Method for preparing 3-methyl-2-butenoic acid

The invention discloses a preparation method of 3-methyl-2-butenoic acid. The existing method has great amount of three wastes which pollute the environment heavily. The method is characterized in that: 2-methyl-3-butyne-2-alcohol is adopted as a raw material; 3-methyl-2-butenoic aldehyde is obtained by the complex system of acetylacetone titania-copper bromide-benzoic acid through catalytic reforming, and finally the 3-methyl-2-butenoic acid is obtained by oxidizing 3-methyl-2-butenoic aldehyde; and an oxidizer adopted is air or oxygen or the mixture of air and oxygen, wherein, the preference is air. The oxidizer adopted by the method is safe, avirulent and easy to be controlled, and has low cost; in addition, the reaction yield is high and the product purity is high on the premise of ensuring no pollution to the environment.