Method for preparing tertiary amino alcohol compound

Abstract

The invention discloses a method for preparing a tertiary amino alcohol compound. According to the method, an amino alcohol compound and an aldehyde compound are subjected to a reductive amination reaction under the action of formic acid to prepare the tertiary amino alcohol compound. The molar ratio of the amino alcohol compound to the aldehyde group compound to the formic acid is 1: (2-4): (2-6). The main raw material amino alcohol compound is commercially available, low in price and sufficient in supply; the reaction conditions are mild, the reaction speed is high, the reaction product selectivity is high, and the product selectivity can reach 98% or above.

Description

Technical Field

[0001] The invention relates to a method for preparing a compound, and in particular to a method for preparing a tertiary amino alcohol compound. Background Art

[0002] Tertiary amino alcohol compounds are an important chemical raw material: they can be used as foaming catalysts, surfactants, resin solubilizers, finishing stabilizers, etc.; they can be used as a low-VOC (low volatile organic content) neutralizer for coatings and paints, and are also used as carbon dioxide capture agents; tertiary amino alcohol compounds can replace amine-containing additives in metalworking fluids to reduce the harm to workers' health during use; tertiary amino alcohol compounds can also be used in the fields of daily chemicals and cosmetics; tertiary amino alcohol compounds can be used to produce cationic waterborne polyurethanes, and can also be used as synthetic raw materials for other useful chemicals.

[0003] The preparation of tertiary amino alcohol compounds generally adopts N-alkylation reaction. The traditional preparation method is generally that amino compounds, hydrogen and aldehyde compounds are hydrogenated and reduced under the catalysis of precious metal catalysts to generate the final product tertiary amino alcohol compounds (Murray Senkus, J.Am.Chem.Soc., 1945). The hydrogenation reaction is generally carried out in a pressurized form, and the pressure is generally 700-7000KPa.

[0004] Angus Chemical Company of the United States (CN103906728A, CN103153942A) has announced a method for preparing tertiary amino alcohol compounds from nitroalkanes. The preparation is divided into three stages. The first step is the Henry reaction of nitroalkanes and aldehyde compounds to generate nitroalcohol compounds. The second step is the catalytic hydrogenation of nitroalcohol compounds in an autoclave without separation to generate aminoalcohol compounds. The third step is the N-alkylation reaction, in which the amino compounds, hydrogen and excess aldehyde compounds that have not been separated and purified are further catalytically hydrogenated and reduced under changing conditions to generate the final product tertiary aminoalcohol compounds. Jiaxing Runbo Chemical Co., Ltd. (CN107488118A) has announced a similar one-pot method for preparing tertiary aminoalcohol compounds from nitroalkanes, except that the Henry reaction is also carried out in a hydrogenation kettle. In addition, the catalysts used in the hydrogenation are different, one using a Ni-based catalyst and the other using a Pa-based catalyst.

[0005] The currently published methods for preparing tertiary amino alcohol compounds have the following major problems: (1) When conducting N-alkylation reaction, the reaction is carried out in situ under high pressure, high temperature and strong stirring conditions. The operation is inconvenient and the equipment cost is greatly increased. In addition, the feeding under the condition of the simultaneous presence of hydrogen and hydrogenation catalyst increases the risk of production. The hydrogenation reaction generally takes a long time, often more than 24 hours.

[0006] (2) Raney nickel is used as the catalyst, which is used in large quantities, has poor catalyst recycling performance, and is not easy to activate and regenerate.

[0007] (3) When Pd-based catalysts are used, the price of the catalysts is high and the catalyst cost accounts for a high proportion.

[0008] (4) The reaction selectivity is relatively low, and the general product selectivity is less than 92%. Summary of the invention

[0009] In view of the above-mentioned defects or deficiencies in the prior art, it is desired to provide a better method for preparing tertiary amino alcohol compounds.

[0010] According to the technical solution provided in the embodiments of the present application, a method for preparing a tertiary amino alcohol compound comprises the following steps: Step 1: Add the amino alcohol compound and the aldehyde compound into a reaction kettle, and heat the reaction kettle under normal pressure until the temperature reaches 90°C.

[0011] Step 2: Control the temperature of the reactor at 90-100°C, slowly add formic acid into the reactor, the molar ratio of the amino alcohol compound, the aldehyde compound and the formic acid is 1:(2-4):(2-6), the addition time is 1-3h, the temperature is controlled not to exceed 108°C after the addition, and the reaction is continued for 0.5-4h to obtain a tertiary amino alcohol compound.

[0012] The obtained tertiary amino alcohol compound includes 2-amino-2-ethyl-1,3-propanediol, 2-amino-2-methyl-1,3-propanediol, 2-amino-2-methyl-1-propanol or trishydroxymethylaminomethane, and aminoethanol.

[0013] In the present invention, the amino alcohol compound is preferably one of 2-amino-2-ethyl-1,3-propanediol, 2-amino-2-methyl-1,3-propanediol, 2-amino-2-methyl-1-propanol, trishydroxymethylaminomethane, and aminoethanol.

[0014] In the present invention, the aldehyde compound is one of formaldehyde, acetaldehyde solution and paraformaldehyde.

[0015] In the present invention, the formic acid includes aqueous formic acid and anhydrous formic acid.

[0016] The preparation method of the present invention has the following beneficial effects: (1) The main raw material amino alcohol is already available on the market, with low price and sufficient supply; (2) The reaction conditions are mild, it is a normal pressure reaction, and the equipment requirements are low; (3) Short reaction time and high preparation efficiency; (4) The reaction product selectivity is high, and the product selectivity can reach more than 98%. DETAILED DESCRIPTION

[0017] The present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention.

[0018] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail with reference to the embodiments below.

[0019] A method for preparing a tertiary amino alcohol has the advantages of fewer reaction steps, simple operation, low equipment requirements, good safety and readily available raw materials. The method comprises the following steps: adding an amino alcohol compound and an aldehyde compound into a reaction kettle, controlling the temperature of the reaction kettle not to exceed 100°C, and finally slowly adding formic acid into the reaction kettle, wherein the molar ratio of the amino alcohol compound, the aldehyde compound and the formic acid is 1:(2-4):(2-6), the adding time is 1-3 hours, the temperature is controlled not to exceed 108°C after the addition is completed, and the reaction is continued for 0.5-4 hours to obtain a tertiary amino alcohol compound.

[0020] The amino alcohol compound is 2-amino-2-ethyl-1,3-propanediol, 2-amino-2-methyl-1,3-propanediol, 2-amino-2-methyl-1-propanol or trishydroxymethylaminomethane, aminoethanol.

[0021] The tertiary amino alcohol compound is 2-dimethylamino-2-ethyl-1,3-propanediol, 2-dimethylamino-2-methyl-1,3-propanediol, 2-dimethylamino-2-methyl-1-propanol, 2-diethylamino-2-methyl-1-propanol, N,N-dimethyltrishydroxymethylaminomethane or N,N-dimethylaminoethanol.

[0022] The aldehyde compound is formaldehyde or acetaldehyde solution or paraformaldehyde.

[0023] The formic acid is aqueous formic acid and anhydrous formic acid of various specifications.

[0024] The reaction releases carbon dioxide, which can be directly discharged into the atmosphere after washing with water, or captured by alkali absorption and converted into other useful chemical raw materials. At the end of the reaction, GC detection shows that the product selectivity is >98%.

[0025] Example 1 Preparation of 2-dimethylamino-2-methyl-1-propanol: 100g of 90% by mass 2-amino-2-methyl-1-propanol aqueous solution was added to a four-necked reaction flask equipped with a thermometer, electric stirring, reflux condenser and feeding pump, and 243g of 37% formaldehyde was added. Stirring was started, and the reaction flask was placed in an electric heating jacket for heating. When the temperature reached 70°C, 184g of anhydrous formic acid was pumped in, and the temperature was controlled not to exceed 100°C. Slow reflux was maintained, and carbon dioxide was released. The addition was completed in about 1.5h, and the temperature was raised to 106°C and continued to heat for 1-2h. Almost no gas was released. Sampling was performed for detection. The product selectivity GC was about 98.4%, and a small amount of by-products were mainly 4,4-dimethyloxazolidine and 4,4,N-trimethyloxazolidine.

[0026] Example 2 Preparation of 2-dimethylamino-2-methyl-1-propanol: 119g of 75% 2-amino-2-methyl-1-propanol aqueous solution and 20g of water were added to a four-necked reaction flask with a thermometer, electric stirring, reflux condenser and feeding pump, and 90g of 92% paraformaldehyde was added. The reaction flask was placed in an electric heating jacket for heating. When the temperature reached 70°C, the paraformaldehyde was completely dissolved. Stirring was started, and 189g of 85% formic acid was pumped in. The temperature was controlled not to exceed 100°C, and slow reflux was maintained. Carbon dioxide was released. The addition was completed in about 1.5h, and the temperature was raised to 106°C and continued to heat for 1-2h. Almost no gas was released. Sampling was tested. The product selectivity GC was about 98.9%, and a small amount of by-products were mainly 4,4-dimethyloxazolidine and 4,4,N-trimethyloxazolidine.

[0027] Example 3 Preparation of 2-diethylamino-2-methyl-1-propanol: 100g of 90% by mass 2-amino-2-methyl-1-propanol aqueous solution was added to a four-necked reaction flask with a thermometer, electric stirring, reflux condenser and feeding pump, 315g of 40% acetaldehyde was added, stirring was started, and the reaction flask was placed in an electric heating jacket for heating. When the temperature reached 70°C, 184g of anhydrous formic acid was pumped in, the temperature was controlled not to exceed 100°C, and slow reflux was maintained. Carbon dioxide was released. The addition was completed in about 1.5h, and the temperature was raised to 106°C and continued to heat for 2-3h. Almost no gas was released. Sampling was performed for detection. The product selectivity GC was about 98.1%, and a small amount of by-products were mainly 2-ethylamino-2-methyl-1-propanol, 4,4-diethyloxazolidine and 4,4,N-triethyloxazolidine.

[0028] Example 4 Preparation of 2-dimethylaminoethanol: 121 g of aminoethanol and 100 g of water were added to a four-necked reaction flask equipped with a thermometer, electric stirring, reflux condenser and feeding pump, and 82 g of 92% paraformaldehyde was added. The reaction flask was placed in an electric heating jacket for heating. When the temperature reached 70°C, the paraformaldehyde was completely dissolved. Stirring was started and 189 g of 85% formic acid was pumped in. The temperature was controlled not to exceed 100°C and reflux was maintained slowly. Carbon dioxide was released and the addition was completed in about 1.5 hours. The temperature was raised to 106°C and heating was continued for 1-2 hours. Almost no gas was released. Sampling was performed for detection. The product selectivity was about 98.0% by GC. A small amount of by-products were mainly oxazolidine and N-methyloxazolidine.

[0029] Example 5 Preparation of N,N-dimethyltris(hydroxymethyl)aminomethane 121g of tris(hydroxymethyl)aminomethane) and 60g of water were added to a four-necked reaction flask equipped with a thermometer, an electric stirrer, a reflux condenser and a feed pump, and 82g of 92% paraformaldehyde was added. The reaction flask was placed in an electric heating jacket for heating. When the temperature reached 70°C, the paraformaldehyde was completely dissolved. Stirring was started, and 189g of 85% formic acid was pumped in. The temperature was controlled not to exceed 100°C, and slow reflux was maintained. Carbon dioxide was released. The addition was completed in about 1.5h. The temperature was raised to 106°C and continued to heat for 2-3h. Almost no gas was released. Sampling was performed for detection. The product selectivity was about 98.0% by GC. A small amount of by-products were mainly 4,4-dihydroxymethyl-N-methyloxazolidine and 4-hydroxymethylbicyclic oxazolidine.

[0030] The above description is only an explanation of the preferred embodiments of the present application and the technical principles and other schemes used. At the same time, the scope of the invention involved in the present application is not limited to the technical scheme formed by a specific combination of the above technical features, but also includes other technical schemes formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with the technical features with similar functions disclosed in the present application (but not limited to) to form a technical scheme.

Claims

1. A method for preparing a tertiary amino alcohol compound, characterized in that it comprises the following steps: Step 1: Add amino alcohol compounds and aldehyde compounds into a reaction kettle, and heat the reaction kettle under normal pressure until the temperature reaches 90°C. Step 2: Control the temperature of the reactor at 90-100°C, slowly add formic acid into the reactor, the molar ratio of the amino alcohol compound, the aldehyde compound and the formic acid is 1:(2-4):(2-6), the addition time is 1-3h, the temperature is controlled not to exceed 108°C after the addition, and the reaction is continued for 0.5-4h to obtain a tertiary amino alcohol compound.

2. A method for preparing tertiary amino alcohol compounds according to claim 1, characterized in that The tertiary amino alcohol compound is 2-dimethylamino-2-ethyl-1,3-propanediol, 2-dimethylamino-2-methyl-1,3-propanediol, 2-dimethylamino-2-methyl-1-propanol, 2-diethylamino-2-methyl-1-propanol or N,N-dimethylaminotrishydroxymethylaminomethane, N,N-dimethylaminoethanol, etc.

3. A method for preparing tertiary amino alcohol compounds according to claim 1, characterized in that The amino alcohol compound is 2-amino-2-ethyl-1,3-propanediol, 2-amino-2-methyl-1,3-propanediol, 2-amino-2-methyl-1-propanol or trishydroxymethylaminomethane, aminoethanol and the like.

4. A method for preparing tertiary amino alcohol compounds according to claim 1, characterized in that The aldehyde compound is formaldehyde or acetaldehyde aqueous solution or paraformaldehyde.

5. A method for preparing tertiary amino alcohol compounds according to claim 1, characterized in that The formic acid includes aqueous formic acid and anhydrous formic acid.