Iodine → 4,4'-Dibromostilbene

Participants

Reaction Conditions

Reaction Steps

Into a reaction flask equipped with a mechanical stirrer, condenser, drying tube and thermometer was charged 76.8 grams (0.15 moles) of the triphenylphosphine salt of p-bromobenzyl bromide prepared in Part A and 11.1 grams (0.159 mole) of sodium ethoxide in 150 milliliters of absolute ethanol. Over a ten minute period, 30.0 grams (0.162 mole, Aldrich, 99 percent) of 4-bromobenzaldehyde in 30 milliliters of absolute ethanol was added to the reaction mixture at a reaction temperature of from 30° C. to 43° C. The 4-bromobenzaldehyde was washed into the reaction flask with 10 milliliters of absolute ethanol. The reaction mixture was then heated to a temperature of 48° C. and maintained at this temperature with continuous stirring overnight. The reaction was quenched by adding 140 milliliters of distilled water to the reaction flask. A soft cream colored precipitate formed in the reaction flask which was filtered and the collected solids dried to give 15.5 grams of a crude product fraction. This crude product fraction was heated to a temperature of 122° C.-128° C. in xylene with a small crystal of iodine, cooled to ambient temperature, filtered and the collected solids were dried in a vacuum oven to give 11.2 grams of 4,4'-dibromostilbene having a melting point of from 211° -213° C.

Provenance & Evidence