US PATENT SUBCLASS 507 / 242
.~.~.~ Nitrogen is part of a hetero ring

Current as of: June, 1999
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507 /   HD   EARTH BORING, WELL TREATING, AND OIL FIELD CHEMISTRY

200  DF  WELL TREATING {4}
203  DF  .~ Contains organic component {17}
239  DF  .~.~ Organic component contains nitrogen attached directly or indirectly to carbon by nonionic bonding {6}
242.~.~.~ Nitrogen is part of a hetero ring {1}
243  DF  .~.~.~.~> Plural heteroatoms in the ring

DEFINITION

Classification: 507/242

Nitrogen is part of a hetero ring:

(under subclass 239) Compositions wherein said component contains nitrogen as part of a hetero ring (e.g., methylene blue, pyridine, piperidine, etc.).

(1) Note. The term "hetero ring" denotes a ring having carbon and at least one atom from the group consisting of nitrogen, oxygen, sulfur, selenium, and tellurium as ring members; and it contains no other element as a ring member. For the purposes of this subclass, the hetero ring requires the presence of nitrogen.