the alkanolamide product, so the excess raw material can be recycled. In the preparation method of the present application, since the alkali metal hydroxide catalyst conventionally used in the prior art, such as sodium hydroxide, potassium hydroxide and other catalysts, is eliminated, and a tertiary amine catalyst is used, the alkali metal is avoided from remaining in the product, that is, there is no catalyst residue, and the chromaticity increase caused by the alkali metal is avoided, so that the prepared product has a lower chromaticity and a higher purity. At the same time, since the raw materials and catalysts can be recycled, the preparation method of the present invention also has a higher comprehensive yield.

[0016] Furthermore, in step (1), the mass ratio of the organic tertiary amine catalyst to the raw material is 0.5 to 5.0:1, and the raw material is the total amount of the alkyl alcohol amine and the fatty acid ester. Within the above mass ratio range, the catalyst function of the organic tertiary amine can be fully exerted. When the amount of the organic tertiary amine is too low, the catalytic effect is affected. When the amount of the organic tertiary amine is too large, the excess organic tertiary amine has no catalytic effect and only increases the total amount of the reaction materials.

[0017] Preferably, in step (1), the fatty acid ester is a monolipid fatty acid ester or a diester fatty acid ester; when the fatty acid ester is a monolipid fatty acid ester, the molar ratio of the alkyl alcohol amine to the fatty acid ester is 1.1-2.0:1.0; when the fatty acid ester is a diester fatty acid ester, the molar ratio of the alkyl alcohol amine to the fatty acid ester is 2.1-6.0:1.0. Different molar ratios are selected according to different types of fatty acid esters so that the reactive groups of the two can match, and the upper limit ratio of the alkyl alcohol amine is appropriately increased when the diester fatty acid ester is used, so as to increase the contact between the alkyl alcohol amine and the fatty acid ester, reduce the mutual influence of the two fatty acid branches in the diester fatty acid ester, and reduce the effective contact rate, thereby ensuring the reaction speed.

[0018] Furthermore, to ensure the smooth progress of the reaction, in step (1), the reaction temperature is 80°C to 150°C, and the reaction pressure is set to -0.03MPa to 0.2MPa.

[0019] Furthermore, in step (2), the temperature during the standing process is 10° C. to 150° C., and the standing time is 1 h to 4 h. Under the above conditions, the materials after the reaction can be smoothly separated. DETAILED DESCRIPTION

[0020] Comparative Example 1

[0021] 75g of monoisopropanolamine and 2.0g of potassium hydroxide were added to a reactor with a distillation tower, the stirring device was turned on, the temperature was raised to 100°C under a pressure of -0.03MPa, 209.5g of methyl cocoate was added through a metering pump to start the reaction, and after the methyl cocoate was added, the stirring reaction was continued for 2 hours to obtain monoisopropanolamide of coconut oil. The product had an amine value of 20.3mgKOH / g and a chromaticity of 783HAPA.

[0022] Comparative Example 2

[0023] 133 g of diisopropanolamine and 2.5 g of sodium hydroxide were added to the reactor, the stirring device was turned on, the temperature was raised to 100° C. under a pressure of -0.02 MPa, and 200 g of methyl cocoate was added through a metering pump to start the reaction. After the methyl cocoate was fed, the reaction was continued with stirring for 2 hours to obtain a coconut acid diisopropanolamide product with an amine value of 48 mgKOH / g and a chromaticity of 473HAPA.

[0024] Comparative Example 3

[0025] 399 g of diisopropanolamine and 4.0 g of potassium hydroxide were added to a reactor with a distillation tower, the stirring device was turned on, the temperature was raised to 100° C. under a pressure of -0.03 MPa, and 174.1 g of dimethyl adipate was added through a metering pump to start the reaction. After the dimethyl adipate was fed, the reaction was continued with stirring for 2 hours. The crude product was treated by a membrane distiller to obtain tetrakis(2-hydroxypropyl)adipamide product with a product purity of 94.3% and a chromaticity of 194HAPA.

[0026] Example 1

[0027] 75 g of monoisopropanolamine and 142.3 g of tripropylamine were added to a reactor with a distillation tower, and the stirring device was turned on. The temperature was raised to 80°C under a pressure of -0.03 MPa, and 209.5 g of methyl cocoate was added through a metering pump to start the reaction. After the feeding of methyl cocoate was completed, the stirring reaction was continued for 2 hours. During the reaction, the by-product methanol was separated and collected by the distillation tower. After the reaction was completed, the reaction materials were cooled to 60°C, and after standing for 1 hour, the lower layer of liquid was separated. The lower layer of liquid was distilled through a film evaporator to obtain 200.1 g of coconut oil isopropanolamide product with an amine value of 10.0 mgKOH / g and a chromaticity of 251HAPA.

[0028] Example 2

[0029] 75 g of monoisopropanolamine and 925 g of N,N-dimethylisopropylamine were added to a reactor with a distillation tower, and the stirring device was turned on. The temperature was raised to 100°C under a pressure of -0.03 MPa, and 110 g of methyl cocoate was added through a metering pump to start the reaction. After the feeding of methyl cocoate was completed, the stirring reaction was continued for 2 hours. During the reaction, the by-product methanol was separated and collected by the distillation tower. After the reaction was completed, the reaction materials were cooled to 60°C, and after standing for 1 hour, the lower layer of liquid was separated. The lower layer of liquid was distilled through a film evaporator to obtain 117.3 g of coconut oil isopropanolamide product with an amine value of 9.3 mgKOH / g and a chromaticity of 232HAPA.

[0030] Example 3

[0031] 75 g of monoisopropanolamine and 275 g of triethylamine were added to a reactor with a distillation tower, and the stirring device was turned on. The temperature was raised to 100°C under a pressure of 0.1 MPa, and 200 g of methyl cocoate was added through a metering pump to start the reaction. After the feeding of methyl cocoate was completed, the stirring reaction was continued for 2 hours. During the reaction, the by-product methanol was separated and collected by the distillation tower. After the reaction was completed, the reaction materials were cooled to 60°C, and after standing for 4 hours, the lower layer of liquid was separated. The lower layer of liquid was distilled through a film evaporator to obtain 103.3 g of coconut oil isopropanolamide product with an amine value of 11.4 mgKOH / g and a chromaticity of 297HAPA.

[0032] Example 4

[0033] 61 g of ethanolamine and 783 g of triethylamine were added to a reactor with a distillation tower, and the stirring device was turned on. The temperature was raised to 100°C under a pressure of 0.1 MPa, and 200 g of methyl cocoate was added through a metering pump to start the reaction. After the feeding of methyl cocoate was completed, the stirring reaction was continued for 2 hours. During the reaction, the by-product methanol was separated and collected by the distillation tower. After the reaction was completed, the reaction materials were cooled to 60°C, and after standing for 4 hours, the lower layer of liquid was separated. The lower layer of liquid was distilled through a film evaporator to obtain 103.3 g of coconut oil isopropanolamide product with an amine value of 10.7 mgKOH / g and a chromaticity of 303HAPA.

[0034] Example 5

[0035] 133 g of diisopropanolamine and 333 g of triethylamine were added to a reactor with a distillation tower, and the stirring device was turned on. The temperature was raised to 100°C under a pressure of -0.02 MPa, and 200 g of methyl cocoate was added through a metering pump to start the reaction. After the feeding of methyl cocoate was completed, the stirring reaction was continued for 2 hours. During the reaction, the by-product methanol was separated and collected by the distillation tower. After the reaction was completed, the reaction materials were cooled to 10°C, and after standing for 4 hours, the lower layer of liquid was separated. The lower layer of liquid was distilled through a film evaporator to obtain 253.4 g of coconut acid diisopropanolamide product with an amine value of 19.4 mgKOH / g and a chromaticity of 285HAPA.

[0036] Example 6

[0037] 133 g of diisopropanolamine and 1215 g of triethylamine were added to a reactor with a distillation tower, and the stirring device was turned on. The temperature was raised to 100°C under a pressure of 0.1 MPa, and 110 g of methyl cocoate was added through a metering pump to start the reaction. After the feeding of methyl cocoate was completed, the stirring reaction was continued for 2 hours. During the reaction, the by-product methanol was separated and collected by the distillation tower. After the reaction was completed, the reaction materials were cooled to 25°C, and after standing for 1 hour, the lower layer of liquid was separated. The lower layer of liquid was distilled through a film evaporator to obtain 247.9 g of coconut acid diisopropanolamide product with an amine value of 19.5 mgKOH / g and a chromaticity of 237HAPA.

[0038] Example 7

[0039] 140.0 g of diisopropanolamine and 138.1 g of tripropylamine were added to a reactor with a distillation tower, and the stirring device was turned on. The temperature was raised to 150°C under a pressure of -0.03 MPa, and 136.2 g of methyl benzoate was added through a metering pump to start the reaction. After the feeding of methyl benzoate was completed, the stirring reaction was continued for 2 hours. During the reaction, the by-product methanol was separated and collected by the distillation tower. After the reaction was completed, the reaction materials were cooled to 120°C, and after standing for 1 hour, the lower layer of liquid was separated. The lower layer of liquid was distilled through a film evaporator to obtain 200.3 g of benzoic acid diisopropanolamide product with a product purity of 95.7% and a chromaticity of 103HAPA.

[0040] Example 8

[0041] 266 g of diisopropanolamine and 2010.8 g of tripropylamine were added to a reactor with a distillation tower, and the stirring device was turned on. The temperature was raised to 150°C under a pressure of -0.03 MPa, and 136.2 g of methyl benzoate was added through a metering pump to start the reaction. After the feeding of methyl benzoate was completed, the stirring reaction was continued for 2 hours. During the reaction, the by-product methanol was separated and collected through a distillation tower. After the reaction was completed, the reaction materials were allowed to stand at 150°C for 1 hour, and the lower layer of liquid was separated. The lower layer of liquid was distilled through a film evaporator to obtain 191.7 g of benzoic acid diisopropanolamide product with a product purity of 97.7% and a chromaticity of 53HAPA.

[0042] Example 9

[0043] 199.5 g of diisopropanolamine and 598.5 g of tripropylamine were added to a reactor with a distillation tower, and the stirring device was turned on. The temperature was raised to 150°C under a pressure of -0.03 MPa, and 136.2 g of methyl benzoate was added through a metering pump to start the reaction. After the feeding of methyl benzoate was completed, the stirring reaction was continued for 2 hours. During the reaction, the by-product methanol was separated and collected through a distillation tower. After the reaction was completed, the reaction materials were cooled to 120°C, and after standing for 4 hours, the lower layer of liquid was separated. The lower layer of liquid was distilled through a film evaporator to obtain 213.5 g of benzoic acid diisopropanolamide product with a product purity of 97.1% and a chromaticity of 64HAPA.

[0044] Example 10

[0045] 199.5 g of diisopropanolamine and 335.7 g of triethylamine were added to a reactor with a distillation tower, and the stirring device was turned on. The temperature was raised to 110°C under a pressure of 0.13 MPa, and 136.2 g of methyl benzoate was added through a metering pump to start the reaction. After the feeding of methyl benzoate was completed, the stirring reaction was continued for 2 hours. During the reaction, the by-product methanol was separated and collected by the distillation tower. After the reaction was completed, the reaction materials were heated to 120°C, and after standing for 1 hour, the lower layer of liquid was separated. The lower layer of liquid was distilled through a film evaporator to obtain 209.5 g of benzoic acid diisopropanolamide product with a product purity of 96.8% and a chromaticity of 71HAPA.

[0046] Embodiment 11

[0047] 266 g of diisopropanolamine and 771.5 g of triethylamine were added to a reactor with a distillation tower, the stirring device was turned on, the temperature was raised to 100°C under a pressure of 0.13 MPa, 136.2 g of methyl benzoate was added through a metering pump to start the reaction, and after the feeding of methyl benzoate was completed, the stirring reaction was continued for 2 hours. During the reaction, the by-product methanol was separated and collected by the distillation tower. After the reaction was completed, the reaction materials were heated to 120°C, and after standing for 2 hours, the lower layer of liquid was separated. The lower layer of liquid was distilled through a film evaporator to obtain 193.4 g of benzoic acid diisopropanolamide product with a product purity of 97.8% and a chromaticity of 56HAPA.

[0048] Example 12

[0049] 199.5 g of diisopropanolamine and 335.7 g of N,N-dimethylisopropylamine were added to a reactor with a distillation tower, the stirring device was turned on, the temperature was raised to 100°C under a pressure of 0.2 MPa, 136.2 g of methyl benzoate was added through a metering pump to start the reaction, and after the feeding of methyl benzoate was completed, the stirring reaction was continued for 2 hours. During the reaction, the by-product methanol was separated and collected through a distillation tower. After the reaction was completed, the reaction materials were allowed to stand at 100°C for 2 hours, and the lower layer of liquid was separated. The lower layer of liquid was distilled through a film evaporator to obtain 205.1 g of benzoic acid diisopropanolamide product with a product purity of 96.1% and a chromaticity of 63HAPA.

[0050] Embodiment 13

[0051] 399 g of diisopropanolamine and 1150 g of tripropylamine were added to a reactor with a distillation tower, and the stirring device was turned on. The temperature was raised to 100°C under a pressure of -0.03 MPa, and 174.1 g of dimethyl adipate was added through a metering pump to start the reaction. After the feeding of dimethyl adipate was completed, the stirring reaction was continued for 2 hours. During the reaction, the by-product methanol was separated and collected through a distillation tower. After the reaction was completed, the reaction materials were allowed to stand at 100°C for 1 hour, and the lower layer of liquid was separated. The lower layer of liquid was distilled through a film evaporator to obtain 302.7 g of tetrakis(2-hydroxypropyl)adipamide product with a product purity of 97.3% and a chromaticity of 97HAPA.

[0052] Embodiment 14

[0053] 292.6 g of diisopropanolamine and 933.4 g of triethylamine were added to a reactor with a distillation tower, and the stirring device was turned on. The temperature was raised to 100°C under a pressure of 0.1 MPa, and 174.1 g of dimethyl adipate was added through a metering pump to start the reaction. After the feeding of dimethyl adipate was completed, the stirring reaction was continued for 2 hours. During the reaction, the by-product methanol was separated and collected through a distillation tower. After the reaction was completed, the reaction materials were allowed to stand at 100°C for 1 hour, and the lower layer of liquid was separated. The lower layer of liquid was distilled through a film evaporator to obtain 278.7 g of tetrakis(2-hydroxypropyl)adipamide product with a product purity of 95.5% and a chromaticity of 46HAPA.

[0054] Embodiment 15

[0055] 532 g of diisopropanolamine and 2118 g of triethylamine were added to a reactor with a distillation tower, and the stirring device was turned on. The temperature was raised to 100°C under a pressure of 0.1 MPa, and 174.1 g of dimethyl adipate was added through a metering pump to start the reaction. After the feeding of dimethyl adipate was completed, the stirring reaction was continued for 2 hours. During the reaction, the by-product methanol was separated and collected by the distillation tower. After the reaction was completed, the reaction materials were allowed to stand at 100°C for 1 hour, and the lower layer of liquid was separated. The lower layer of liquid was distilled through a film evaporator to obtain 253.4 g of tetrakis(2-hydroxypropyl)adipamide product with a product purity of 98.4% and a chromaticity of 43HAPA.

[0056] Example 16

[0057] 105 g of diethanolamine and 305 g of triethylamine were added to a reactor with a distillation tower, and the stirring device was turned on. The temperature was raised to 100°C under a pressure of -0.02 MPa, and 200 g of methyl cocoate was added through a metering pump to start the reaction. After the feeding of methyl cocoate was completed, the stirring reaction was continued for 2 hours. During the reaction, the by-product methanol was separated and collected through a distillation tower. After the reaction was completed, the reaction materials were cooled to 20°C, and after standing for 4 hours, the lower layer of liquid was separated. The lower layer of liquid was distilled through a film evaporator to obtain 253.4 g of coconut oil diethanolamide product with an amine value of 15.7 mgKOH / g and a chromaticity of 261HAPA.

[0058] Embodiment 17

[0059] 78.8 g of N-methylethanolamine and 600 g of triethylamine were added to a reactor with a distillation tower, and the stirring device was turned on. The temperature was raised to 100° C. under a pressure of -0.01 MPa, and 220 g of methyl cocoate was added through a metering pump to start the reaction. After the feeding of methyl cocoate was completed, the stirring reaction was continued for 2 hours. During the reaction, the by-product methanol was separated and collected through a distillation tower. After the reaction was completed, the reaction materials were cooled to 20° C. and allowed to stand for 4 hours. The lower layer of liquid was separated and the lower layer of liquid was distilled through a film evaporator to obtain 192.1 g of N-methyl cocoate ethanolamide product with an amine value of 18.9 mgKOH / g and a chromaticity of 277HAPA.

[0060] Comparative Example 1 corresponds to Example 1, Comparative Example 2 corresponds to Example 5, and Comparative Example 3 corresponds to Example 13. It can be seen from the above comparative examples and examples that the products produced by the preparation method of the present invention have low amine value and chromaticity, or have higher purity and lower chromaticity.

Claims

1. A method for preparing an alkanolamide, It is characterized in that The steps include: (1) adding an excess of alkyl alcohol amine and an organic tertiary amine catalyst into a distillation reactor, raising the temperature to the reaction temperature, adding a fatty acid ester dropwise, and reacting under a set reaction pressure; the distillation reactor is a reactor with a distillation tower; (2) After the reaction is completed, the materials in the reactor are allowed to stand and separate into layers, and the lower layer of liquid is separated from the distillation reactor; (3) distilling the lower layer liquid to separate the organic tertiary amine catalyst and the unreacted alkyl alcohol amine to obtain the alkanolamide product; the upper layer liquid is used as the reaction raw material to continue the reaction in the reactor; In step (1), the mass ratio of the organic tertiary amine catalyst to the raw material is 0.5-5.0:1, and the raw material is the total amount of the alkyl alcohol amine and the fatty acid ester; In step (1), the fatty acid ester is a monolipid fatty acid ester or a diester fatty acid ester; When the fatty acid ester is a monolipid fatty acid ester, the molar ratio of the alkyl alcohol amine to the fatty acid ester is 1.1-2.0:1.0; When the fatty acid ester is a diester fatty acid ester, the molar ratio of the alkyl alcohol amine to the fatty acid ester is 2.1-6.0:1.0; In step (1), the organic tertiary amine catalyst is any one of triethylamine, tripropylamine, and N, N-dimethylisopropylamine; In step (1), the alkyl alcoholamine is ethanolamine, diethanolamine, N-methylethanolamine, monoisopropanolamine, or diisopropanolamine; The fatty acid ester is at least one of methyl coconut oil, methyl benzoate and dimethyl adipate.

2. The preparation method according to claim 1, It is characterized in that In step (1), the reaction temperature is 80°C to 150°C, and the reaction pressure is set to -0.03MPa to 0.2MPa.

3. The preparation method according to claim 1, It is characterized in that In step (2), the temperature during the standing process is 10° C. to 150° C., and the standing time is 1 h to 4 h.

4. The preparation method according to claim 1, It is characterized in that In step (3), the distillation equipment is a film evaporator or an ultra-gravity rectifier.