Iodine → 2-Methyl-1-(2-methylphenyl)naphthalene

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Reaction Steps

Magnesium turnings (4.00 gr, 0.165 mol) and anhydrous diethyl ether (30 mL) were placed in a 500-mL three-neck round bottom flask, fitted with a condenser, addition funnel and nitrogen inlet. A crystal of iodine and 3-4 drops of 1,2-dibromoethane were added and the mixture was stirred magnetically. A solution of 1-bromo-2-methylnaphthalene (33.20 gr, 0.150 mol) in a 1:1 mixture of diethyl ether-benzene (120 mL) was added dropwise at a rate such that gentle reflux was maintained. After the addition was complete (about 1.5 hour), the mixture was heated at reflux for an additional hour, then cooled to room temperature. This mixture was then added rapidly under nitrogen to a stirring mixture of 2-bromotoluene (22.90 gr, 0.134 mol) and bis(triphenylphosphine)nickel dichloride (1.0 gr, 1.52 mmol) in diethyl ether (100 mL). The flask which had contained the Grignard reagent was rinsed with additional diethyl ether (60 mL), which was then added to the reaction mixture. The mixture was heated at reflux for 16 hours and then cooled to room temperature. Water (100 mL) was added, followed by the addition of 20 percent hydrochloric acid (100 mL). After stirring about 1 hour, the mixture was transferred to a separatory funnel and the layers were separated. The organic solution was washed twice with water (100 mL each) and then dried (MgSO4). After filtration, the solvent was evaporated from the filtrate and the residue was distilled to give the desired product (I), boiling point 156°-163°/0.5 mm Hg, 23.82 gr (77 percent), as a thick, light yellow liquid.

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