Phosphoric Acid → 4-Cyclopentylresorcinol monohydrate

Participants

Reaction Conditions

Reaction Steps

To a N2 purged pressure reactor is charged resorcinol (44.0 g, 0.40 mol), cyclopentanol (44 mL, 0.49 mol) and 85% aqueous H3PO4 (55 mL, 0.80 mol). The slurry is heated to 95-120° C. for 6-18 hours. The pink reaction mixture is cooled to ˜70° C. and diluted with water (50 mL) and toluene (200 mL). The layers are allowed to separate at 60±5° C. The bottom orange aqueous layer is cut away. The remaining pink organic layer is extracted with 2×50 mL water at 60±5° C. and then stirred with carbon (5 g) at 60±5° C. for 1-2 hours. The slurry is filtered hot through Supercel, rinsing the cake with hot toluene (50 mL). The orange filtrate is diluted with 5 mL water and allowed to cool to ˜30° C. at which time the product crystallizes. The slurry is cooled to 0-5° C. and the product collected, washed with cold toluene (40 mL) and pulled dry on the funnel to afford 41 g of 4-cyclopentyl resorcinol monohydrate as a white to pale pink solid (≧98% area by HPLC). The material can be recrystallized if desired from hot toluene (5 mL/g) and carbon (10% by weight) filtering through Supercel and/or silica gel to the Form I polymorph of 4-cyclopentyl resorcinol afford as a white solid (≧99.7% by HPLC).

Provenance & Evidence