A method for hydrogenation reduction of alkenyl aromatic halogenated derivatives

Abstract

The invention discloses a method for hydrogenation reduction of an alkenyl aromatic halogenated derivative. The method comprises the following steps that in a reaction vessel, the alkenyl aromatic halogenated derivative is dissolved in a polar proton solvent, then a catalyst is added, and a stirring reaction is conducted at the hydrogen pressure of 0.01-0.07 mpa; obtained reaction liquid is filtered and concentrated to obtain a crude product; the crude product is subjected to post-treatment to obtain an ethyl aromatic halogenated derivative as a reduction product. According to the method, thepolar proton solvent (anhydrous methanol or absolute ethyl alcohol) is adopted, platinum dioxide is added as the catalyst, alkenyl groups are thoroughly reduced under the low hydrogen pressure, aromatic ring halogen is protected, and the ethyl aromatic halogenated derivative is obtained. The method has the advantages of being mild in operation condition, high in efficiency, safe, simple in treatment, thorough in reaction, high in selectivity and the like.

Description

technical field [0001] The invention relates to a method for synthesizing organic compounds, in particular to a hydrogenation reduction method for a class of chemical intermediates - alkenyl aromatic halogenated derivatives, and belongs to the field of organic synthesis. Background technique [0002] Ethyl aromatic halogenated derivatives are a class of useful pharmaceutical intermediates and fine chemical intermediates, which are biologically active, and are generally only produced by certain specific microorganisms in nature, such as Pseudomonas putida UV4, etc. Molecules obtained through biotransformation are used as fragments to continue to synthesize other pharmaceutical products. [0003] The general formula of the raw material alkenyl aromatic halogenated derivative refers to the aromatic ring derivative that conforms to the following form, or contains its structure: [0004] [0005] Among them, -X refers to a halogen atom: -Cl, -Br, -I, and usually refers to -Br...

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Problems solved by technology

The process of this method is cumbersome, and the THF solution of ferric chloride should be added to the THF suspension of lithium aluminum hydride. After stirring for ten minutes, styrene is added to replace the hydrogen pressure reduction. The analytical yield obtained by the reaction is also average, only about 74%.

[0008] Method 2, the hydrogenation reduction of 2-bromostyrene (Jay J.Dunsford, a Dorette S.Tromp, bKingsley J.Cavell.N-alkyl functionalised expanded ring N-heterocyclic carbenecomplexes of rhodium(I)and iridium(I):structural investigations and preliminary catalytic evaluation), 0.5mpa hydrogen pressure, use 0.01 moles of substrate Equivalent catalyst [Ir(6-Neo)(COD)Cl], the catalyst is expensive, and the analytical yield is not high, only about 69% of the product can be obtained

[0009] Since the halogen is located at the ortho position of the alkenyl, a problem will be involved in these hydrogenation methods, that is, the halogen atom (specifically chlorine, bromine, iodine) directly connected to the aromatic ring is sensitive to the hydrogen pressure during the hydrogenation process, if the hydrogen pressure exceeds It is easy to remove, and the resulting product is difficult to separate from the non-dehalogenated product. The reason for the difficulty in separation is that the structure is too similar, the polarity and solubility in various solvents are similar, and the physical properties such as boiling points are usually very close. Difficult to separate through conventional purification methods (column chromatography or distillation, etc.); if the hydrogen pressure is small, the reaction is difficult to carry out thoroughly (that is, when the hydrogen pressure is less than 0.1mpa, the yield will be reduced to less than 58%), the amount of catalyst Increase the cost and increase the processing cumbersome

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