What is the structure and IUPAC name of butyl cyclopentane ?

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ncchemist eNotes educator| Certified Educator

The term "butyl cyclopentane" is a bit vague but I am assuming that you are talking about a chemical with a cyclopentane core and a linear, unbranched butane group attached to it.  Normally we look for the longest unbroken carbon chain but in the case of cycloalkanes we should treat the cyclopentane as a single unit.  So since cyclopentane has 5 carbons and butane has 4 carbons, the name will be based on cyclopentane.  The butyl group will be treated as a substituent.  Since there is only one substituent off of it, that carbon will be carbon #1.  The linear form of butane is called n-butane, so the IUPAC name for the chemical is 1-n-butylcyclopentane.

I cannot draw the structure here, but the cyclopenane would be drawn like a pentagon with a carbon in each corner.  At one of the carbons, draw a 4 carbon chain for the n-butyl group.