CN112409182A - Synthesis, purification and separation method of menthyl lactate - Google Patents
Synthesis, purification and separation method of menthyl lactate Download PDFInfo
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- CN112409182A CN112409182A CN202011382744.6A CN202011382744A CN112409182A CN 112409182 A CN112409182 A CN 112409182A CN 202011382744 A CN202011382744 A CN 202011382744A CN 112409182 A CN112409182 A CN 112409182A
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- menthyl lactate
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/08—Preparation of carboxylic acid esters by reacting carboxylic acids or symmetrical anhydrides with the hydroxy or O-metal group of organic compounds
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/48—Separation; Purification; Stabilisation; Use of additives
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/48—Separation; Purification; Stabilisation; Use of additives
- C07C67/52—Separation; Purification; Stabilisation; Use of additives by change in the physical state, e.g. crystallisation
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Abstract
The invention provides a method for synthesizing, purifying and separating menthyl lactate, which comprises the following steps: step one, sequentially adding L-lactic acid, L-menthol and a catalyst into a three-neck flask provided with a thermometer and an oil-water separator, vacuumizing, heating to gradually raise the temperature to 60-80 ℃, and preserving heat and dehydrating for 7-10 hours. The invention mainly prepares menthyl lactate by a one-pot method, L-lactic acid, a catalyst and L-menthol are added under the vacuum condition, the temperature is raised, negative pressure dehydration is carried out for a certain time, the obtained menthyl lactate crude product is dripped with water, a lower water phase is separated, the lactic acid is recovered from the water phase, and the lactic acid can be recycled after negative pressure concentration dehydration. Neutralizing the crude menthyl lactate by sodium bicarbonate, distilling the oil phase by steam, distilling unreacted menthol by azeotropic distillation under normal pressure, then separating water to obtain menthyl lactate with the content of more than or equal to 99.0 percent, and crystallizing to obtain colorless crystalline menthyl lactate.
Description
Technical Field
The invention relates to the technical field of fine chemical synthesis, in particular to a method for synthesizing, purifying and separating menthyl lactate.
Background
Menthyl lactate is a mint-derived cooling agent, has mild and lasting cooling feeling, has no irritation and bitterness of mint, and is widely applied to various fields such as food, daily chemicals, cosmetics and the like. The synthesis method in the market at present is mainly obtained by dehydrating L- (+) lactic acid and L-menthol through esterification reaction under the condition of a catalyst, and the method is a well-known technical scheme. The dehydration is generally performed by using solvents such as toluene, benzene, n-heptane, cyclohexane and the like, solvent volatilization factors exist in the production, and the method is not green and environment-friendly. In the post-treatment step, the L-menthol obtained by hydrolyzing unreacted menthol and menthyl lactate in the post-treatment step influences the crystallization of menthyl lactate, so that how to prepare green preparation and purification are the core contents for synthesizing menthyl lactate.
Disclosure of Invention
The technical problem to be solved by the present invention is to provide a method for synthesizing, purifying and separating menthyl lactate, so as to solve the problems proposed in the background art.
The technical problem solved by the invention is realized by adopting the following technical scheme: a method for synthesizing, purifying and separating menthyl lactate comprises the following steps:
step one, sequentially adding L-lactic acid, L-menthol and a catalyst into a three-neck flask provided with a thermometer and an oil-water separator, vacuumizing, heating to gradually raise the temperature to 60-80 ℃, and preserving heat for dehydration for 7-10 hours;
step two, after the step one is finished, cooling to 35-45 ℃, dripping 50-70 ml of water, standing for layering, separating out a lower-layer water phase, and recovering lactic acid after negative pressure dehydration;
washing the oil phase in the step once with saturated sodium bicarbonate solution until no bubbles are discharged, and then washing with saturated saline until the oil phase is neutral;
putting the oil phase into a flask with an oil-water separator, heating at normal pressure, carrying out azeotropic distillation on water to receive an oil-water mixture until no oil drops exist, and detecting the components of the menthyl lactate in the kettle;
and step five, separating water from the oil-water mixture to obtain an oil phase, drying the oil phase, adding a solvent for crystallization, filtering and drying to obtain colorless crystalline menthyl lactate.
Preferably, the content of the L-lactic acid added in the step one is more than or equal to 85%, the content of the L-menthol is more than or equal to 99.0%, and the weight ratio of the L-lactic acid to the L-menthol is 1-3: 1.
Preferably, the catalyst is p-toluenesulfonic acid, and the addition amount of the catalyst is 1-3% of the total weight of the L-lactic acid and the L-menthol.
Preferably, the vacuum degree in the first step is 0.95-0.97 Mpa.
Preferably, the solvent in the fifth step is ethyl acetate or acetone, the purity of the ethyl acetate or acetone is more than 95%, and the dosage of the solvent is 0.3-0.5 times of the weight of the oil phase obtained by water separation in the fifth step.
Compared with the prior art, the invention has the beneficial effects that: the invention mainly prepares menthyl lactate by a one-pot method, L-lactic acid, a catalyst and L-menthol are added under the vacuum condition, the temperature is raised, negative pressure dehydration is carried out for a certain time, the obtained menthyl lactate crude product is dripped with water, a lower water phase is separated, the lactic acid is recovered from the water phase, and the lactic acid can be recycled after negative pressure concentration dehydration. Neutralizing the crude menthyl lactate by sodium bicarbonate, distilling the oil phase by steam, distilling unreacted menthol by azeotropic distillation under normal pressure, then separating water to obtain menthyl lactate with the content of more than or equal to 99.0 percent, and crystallizing to obtain colorless crystalline menthyl lactate. The method has the advantages of no solvent, environmental protection, recyclable lactic acid, simple and feasible product separation and purification method, high product yield and industrial application.
Detailed Description
The present invention is further described in order to make the technical means, the creation features, the achievement purposes and the effects of the present invention easy to understand.
A method for synthesizing, purifying and separating menthyl lactate comprises the following steps:
step one, sequentially adding L-lactic acid, L-menthol and a catalyst into a three-neck flask provided with a thermometer and an oil-water separator, vacuumizing, heating to gradually rise the temperature to 60-80 ℃, preserving heat and dehydrating for 7-10 hours to obtain a menthyl lactate crude product;
step two, after the step one is finished, cooling to 35-45 ℃, dripping 50-70 ml of water, standing for layering, separating out a lower-layer water phase, and recovering lactic acid after negative pressure dehydration;
washing the oil phase in the step once with saturated sodium bicarbonate solution until no bubbles are discharged, and then washing with saturated saline until the oil phase is neutral;
putting the oil phase into a flask with an oil-water separator, heating at normal pressure, carrying out azeotropic distillation on water to receive an oil-water mixture until no oil drops exist, and detecting the components of the menthyl lactate in the kettle;
and step five, separating water from the oil-water mixture to obtain an oil phase, drying the oil phase, adding a solvent for crystallization, filtering and drying to obtain colorless crystalline menthyl lactate.
The content of the L-lactic acid added in the step one is more than or equal to 85%, the content of the L-menthol is more than or equal to 99.0%, and the weight ratio of the L-lactic acid to the L-menthol is 1-3: 1.
The catalyst is p-toluenesulfonic acid, and the addition amount of the catalyst is 1-3% of the total weight of the L-lactic acid and the L-menthol.
The vacuum degree in the first step is 0.95-0.97 Mpa.
And the solvent in the step five is ethyl acetate or acetone, the purity of the ethyl acetate or the acetone is more than 95%, and the dosage of the solvent is 0.3-0.5 times of the weight of the oil phase obtained by water separation in the step five.
Example one:
a method for synthesizing, purifying and separating menthyl lactate comprises the following steps:
180g of L-lactic acid (the content is more than or equal to 85 percent), 78g of L-menthol (the content is more than or equal to 99.0 percent) and 3.8g of catalyst are added into a three-neck flask provided with a thermometer and an oil-water separator, the three-neck flask is vacuumized, the vacuum degree is 0.96Mpa, the temperature is gradually increased to 70 ℃, and the three-neck flask is kept warm and dehydrated for 8 hours. Then, the temperature is reduced to 40 ℃, 60ml of water is dripped, standing and layering are carried out, a lower-layer water phase is separated, and lactic acid is recovered after negative pressure dehydration. The oil phase was washed once with saturated sodium bicarbonate solution and then with saturated brine to neutral. And (3) putting the oil phase into a flask with an oil-water separator, heating at normal pressure, carrying out azeotropic distillation on water to receive the oil-water mixture until no oil drops exist, and detecting the components (the content is more than or equal to 98.0%) of the menthyl lactate in the kettle. Water is separated to obtain an oil phase, 116g (the content is 98.2 percent) of oil phase is dried, solvent is added for crystallization, the solvent is acetone, the dosage of the acetone is 0.4 time of the oil phase, and 105g (the content is 99.4 percent) of colorless crystalline menthyl lactate is obtained after filtration and drying.
Example two:
a method for synthesizing, purifying and separating menthyl lactate comprises the following steps:
90g of L-lactic acid (the content is more than or equal to 85 percent), 78g of L-menthol (the content is more than or equal to 99.0 percent) and 3.8g of catalyst are added into a three-neck flask provided with a thermometer and an oil-water separator, the three-neck flask is vacuumized, the vacuum degree is 0.96Mpa, the temperature is gradually increased to 70 ℃, and the three-neck flask is kept warm and dehydrated for 8 hours. Then, the temperature is reduced to 40 ℃, 60ml of water is dripped, standing and layering are carried out, a lower-layer water phase is separated, and lactic acid is recovered after negative pressure dehydration. The oil phase was washed once with saturated sodium bicarbonate solution and then with saturated brine to neutral. And (3) putting the oil phase into a flask with an oil-water separator, heating at normal pressure, carrying out azeotropic distillation on water to receive the oil-water mixture until no oil drops exist, and detecting the components (the content is more than or equal to 98.0%) of the menthyl lactate in the kettle. Separating water to obtain oil phase, drying to obtain 110g (content: 97.5%), adding solvent (acetone) 0.4 times of the oil phase for crystallization, filtering, and drying to obtain colorless crystalline menthyl lactate (content: 99.5%) 100 g.
According to the method, a water-carrying agent is not added, vacuum negative pressure dehydration is utilized, menthyl lactate is separated and purified by a normal pressure water azeotropy method, and the menthyl lactate with high yield is obtained through recrystallization.
The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (5)
1. A method for synthesizing, purifying and separating menthyl lactate is characterized in that: the method comprises the following steps:
step one, sequentially adding L-lactic acid, L-menthol and a catalyst into a three-neck flask provided with a thermometer and an oil-water separator, vacuumizing, heating to gradually raise the temperature to 60-80 ℃, and preserving heat for dehydration for 7-10 hours;
step two, after the step one is finished, cooling to 35-45 ℃, dripping 50-70 ml of water, standing for layering, separating out a lower-layer water phase, and recovering lactic acid after negative pressure dehydration;
washing the oil phase in the step once with saturated sodium bicarbonate solution until no bubbles are discharged, and then washing with saturated saline until the oil phase is neutral;
putting the oil phase into a flask with an oil-water separator, heating at normal pressure, carrying out azeotropic distillation on water to receive an oil-water mixture until no oil drops exist, and detecting the components of the menthyl lactate in the kettle;
and step five, separating water from the oil-water mixture to obtain an oil phase, drying the oil phase, adding a solvent for crystallization, filtering and drying to obtain colorless crystalline menthyl lactate.
2. The method for synthesizing, purifying and separating menthyl lactate according to claim 1, characterized in that: the content of the L-lactic acid added in the step one is more than or equal to 85%, the content of the L-menthol is more than or equal to 99.0%, and the weight ratio of the L-lactic acid to the L-menthol is 1-3: 1.
3. The method for synthesizing, purifying and separating menthyl lactate according to claim 2, characterized in that: the catalyst is p-toluenesulfonic acid, and the addition amount of the catalyst is 1-3% of the total weight of the L-lactic acid and the L-menthol.
4. The method for synthesizing, purifying and separating menthyl lactate according to claim 1, characterized in that: the vacuum degree in the first step is 0.95-0.97 Mpa.
5. The method for synthesizing, purifying and separating menthyl lactate according to claim 1, characterized in that: and the solvent in the fifth step is ethyl acetate or acetone, the purity of the ethyl acetate or acetone is more than 95%, and the dosage of the solvent is 0.3-0.5 times of the weight of the oil phase obtained by water separation in the fifth step.
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| CN202011382744.6A CN112409182A (en) | 2020-11-30 | 2020-11-30 | Synthesis, purification and separation method of menthyl lactate |
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| CN202011382744.6A CN112409182A (en) | 2020-11-30 | 2020-11-30 | Synthesis, purification and separation method of menthyl lactate |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115806481A (en) * | 2022-12-05 | 2023-03-17 | 安徽丰乐香料有限责任公司 | Separation and purification method of L-menthyl formic acid |
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| US20100274044A1 (en) * | 2009-04-22 | 2010-10-28 | Erman Mark B | Process for making menthyl glutarate |
| CN103058868A (en) * | 2013-01-18 | 2013-04-24 | 河南省科学院化学研究所有限公司 | Menthyl lactate preparation method |
| CN103588642A (en) * | 2012-08-17 | 2014-02-19 | 太仓市运通化工厂 | Synthetic method for mint benzoate |
| CN104987290A (en) * | 2015-06-15 | 2015-10-21 | 安徽中草香料有限公司 | Crystallizing method for menthyl lactate |
| CN108046993A (en) * | 2017-12-28 | 2018-05-18 | 安徽丰乐香料有限责任公司 | A kind of azeotropic joint rectification under vacuum technology prepares plurality of specifications peppermint oil dementholized, the method for menthol |
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2020
- 2020-11-30 CN CN202011382744.6A patent/CN112409182A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20100274044A1 (en) * | 2009-04-22 | 2010-10-28 | Erman Mark B | Process for making menthyl glutarate |
| CN103588642A (en) * | 2012-08-17 | 2014-02-19 | 太仓市运通化工厂 | Synthetic method for mint benzoate |
| CN103058868A (en) * | 2013-01-18 | 2013-04-24 | 河南省科学院化学研究所有限公司 | Menthyl lactate preparation method |
| CN104987290A (en) * | 2015-06-15 | 2015-10-21 | 安徽中草香料有限公司 | Crystallizing method for menthyl lactate |
| CN108046993A (en) * | 2017-12-28 | 2018-05-18 | 安徽丰乐香料有限责任公司 | A kind of azeotropic joint rectification under vacuum technology prepares plurality of specifications peppermint oil dementholized, the method for menthol |
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| CN115806481A (en) * | 2022-12-05 | 2023-03-17 | 安徽丰乐香料有限责任公司 | Separation and purification method of L-menthyl formic acid |
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