Calcium Carbide Directly As A Source Of Acetylene To Build Triaroylcyclohexanes And Synthesis Of The Dihydropyrazoles

Calcium carbide is an industrial solid raw material,cheap and easy to get.It is calcined by calcium oxide and coke in high temperature in the electric furnace.In recent years,it has been shown that calcium carbide can be obtained from the renewable biochar at low temperature,which makes calcium carbide an extremely green raw material of chemical reaction.Traditionally,the use of calcium carbide as a raw material for the preparation of organic compounds,needs to first convert it to acetylene,and then acetylene is used to prepare other chemicals.The acetylene as a gas,the characteristics of its flammable and explosive makes storage and transportation inconvenient.In addition,the reaction conditions are harsh and difficult for operation.Therefore,direct use of solid calcium carbide as a green raw material and avoiding the steps of acetylene to prepare a variety of important organic compounds will be a simple and environmentally friendly pathway.Pyrazole is a class of important nitrogen-containing five-membered ring,which is closely related to the pharmaceutical industry and materials.Substituted pyrazoles have a wide range of pharmacological activities,such as antibacterial,anti-hyperglycemia,anti-inflammatory,analgesic,hypoglycemic,sedative and hypnotic activities.Some processes for the preparation of pyrazoles have been reported,including 1,3-dipolar additions;cyclization condensation of hydrazine derivatives with 1,3-dicarbonyl compounds or α,β-unsaturated carbonyl compounds;and metal catalyzed nucleophilic additions of alkynes to hydrazines etc.However,most of these methods use stoichiometric or excessive oxidants,or use Pd / C catalyst.Therefore,it is necessary to explore a more green catalytic system to replace expensive metals.In this paper,we focus on the method of constructing triaroylcyclohexanes directly use of calcium carbide as the source of acetylene by reactions with various aldehydes using DMF as solvent and KOH as base,and the synthesis of dihydropyrazoles under green,metal-free conditions.This paper is divided into three chapters:Chapter 1: Literature Review.Some advances of use of calcium carbide in organic synthesis and the progress of the synthesis and applications of pyrazole compounds were reviewed.Chapter 2: A series of triaroylcyclohexanes were synthesized by direct reactions of calcium carbide with various aldehydes.This method effectively avoids the use of precious transition metal catalysts as well as flammable and explosive gases.And the raw materials are readily available and renewable.The reactions do not need high temperature and high pressure conditions,and have high yield and simple work-up procedure.Chapter 3: A series of aryl substituted dihydropyrazole compounds were prepared by reactions of aryl dienone and phenylhydrazine.The method has advantages of use of environmentally friendly solvent,no metal catalyst and high yield.