Acetyl phosphate synthesis by reaction of isopropenyl acetate and phosphoric acid.

200 ml. of isopropenyl acetate (Tennessee Eastman Corporation) are cooled in an ice bath and then, with stirring, 25 ml. of 85 per cent syrupy phosphoric acid (35 gm. of H3P04) are added dropwise, and finally 1.0 ml. of concentrated sulfuric acid is added as catalyst. The reaction mixture is placed in a water bath at 25” and stirred constantly to prevent localized heating. After 35 minutes at this temperature, the reaction mixture becomes deep orange in color. It is then cooled in an ice bath and 50 ml. of ice-cold water are added cautiously. A too rapid addition of water results in a rapid rise in temperature and consequently lower yields of acetyl phosphate. The mixture is t,hen neutralized to about pH 5.0 with cold 4 N lithium hydroxide (about 300 ml.). During the neutralization, the mixture may separate into two phases, since the isopropenyl acetate which was added in excess is relatively insoluble in water. It is therefore necessary to mix the layers thoroughly while adding the lithium hydroxide so as to extract the acetyl phosphate from the organic phase. The neutralization should be carried out as rapidly as possible without, however, causing the tem-