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I came across this compound recently, and havent been able to find out what it's name could possibly be:

enter image description here

My guess was maybe it's "cyclohexylene cyclohexane", but not quite sure. Can anyone tell me what this compound could be called?

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Chemspider tells me that the name should be

1,1'-Bi(cyclohexylidene)

http://www.chemspider.com/Chemical-Structure.121798.html?rid=e40cd595-d5e5-450e-bdb3-3e558a9da92d

While PubChem mentions:

Cyclohexylidenecyclohexane

https://pubchem.ncbi.nlm.nih.gov/compound/Cyclohexylidenecyclohexane


My guess was maybe it's "cyclohexylene cyclohexane"

There's a flaw to this thinking, to name this, I'd suggest you choose one of the cyclohexane rings to act as the word-root. Now you've to just add the name of the substituent.

Recall that (source: http://www.ebi.ac.uk/chebi/searchId.do?chebiId=65236) also click this link for an example (this website particularly has propylidene group as the example):

An alkylidiene group formed from propane by removal of two hydrogen atoms from the same carbon atom, the free valencies of which are part of a double bond.

So, the substituent in this case would be called "cyclohexyl idene " (without the space). And hence, the name should be cyclohexylidenecyclohexane.

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    $\begingroup$ 1,1'-Bi(cyclohexylidene) appears to be a preferred name, however it is not very suitable for speech communication, because is may sound like some bicyclo- compound. $\endgroup$ – mykhal May 24 '17 at 14:17
  • $\begingroup$ Btw, it's better to link via the ID: pubchem.ncbi.nlm.nih.gov/compound/138159. They list alternative name Delta1,1'-Bicyclohexane, which is very weird (and likely wrong), maybe incomprehensible misuse of "delta convention". $\endgroup$ – mykhal May 24 '17 at 16:20
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Assemblies of two identical rings linked by a single bond are described in the current version of Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013 (Blue Book) as follows:

P-28.2 RING ASSEMBLIES OF TWO IDENTICAL CYCLIC SYSTEMS

P-28.2.1 Ring assemblies with a single bond junction

Assemblies of two identical cyclic systems joined by a single bond are named by one of two methods:

(1) by placing the prefix ‘bi’ (see P-14.2.3) before the name of the corresponding parent hydride enclosed in parentheses, if necessary. Parentheses are used to avoid confusion with von Baeyer names;

(2) by placing the prefix ‘bi’ (see P-14.2.3) before the name of the corresponding substituent group (for names of substituent groups, see P-29), enclosed in parentheses, if necessary.

Each cyclic system is numbered in the traditional way, one with unprimed locants, the other with primed locants. Lowest possible locants must be used to denote the positions of attachment. These locants must be cited in preferred IUPAC names; they can be omitted in general nomenclature when no ambiguity would result.

The name biphenyl is retained as 1,1'-biphenyl.

For assemblies of two identical rings linked by a double bond, the formation of names is restricted to a single method:

P-28.2.2 Ring assemblies with a double bond junction

When two cyclic systems are linked by a double bond, method (2) described in P-28.2.1 is the only recommended method. Method (2) has also been used in which the presence of a double bond is indicated by the Greek letter Δ and the point of attachment of the ring is given by superscript locant numbers. This method is not continued in these recommendations; accordingly, ring assemblies of three or more identical cyclic systems interconnected by double bonds must be named by other methods (see P-31).

Therefore, the preferred IUPAC name of the compound that is given in the question is 1,1'-bi(cyclohexylidene). The name Δ1,1'-bicyclohexylidene is no longer recommended.

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It's called cyclohexylidenecyclohexane.

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