Preparation method for p-isoproplyl toluene

Abstract

The invention relates to a process for preparing p-Cymene, which takes dipentene as raw material and palladium carbon as catalyst to react at a temperature of 160DEG C-180DEG C for 1-12 hours to obtain mixture of p-Cymene and p-menthane, then the p-menthane is removed via fractional distillation to obtain crude products of p-Cymene, and lastly water containing soda is added in the crude products of p-Cymene which are then heated to 170DEG C-190DEG C and after heat preservation for 5-30 minutes charged in a fractionating tower for fractionating operation to obtain products of p-Cymene. The content of p-Cymene obtained through the preparing process of the invention reaches above 99% with low production cost.

Description

technical field [0001] The invention relates to a preparation method of p-cymene. Background technique [0002] p-Cymene is p-cymene, which is not only the raw material for the synthesis of precious fragrances such as sandalwood musk and tuna musk, but also the raw material for the synthesis of important chemical products p-cresol. my country is rich in turpentine resources, and a large amount of by-product dipentene is produced in the production process of synthesizing camphor and terpineol with turpentine as raw materials. At present, the camphor and terpineol manufacturers in my country produce thousands of tons of dipentene every year, which are mainly used as solvents with low prices. Using catalytic hydrogenation to convert dipentene into p-cymene can greatly improve its use value and economic benefits. There are many reports about the synthesis of dipentene to cymene, such as utilizing the gas-phase dehydrogenation of heavy metal catalysts, although satisfactory res...

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Problems solved by technology

There are many reports about the synthesis of dipentene to cymene, such as utilizing the gas-phase dehydrogenation of heavy metal catalysts, although satisfactory results can be obtained, but the catalyst is more expensive, and the requirements for reaction equipment are higher (gasification bed is required), and the production High cost; Chinese patent ZL03113830.6 records that heteropolyacid is used as catalyst, and p-cymene is prepared by liquid-phase dehydrogenation under the protection of inert gas. Although the production cost can be reduced, it is very corrosive to equipment due to the use of acid as catalyst Large, and the content of p-cymene obtained by this method is only about 80%