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By the method of Preparation 1, 2-fluoronaphthalene (10 g., 0.068 mole) in 200 ml. of methylene chloride was reacted with titanium tetrachloride (25.5 g., 14.7 ml. 0.136 mole) and 1,1-dichloromethyl methyl ether (10.1 g., 0.088 mole). The resulting crude product (11 g.) was first recrystallized from hexane to yield 7-fluoro-1-naphthaldehyde [2.5 g., m.p. 95°-96° C., Rf 0.25 (1:1 chloroform:hexane)]. The mother liquor was evaporated to dryness and the residue chromatographed on 400 g. of silica gel, eluting initially with 3:1 hexane: chloroform and then with 3:2 hexane:chloroform. The column was monitored by tlc. Fractions contain clean 2-fluoro-1-naphthaldehyde [Rf 0.31 (3:2 hexane:chloroform)] were combined and evaporated to dryness, yielding purified 2-fluoro-1-naphthaldehyde (2.8 g., m.p. 60°-62° C.).

1. customThe resulting crude product (11 g.) was first recrystallized from hexane