Ethyl Bromide → Sodium

Participants

Reaction Steps

A 60% dispersion of sodium hydride (0.74 g, 18.45 mmol) in mineral oil is washed with hexanes twice and suspended in 35 mL of DMF. To this mixture is added slowly via an addition funnel 7-hydroxynaphthalene-2-sulfonic acid, sodium salt (2.5 g, 10.1 mmol) in 50 mL of DMF at room temperature. The reaction mixture is stirred for 75 min during which time mild bubbling is observed (H2 evolution). The mixture is treated with bromoethane (2.42 mL, 32.5 mmol) and stirred for 16 hours at room temperature. A little ice is added to decompose the excess NaH and the resultant mixture is concentrated in vacuo. The residue is suspended in acetone and concentrated in vacuo two times and then is dried under high vacuum. The solid is suspended in acetone, filtered and dried to yield the crude 7-ethoxynaphthalene-2-sulfonic acid, sodium salt as a beige solid. A mixture of the sulfonic acid, sodium salt (3.77 g) in 10 mL of thionyl chloride is heated at 80° C. for 2 hours. The mixture is allowed to cool to room temperature and concentrated in vacuo. The residue is diluted in EtOAc and washed successively with water (2×), saturated NaHCO3 solution and saturated NaCl. The organic layer is dried over anhydrous MgSO4, filtered and concentrated to yield 2.65 g of a crude brown oil. The crude product is purified by column chromatography in a gradient of 10% EtOAc/hexanes to 20% EtOAc/hexanes to afford the title compound (1.67 g, 6.17 mmol) as a pale yellow solid.

Provenance & Evidence