Carbon Environment	Typical δ Range	Note
Alkyl carbon (sp³), not adjacent to a heteroatom	0–40	Baseline aliphatic region
Carbon attached to a halogen	0–70	Range depends heavily on which halogen
Carbon attached to oxygen or nitrogen (C–O, C–N)	50–90	—
Alkyne carbon (sp)	65–90	—
Alkene and aromatic carbon (sp²)	100–150	—
Carboxylic acid, ester, and amide carbonyl carbon	160–185	Shifted upfield relative to ketones/aldehydes by resonance donation from the attached heteroatom (same reasoning as the IR C=O trend above)
Aldehyde carbonyl carbon	190–205	—
Ketone carbonyl carbon	205–220	Furthest downfield — no adjacent heteroatom lone pair to donate into the carbonyl and reduce its electron deficiency

Reading the carbonyl region as a shortcut: a signal above 190 ppm signals an aldehyde or ketone; a signal in the 160–185 range signals an acyl derivative with an attached heteroatom (acid, ester, or amide) — the same addition-vs-substitution distinction from Appendix C shows up directly in the carbon shift.

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