Process for the manufacture of 1-hydroxy-2-pyridones
Patent 3968118 Issued on July 6, 1976. Estimated Expiration Date: 
July 6, 1993. 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.
July 6, 1993. 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 2540218 2748142 3227708 3269904 3883545 InventorsAssigneeApplicationNo. 502063 filed on 08/30/1974US Classes:546/283.4, The additional hetero ring is five-membered28/103, Fiber entangling and interlocking28/254, Jet feed to impact surface546/142, Plural chalcogens attached directly to the six-membered hetero ring by nonionic bonding546/183, Chalcogen bonded directly to ring carbon of the bicyclo ring system546/296Plural chalcogens bonded directly to ring carbons of the six-membered hetero ringExaminersPrimary: Randolph, John D.Attorney, Agent or FirmForeign Application Priority Data1968-08-31 DTAbstractNew 1-hydroxy-2-pyridones of the general formula ##SPC1##In which R1 is alkyl of 1 to 17 carbon atoms, cycloalkyl of 5 to 8 carbon atoms, cyclohexylalkyl or phenalkyl both having 1 to 3 carbon atoms in the alkylene chain or -furyl, all of which may be substituted by halogen, and R2 to R4 are hydrogen or lower alkyl, or two adjacent substituents together form a trimethylene or tetramethylene chain, and in which R1 to R4 together contain at least 2 carbon atoms, are prepared by contacting unsaturated δ-keto esters or mixtures thereof with hydroxylamine and subjecting the products to cyclization.Other References
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