Q.I. Identify primary, secondary, tertiary and quaternary carbon in the following compounds.
a. CH3-C(CH3)(CH3)-CH(CH3)-CH2-CH2-CH3
b. A second structure was printed here as a diagram; it is not present in the extracted source text.

Step 1. Structure of (a). CH3-C(CH3)(CH3)-CH(CH3)-CH2-CH2-CH3, i.e. 2,2,3-trimethylhexane: a 6-carbon main chain (C1-C6) with two methyl branches on C2 and one methyl branch on C3.

Step 2. Classify each carbon by how many OTHER carbons it is directly bonded to (section 14.4.1's Remember box).

• C1: bonded only to C2 -> primary.
• C2: bonded to C1, C3, and its two methyl branches -> 4 carbons total -> quaternary.
• C3: bonded to C2, C4, and its one methyl branch -> 3 carbons total -> tertiary.
• C4: bonded to C3 and C5 -> secondary.
• C5: bonded to C4 and C6 -> secondary.
• C6: bonded only to C5 -> primary.
• Each of the three methyl branches (two on C2, one on C3) is bonded to only its own attachment carbon -> primary. …

Counting, for each carbon of the reconstructed structure in (a), how many other carbon atoms it is directly, singly bonded to, and classifying accordingly pe …

• Counting a branch's own carbon count (e.g. a longer substituent) instead of simply counting how many OTHER carbons are directly bonded to the carbon being classified. …