The invention discloses a method for producing high-purity N-
alkyl imidazole, comprising the following steps of: a, putting
imidazole and
alkali metal hydroxide or alkaline-earth
metal hydroxide into a reaction
bottle in a mol ratio
ranging from (1: 0.5) to (1: 1.5); violently agitating at 90-150 DEG C for 0.2-24 hours; b, reducing the temperature to 0-60 DEG C and adding
tetrahydrofuran (THF), wherein the ratio of the volume THF to the
mass of the
imidazole is (1-100): 1; c, adding
alkyl halide according to the mol ratio
ranging from (1: 0.8) to (1: 1.5) (imidazole to RX); reacting at 20-80 DEG C for 4-48 hours, wherein R is any one of straight-chain
alkyl with a
carbon number of 1-16, naphthenic base with a
carbon number of 3-8, allyl,
propargyl and benzyl, and X is any one of
chlorine and
bromine; d, after the reaction, filtering; utilizing the THF which is 10% of the previous volume to wash a
solid for three times; dissolving the
solid into a suitable amount of hot water to carry out
crystallization and purification, and obtaining a by-product to be stored for other use; and e, distilling the THF from an organic phase, and recycling; and finally, rectifying residual liquid to obtain a high-purity product. The method disclosed by the invention has the advantages that 1, the process is simple to operate; water-removing operation is not needed after a first-step reaction, and a second-step reaction is directly carried out; 2, the product is high-purity colorless transparent liquid or white
solid; and 3, the synthesizing time is short, suitable conditions are wide and
pollution to the environment is small, so that the method is suitable for industrial production.