Potassium Hydroxide → 2,4-Dimethyl-2-pentenoic acid

Participants

Reaction Steps

A mixture of 2,4-dimethylpent-2-enoic acid ethyl ester (116 g, 742 mmol) and KOH 85% (147 g, 2.23 mol) in water/EtOH (1:1, 2.0 L) was refluxed for 1 d. The EtOH was stripped off on a rotary evaporator, and the remaining mixture was washed with Et2O. The combined ethereal washings were extracted with 2 N aq. NaOH (100 ml), and all aqueous solutions were combined. Under cooling with an ice/water bath, conc. aq. H3PO4 (200 ml) was added to adjust the combined aqueous solutions to pH 3, and the product was extracted with Et2O (200 ml). The ethereal solution was washed with water (200 ml) and brine (25 ml). After drying (Na2SO4), the solvent was evaporated in a rotary evaporator to furnish 94.2 g (99%) of 2,4-dimethyl-pent-2-enoic acid.

Provenance & Evidence