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How would you name the above compound according to IUPAC rules? I see some sources say it is 2-phenyloctane, but ChemDraw and a few other sources say it is 2-octanylbenzene.

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The current version of Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013 (Blue Book) reads as follows:

P-44.1.2.2 Systems composed of rings and chains (exclusive of linear phanes)

Two methods are recognized to name systems composed of rings and chains (exclusive of linear phanes).

(1) Within the same class, a ring or ring system has seniority over a chain. When a ring and a chain contain the same senior element, the ring is chosen as parent. Rings and chains are chosen regardless of their degree of hydrogenation. As a consequence, this approach prefers the choice of a ring over a chain in systems composed of cyclic and acyclic hydrocarbons.

(2) The context may favor the ring or the chain, so that, for example, substituents may be treated alike or an unsaturated acyclic structure may be recognized, or the one chosen has the greater number of skeletal atoms in the ring or in the principal chain of the acyclic structure.

(…) For selection of a preferred IUPAC name, see P-52.2.8.

 

P-52.2.8 Selection between a ring and a chain as parent hydride

Within the same heteroatom class and for the same number of characteristic groups cited as the principal characteristic group, a ring is always selected as the parent hydride to construct a preferred IUPAC name. In general nomenclature, a ring or a chain can be the parent hydride (see P-44.1.2.2).

Method (1): “octan-2-ylbenzene” (preferred IUPAC name; ring preferred to chain)

Method (2): “2-phenyloctane” (chain has greater number of skeletal atoms)

The function Convert Structure to Name of ChemDraw correctly yields “octan-2-ylbenzene”.

octan-2-ylbenzene

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  1. Well basically there are 8 carbons in the long chain
  2. The Phenyl Group is actually considered to be kind of a Functional Group
  3. Hence the name should be:

"octan-2-ylbenzene"

Although some sources say that the name should be 2-phenyloctane , They do it on the basis that :the unsaturated acyclic structure is recognized, or the one chosen has the greater number of skeletal atoms in the ring or in the principal chain of the acyclic structure, which is kind of not used and considered to be wrong by many according to IUPAC rules.

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