Method of preparing D-propoxyphene
Patent 5312970 Issued on May 17, 1994. Estimated Expiration Date: 
March 19, 2012. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
March 19, 2012. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 2728779 3065261 3487469 3728379 Synthesis and purification of d-propoxyphene hydrochloride Patent #: 4661625 InventorAssigneeApplicationNo. 853847 filed on 03/19/1992US Classes:560/250Nitrogen in alcohol moiety other than as nitro, nitroso or isocyanateExaminersPrimary: Dees, Jose G.Assistant: Conrad, Joseph Attorney, Agent or FirmForeign Patent References
International ClassC07C 067/02AbstractD-propoxyphene can be prepared by reacting d-oxyphene and propionic anhydride. Preferably, an excess of propionic anhydride is used. The reaction easily proceeds at temperatures of 70° to 80° C. and produces yields exceeding 95 percent of theory. The free base d-propoxyphene can easily be converted in high yields to its hydrochloride or napsylate salts, both analgesics.Other References
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