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Synthetic method for 1-hydroxy-2-methyl-4-acetyloxy-2-butene
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A technique for the synthesis of acetoxy, which is applied in the field of synthesis of 1-hydroxy-2-methyl-4-acetoxy-2-butene, and can solve the problems of difficult control of reaction conditions, troublesome post-processing, loss of catalyst, etc. problem, to achieve the effect of shortened reaction time, simplified post-processing, and improved selectivity
Inactive Publication Date: 2012-05-09
JIANGSU STERRIC CHEM IND
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We found that the reaction is very difficult, the selectivity is low, and the reaction conditions are difficult to control; although a large number of conditional experiments have explored the influence of the amount of catalyst, methanol, and reaction temperature on the reaction, it is difficult to achieve satisfactory selectivity. and yield, usually the content of the main product is lower than 90% after the reaction is good; After methanol and filtration to remove solids, there is still a large amount of catalyst sodium bicarbonate dissolved in the crude product five-carbon alcohol, which not only causes catalyst loss, but also the residual sodium bicarbonate will continue to catalyze the decomposition of the main product, usually the crude product after post-treatment The five-carbon alcohol content will be further reduced to below 85%
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Embodiment 1
[0021] Example 1: Preparation of 1-formyloxy-2-methyl-4-acetoxy-2-butene
[0022] Starting material 1-chloro-2-methyl-4-acetoxy-2-butene was prepared according to the method of Babler (Babler, James.H., PCT.Int.Appl.7900,485, E-4-Acetoxy-2 -methyl-2-butenal, [P] 1979), is a colorless transparent liquid with a G.C. content of 93.5%; in a 500ml three-necked bottle, add 1-chloro-2-methyl-4-acetoxy-2-butyl 50g (0.288mol) of alkenes, 200ml of DMF and 33.5g (0.4mol) of potassium formate were stirred and heated up at 60°C for 5 hours, and the gas phase tracking showed that the conversion of the raw materials had been completed; the temperature was lowered, and the reaction mixture was poured into 300ml of water, and after layering, The aqueous layer was extracted twice with dichloromethane (100ml each time), and the organic layer was combined and washed with 100ml of water. After recovering the solvent from the organic layer, 51g (content 95%) of the crude esterified product was obta...
[0024] In a 500ml there-necked flask equipped with a rectifying column, add 50 g of the crude product 1-formyloxy-2-methyl-4-acetoxy-2-butene (content 95%, 0.276mol), 200ml of methanol and 10g of phosphotungstic acid supported by diatomaceous earth was stirred and heated at 63°C-65°C for 3 hours, during which the low-boiling by-products were continuously evaporated, and gas phase tracking showed that the conversion of the raw materials had been completed; the solvent methanol was recovered under reduced pressure, and filtered to obtain the crude product 5 Carbon alcohol 39.5g, is light yellow transparent liquid, content 94.3%, yield 94.3%, catalyst wet product can be applied mechanically directly.
Embodiment 3
[0025] Example 3: In a 500ml there-necked flask equipped with a rectification column, add crude product 1-formyloxy-2-methyl-4-acetoxy-2-butene 50g (content 95%, 0.276mol), ethanol 200ml and 10g diatomite-loaded phosphotungstic acid heteropoly acid, stirred and heated at 75°C-78°C for 4 hours, during which the low-boiling by-products were continuously evaporated, and the gas phase tracking showed that the conversion of the raw materials had been completed; after the solvent ethanol was recovered under reduced pressure , filtered to get 38.5g of crude product pentacarbon alcohol, which is a light yellow transparent liquid with a content of 93.5% and a yield of 91.1%. The wet product of the catalyst can be directly applied mechanically.
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Abstract
The invention discloses a synthetic method for 1-hydroxy-2-methyl-4-acetyloxy-2-butene, which comprises the following steps: taking 1-formyloxy-2-methyl-4-acetyloxy-2-butene as a raw material for esteThe invention discloses a synthetic method for 1-hydroxy-2-methyl-4-acetyloxy-2-butene, which comprises the following steps: taking 1-formyloxy-2-methyl-4-acetyloxy-2-butene as a raw material for ester exchange reaction in an alcohols system under the action of heteropoly acid supported on diatomite; only selectively disassociating formic ether between the formic ether and acetic ester; continuousr exchange reaction in an alcohols system under the action of heteropoly acid supported on diatomite; only selectively disassociating formic ether between the formic ether and acetic ester; continuously transferring byproducts generated in the reaction out of the reaction system; distilling and recovering a solvent after the reaction is finished; and filtering and recovering a solid catalyst afterly transferring byproducts generated in the reaction out of the reaction system; distilling and recovering a solvent after the reaction is finished; and filtering and recovering a solid catalyst after distilling the solvent to dryness, and obtaining a crude product of the 1-hydroxy-2-methyl-4-acetyloxy-2-butene. The heteropoly acid supported on the diatomite has good selectivity, stability and catdistilling the solvent to dryness, and obtaining a crude product of the 1-hydroxy-2-methyl-4-acetyloxy-2-butene. The heteropoly acid supported on the diatomite has good selectivity, stability and catalytic activity; and a particle material is even and resistant to wear, and has high poriness to improve the selectivity of the ester exchange reaction greatly, shorten the reaction time, improve thealytic activity; and a particle material is even and resistant to wear, and has high poriness to improve the selectivity of the ester exchange reaction greatly, shorten the reaction time, improve theyield and simplify post treatment, and the synthetic method is particularly suitable for continuous industrial production.yield and simplify post treatment, and the synthetic method is particularly suitable for continuous industrial production.
Description
technical field [0001] The present invention relates to the V A Synthetic method of 1-hydroxy-2-methyl-4-acetoxy-2-butene, an important intermediate of acetate. Background technique [0002] Vitamin A (V A ) and its derivatives are an important class of drugs, and the products of major companies in the world are marked with V A Acetate-based ((Encyclopedia of Chemical Engineering) Editorial Committee, Encyclopedia of Chemical Engineering, Chemical Industry Press, first edition in 1996, Vol.16, P719-729). 4-Acetoxy-2-methyl-2-buten-1-aldehyde (MW142, referred to as five-carbon aldehyde) is a C characterized by Wittig reaction 15 +C 5 Route Synthesis V A The key intermediate of acetate (Tanaka, USP5,424,478, Process for producing Vitamin A Derivatives, [P] 1995; Tanaka, et al., JP 06,329,623, Preparation of Vitamin A Derivatives, [P] 1994; Zutter, Ulrich, Ep 648,735, Preparation of an intermediate for Vitamin A acetate, [P] 1995; Wang Lanming, Beijing Medicine, New Synth...
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