Preparation method of alpha-hydroxypyridine by acetone cyanohydrin
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A technology of acetone cyanohydrin and hydroxynitrile, which is applied in the field of preparation of α-hydroxynitrile, can solve the problems of complex preparation method, high catalyst toxicity, long reaction time, etc., and achieve the advantages of avoiding side reactions, simplifying post-treatment process, and shortening reaction time Effect
Active Publication Date: 2017-12-01
HARBIN UNIV OF SCI & TECH
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[0004] The present invention aims to solve the problems of low yield, high catalyst toxicity, high price, complex preparation method and long reaction time in the existing α-hydroxynitrile preparation method, and provides a method for preparing α-hydroxynitrile by utilizing acetone cyanohydrin
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specific Embodiment approach 1
[0025] Specific embodiment one: the present embodiment utilizes acetone cyanohydrin to prepare the method for α-hydroxynitrile, comprises the following steps:
[0026] One, the preparation of catalyst:
[0027] immersing the cation exchange resin in a 20% by weight organic amine methanol solution for 6-8 hours, filtering, washing with methanol for 3-5 times, and drying to obtain a catalyst;
[0028] Two, the preparation of α-hydroxynitrile:
[0029] Dissolve acetone cyanohydrin and aromatic aldehyde in methanol at a molar ratio (1.1 to 1.3): 1, add a catalyst, react at room temperature for 2 to 10 hours, and obtain α-hydroxynitrile; wherein the mass of the catalyst is 3% to 10% of the mass of the aromatic aldehyde ;
[0030] The catalyst was filtered off, methanol and by-product acetone were distilled off under reduced pressure, the residue was extracted and separated by adding ethyl acetate and water, the ethyl acetate layer was washed 2 to 3 times with 20% brine, and after...
specific Embodiment approach 2
[0031] Embodiment 2: This embodiment differs from Embodiment 1 in that the cation exchange resin in step 1 is a macroporous weakly acidic acrylic cation exchange resin. Others are the same as in the first embodiment.
specific Embodiment approach 3
[0032] Embodiment 3: The difference between this embodiment and Embodiment 1 or 2 is that the organic amine in step 1 is 2,5-lutidine, 2-picoline, 2-aminopyridine, 4-aminopyridine, Pyrazine, piperidine, triallylamine, tributylamine or dimethyloctylamine. Others are the same as in the first or second embodiment.
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Abstract
The invention relates to a preparation method of alpha-hydroxypyridine by acetone cyanohydrin, and relates to a preparation method of alpha-hydroxypyridine. The method solves the problems that the existing preparation method of the alpha-hydroxypyridine is low in yield, big in catalyst toxicity, high in price, complex in preparation method, and long in reaction time. The method includes steps of firstly, immersing cation exchange resin in 20% by weight of organic amine methanol solution; filtering, washing and drying the solution to obtain catalyst; secondly, dissolving acetone cyanohydrin and aromatic aldehyde in the methanol, and adding catalyst to react and obtain the alpha-hydroxypyridine; filtering the catalyst, depressurizing and evaporating methanol and acetone; extracting and separating the methanol and acetone; after drying, rotationally evaporating and removing ethyl acetate to obtain the alpha-hydroxypyridine. The method applies the simple and easily-prepared catalyst, and the reaction can be completed under room temperature condition; the reaction yield is up to over 95%. The operation method is simple and easy to practice, and the catalyst can be repeatedly used and is more applicable to the industrial production. The preparation method is applied to prepare alpha-hydroxypyridine.
Description
technical field [0001] The present invention relates to a method for preparing α-hydroxynitriles. Background technique [0002] α-Hydroxynitrile is a class of important pharmaceutical intermediates, such as mandelonitrile is a synthetic ampicillin (also known as ampicillin) and cephalexin (cephalosporin or Pioneer No. 4), cephradine (Pioneer No. 6), ampicillin sodium, piperazine It is an important intermediate of β-lactam antibiotics such as racillin, ceftriaxone and benzamicillin. p-Hydroxymandelonitrile is mainly used in the synthesis of amoxicillin (amoxicillin), cefadroxil (cephalosporin 5), cefoperazone, ceftriaxone and other drugs. The main synthetic method of this series of products is NaCN-benzaldehyde (KCN-benzaldehyde) method at present, and this method is to use excessive highly poisonous potassium cyanide or sodium cyanide to make cyanide reagent, and benzaldehyde or substitute in aqueous solution Benzaldehyde reacts, because potassium cyanide or sodium cyanide...
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