Method for preparing 1-halogenated alkyne under catalysis of heterogeneous Ag catalyst at room temperature

Abstract

The invention discloses a novel method for preparing 1-halogenated alkyne under the catalysis of a heterogeneous Ag catalyst at room temperature. The method comprises the steps of mixing terminal alkyne compounds containing different substituent groups, N-halogenated imide and an Ag@C catalyst, putting the mixture into an organic solvent, and preparing three types of 1-halogenated alkyne compounds (1-chloro alkyne, 1-bromo alkyne and 1-iodo alkyne) with different substituent groups under certain catalytic conditions. The catalytic reaction conditions of the reaction are as follows: the addition amount of the catalyst is 20-30 mg, the acetonitrile solvent is used, the stirring speed is 500-800 rpm, and the reaction time is 3-6 hours at room temperature. The Ag@C catalyst is prepared by adopting an impregnation method, an Ag complex is subjected to in-situ reduction with bamboo powder to generate Ag nano-particles, and finally the Ag nano-particles are carbonized to prepare the biomass carbon-loaded Ag nano-catalyst. According to the method, biomass is used as a raw material to synthesize the catalyst, a reducing agent does not need to be additionally added, and the catalyst can be repeatedly used and is environment-friendly; the reaction system is simple and efficient, the 1-halogenated alkyne can be synthesized at high yield at room temperature, and industrialization is facilitated.

Description

technical field [0001] The invention relates to the field of chemistry, in particular to a method for catalytically synthesizing 1-halogenated alkyne with a heterogeneous Ag catalyst at room temperature. Background technique [0002] 1-Haloalkynes are important intermediates in organic synthesis because of their electrophilic and nucleophilic properties. Haloalkyne compounds are not only the precursors of many fine chemicals, drug molecules and advanced materials, but also widely used in the fields of natural product synthesis, pesticides, materials and drugs. Therefore, the development of facile, efficient and green methods for the synthesis of 1-haloalkyne compounds has attracted extensive attention. [0003] The most common method for the synthesis of 1-haloalkynes is through direct C–H halogenation of terminal alkynes. Compared with 1-bromoalkynes and 1-iodoalkynes, the synthesis of 1-chloroalkynes under mild conditions is more challenging. The methods for synthesizin...

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Problems solved by technology

Compared with 1-bromoalkynes and 1-iodoalkynes, the synthesis of 1-chloroalkynes under mild conditions is more challenging

The methods for synthesizing 1-chloroalkynes that have been reported so far include: using a strong base or hypochlorite to react with a halogenating reagent under harsh conditions (-78°C) to generate 1-halogenated alkynes (Synthesis, 1979, 4, 296-297; J Mol Catal A Chem, 2001, 165(1-2), 121-126; J Am Chem Soc, 2007, 129(2), 441-449), which not only requires complex reaction processes, And the product selectivity is very low

In addition, using a phase transfer catalyst tetrabutylammonium fluoride (TBAF) ( Chem. Eur. J , 2014, 20 , 2746-2749) and the organic base 1,8-Diazabicycl o[5.4.0]undec-7-ene (DBU) ( RSC Adv , 2014, 4 , 30046-30049) catalyzed the chlorination reaction of terminal alkynes at room temperature. Although it has also been reported, the substrate applicability of these reaction systems is limited, and the catalyst cannot be recycled and reused.

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