Preparation technique of 1,6-dimethoxynaphthalene

Abstract

The invention puts forward a novel process for synthesizing 1,6-dimethoxynaphthalene. The process comprises the steps of adding sodium hydrosulfite for preventing oxidation to a medium of petroleum ether and NaOH aqueous solution, adding quaternary ammonium salt as a phase transition catalyst, using dimethyl sulfate to methylate 1,6-dihydroxynaphthlene, adding NaOH aqueous solution and dimethyl sulfate by stages, performing reaction at a temperature between 50 and 60 DEG C and preparing the 1,6-dimethoxynaphthalene. In a first stage, the weight ratio of petroleum ether, the NaOH aqueous solution, the sodium hydrosulfite, the quaternary ammonium salt and the dimethyl sulfate to the 1,6-dimethoxynaphthalene is 4.5-8:1, 4.6-6:1, 0.02-0.06:1, 0.02-0.05:1 and 1.2-1.8:1 respectively; the time of dripping the dimethyl sulfate is 10 to 60 minutes; and in a second stage, the weight ratio of the added NaOH aqueous solution and the dimethyl sulfate to the 1,6-dimethoxynaphthalene is 2.3-3:1 and 0.88-1.2:1 respectively. The method has the advantages that reaction conditions are easy to control; the petroleum ether can be recovered and indiscriminately used; and the 1,6-dimethoxynaphthalene is high in purity and does not need to be refined by use of solvents.

Description

Technical field: [0001] The invention belongs to the methylation method of naphthol compounds, and particularly proposes a preparation method of 1,6-dimethoxynaphthalene. Background technique: [0002] 1,6-dimethoxynaphthalene is an important organic intermediate used in the synthesis of medicines, pesticides, dyes and other functional materials, and has a good market prospect. [0003] From 1,6-dihydroxynaphthalene, after dimethyl sulfate dimethylation, 1,6-dimethoxynaphthalene can be prepared. The reaction medium can be NaOH aqueous solution, methanol-NaOH-water solution, K 2 CO 3 - Acetone mixture. Methylation in NaOH aqueous solution, dimethyl sulfate is easily hydrolyzed, 1,6-dihydroxynaphthalene is easily oxidized, and the yield is low. Methylation in methanol-NaOH-water solution, the solvent methanol is not easy to recover. in K 2 CO 3 —Methylation of acetone mixture, K 2 CO 3 , Acetone is more expensive and the cost is higher. In the above several synthetic...

AI Technical Summary

Problems solved by technology

Methylation in methanol-NaOH-water solution, the solvent methanol is not easy to recover

in K 2 CO 3 —Methylation of acetone mixture, K 2 CO 3 , Acetone is more expensive and the cost is higher

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