Preparation method of trimethylolpropane

The invention discloses a trimethylolpropane preparation method, which comprises: dissolving calcium hydroxide in water in an ice-water bath, adding formaldehyde, n-butyraldehyde and an organic amine catalyst, stirring, reacting for 1-2 h at a temperature of 35-45 DEG C, compounding calcium hydroxide with a catalytic system of organic amine, and carrying out a Cannizaro reaction to prepare the target product trimethylolpropane, the main by-product is ditrimethylolpropane. The trimethylolpropane is prepared through a Cannizaro method by adopting a catalytic system of compounding calcium hydroxide with organic amine, the yield of a product can be improved, so that the utilization rate of formaldehyde is improved, formation of formate can be reduced by using the organic amine catalyst, a post-treatment process is properly simplified, and the requirements of fine green chemical industry are met. The yield of trimethylolpropane can reach 90% or above, and the yield of ditrihydroxypropane is larger than 3%. 本发明公开了一