Chemistry Forum

Hello, sorry for my bad english. I’ve got a problem with an exercise. I’ve got a compound of which the exercise want to know the name. According to the text is 5-ethyl-4,4-dimethyloctane but for me is 4-ethyl-5,5-dimethyloctane. Because ethyl comes first considering the alphabetical order.

CH₃ CH₂CH₂CH₃
| |
CH₃C—CHCH₂CH₃
|
CH₂CH₂CH₃

The propyhl is attached to the CH carbon on the right, there’s an error

The whole drawing makes no sense.

5-ethyl-4,4-dimethyloctane

CH₃CH₂CH₂C(CH₃)₂CH(C₂H₅)CH₂CH₂CH₃

https://pubchem.ncbi.nlm.nih.gov/compou ... thyloctane


4=ethyl-5,5-dimethyloctane.

CH₃CH₂CH₂CH(C₂H₅]C(CH₃)₂CH₃CH₂CH₃

Wrong,
Ethyl comes first in both formula name, but the number of the C with the two methyl has to be smaller.

Thanks. Could you please explain why the number of the carbon with the two methyl has to be smaller?

It is one of the laws number has to small as possible, especially more substituents are present.