| 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} | 
| 512 | DF | .~.~.~ The hetero ring is three-membered consisting of one oxygen and two carbons {7} | 
| 513 | DF | .~.~.~.~ Processes {5} | 
| 518 | DF | .~.~.~.~.~ Oxirane ring formed {3} | 
| 523 | DF | .~.~.~.~.~.~ Epoxidation at site of ethylenic unsaturation {2} | 
| 524 | DF | .~.~.~.~.~.~.~ Liquid phase epoxidation {4} | 
| 532 | DF | .~.~.~.~.~.~.~.~ Air or molecular oxygen utilized {1} | 
| 533 |  | .~.~.~.~.~.~.~.~.~ Heavy metal containing catalyst utilized |