Phosphoric Acid → 4,4-Dimethylthiochroman

Participants

Reaction Steps

A mixture of 15.00 grams (0.076 mol) of 2-methyl-4-(phenylthio)-2-butanol, 12.75 grams of H3PO4, 27.0 grams (0.190 mol) of P2O5 [this is added in three equal portions every 8 h]and 60 mL of sodium-dried benzene was boiled under N2 for 24 hours in a 250-mL, round-bottom flask equipped with a condenser and nitrogen inlet. The resulting, cooled heterogeneous mixture was separated and the P2O5 layer was extracted with ether. The combined organic layers were washed with H2O, brine, dried with Na2SO4 (4 h). Evaporation and vacuum distillation gave 11.68 grams (86.0%) of 4,4-dimethylthiochroman as a clear colorless liquid: bp 75°-82° C./0.1 mm; 1H NMR (DCCl3) δ1.29 [s, 6 H, (CH3)2C]1.92 [m, 2 H, ArSCH2CH2 ]3.00 [m, 2 H, ArSCH2CH2 ]6.90-7.32 [m, 4 H, Ar-H]; 13C NMR (DCCl3) ppm 22.8 [ArSCH2CH2 ], 29.9 [(CH3)2C]32.6 [(CH3)C], 37.4 [ArSCH2CH2 ], 123.7, 125.7, 126.1, 126.2, 131.5, 141.5. ##STR13##

Provenance & Evidence