Method for preparing 3,3-dimethyl butyraldehyde

Abstract

The invention relates to a method for preparing 3,3-dimethyl butyraldehyde. The method comprises the following steps: (1) vacuumizing a closed reaction kettle, adding a dichloromethane solvent, dripping vinyl acetate, introducing a catalyst after dripping is ended, and introducing hydrogen chloride gas, so that the pressure reaches 0-1MPa, slowly dripping tert butyl chloride for reacting, removing excessive hydrogen chloride gas after the reaction is ended to obtain a distillation product, raising the temperature and distilling to obtain 1-chloro-3,3-dimethyl butyl acetate; and (2) adding the 1-chloro-3,3-dimethyl butyl acetate and water into the reaction kettle, controlling the temperature to be 120 DEG C, performing hydrolysis disproportionation on the 1-chloro-3,3-dimethyl butyl acetate to obtain a hydrolysis disproportionation reaction mixture containing 3,3-dimethyl butyraldehyde, and distilling and purifying to obtain the 3,3-dimethyl butyraldehyde. According to the method disclosed by the invention, the production cost is low, the production process is shortened, the reaction conditions are mild, the production safety is high, and the preparation method is simple in preparation process, easy to control, high in yield and safe.

Description

technical field [0001] The invention relates to a preparation method of 3,3-dimethylbutyraldehyde. Background technique [0002] Neotame (N-[N-(3,3-dimethylbutyl)-L-α-aspartic acid]-L-phenylalanine-1--methyl ester) in the sweetener is derived from The high-power sweetener developed by Newtrathwaite Company of the United States has the advantages of high sweetness, low calorie, high stability, etc., and is safe and harmless to the human body. It is a kind of non-nutritional strong sweetener with excellent performance. Huge market potential, and 3,3-dimethylbutyraldehyde is an important intermediate of neotame. Due to its high market price, the product price cannot be reduced. Therefore, it is necessary to study an economical and specific method for preparing this intermediate . [0003] There are many preparation methods for 3,3-dimethylbutyraldehyde: in CN101311151, ethylene gas is used as raw material for preparation, but ethylene gas has higher requirements in terms of t...

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Problems solved by technology

[0003] There are many preparation methods for 3,3-dimethylbutyraldehyde: in CN101311151, ethylene gas is used as raw material for preparation, but ethylene gas has higher requirements in terms of transportation, storage, production equipment, etc., and this preparation method flow It is long and consumes a lot of energy. It needs to be obtained by gasifying 3,3-dimethylbutanol and water at a high temperature above 300°C with an inert gas as a carrier gas, and then catalytic dehydrogenation in the presence of precious metals. The production cost High, production safety is low; In the disclosed method of CN1301247A, use 3,3-dimethyl butyl chloride as raw material, raw material cost price is high, and produce the dimethyl sulfide compound of stench in the production process, to environment The pollution is heavy, and the control of this pollution requires higher production costs, and it is not easy to carry out industrial production; in US5994593, it is prepared by hydrolysis of 1,1-dichloro-3,3-dimethylmethane. The disadvantage of this preparation method is that the raw materials are expensive. It is not suitable for large-scale industrial production; in US5856584, it is prepared by oxidation of 1-chloro-3,3-dimethylbutane. The disadvantage of this method is that it uses iodide as a catalyst, which is expensive and difficult to recycle, and the reaction produces foul-smelling di Methyl sulfide by-products, high processing costs