Formaldehyde → 2-Ethylacrylic acid

Participants

Reaction Conditions

Reaction Steps

2-Ethylacrylic acid was prepared from diethyl ethylmalonate using procedures set forth in the literature (e.g., Ferrito et al., Macromol. Synth., 11, pp. 59-62 (1992)). Diethyl ethylmalonate (100 g, 0.53 mol) was added to a 1 L round bottom flask and stirred overnight with 700 mL of 1 M KOH in 95% ethanol. The ethanol was then removed with a rotary evaporator and the residue was dissolved in a minimum amount of water and acidified to a pH of 2.0 by slow addition of concentrated HCl. The separated oil (2-carboethoxybutyric acid) was taken up into diethyl ether (3×200 mL portions of ether in a separatory funnel), dried over magnesium sulfate and concentrated on a rotary evaporator. The crude 2-carboethoxybutyric acid (84.9 g, 0.53 mol) was placed in a 1 L round bottom flask and cooled to −5° C. Diethylamine (55 mL, 0.53 mol) was then added to the flask and an addition funnel containing 43.5 g formaline solution (0.54 mol) was added dropwise to the reaction mixture while allowing the solution to slowly warm to room temperature. After stirring for 24 hours, the addition funnel was replaced with a reflux condenser and the reaction was warmed to 60° C. for 8 hours. The reaction mixture was then cooled to 0° C. and concentrated sulfuric acid was added slowly until evolution of gas ceases. The mixture was extracted with three 200 mL portions of diethyl ether, dried over magnesium sulfate, and concentrated on a rotary evaporator to obtain 2-ethylacrylate. Crude 2-ethylacrylate (64.1 g, 0.5 mol) was placed in a 1 L round bottom flask and 600 ml of 2M aqueous KOH was added. The flask was fitted with a reflux condenser and the reaction was refluxed for 20 hours. The solution was allowed to cool to room temperature and was acidified with 1N HCl to a pH of 2. The separated oil was extracted four times with 700 mL of ether, dried over magnesium sulfate and concentrated on a rotary evaporator. The yellow oil was vacuum distilled (bp 50° C./1 mm Hg) to yield pure, colorless 2-ethylacrylic acid (35 g).

Provenance & Evidence