Method for improving aroma of 1, 2-pentanediol

Abstract

The invention discloses a method for improving fragrance of 1, 2-pentanediol, which belongs to the technical field of fine chemical engineering, and comprises the following steps: preparing a sodium borohydride basic catalyst solution, slowly dropwise adding into a flask filled with 1, 2-pentanediol at normal pressure and normal temperature, heating, preserving heat, adding distilled water, and stirring for 2 hours; establishing flash evaporation equipment, starting coarse vacuum, heating to 110 DEG C, slightly cooling, cutting water and weighing; starting an oil pump, quickly flashing, and collecting an intermediate crude product; transferring the intermediate crude product into a fractionation kettle, adding distilled water for dilution and dissolution, starting crude vacuum, raising the temperature until discharging and refluxing for 4 hours, changing an oil pump for collection when the temperature is raised to 110 DEG C, and cutting water and weighing when the temperature is maintained within 115 DEG C and no discharging exists; continuing to heat, collecting a finished product, and stopping collecting when the temperature is raised to 130 DEG C. According to the invention, the 1, 2-pentanediol base material is treated by a chemical treatment method, so that the produced 1, 2-pentanediol is odorless after being heated and cooled to normal temperature.

Description

Technical Field

[0001] The invention belongs to the technical field of fine chemicals, and in particular relates to a method for improving the aroma of 1,2-pentanediol. Background Art

[0002] Up to now, most methods for preparing 1,2-pentanediol use n-pentene, formic acid and hydrogen peroxide as raw materials. The main contents of this method are: adding formic acid and hydrogen peroxide into a reactor under low temperature conditions; dropping n-pentene solution, and then keeping it warm for a period of time to fully react; hydrolyzing under alkaline conditions to obtain crude 1,2-pentanediol; extracting with an organic solvent; distilling the organic phase to recover the solvent, and rectifying to obtain high-purity 1,2-pentanediol. This method is simple to operate, and the purity of the obtained 1,2-pentanediol is greater than 99.0%, which is particularly suitable for industrial production.

[0003] From the properties of 1,2-pentanediol itself, 1,2-pentanediol contains two hydroxyl groups and has a moisturizing function, and its moisturizing function is better than other diols. Patent W01995 / 001151 reported that 1,2-pentanediol is used as a cosmetic moisturizing active substance, and the amount used in the range of 2% to 5% has a very good skin moisturizing effect. Patent DE4320744 reported that 1,2-pentanediol is used as a moisturizer in cosmetics. Clinical experiments have shown that a formula containing 5% 1,2-pentanediol increases the skin's water content by about 30% compared with a placebo. Another study clinically compared the moisturizing properties of 1,2-pentanediol and propylene glycol on the skin. In two O / W emulsion formulas, one contained 5% 1,2-pentanediol and the other contained 5% propylene glycol. The results showed that the formula containing 1,2-pentanediol could increase the skin's water content by nearly 90% compared with the formula containing propylene glycol. Patent EP1078638 describes in detail that 1,2-pentanediol can improve the water resistance of sunscreen formulations.

[0004] However, since the 1,2-pentanediol produced by the above industrial method has a distinct characteristic odor at room temperature, it is not suitable for the preparation of cosmetics. In order to further apply the material to the cosmetics, skin care products and other industries, its aroma improvement is imminent. According to literature retrieval, there are almost no domestic or international literature or patents on the improvement of the aroma of 1,2-pentanediol. Therefore, this method is of great significance for improving the aroma of 1,2-pentanediol. Summary of the invention

[0005] The object of the present invention is to provide a method for improving the aroma of 1,2-pentanediol, which is treated by a chemical treatment method so that the produced 1,2-pentanediol is odorless when cooled to room temperature after heating.

[0006] The purpose of the present invention can be achieved through the following technical solutions: A method for improving the aroma of 1,2-pentanediol comprises the following steps: S1: Prepare a sodium borohydride alkaline catalyst solution of a certain concentration, slowly drop it into a flask containing 1,2-pentanediol base material under normal pressure and temperature. After the dropwise addition is completed, slowly heat it to 50°C and keep it warm for 2 hours. Stop heating and add a certain amount of distilled water while stirring. When the color of the solution changes from turbid to clear, start stirring for 2 hours; S2: Build a flash evaporation device, start a rough vacuum, slowly raise the temperature to 110°C, slightly cool down, cut off the water, and weigh; start the oil pump, flash evaporate quickly, collect about 10% of the total feed at the beginning and end, and collect the intermediate crude product for further fractionation; S3: Transfer the intermediate crude product to the fractionation kettle, add a certain amount of distilled water to dilute and dissolve, turn on the rough vacuum, slowly raise the temperature until there is discharge, reflux for 4 hours, when the temperature reaches 110°C, change the oil pump for collection, when the temperature is maintained below 115°C and there is no discharge, cut off the water and weigh; continue to heat up, collect 5% of the weight of the crude product, change the receiver to collect the finished product, when the temperature reaches 130°C, stop collecting, cool down, and collect the contents of the kettle.

[0007] Furthermore, the mass ratio of the sodium borohydride input amount used in step S1 to the total input material is in the range of 5 / 10000 to 25 / 10000.

[0008] Furthermore, the alkaline substance concentration of the sodium borohydride alkaline catalyst solution prepared in step S1 is in the range of 5% to 15%.

[0009] Furthermore, the alkaline substance in the sodium borohydride alkaline catalyst solution used in step S1 is selected from a mixture of one or more of flake caustic soda, triethylamine, and triethanolamine.

[0010] Furthermore, the insulation temperature range selected in step S1 is 40° C. to 80° C.

[0011] Furthermore, the proportion of distilled water added in step S1 ranges from 5% to 20%.

[0012] Furthermore, the reaction in step S1 is carried out under a nitrogen protection environment before adding water.

[0013] Furthermore, the proportion of distilled water added in step S3 ranges from 5% to 20%.

[0014] Beneficial effects of the present invention: The present invention can effectively remove trace odorous impurity molecules contained in 1,2-pentanediol industrial products through sodium borohydride alkaline catalyst solution treatment, flash distillation, fractionation and other operations in sequence. Although the content of the impurity molecules is very small, they have a great influence on the odor of 1,2-pentanediol. Therefore, the present invention can effectively reduce the odor of 1,2-pentanediol, so that the produced 1,2-pentanediol is odorless after being cooled to room temperature after heating, thereby improving the fragrance characteristics of 1,2-pentanediol and expanding the application of 1,2-pentanediol in the cosmetics and skin care products industries. DETAILED DESCRIPTION

[0015] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0016] Embodiment 1 Open the initial vacuum, transfer 600g 1,2-pentanediol into a 1000ml three-necked flask, start stirring, prepare 12g 10% catalyst alkaline aqueous solution at room temperature, slowly add it into the flask, slowly heat to 50℃, keep warm for 2h, stop heating, add 50.4g distilled water into the reaction flask, stirring while adding, start stirring for 2h after the color of the solution changes from turbid to clear, cool and discharge.

[0017] Build a 1000ml flash kettle, start the initial vacuum and transfer the synthesized materials into the flash kettle, start stirring, slowly increase the temperature, discharge all, increase the temperature to 110℃, cut the material in the receiving tank (57.6g), and discard it; cool down to 80℃ and turn on the oil pump, collect with the head tank, collect 5% of the total weight in the kettle (28.2g), weigh and sample; change to the intermediate tank for collection, when the temperature reaches 130℃ and there is no material discharge, cool down, cut the material, and weigh (545g); when the temperature drops to 70℃, add a certain amount of water to the stirring position, stir for 0.5h, transfer to the kettle residue tank, and calculate the kettle residue weight (25.4g).

[0018] Open the initial vacuum, transfer the middle section collected in the flash kettle into a 1000ml fractionation kettle, add distilled water of 10% of the weight of the crude flash product, start stirring, slowly heat up, discharge all, heat up to 110℃, cut the material in the receiving tank, weigh (53.1g), and discard; open the second and third stage pumps, collect with the head tank, change the reflux ratio to 2 / 30 (depending on the discharge situation), collect 5% of the total weight in the kettle (26.7g), content (99.61%), and measure the water content (0.27%); change to the finished product tank for collection, change the reflux ratio to 2 / 10 (depending on the discharge situation), when the temperature reaches 130℃ and there is no discharge, cool down, weigh (488g), take a sample (99.8%), measure the water content (0.15%), smell the aroma, and put it into the finished product barrel after passing the test; when the temperature drops to 50℃, put the remaining material in the kettle, weigh (28.9g), and take a sample (99.54%).

[0019] Embodiment 2 Open the initial vacuum, transfer 30kg1,2-pentanediol into a 50L synthesis kettle, start stirring, prepare 600g of 10% catalyst alkaline aqueous solution at room temperature, slowly add it into the kettle, slowly heat to 50℃, keep warm for 2h, stop heating, add 2.49kg of distilled water into the reaction bottle, stirring while adding, start stirring for 2h after the color of the solution changes from turbid to clear, cool and discharge.

[0020] Open the initial vacuum, transfer the material in the synthesis kettle into the 50L flash kettle, start stirring, slowly increase the temperature, discharge all, raise the temperature to 110℃, cut the material in the receiving tank (2.85kg), and discard; cool down to 80℃, turn on the oil pump, collect in the head tank, collect 5% of the total weight in the kettle (1.5kg), weigh and sample; change to the intermediate tank for collection, when the temperature reaches 130℃ and there is no material discharge, cool down, cut the material, and weigh (27.2kg); when the temperature drops to 70℃, add a certain amount of water to the stirring position, stir for 0.5h, transfer to the kettle residue tank, and calculate the kettle residue weight (1.2kg).

[0021] Open the initial vacuum, transfer the middle section collected in the flash kettle into a 50L fractionating kettle, add distilled water of 10% of the weight of the crude flash product, start stirring, slowly increase the temperature, discharge it all, increase the temperature to 110℃, cut the material in the receiving tank, weigh it (2.5kg), and discard it; open the second and third stage pumps, collect it with the head tank, change the reflux ratio to 2 / 30 (depending on the discharge situation), collect 5% of the total weight in the kettle (1.3kg), content (99.5%), and measure the water content (0.35%); change to the finished product tank for collection, change the reflux ratio to 2 / 10 (depending on the discharge situation), when the temperature reaches 130℃ and there is no discharge, cool down, weigh (24.5kg), take a sample (99.6%), measure the water content (0.12%), evaluate the aroma, and put it into the finished product barrel after passing the aroma evaluation; when the temperature drops to 50℃, put the remaining material in the kettle, weigh it (1.2kg), and take a sample (99.46%).

[0022] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A method for improving the aroma of 1,2-pentanediol, characterized in that: The steps include: S1: Prepare a sodium borohydride alkaline catalyst solution of a certain concentration, slowly drop it into a flask containing 1,2-pentanediol base material under normal pressure and temperature. After the dropwise addition is completed, slowly heat it to 50°C and keep it warm for 2 hours. Stop heating and add a certain amount of distilled water while stirring. When the color of the solution changes from turbid to clear, start stirring for 2 hours; S2: Build a flash evaporation device, start a rough vacuum, slowly raise the temperature to 110°C, slightly cool down, cut off the water, and weigh; start the oil pump, flash evaporate quickly, collect about 10% of the total feed at the beginning and end, and collect the intermediate crude product for further fractionation; S3: Transfer the intermediate crude product to the fractionation kettle, add a certain amount of distilled water to dilute and dissolve, start the rough vacuum, slowly heat up until there is material discharge, reflux for 4 hours, when the temperature rises to 110°C, change the oil pump for collection, when the temperature is maintained within 115°C and there is no material discharge, cut off the water and weigh; Continue to raise the temperature, collect 5% of the weight of the crude product, change the receiver to collect the finished product, and when the temperature reaches 130°C, stop collecting, cool down, and collect the contents of the kettle.

2. The method for improving the aroma of 1,2-pentanediol according to claim 1, characterized in that: The mass ratio of the sodium borohydride input amount used in step S1 to the total input material is in the range of 5 / 10000 to 25 / 10000.

3. The method for improving the aroma of 1,2-pentanediol according to claim 1, characterized in that: The alkaline substance concentration of the sodium borohydride alkaline catalyst solution prepared in step S1 is in the range of 5% to 15%.

4. The method for improving the aroma of 1,2-pentanediol according to claim 3, characterized in that: The alkaline substance in the sodium borohydride alkaline catalyst solution used in step S1 is selected from a mixture of one or more of flake caustic soda, triethylamine and triethanolamine.

5. The method for improving the aroma of 1,2-pentanediol according to claim 1, characterized in that: The insulation temperature range selected in step S1 is 40°C to 80°C.

6. The method for improving the aroma of 1,2-pentanediol according to claim 1, characterized in that: The proportion of distilled water added in step S1 ranges from 5% to 20%.

7. The method for improving the aroma of 1,2-pentanediol according to claim 1, characterized in that: The reaction in step S1 is carried out under nitrogen protection before adding water.

8. The method for improving the aroma of 1,2-pentanediol according to claim 1, characterized in that: The proportion of distilled water added in step S3 ranges from 5% to 20%.