| 549 / | HD | ORGANIC COMPOUNDS -- PART OF THE CLASS 532-570 SERIES |
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| * | 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} |
| 263 | DF | .~.~.~ Lactones (i.e., -C(=X)O-, wherein X is chalcogen, is part of the hetero ring) {6} |
| 266 |  | .~.~.~.~ The lactone ring has at least seven members {4} |
| 267 | DF | .~.~.~.~.~> Plural ring oxygens in the lactone ring |
| 268 | DF | .~.~.~.~.~> Polycyclo ring system having the lactone ring as one of the cyclos {1} |
| 271 | DF | .~.~.~.~.~> Additional chalcogen attached directly or indirectly to the lactone ring by nonionic bonding |
| 272 | DF | .~.~.~.~.~> Preparing from a cyclic ketone (i.e., a ketone where the carbonyl is part of a ring) |