4-Hydroxybenzaldehyde → HCID 14018450, compound

Participants

Reaction Conditions

Reaction Steps

A 2.5l sulfonation flask equipped with stirrer, thermometer, reflux condenser, addition funnel and bubble counter connected to an argon flask is charged with 92.2 g Mg turnings, (4.0 mol) and 150 ml THF. After the system has been flushed with argon one iodine crystal is added followed by 30 drops of a solution of 192.6 g vinyl bromide (1.8 mol) in 300 ml THF. Using an oil bath, the reaction flask is heated to 70° C. and one drop of bromine is added. After ignition of the Grignard-reaction the oil bath is removed and the vinyl bromide-THF solution is added steadily at ambient temperature over a period of 6 hours. Stirring is continued for another 30 minutes and the cloudy, black-grey mixture obtained is cooled to 0° with an ice bath. After dilution with 600 ml THF, a solution of 61.05 g 4-hydroxy-benzaldehyde (0.5 mol) in 150 ml THF is added under efficient cooling (ice bath) over a period of 30 minutes. The thick, but stirrable suspension obtained is stirred at room temperature overnight and then cooled to 0° C. Under vigorous stirring a solution of 133.7 g NH4Cl (2.5 mol) in 350 ml H2O is added very carefully over a period of 1.5 hours. The suspension obtained is stirred for another 1.5 hours, the precipitated solids are separated by filtration and the reaction vessel is rinsed several times with a total of 600 ml MTBE. The combined organic layers are washed 2× with 500 ml water, 2× with 500 ml aq. NaHSO3 (10%), 2× with 500 ml H2O, 1× with 500 ml saturated NaHCO3 and 2× with 500 ml brine/water ca 2:1. Each aqueous phase is extracted 1× with 500 ml MTBE, the combined organic phases are dried over MgSO4 and concentrated in vacuo. The crude product is purified by flash chromatography (silica gel 60, Merck Flash; 30 cm column with 7.5 cm diameter; solvent: hexane/MTBE 1:1) to give 56.0 g (75%) 4-(1-hydroxyallyl)-phenol in the form of a yellowish, viscous oil that slowly crystallizes.

Provenance & Evidence