Preparation process of ascorbyl ethyl ether

A technology for the preparation of ethyl ascorbic acid ether, which is applied in the production of organic chemistry and bulk chemicals, can solve the problems of increased production costs, many by-products, environmental pollution, etc., and achieve reduced production and treatment costs, reduced waste water discharge, and reduced The effect of production costs

Active Publication Date: 2020-08-21
ZHENGZHOU UNIVERSITY OF LIGHT INDUSTRY +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The one-step process is simple, but the yield of ascorbic acid-3-O-alkylated products is limited and there are many by-products; on the other hand, ascorbic acid-3-O-alkylated products have high solubility in DMSO and DMF, and DMSO and DMF have high melting points and are harmful to the ecological environment, and the product can only be separated and purified by column chromatography, so this process is not suitable for industrial production
The pH of triethylamine is close to 13, which is a strong base, which can simultaneously activate the 3- and 2-hydroxyl groups in ascorbic acid to obtain 2,3-O-alkylated products, which makes separation difficult; in addition, triethylamine has Odor, after the reaction, the organic waste alkali is processed, causing environmental pollution, which is not conducive to industrial production
(2) Three-step process: firstly, the 5,6-hydroxyl group in ascorbic acid is protected by acetone to obtain 5,6-O-isopropylidene-L-ascorbic acid, which is prepared from ascorbic acid and acetone, and the catalyst generally chooses fume Sulfuric acid, acetyl chloride, copper sulfate, etc.; but the reaction requires a large amount of acetone. After the end, the mother liquid acetone is accompanied by acidic substances such as acetic acid and hydrogen chloride, which are not easy to remove, making it difficult to recycle acetone and produce a large amount of waste liquid; secondly, 5,6-O -Isopropylidene-L-ascorbic acid reacts with an ethylating reagent to give 3-O-ethyl-5,6-O-isopropylidene-L-ascorbic acid, 5,6-O-isopropylidene-L - Ascorbic acid contains two active enol hydroxyl groups at the 2-position and the 3-position, and has a certain acidity. When carrying out the ethylation reaction, the solvent, alkali, temperature and reaction time in the system have a great influence on the yield of the ethylated product. certain influence
Japanese patent (JPH08134055) removes isopropylidene protecting group by acidic cation exchange resin, involving resin preparation, preactivation and recovery process, resulting in increased production cost; using alcohol to dissolve 3-O-alkyl-5,6-O -Isopropylidene-L-ascorbic acid, adding hydrochloric acid to remove isopropylidene, to obtain 3-O-alkyl-L-ascorbic acid, after the reaction involves waste water treatment, which increases the cost of production treatment

Method used

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  • Preparation process of ascorbyl ethyl ether
  • Preparation process of ascorbyl ethyl ether
  • Preparation process of ascorbyl ethyl ether

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0049] Example 1 Preparation of 5,6-O-isopropylidene-L-ascorbic acid

[0050] 176 g (1 mol) of ascorbic acid and 870 g (15 mol) of acetone were sequentially added into a 5L reactor, stirred for 10 minutes, 6.5 g (0.05 mol) of oxalyl chloride was added dropwise under ice-cooling conditions, and reacted at 30°C for 9 hours. After the reaction was completed, the filter cake and filtrate A were obtained after filtration. The filtrate A was used for later use. The filter cake was washed with 80 g of acetone and dried to obtain 195.1 g of 5,6-O-isopropylidene-L-ascorbic acid with a yield of 90.2%.

[0051] Add 74 grams of calcium oxide (1.32mol) to filtrate A, stir for 3 hours, filter, and use 90 grams of filtrate Molecular sieves were dried for 12 hours and filtered to obtain the treated acetone filtrate B, which can be reused.

[0052] 176 g of ascorbic acid was added to the treated acetone filtrate B, stirred for 10 minutes, 6.5 g of oxalyl chloride was added dropwise under ice...

Embodiment 2

[0055] Example 2 Preparation of 3-O-ethyl-5,6-O-isopropylidene-L-ascorbic acid

[0056] (1) Add 216.2 grams of 5,6-O-isopropylidene-L-ascorbic acid prepared in Example 1 into a 5L reactor, add 430 grams (9.3 mol) of ethanol, stir for 30 minutes, and add sodium bicarbonate 131 grams (1.56mol), slowly dropwise added 200 grams of diethyl sulfate (1.3mol), gradually heated to 55 ° C, reacted at this temperature for 6.5 hours, then concentrated the reaction solution, added 250 grams of dichloromethane (2.94mol ), filtered, and recrystallized to obtain 203.5 grams of 3-O-ethyl-5,6-O-isopropylidene-L-ascorbic acid, with a yield of 83.4%.

[0057] (2) Using the same method, use the ethylating reagent bromoethane instead of diethyl sulfate for operation, and explore the influence of different ethylating reagents on the yield.

[0058] Add 216.2 grams of 5,6-O-isopropylidene-L-ascorbic acid prepared in Example 1, 430 grams of ethanol, stir for 30 minutes, add 131 grams of sodium bicarb...

Embodiment 3

[0061] The preparation of embodiment 3 ascorbic acid ethyl ethers

[0062] Add 244 grams of 3-O-ethyl-5,6-O-isopropylidene-L-ascorbic acid, 320 grams of ethanol, stirred to dissolve, 55 grams of hydrogen chloride ethanol solution, water 30 grams, heated to 55 ° C, reacted for 4 hours, concentrated the reaction solution to one-third of the original volume, added an equal volume of dichloromethane for recrystallization, and obtained 190.4 grams of ascorbic acid ethyl ether, with a yield of 93.3%; Recrystallized with ethanol (volume ratio 2:1) to obtain 177.5 g of ascorbic acid ethyl ether (molecular weight: 204.18), with a yield of 86.9%.

[0063] Embodiment 3 gained ascorbic acid ethyl ether is carried out liquid chromatography and magnetic resonance analysis, and the results are as follows:

[0064] The purity determined by HPLC is 99.95%, 1 H-NMR (400MHz, CDCl 3 ):4.80(s,1H),4.42-4.44(m,2H),3.91-3.93(m,1H),3.61-3.63(m,2H),1.24-1.27(t,3H). 13 C-NMR (100MHz, CDCl 3 ): 173....

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Abstract

The invention relates to a preparation process of ascorbyl ethyl ether. The preparation process comprises the following steps: with ascorbic acid and acetone as raw materials, carrying out reacting for 8-10 hours under the catalysis of oxalyl chloride, and then carrying out filtering, washing and drying to obtain 5,6-O-isopropylidene-L-ascorbic acid; adding alkaline-earth metal oxide into mother liquor to remove oxalic acid, hydrogen chloride and moisture, and drying acetone with a molecular sieve for reuse; dissolving an ethylation reagent, inorganic base and 5,6-O-isopropyl-L-ascorbic acid in ethanol, carrying out reacting for 6-8 hours at 40-60 DEG C, and carrying out purifying to obtain 3-ethyl-5,6-O-isopropyl-L-ascorbic acid; removing isopropyl protecting groups through an alcohol solution of hydrogen chloride, carrying out concentrating, adding a solvent with low solubility, and conducting recrystallizing to obtain the ascorbyl ethyl ether. The process solves problems in recoveryand reuse of acetone, does not use toxic and harmful solvents and organic alkali, does not produce a large amount of waste liquid, and is economic and environment-friendly; technological process is easy to control; and the process is high in yield and easy to industrially popularize.

Description

technical field [0001] The invention relates to the field of cosmetic chemistry, in particular to a preparation process of ascorbic acid ethyl ether. Background technique [0002] Ascorbic acid is a naturally occurring antioxidant and free radical scavenger, a reducing agent in the conversion process of biological enzymes, and has a preventive effect on some chronic diseases (cancer, diabetes and allergic skin diseases). Ascorbic acid is easily soluble in water and not easily absorbed directly by the skin. Based on the poor fat solubility of ascorbic acid, it is easy to oxidize and discolor when placed in the air, and it is unstable to heat, which reduces the utilization efficiency of ascorbic acid and its commercial value in daily chemical, medical and health care industries. Therefore, the development of stable fat-soluble ascorbic acid derivatives has broad application prospects. [0003] Ascorbic acid contains 4 hydroxyl groups, of which 2 are enol hydroxyl groups. Stu...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D307/62C07D407/04
CPCC07D307/62C07D407/04Y02P20/55
Inventor 钱恒玉朱金辉尹志刚彭东来
Owner ZHENGZHOU UNIVERSITY OF LIGHT INDUSTRY
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