| 558 / | HD | ORGANIC COMPOUNDS -- PART OF THE CLASS 532-570 SERIES |
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| * | DD | ORGANIC COMPOUNDS (Class 532, Subclass 1) {21} |
| 70 | DF | .~ Phosphorus esters (i.e., compounds having the phosphorus ester group, wherein trivalent or pentavalent phosphorus and carbon are bonded directly to the same divalent chalcogen, and wherein the carbon may be single bonded to any atom but may be multiple bonded only to carbon) {18} |
| 199 |  | .~.~ Nitrogen bonded directly to the phosphorus {2} |
| 200 | DF | .~.~.~> Benzene ring and the phosphorus bonded directly to the same chalcogen (i.e., the carbon of the phosphorus ester group is part of a benzene ring) |
| 201 | DF | .~.~.~> Acyclic carbon chain containing carbon to carbon unsaturation attached indirectly to the phosphorus by acyclic nonionic bonding |