Hydrochloric Acid → Benzophenone

Participants

Reaction Steps

The free base of 2-isopropoxyphenyl piperazine was prepared by treatment of the fumarate salt with aqueous bicarbonate followed by extraction into chloroform, to provide a brown oil (7.28 g, 33.0 mmol) which was dissolved in 75 mL of tetrahydrofuran. To this solution was added a solution of 3-(bromomethyl)benzophenone (10.0 g, 3.63 mmol) in 75 mL of tetrahydrofuran followed by triethylamine (5.53 mL, 39.6 mmol). The reaction mixture was refluxed for 19 h. After cooling to ambient temperature the reaction mixture was poured into 1N HCl solution. After washing with ether, the aqueous solution was basified with solid K2CO3 and extracted with chloroform. The chloroform extracts were combined, dried (Na2SO4), and concentrated to provide a dark brown oil which was purified on a Waters 500A Prep LC apparatus (1% hexanes-chloroform) to afford 9.09 g of pure benzophenone intermediate as a brown oil. The oil was dissolved in acetone and treated with concentrated HBr (2.5 mL). When diethyl ether was added, a fine white precipitate fell out of solution. This solid was recrystallized from acetone/ether to provide 4.59 g of a white solid. A second crop of crystals was also collected. These were combined to provide 7.94 g (46%) of aryl piperazine benzophenone intermediate, mp 193°-197° C. The 1H NMR in CD3OD supported the assigned structure.

Provenance & Evidence