Synthesis method of neopentyl glycol diheptanoate

Abstract

The invention discloses a synthesis method of neopentyl glycol diheptanoate, and belongs to the technical field of organic synthesis, the key point of the technical scheme is that the synthesis method of neopentyl glycol diheptanoate comprises the following synthesis steps: S1, stirring and mixing neopentyl glycol, n-heptanoic acid and an inorganic tin catalyst, and starting to heat; s2, the reaction is divided into two stages, the reaction temperature of the first stage is 130-150 DEG C, the reaction lasts for 3-5 h, the reaction temperature of the second stage is 160-200 DEG C, the reaction vacuum degree is 0.04-0.1 MPa, and the heat preservation reaction lasts for 4-10 h; s3, starting a vacuum pump, deacidifying under reduced pressure when the vacuum degree gradually reaches 2Pa, adding a decolorizing agent after the acid content and the moisture content reach the standard, stirring for 30-60 minutes under reduced pressure at 110-120 DEG C, filtering to obtain a crude product, performing alkali washing and water washing on the crude product, and performing high-temperature vacuum drying to obtain neopentyl glycol diheptanoate. And the production cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of organic synthesis, and in particular to a method for synthesizing neopentyl glycol diheptanoate. Background Art

[0002] Neopentyl glycol diheptanoate is colorless, odorless, non-greasy, and easy to spread. It is a very light and dry ester and can be used in sunscreen products, refreshing moisturizing creams, facial lotions, self-tanning lotions, foundations, antiperspirant products, etc. Neopentyl glycol diheptanoate is a substitute for cyclomethylsiloxane, an ideal solvent for organic ultraviolet absorbers, and also an excellent solvent for fragrances.

[0003] Common catalysts used in the existing synthesis of neopentyl glycol diheptanoate include acidic catalysts (sulfuric acid, p-toluenesulfonic acid) and solid acid catalysts (molecular sieves, ion exchange resins, etc.). The problems of these two catalysts are as follows: Acidic catalysts are prone to corrode equipment and easily cause dehydration or oxidation by-products; solid acid catalysts have high costs and the yield is not as good as that of traditional acidic catalysts. Although they have advantages in environmental protection compared to sulfuric acid and can be recycled, improper treatment may lead to catalyst carbon deposition or poisoning, resulting in a shortened service life and the need for frequent replacement, increasing production costs. Summary of the Invention

[0004] In order to solve the problems in the prior art, the present invention provides a method for synthesizing neopentyl glycol diheptanoate, which shortens the esterification cycle, improves the conversion rate, and reduces the production cost by using an inorganic tin catalyst.

[0005] The method for synthesizing neopentyl glycol diheptanoate provided by the present invention adopts the following technical scheme: A method for synthesizing neopentyl glycol diheptanoate, comprising the following synthesis steps: S1. Stir and mix neopentyl glycol, n-heptanoic acid, and an inorganic tin catalyst and start heating up; S2. Divide the reaction into two stages. The reaction temperature in the first stage is 130 - 150 °C, and the reaction lasts for 3 - 5 h. The reaction temperature in the second stage is 160 - 200 °C, and the reaction vacuum degree is 0.04 - 0.1 MPa, and keep the temperature for reaction for 4 - 10 h; S3. Turn on the vacuum pump, and when the vacuum degree gradually reaches 2 Pa, carry out acid removal under reduced pressure. After the acid content and water content meet the standards, add a decolorizing agent, stir under reduced pressure at 110 - 120 °C for 30 - 60 min, filter to obtain the crude product, and after alkali washing and water washing of the crude product, carry out high-temperature vacuum drying to obtain neopentyl glycol diheptanoate.

[0006] By adopting the above technical solution, the present application uses an inorganic tin catalyst in the synthesis of neopentyl glycol diheptanoate, which not only shortens the esterification cycle, but also improves the conversion rate of reactants and reduces production costs. In addition, when the reaction is divided into two stages in the present application, the first stage is conducive to the formation of monoester, and the second stage is conducive to the formation of diester. Therefore, dividing the reaction stage into two stages can improve the conversion rate of the product. At the same time, the ester product has a light color and high quality during the reaction process, and it also avoids equipment corrosion and does not pollute the environment.

[0007] In a preferred embodiment, the addition amount of the inorganic tin catalyst is 0.1-1% of the total weight of neopentyl glycol and n-heptanoic acid.

[0008] In a preferred embodiment, the inorganic tin catalyst is one or more of tin oxide, stannous chloride, and stannous sulfate.

[0009] In a preferred embodiment, the addition amount of neopentyl glycol is 20-30 wt%, and the addition amount of n-heptanoic acid is 70-80 wt%.

[0010] In a preferred embodiment, the acid value of the neopentyl glycol diheptanoate obtained in step S3 is 0-0.5 mg KOH / g, the saponification value is 325-355 mg KOH / g, and the moisture content is 0-0.5%.

[0011] In summary, the present invention has the following beneficial effects: 1. The present application uses an inorganic tin catalyst to replace the existing acidic catalyst, which not only shortens the esterification cycle (compared with the solid acid catalyst, the esterification cycle of the present application is shortened by about 30-50%), improves the conversion rate of reactants, and at the same time, the inorganic tin catalyst does not pollute the environment and avoids equipment corrosion.

[0012] 2. The present application divides the reaction of neopentyl glycol and n-heptanoic acid into two stages. The first low-temperature stage helps the formation of monoester, and the second high-temperature stage helps the formation of diester, thereby further improving the conversion rate of reactants. Detailed implementation manners

[0013] The following further elaborates on the present invention in conjunction with examples. All reagents not indicating the manufacturer can be obtained as conventional reagent products through commercial purchase.

[0014] Example 1 A method for synthesizing neopentyl glycol diheptanoate includes the following synthesis steps: S1. Stir and mix 0.2 kg of neopentyl glycol, 0.8 kg of n-heptanoic acid, and 0.001 kg of tin oxide catalyst and start heating; S2. Divide the reaction into two stages. The reaction temperature in the first stage is 130°C, and the reaction lasts for 3 h. The reaction temperature in the second stage is 160°C, the reaction vacuum degree is 0.04 MPa, and keep the temperature for reaction for 4 h; S3. Turn on the rotary vane vacuum pump. With the pumping rates of 1 L / s, 4 L / s, and 8 L / s respectively, reduce the pressure to remove acid until the vacuum degree gradually reaches 2 Pa. After the acid content and water content meet the standards, add the decolorizing agent activated carbon, stir under reduced pressure at 110°C for 30 min, filter to obtain the crude product. After alkali washing and water washing the crude product, perform high-temperature vacuum drying to obtain neopentyl glycol diheptanoate. The conversion rate of neopentyl glycol is 96.1%. After detection, the indexes of neopentyl glycol diheptanoate are as follows: it is a colorless to light yellow transparent liquid at 20°C, odorless or with a slight characteristic odor at 20°C, the acid value is 0 mg KOH / g (obtained according to the detection method in GB / T5009.229-2016), the saponification value is 338 mg KOH / g (obtained according to the detection method in GB / T5534-2008), and the water content is 0.01% (obtained according to the detection method in GB / T6283-2008).

[0015] Example 2 A synthesis method of neopentyl glycol diheptanoate, comprising the following synthesis steps: S1. Stir and mix 0.2 kg of neopentyl glycol, 0.8 kg of n-heptanoic acid, and 0.001 kg of stannous chloride catalyst, and start heating up; S2. Divide the reaction into two stages. The reaction temperature in the first stage is 140°C, and the reaction lasts for 4 h. The reaction temperature in the second stage is 160°C, the reaction vacuum degree is 0.04 MPa, and keep the temperature for reaction for 4 h; S3. Turn on the rotary vane vacuum pump. With the pumping rates of 1 L / s, 4 L / s, and 8 L / s respectively, reduce the pressure to remove acid until the vacuum degree gradually reaches 2 Pa. After the acid content and water content meet the standards, add the decolorizing agent activated carbon, stir under reduced pressure at 110°C for 30 min, filter to obtain the crude product. After alkali washing and water washing the crude product, perform high-temperature vacuum drying to obtain neopentyl glycol diheptanoate. The conversion rate of neopentyl glycol is 96.4%. After detection, the indexes of neopentyl glycol diheptanoate are as follows: it is a colorless to light yellow transparent liquid at 20°C, odorless or with a slight characteristic odor at 20°C, the acid value is 0.01 mg KOH / g (obtained according to the detection method in GB / T5009.229-2016), the saponification value is 335 mg KOH / g (obtained according to the detection method in GB / T5534-2008), and the water content is 0.01% (obtained according to the detection method in GB / T6283-2008).

[0016] Example 3 A synthesis method of neopentyl glycol diheptanoate, comprising the following synthesis steps: S1. Stir and mix 0.3 kg of neopentyl glycol, 0.7 kg of n-heptanoic acid, and 0.001 kg of stannous chloride catalyst, and start heating up; S2. Divide the reaction into two stages. The reaction temperature in the first stage is 150 °C, and the reaction lasts for 5 h. The reaction temperature in the second stage is 160 °C, the reaction vacuum degree is 0.04 MPa, and keep the temperature for reaction for 4 h; S3. Start the rotary vane vacuum pump. With the pumping rates of 1 L / s, 4 L / s, and 8 L / s respectively, reduce the pressure to remove acid until the vacuum degree gradually reaches 2 Pa. After the acid content and water content meet the standards, add a decolorizing agent, stir under reduced pressure at 120 °C for 60 min, and then filter to obtain the crude product. After alkali washing and water washing the crude product, perform high-temperature vacuum drying to obtain neopentyl glycol diheptanoate. The conversion rate of neopentyl glycol is 96.6%. After detection, the indexes of neopentyl glycol diheptanoate are: colorless to light yellow transparent liquid at 20 °C, odorless or with a slight characteristic odor at 20 °C, acid value of 0.01 mg KOH / g (obtained according to the detection method in GB / T5009.229-2016), saponification value of 345 mg KOH / g (obtained according to the detection method in GB / T5534-2008), and water content of 0.01% (obtained according to the detection method in GB / T6283-2008).

[0017] Example 4 A synthesis method of neopentyl glycol diheptanoate, including the following synthesis steps: S1. Stir and mix 0.2 kg of neopentyl glycol, 0.8 kg of n-heptanoic acid, and 0.001 kg of stannous chloride catalyst, and start heating up; S2. Divide the reaction into two stages. The reaction temperature in the first stage is 140 °C, and the reaction lasts for 4 h. The reaction temperature in the second stage is 180 °C, the reaction vacuum degree is 0.08 MPa, and keep the temperature for reaction for 7 h; S3. Start the rotary vane vacuum pump. With the pumping rates of 1 L / s, 4 L / s, and 8 L / s respectively, reduce the pressure to remove acid until the vacuum degree gradually reaches 2 Pa. After the acid content and water content meet the standards, add the decolorizing agent activated carbon, stir under reduced pressure at 110 °C for 30 min, and then filter to obtain the crude product. After alkali washing and water washing the crude product, perform high-temperature vacuum drying to obtain neopentyl glycol diheptanoate. The conversion rate of neopentyl glycol is 97.1%. After detection, the indexes of neopentyl glycol diheptanoate are: colorless to light yellow transparent liquid at 20 °C, odorless or with a slight characteristic odor at 20 °C, acid value of 0.02 mg KOH / g (obtained according to the detection method in GB / T5009.229-2016), saponification value of 342 mg KOH / g (obtained according to the detection method in GB / T5534-2008), and water content of 0.01% (obtained according to the detection method in GB / T6283-2008).

[0018] Example 5 A synthesis method of neopentyl glycol diheptanoate, comprising the following synthesis steps: S1. Stir and mix 0.2 kg of neopentyl glycol, 0.8 kg of n-heptanoic acid, and 0.001 kg of stannous chloride catalyst, and start heating up; S2. Divide the reaction into two stages. The reaction temperature in the first stage is 140 °C, and the reaction lasts for 4 h. The reaction temperature in the second stage is 200 °C, and the reaction vacuum degree is 0.1 MPa. Keep the temperature for reaction for 10 h; S3. Start a rotary vane vacuum pump, with the air extraction rates of 1 L / s, 4 L / s, and 8 L / s respectively, to gradually reduce the pressure to remove acid until the vacuum degree reaches 2 Pa. After the acid content and water content meet the standards, add the decolorizing agent activated carbon, stir under reduced pressure at 110 °C for 30 min, filter to obtain the crude product, and after alkali washing and water washing of the crude product, perform high-temperature vacuum drying to obtain neopentyl glycol diheptanoate. The conversion rate of neopentyl glycol is 97.2%. After detection, the indexes of neopentyl glycol diheptanoate are: colorless to light yellow transparent liquid at 20 °C, odorless or with a slight characteristic odor at 20 °C, acid value of 0 mg KOH / g (obtained according to the detection method in GB / T5009.229-2016), saponification value of 345 mg KOH / g (obtained according to the detection method in GB / T5534-2008), and water content of 0.01% (obtained according to the detection method in GB / T6283-2008).

[0019] Example 6 A synthesis method of neopentyl glycol diheptanoate, comprising the following synthesis steps: S1. Stir and mix 0.2 kg of neopentyl glycol, 0.8 kg of n-heptanoic acid, and 0.007 kg of stannous chloride catalyst, and start heating up; S2. Divide the reaction into two stages. The reaction temperature in the first stage is 140 °C, and the reaction lasts for 4 h. The reaction temperature in the second stage is 180 °C, and the reaction vacuum degree is 0.08 MPa. Keep the temperature for reaction for 7 h; S3. Start a rotary vane vacuum pump, with the air extraction rates of 1 L / s, 4 L / s, and 8 L / s respectively, to gradually reduce the pressure to remove acid until the vacuum degree reaches 2 Pa. After the acid content and water content meet the standards, add the decolorizing agent activated carbon, stir under reduced pressure at 110 °C for 30 min, filter to obtain the crude product, and after alkali washing and water washing of the crude product, perform high-temperature vacuum drying to obtain neopentyl glycol diheptanoate. The conversion rate of neopentyl glycol is 98.2%. After detection, the indexes of neopentyl glycol diheptanoate are: colorless to light yellow transparent liquid at 20 °C, odorless or with a slight characteristic odor at 20 °C, acid value of 0.01 mg KOH / g (obtained according to the detection method in GB / T5009.229-2016), saponification value of 340 mg KOH / g (obtained according to the detection method in GB / T5534-2008), and water content of 0% (obtained according to the detection method in GB / T6283-2008).

[0020] Example 7 A method for synthesizing neopentyl glycol diheptanoate, comprising the following synthesis steps: S1. Stir and mix 0.2 kg of neopentyl glycol, 0.8 kg of n-heptanoic acid, and 0.01 kg of stannous sulfate catalyst, and start heating up; S2. Divide the reaction into two stages. The reaction temperature in the first stage is 140 °C and the reaction lasts for 4 h. The reaction temperature in the second stage is 180 °C, the reaction vacuum degree is 0.08 MPa, and keep the temperature for reaction for 7 h; S3. Turn on the rotary vane vacuum pump, with the air extraction rates of 1 L / s, 4 L / s, and 8 L / s respectively, to gradually reduce the pressure to deacidify until the vacuum degree reaches 2 Pa. After the acid content and water content meet the standards, add the decolorizing agent activated carbon, stir under reduced pressure at 110 °C for 30 min, and then filter to obtain the crude product. After alkali washing and water washing of the crude product, high-temperature vacuum drying is carried out to obtain neopentyl glycol diheptanoate. The conversion rate of neopentyl glycol is 97.8%. After detection, the indexes of neopentyl glycol diheptanoate are: colorless to light yellow transparent liquid at 20 °C, odorless or with a slight characteristic odor at 20 °C, acid value of 0.02 mg KOH / g (obtained according to the detection method in GB / T5009.229-2016), saponification value of 348 mg KOH / g (obtained according to the detection method in GB / T5534-2008), and water content of 0.01% (obtained according to the detection method in GB / T6283-2008).

[0021] Example 8 A method for synthesizing neopentyl glycol diheptanoate, comprising the following synthesis steps: S1. Stir and mix 0.2 kg of neopentyl glycol, 0.8 kg of n-heptanoic acid, and 0.007 kg of inorganic tin catalyst, and start heating up; the inorganic tin catalyst is composed of tin oxide and stannous chloride with a weight ratio of 1:1 S2. Divide the reaction into two stages. The reaction temperature in the first stage is 140 °C and the reaction lasts for 4 h. The reaction temperature in the second stage is 180 °C, the reaction vacuum degree is 0.08 MPa, and keep the temperature for reaction for 7 h; S3. Turn on the rotary vane vacuum pump and carry out vacuum deacidification at the pumping rates of 1 L / s, 4 L / s, and 8 L / s respectively until the vacuum degree gradually reaches 2 Pa. After the acid content and moisture content meet the standards, add the decolorizing agent activated carbon, stir under reduced pressure at 110 °C for 30 min, and then filter to obtain the crude product. After alkali washing and water washing the crude product, carry out high-temperature vacuum drying to obtain neopentyl glycol diheptanoate. The conversion rate of neopentyl glycol is 98.5%. After detection, the indicators of neopentyl glycol diheptanoate are as follows: it is a colorless to light yellow transparent liquid at 20 °C, odorless or with a slight characteristic odor at 20 °C, the acid value is 0 mg KOH / g (obtained according to the detection method in GB / T 5009.229-2016), the saponification value is 355 mg KOH / g (obtained according to the detection method in GB / T 5534-2008), and the moisture content is 0% (obtained according to the detection method in GB / T 6283-2008).

[0022] Comparative Example 1 A method for synthesizing neopentyl glycol diheptanoate, which is different from Example 4 in that there is no first stage in the reaction, only the second stage, that is, under the conditions of a temperature of 180 °C and a reaction vacuum degree of -0.08 MPa, keep the temperature for reaction for 7 h, and the others are the same as in Example 4. The conversion rate of neopentyl glycol is 85%. After detection, the indicators of neopentyl glycol diheptanoate are as follows: it is a colorless to light yellow transparent liquid at 20 °C, odorless or with a slight characteristic odor at 20 °C, the acid value is 0.01 mg KOH / g (obtained according to the detection method in GB / T 5009.229-2016), the saponification value is 355 mg KOH / g (obtained according to the detection method in GB / T 5534-2008), and the moisture content is 0.01% (obtained according to the detection method in GB / T 6283-2008).

[0023] Comparative Example 2 A method for synthesizing neopentyl glycol diheptanoate, which is different from Example 4 in that there is no second stage in the reaction, only the first stage, that is, under the condition of a temperature of 140 °C, keep the temperature for reaction for 4 h, and the others are the same as in Example 4. The conversion rate of neopentyl glycol is 60%. After detection, the indicators of neopentyl glycol diheptanoate are as follows: it is a colorless to light yellow transparent liquid at 20 °C, odorless or with a slight characteristic odor at 20 °C, the acid value is 0 mg KOH / g (obtained according to the detection method in GB / T 5009.229-2016), the saponification value is 362 mg KOH / g (obtained according to the detection method in GB / T 5534-2008), and the moisture content is 0.02% (obtained according to the detection method in GB / T 6283-2008).

[0024] Control Example A method for synthesizing neopentyl glycol diheptanoate, which is different from Example 4 in that an equal amount of solid acid catalyst (molecular sieve) is used instead of stannous chloride catalyst, and the others are the same as in Example 4. The conversion rate of neopentyl glycol is 65%. The indexes of neopentyl glycol diheptanoate are as follows: it is a colorless to light yellow transparent liquid at 20 °C, odorless or with a slight characteristic odor at 20 °C, the acid value is 0 mg KOH / g (obtained according to the detection method in GB / T 5009.229-2016), the saponification value is 360 mg KOH / g (obtained according to the detection method in GB / T 5534-2008), and the water content is 0.01% (obtained according to the detection method in GB / T 6283-2008). It can be seen from the examples and Comparative Examples 1-2 of this application that after the reaction is divided into two stages, the conversion rate of neopentyl glycol can be effectively increased, and thus the yield of neopentyl glycol diheptanoate can also be increased. Compared with Example 4 of this application, under the same reaction conditions and the same amount of catalyst used, when a solid acid catalyst is used, the conversion rate of neopentyl glycol is only 65% under the same reaction time. Thus, it can be seen that after using an inorganic tin catalyst, not only the reaction time is saved, but also the conversion rate of neopentyl glycol is increased.

[0025] The examples of this specific implementation manner are all preferred examples of the present invention, and do not limit the protection scope of the present invention accordingly. Therefore, all equivalent changes made according to the structure, shape, and principle of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for synthesizing neopentyl glycol diheptanoate, characterized in that: The method comprises the following synthesis steps: S1, mixing neopentyl glycol, n-heptanoic acid and an inorganic tin catalyst and starting to heat up; S2, the reaction is divided into two stages, the reaction temperature of stage one is 130-150°C, the reaction time is 3-5h, and the reaction temperature of stage two is 160-200°C, the reaction vacuum degree is 0.04-0.1MPa, and the reaction time is 4-10h; S3. Turn on the vacuum pump, and when the vacuum degree gradually reaches 2Pa, deacidify under reduced pressure. After the acid content and water content meet the standards, add a decolorizing agent, stir under reduced pressure at 110-120°C for 30-60min, and filter to obtain a crude product. Wash the crude product with alkali and water, and then dry it in high temperature vacuum to obtain neopentyl glycol diheptanoate.

2. The method for synthesizing neopentyl glycol diheptanoate according to claim 1, wherein: The addition amount of the inorganic tin catalyst is 0.1-1% of the total weight of the neopentyl glycol and n-heptanoic acid.

3. The method for synthesizing neopentyl glycol diheptanoate according to claim 2, wherein: The inorganic tin catalyst is one or more of tin oxide, stannous chloride and stannous sulfate.

4. The method for synthesizing neopentyl glycol diheptanoate according to claim 1, characterized in that: The amount of the neopentyl glycol added is 20-30 wt %, and the amount of the n-heptyl acid added is 70-80 wt %.

5. The method for synthesizing neopentyl glycol diheptanoate according to claim 1, characterized in that: The neopentyl glycol diheptanoate obtained in step S3 has an acid value of 0-0.5 mgKOH / g, a saponification value of 325-355 mgKOH / g, and a moisture content of 0-0.5%.