US PATENT SUBCLASS 549 / 253
.~.~.~.~.~ Nitrogen or additional chalcogen attached directly or indirectly to the cyclic anhydride by nonionic bonding

Current as of: June, 1999
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549 /   HD   ORGANIC COMPOUNDS -- PART OF THE CLASS 532-570 SERIES

*  DD  ORGANIC COMPOUNDS (Class 532, Subclass 1) {1}
*  DD  .~ HETEROCYCLIC CARBON COMPOUNDS CONTAINING A HETERO RING HAVING CHALCOGEN (I.E., OXYGEN, SULFUR, SELENIUM, OR TELLURIUM) OR NITROGEN AS THE ONLY RING HETERO ATOMS (Class 540, subclass 1) {2}
200  DF  .~.~ Oxygen containing hetero ring (e.g., dioxirane, etc.) {16}
231  DF  .~.~.~ Cyclic anhydrides (i.e., -C(=X)OC(=X)-, wherein the X's are the same or diverse chalcogens, is part of the hetero ring) {2}
233  DF  .~.~.~.~ The cyclic anhydride is five-membered (e.g., succinic anhydride, etc.) {7}
253.~.~.~.~.~ Nitrogen or additional chalcogen attached directly or indirectly to the cyclic anhydride by nonionic bonding

DEFINITION

Classification: 549/253

(under subclass 233) Compounds wherein nitrogen or additional chalcogen (i.e., oxygen, sulfur, selenium or tellurium) is attached directly or indirectly to the cyclic anhydride by nonionic bonding.

(1) Note. Examples of compounds provided for herein are: [figure] [figure] [figure] [figure]