Question

What is a more substituted carbon from a less substituted carbon? What does substituted mean?

Answer 1

It just means that there are a different number of non-hydrogen groups on a particular atom. Below, (1) is a tertiary (`3^@`), (2) is a secondary (`2^@`), and (3) is a primary (`1^@`) central carbon.

`" "" "" "`(1)`" "" "" "" "" "`(2)`" "" "" "" "`(3)

The highlighted carbon is currently being considered the "central" carbon.

Simply put...

• Since isobutane (1) has one more atom or group attached to the central carbon than propane (2), it is more substituted.
• Since propane (2) has one more atom or group attached to the central carbon than ethane (3), it is more substituted.