In this lesson, we will learn how to name cycloalkanes (rings). We will separate naming cycloalkanes into four categories: cycloalkane only, cycloalkane with one substituent, cycloalkane with two substituents, cycloalkane with more than two substituents.
Ring only
Name the ring beginning with “cyclo” and using a prefix signifying the number of carbons that the ring has. For example, a ring with 5 carbons is called cyclopentane.
Ring with one substituent
Add the name of the substituent in front of the parent name. For example: methylcyclohexane. No numbers are needed here.
Ring with two substituents
Number the ring starting with the group whose name is first alphabetically. Go in the direction to give the next group the lowest number possible. For example if the ring has two groups attached, methyl and ethyl, we need to give number 1 to ethyl because letter e is before m. Then, we go in the direction to give methyl the lowest number possible.
Ring with more than two substituents
Number the ring so that all the substituents get the lowest numbers possible. List the substituents in alphabetical order followed by the name of the ring.
Ring versus Chain
When a ring is attached to a carbon chain that has more carbons than the ring, the chain will be the parent. The ring is a subsituent and will be named ending in “yl”. For example, cyclopropyl.
LINKS
Online Organic Chemistry Tutoring
References:
Organic Chemistry by T.W. GRAHAM SOLOMONS, CRAIG B. FRYHLE, SCOTT A. SNYDER