Chemistry - Nomenclature Question with Solution | TestHub

The longest chain has 8 carbons (octane). The branches are a tert-butyl group, named 1,1-dimethylethyl, and an ethyl group on adjacent carbons.

Numbering from either end gives the locants 4 and 5, so the tie is broken alphabetically. A complex substituent is alphabetised under the first letter of its full name: dimethylethyl (d) comes before ethyl (e). So (1,1-dimethylethyl) gets ${\mathrm{C}}_4$ and ethyl gets ${\mathrm{C}}_5$.

Name: 4-(1,1-dimethylethyl)-5-ethyloctane.