Name the following cycloalkenes:

SOLUTION:


1. Main chain: 3-membered cycle (cyclopropene)
2. Numbering: the double bond takes the smallest locants
3. Substituents: methyl in position 3
4. Name: 3 -Methylcyclopropene


In cyclic molecules the double bond will always occupy the position 1 and this locant can be omitted when naming the alkene (this is true in the absence of functional groups)

1. Main chain: 4-membered cycle (cyclobutene)
2. Numbering: numbering begins at the methyl carbon so that double bond and the substituents take the minor locants.
3. Substituents: methyl in position 1 and ethyl in 4
4. Name: 4 -Ethyl- 1 -methylcyclobutene




1. Main chain: 5-membered cycle (cyclopentadiene)
2. Numbering: lowest possible locants to double bonds and to methyls.
3. Substituents: methyls in position 1,3 .
4.

Name: 1,3 -Dimethylcyclopenta- 1,3 -diene

1. Main chain: 6-membered cycle (cyclohexene)
2. Numbering: we number from the double bond, so that the isopropyl takes the lowest locant.
3. Substituents: isopropyl in position 3 .
4. Name: 3 -Isopropylcyclohexene



1. Main chain: 7-membered cycle (cycloheptene)
2. Numbering: we number from the double bond, so that the methyls take the lowest possible locant.
3. Substituents: methyls in position 3,3 .
4. Name: 3,3 -Dimethylcycloheptene



1. Main chain: 8-membered cycle (cyclooctatriene)
2. Numbering: lowest possible locants to double bonds.
3. Substituents: none.
4. Name: Cycloocta- 1,3,5 -triene



1. Main chain: 6-membered cycle (cyclohexene)
2. Numbering: locant 1 to the isopropyl double bond since it comes first in alphabetical order.
3. Substituents: 1- position isopropyl 3 -position methyl .
4. Name: 1 -Isopropyl- 4 -methylcyclohexa- 1,3 -diene

1. Main chain: 5-membered cycle (cyclopentene)
2. Numbering: we number from the double bond so that the methyl takes the lowest locant.
3. Substituents: methyl in position 3 .
4. Name: 3 -Methylcyclopentene