Water → 1-(5-Methyl-2-propyl-1H-imidazol-4-yl)ethan-1-one

Participants

Reaction Steps

A suspension of 86.2 g. of α,5-dimethyl-2-n-propyl-4-imidazolemethanol in 2.16 liters of acetone is stirred in an ice bath and 430.9 ml. of Jones' reagent (120 g. of chromium trioxide, 257 ml. of water, 106.7 ml. of concentrated sulfuric acid, combined and diluted to 461.7 ml. with water) is dripped in at 20°-30° C. internal temperature over a period of one hour. Stirring is continued for 30 miuntes after the addition is complete, then 256 ml. of water were added. The reaction is then cooled in an ice bath and 256 ml. of 2-propanol are slowly added, maintaining the internal temperature at 20°-30° C. Stirring is continued for one hour, giving a suspension of solid and liquid. The liquid is decanted, concentrated to remove most of the acetone, and the aqueous residue is recombined with the solid. This mixutre is basified with concentrated aqueous potassium bicarbonate and an additional amount of solid potassium bicarbonate. The mixture is extracted with three 300 ml. portions of ethyl acetate. The extracts are combined, back washed with 100 ml. of saturated aqueous potassium bicarbonate dried over sodium sulfate and the solvent is removed in vacuo, giving the desired ketone which crystallizes on standing.

Provenance & Evidence