Method for preparing dodecyl methyl sulfoxide

The invention relates to a method for preparing dodecyl methyl sulfoxide. The method comprises two parts namely chemical synthesis as well as separation and purification of dodecyl methyl sulfoxide: performing single methylation on n-dodecanethiol through a methylation reagent, and performing selective oxidation on the intermediate product n-dodecyl methyl sulfide through an oxidizing agent to obtain dodecyl methyl sulfoxide; performing methylation reaction on n-dodecanethiol, performing preliminary purification on n-dodecanethiol, performing suction filtration to remove solid potassium carbonate, extracting the filtrate through ethyl acetate, adjusting the pH to be neutral, adding saturate saline solution to wash an organic phase, adopting anhydrous sodium sulfate or anhydrous magnesium sulfate for water absorption and drying, performing suction filtration to remove solid, and performing distillation to remove ethyl acetate so as to obtain a n-dodecyl methyl sulfide crude product. According to the invention, the methylation reagent which is environment-friendly, low in price and toxicity is selected to replace iodomethane, the oxidizing agent which is environment-friendly and excellent in oxidation selectivity for n-dodecyl methyl sulfide is selected to replace sodium periodate, and the technological conditions are controlled and researched, so that the method for preparing dodecyl methyl sulfoxide is environment-friendly.