Benzophenone → 4-METHOXY-2'-METHYLBENZOPHENONE

Participants

Reaction Steps

2-methyl-4'-methoxybenzophenone was prepared by the Friedel-Crafts reaction of ortho-toluoyl chloride and anisole using aluminum chloride as a catalyst and carbon disulfide as the solvent. 11.1 grams (0.05 mole) of the resulting benzophenone was converted to the propargyl alcohol using the method described in Example 1, Step 2. The crude product was mixed with 6 grams of 2-naphthol and 0.1 gram of p-toluene sulfonic acid in 200 milliliters of benzene and the mixture stirred overnight at room temperature. The resultant reaction mixture was poured into an equal volume of aqueous 5 percent sodium hydroxide to remove unreacted naphthol. The organic layer was washed with water and the benzene solvent removed on a rotary evaporator. The resulting oil residue was column chromatographed on silica using a 1:1 mixture of chloroform and hexane as elutant. The photochromic fractions were combined and the product crystallized from a mixture of hexane and diethyl ether. The product (4.8 grams) had a melting range of 131-133° C. NMR analysis of the product confirmed it to be 3(2-methylphenyl)-3-(4-methoxyphenyl)-3H-naphtho[2,1-b]pyran.

Provenance & Evidence