Question

file:///C:/Users/candi/Desktop/08_05d_01.jpg

What is the best name for the molecule below?


4-propyl-1-pentene
4-methyl-6-heptene
2-propyl-4-pentene
5-methyl-1-octene

Answer 1

A compound with a total of eight carbons total with a double bond and the rest single bonds. There is a straight chain of five carbons across the bottom with a double bond between the fourth and fithcarbons when counting from left to right. There is a propyl group branching off of the second carbon from the left.

CH2 - CH2-CH3
I
CH3 - CH - CH2 - CH2 - CH = CH2

Answer 2

Start numbering from the carbon with the double bond and go through the longest carbon chain

Answer 3

hints:
1. choose the longest root chain that contains the double bond
(sometimes they provide a misleading figure)
2. start number from the end closer to the double bond.

What do you think the root chain is, that is, how long?

Answer 4

@mathmate 6?

Answer 5

The straight line right?

Answer 6

Recall:
1. choose the \(\color{red}{longest}\) root chain that contains the double bond
(sometimes they provide a misleading figure)

Answer 7

So it would be 8 @mathmate

Answer 8

Exactly! Whenever there is a branch, decide which one to take. Make sure you include the double bond, in the root chain, otherwise it won't be an alkene!

With eight carbon atoms in the root chain, it is an octene.

Now start counting from the \(end\) closest to the double bond. Call that end carbon atom #1, and count.
If the double bond starts on the nth carbon atom, it is n-octene.
Then you would name the branches according to what the branch contains, and the location of the branch.

As an exercise, it would be good practice for you to draw each of the four choices.