Benzene → 2,7,9,9-Tetramethyl-1,4-dioxaspiro[4,5]dec-6-en-8-one

Participants

Reaction Steps

To a 2 liter flask fitted with a reflux condenser, a water separator and a stirrer is charged 265 g of 2,6,6-trimethylcyclohex-2-en-1,4-dione (prepared by the method described in Helv.Chim.Acta. 39, 2041(1956)), 266 g of propylene glycol, 500 ml of benzene and 1 g of p-toluenesulfonic acid. The reactants are stirred and refluxed until no additional water is collected in the water separator. The product is washed with water to a pH of 6 and the solvent is stripped off. The residue is vacuum distilled through a nine inch Goodloe column to yield 257 g of product, b.p. 92° at 1 mm Hg (80% yield).

Provenance & Evidence