CN112500263A - Method for preparing higher alkanol by reducing white wax with red aluminum under normal pressure - Google Patents
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- C07C29/132—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group
- C07C29/136—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group of >C=O containing groups, e.g. —COOH
- C07C29/147—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of an oxygen containing functional group of >C=O containing groups, e.g. —COOH of carboxylic acids or derivatives thereof
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Abstract
The invention relates to a method for preparing higher alkanol by reducing white wax with red aluminum under normal pressure, which comprises the following steps: grinding and sieving white wax, placing the white wax in a reaction container, adding a reducing agent, adding an organic solvent, and heating and refluxing for reaction for 2-6 h, wherein the reducing agent is 70% of a red aluminum toluene solution; step two: after the reaction is finished and the solvent is recovered by rotary evaporation, distilled water, a sodium hydroxide solution and distilled water are slowly added in sequence, then hydrochloric acid is used for neutralizing the reaction liquid to be neutral, the filtration is carried out, and the filter cake is dried at low temperature, thus obtaining the higher alkanol. The preparation method of the invention prepares the high-grade alkanol by reducing the white wax with the red aluminum under normal pressure, has simple process, safety and lower cost, and the obtained high-grade alkanol has higher purity.
Description
Technical Field
The invention relates to the technical field of preparation of higher alkanol, in particular to a method for preparing higher alkanol by reducing white wax with red aluminum under normal pressure.
Background
Higher alkanols, also called higher fatty alcohols, are generally straight chain saturated primary monohydric alcohols with 20-34 carbon atoms, originally extracted from sugar cane wax by the guba researchers, and later expanded from other vegetable and animal waxes, mainly including rice bran wax, palm wax, beeswax, insect wax, and the like. The higher alkanol has rich functional activity, mainly comprises blood fat reduction, cholesterol reduction, atherosclerosis resistance and the like, has definite drug effect, is non-toxic and harmless, becomes one of hot points of research of pharmacologists, and has potential application prospect in the industries of medicines, foods, health care products and the like.
Currently, there are 3 methods for preparing higher alkanol from biological wax, namely hydrolysis method, ester exchange method and reduction method. The hydrolysis method generally hydrolyzes biological wax into carboxylate and alkanol under the alkaline condition, and then extracts by using an organic solvent, and has the main defects of low conversion rate, large using amount of alkali liquor and low purity of the obtained higher alkanol; the ester exchange method comprises the steps of firstly carrying out alcoholysis on wax, then separating different fractions by a distillation method according to different boiling points of reaction products, and having high requirements on equipment and needing to be completed by adopting special instruments such as molecular distillation and the like; the reduction method is to directly reduce the biological wax into the fatty alcohol by using a reducing agent under certain conditions, and lithium aluminum hydride is usually used as the reducing agent. The method has high efficiency, but the used reducing agent is expensive, and is dangerous chemical, flammable and explosive, and the reaction needs to strictly control the water content in the materials. The Chinese patent with application number of 200810058584.2 discloses a method for preparing a higher alkanol mixture from Chinese insect wax; the Chinese patent with application number 200810058866.2 discloses a method for preparing a higher alkanol mixture by a non-solvent reduction method; the Chinese patent with the application number of 201510404794.2 discloses a method for efficiently preparing higher alkanol from Chinese insect wax by a two-step method. The above patents all adopt lithium aluminum hydride as a reducing agent, and have the disadvantages of high cost, low safety, difficult industrialization and the like. Therefore, it is important to find a method for obtaining higher alkanol from white wax with low cost, high efficiency and safety.
Red aluminum, known as sodium dihydrobis (2-methoxyethoxy) aluminate, having the formula of NaAlH2(OCH2CH2OMe2) It is a new reducing agent developed by Jaroslav Vit et al, a 70% solution in toluene, which is colorless or slightly yellowish in 1968. Research shows that the reagent has the following characteristics: (1) strong reducibility, although slightly lower than LiAlH4But the price is far lower than LiAlH4(ii) a (2) The solubility is good, and the solvent can be dissolved in aromatic hydrocarbon, ether and other weak polar solvents; (3) the safety is high, and the flame-retardant coating does not burn when meeting water or oxygen; (4) the method has wide application conditions and can be used for reaction at 200 ℃. Therefore, the red aluminum quickly becomes a reagent with very high cost performance and is widely applied to organic synthesis and preparation reactions. The red aluminum can be regarded as alkoxy substituted lithium aluminum hydride in nature, the structural formula is shown in figure 1, carbonyl-containing substances such as aldehyde, ketone, carboxylic acid, ester and the like can be efficiently reduced, and the reduction reaction mechanism is similar to that of the lithium aluminum hydride (negative hydrogen ion addition), as shown in figure 2. The main component of the white wax is a substance formed by mixing the twenty-four, twenty-six and octacosanoic acid ester, so theoretically, the red aluminum is adopted to replace the lithium aluminum hydride to reduce the white wax to prepare the high-grade alkanol, the experimental cost can be obviously reduced, and the production safety is greatly improved.
Disclosure of Invention
The technical problem to be solved is as follows: aiming at the defects of high cost and poor safety of the existing reducing agent for preparing the higher alkanol, the invention provides the method for preparing the higher alkanol by reducing the white wax with the red aluminum under the normal pressure, and the method has the advantages of low cost, simplicity, easy operation, safety and high efficiency.
The technical scheme is as follows: a method for preparing higher alkanol by reducing white wax with red aluminum under normal pressure comprises the following steps:
the method comprises the following steps: grinding and sieving white wax, placing the white wax in a reaction container, adding a reducing agent, adding an organic solvent, and heating and refluxing for reaction for 2-6 h, wherein the reducing agent is 70% of a red aluminum toluene solution;
step two: after the reaction is finished and the solvent is recovered by rotary evaporation, distilled water, a sodium hydroxide solution and distilled water are slowly added in sequence, then hydrochloric acid is used for neutralizing the reaction liquid to be neutral, the filtration is carried out, and the filter cake is dried at low temperature, thus obtaining the higher alkanol.
In the first step, the white wax is ground to pass through a 100-mesh sieve.
In the first step, the mass ratio of the white wax to the red aluminum toluene solution is 1: (0.5-1), adding 5-8 mL of organic solvent into each gram of white wax.
In the first step, the organic solvent is one or more of tetrahydrofuran, benzene and toluene.
And in the second step, distilled water, a sodium hydroxide solution and distilled water are sequentially and slowly added, wherein the volume of the distilled water is 1mL, 2mL and 3mL per gram of the red aluminum toluene solution.
In the second step, the concentration of the sodium hydroxide solution is 10% and the concentration of the hydrochloric acid is 10 mol/L.
And in the second step, the low-temperature drying temperature of the filter cake is 50-60 ℃, and the time is 12-24 hours.
Has the advantages that: the method for preparing the high-grade alkanol by reducing the white wax with the red aluminum under the normal pressure has the following beneficial effects: the method is carried out in a normal-pressure open system, the high-grade alkanol is prepared by reducing the white wax with the red aluminum, the process is simple, the method is safe and low in cost, and the obtained high-grade alkanol has high purity and can be compared favorably with lithium aluminum hydride.
Drawings
FIG. 1 shows the structural formula of red aluminum.
FIG. 2 is a diagram of the mechanism of reducing carbonyl groups with red aluminum.
FIG. 3 is a standard graph of tetracosanol.
FIG. 4 is a standard graph of hexacosanol.
FIG. 5 is a standard graph of octacosanol.
FIG. 6 is a standard graph of hexadecanol.
FIG. 7 is a gas chromatogram of the higher alkanol produced in example 1.
FIG. 8 is a gas chromatogram of the higher alkanol produced in example 2.
FIG. 9 is a gas chromatogram of the higher alkanol produced in example 3.
Detailed Description
To further clarify the objects, summary and advantages of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. It is to be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention, which is to be given the full breadth of the appended claims and any and all equivalent modifications thereof which may occur to those skilled in the art upon reading the present specification.
The following examples use the following conditions for the gas chromatography test:
the instrument comprises the following steps: agilent 7890B GC (Agilent, usa);
a chromatographic column: agilent HP-5 capillary column, 30 m × 0.32 mm × 0.25 μm;
column temperature: keeping at 200 deg.C for 1min, heating to 320 deg.C at a rate of 5 deg.C/min, and keeping for 10 min.
Sample inlet temperature: 320 ℃; detector temperature: 340 ℃;
carrier gas: nitrogen with purity more than or equal to 99.99%, fuel gas: hydrogen with the purity more than or equal to 99.99 percent;
column flow rate: 1.0 mL/min, hydrogen flow rate: 30 mL/min, air flow rate: 300 mL/min;
sample loading amount: 2 muL.
Example 1
A method for preparing higher alkanol by reducing white wax with red aluminum under normal pressure comprises the following steps:
the method comprises the following steps: grinding white wax, sieving with a 100-mesh sieve, weighing 10g of white wax powder, placing into a round bottom flask, adding 5g of red aluminum toluene solution, adding 50mL of organic solvent tetrahydrofuran, heating in a water bath kettle to 85 ℃, and refluxing for 6 h;
step two: after the reaction is finished and the solvent is recovered by rotary evaporation, 5mL, 10mL and 15mL of distilled water, 10% sodium hydroxide solution and distilled water are slowly added in sequence, 10 mol/L of hydrochloric acid is added to make the reaction solution neutral, the filtration is carried out, and the filter cake is dried for 20 hours at the temperature of 50 ℃ to obtain the higher alkanol.
As shown in fig. 3, 4, 5, 6 and 7, the obtained higher alkanol mainly contains 4 higher alkanols, namely tetracosanol, hexacosanol, octacosanol and triacontanol, with the contents of 9.22%, 27.67%, 19.90% and 4.13%, and the total content of 60.92% by gas chromatography.
Example 2
A method for preparing higher alkanol by reducing white wax with red aluminum under normal pressure comprises the following steps:
the method comprises the following steps: grinding white wax, sieving with a 100-mesh sieve, weighing 50g of white wax powder, placing in a round-bottom flask, adding 40g of red aluminum toluene solution, adding 300mL of organic solvent benzene, heating in a water bath kettle to 85 ℃, and refluxing for 6 h;
step two: after the reaction is finished and the solvent is recovered by rotary evaporation, 40 mL, 80mL and 120mL of distilled water, 10% sodium hydroxide solution and distilled water are slowly added in sequence, then 10 mol/L of hydrochloric acid is added to make the reaction solution neutral, the filtration is carried out, and the filter cake is dried for 24 hours at the temperature of 60 ℃ to obtain the higher alkanol.
As shown in fig. 3, 4, 5, 6 and 8, the obtained product mainly contains 4 higher alkanols, namely tetracosanol, hexacosanol, octacosanol and triacontanol, with the content of 9.85%, 31.08%, 23.01% and 4.34%, and the total content of 68.28% by gas chromatography.
Example 3
A method for preparing higher alkanol by reducing white wax with red aluminum under normal pressure comprises the following steps:
the method comprises the following steps: grinding white wax, sieving with a 100-mesh sieve, weighing 500g of white wax powder, placing into a round bottom flask, adding 500g of red aluminum toluene solution, adding 4000mL of organic solvent tetrahydrofuran, heating in a water bath kettle to 85 ℃, and refluxing for 6 h;
step two: after the reaction is finished, recovering the solvent by rotary evaporation, slowly adding 500mL, 1000mL and 1500mL of distilled water, 10% sodium hydroxide solution and distilled water in sequence, then adding 10 mol/L of hydrochloric acid to make the reaction liquid neutral, filtering, and drying the filter cake at 60 ℃ for 24h to obtain the higher alkanol.
As shown in fig. 3, 4, 5, 6 and 9, the obtained product mainly contains 4 higher alkanols, namely tetracosanol, hexacosanol, octacosanol and triacontanol, respectively, with the content of 12.40%, 35.79%, 26.65% and 5.23%, and the total content of 80.07% by gas chromatography.
The embodiments of the present invention have been described in detail with reference to the above examples, but the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the knowledge of those skilled in the art. The above description is only for the purpose of illustrating preferred embodiments of the present invention and is not intended to limit the scope of the present invention, which is defined by the appended claims.
Claims (7)
1. A method for preparing higher alkanol by reducing white wax with red aluminum under normal pressure is characterized by comprising the following steps:
the method comprises the following steps: grinding and sieving white wax, placing the white wax in a reaction container, adding a reducing agent, adding an organic solvent, and heating and refluxing for reaction for 2-6 h, wherein the reducing agent is 70% of a red aluminum toluene solution;
step two: after the reaction is finished and the solvent is recovered by rotary evaporation, distilled water, a sodium hydroxide solution and distilled water are sequentially added, then hydrochloric acid is used for neutralizing the reaction liquid to be neutral, the filtration is carried out, and the filter cake is dried at low temperature, thus obtaining the higher alkanol.
2. The method for preparing higher alkanol by reducing white wax with red aluminum under normal pressure according to claim 1, which is characterized in that: in the first step, the white wax is ground to pass through a 100-mesh sieve.
3. The method for preparing higher alkanol by reducing white wax with red aluminum under normal pressure according to claim 1, which is characterized in that: the mass ratio of the white wax to the red aluminum toluene solution in the first step is 1: (0.5-1), adding 5-8 mL of organic solvent into each gram of white wax.
4. The method for preparing higher alkanol by reducing white wax with red aluminum under normal pressure according to claim 3, which is characterized in that: in the first step, the organic solvent is one or more of tetrahydrofuran, benzene and toluene.
5. The method for preparing higher alkanol by reducing white wax with red aluminum under normal pressure according to claim 1, which is characterized in that: and in the second step, distilled water, a sodium hydroxide solution and distilled water are sequentially added, wherein the volume of the distilled water is 1mL, 2mL and 3mL of the red aluminum toluene solution per gram.
6. The method for preparing higher alkanol by reducing white wax with red aluminum under normal pressure according to claim 5, wherein the method comprises the following steps: in the second step, the concentration of the sodium hydroxide solution is 10 percent, and the concentration of the hydrochloric acid is 10 mol/L.
7. The method for preparing higher alkanol by reducing white wax with red aluminum under normal pressure according to claim 1, which is characterized in that: and in the second step, the low-temperature drying temperature of the filter cake is 50-60 ℃, and the time is 12-24 hours.
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| CN113057941A (en) * | 2021-03-26 | 2021-07-02 | 中国林业科学研究院资源昆虫研究所 | Higher alkanol liposome for improving learning memory and preparation method thereof |
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| CN113057941A (en) * | 2021-03-26 | 2021-07-02 | 中国林业科学研究院资源昆虫研究所 | Higher alkanol liposome for improving learning memory and preparation method thereof |
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