2,2-Dimethyl-but-3-ynoic acid

56663-75-3

56663-76-4

NaNH2 (17.8 g, 0.458 mol, solid) and DMSO (50 mL) were added to a 500 mL three-neck flask. The mixture was stirred at room temperature until no more NH3 gas was released. A solution of 3-chloro-2,2-dimethylbut-3-enoic acid (17.0 g, 114 mmol) in DMSO (50 mL) was added slowly and dropwise at 0 °C. The reaction mixture was gradually warmed to 50 °C and stirred at this temperature for 5 h, followed by continued stirring at room temperature overnight. Upon completion of the reaction, the mixture was slowly poured into a pre-cooled 20% HCl solution and extracted three times with ether. The ether extracts were combined, dried with anhydrous Na2SO4 and concentrated under reduced pressure to give a mixture of the raw material and 2,2-dimethylbut-3-ynoic acid (in a ratio of about 6:1). The residue was again dissolved in ether, dried by adding anhydrous Na2SO4 and the above reaction conditions were repeated. The reaction mixture was subjected to the same treatment to give the final 2,2-dimethylbut-3-ynoic acid (12.0 g, 94% yield).