(2) |
In this class, in the absence of an indication to the contrary, and with the exception referred to below, a compound is classified in the last appropriate place, e.g. a compound containing an acyclic chain and a heterocyclic ring is classified only as a heterocyclic compound, and a steroid is classified only as a cyclopentanophenanthrene compound. In general, and in the absence of an indication to the contrary (such as groups
C 07 C 59/58, C 07 C 59/70), the terms "acyclic" and "aliphatic" are used to describe compounds in which there is no ring; and, if a ring were present, the compound would be taken by the "last place" rule to a later group for cycloaliphatic or aromatic compounds, if such a group exists. Where a compound or an entire group of compounds exists in tautomeric forms, it is classified as though existing in the form which is classified last in the system, unless the other form is specifically mentioned earlier in the system. |
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