E-Z isomerism

Animal lover :))

I don't understand why the answer is c

On the left-most side of the double bond labelled C, that carbon in the double bond is bonded to two other carbons, one from each group. Since these two carbons have the same atomic number, we move on to the atom with the next-highest atomic number that is bonded to each carbon. In the case of the methyl group, it would be H. For the other group, it would be another C. The C has a higher atomic number than the H, so this group has higher priority.
On the right-most side of the double bond labelled C, that carbon is bonded to a H as well as a C. Same rules apply - the C has a higher atomic number than H so the group that it is part of has higher priority.

Overall, the two highest-priority groups on either side are on the same side of the double bond, so it is a Z stereoisomer.

Reply 3

Animal lover :))

Original post by Methene

On the left-most side of the double bond labelled C, that carbon in the double bond is bonded to two other carbons, one from each group. Since these two carbons have the same atomic number, we move on to the atom with the next-highest atomic number that is bonded to each carbon. In the case of the methyl group, it would be H. For the other group, it would be another C. The C has a higher atomic number than the H, so this group has higher priority.
On the right-most side of the double bond labelled C, that carbon is bonded to a H as well as a C. Same rules apply - the C has a higher atomic number than H so the group that it is part of has higher priority.
Overall, the two highest-priority groups on either side are on the same side of the double bond, so it is a Z stereoisomer.

Hi thank u for the help, I kind of understand but I still need a bit more help pls.
I have attached a pic of what I've understood but I don't get the part where u said "For the other group, it would be another C. The C has a higher atomic number than the H, so this group has higher priority." Pls can u help me.

Hey, sorry for the fat fingered drawing but the displayed formula may be easier to visualise. I've drawn from the left of the double bond labelled C.

As you've noted this carbon in the double bond is bonded to a carbon in a methyl group. It's also bonded to another carbon, the one on the right in the double bond labelled B.

Since these two carbons have the same atomic number, to determine which group is higher priority, we have to look at the next largest adjacent atom. So on the methyl group, it would be H. On the other group, it would be the carbon on the left of the double bond labelled B. This carbon has a higher atomic number than the H in the methyl group. So this group is higher priority.

1000011515.jpg91.3KB

Reply 6

Animal lover :))

Original post by Methene

Hey, sorry for the fat fingered drawing but the displayed formula may be easier to visualise. I've drawn from the left of the double bond labelled C.
As you've noted this carbon in the double bond is bonded to a carbon in a methyl group. It's also bonded to another carbon, the one on the right in the double bond labelled B.
Since these two carbons have the same atomic number, to determine which group is higher priority, we have to look at the next largest adjacent atom. So on the methyl group, it would be H. On the other group, it would be the carbon on the left of the double bond labelled B. This carbon has a higher atomic number than the H in the methyl group. So this group is higher priority.