Chapters 18–20 deliberately teach spectroscopy as a process of reasoning — narrowing down structural possibilities by combining evidence — rather than a set of numbers to memorize. This appendix is the numeric companion to that process: representative IR absorptions, NMR chemical shifts, splitting patterns, and mass spectrometry fragmentation patterns, organized for lookup once a spectrum is at hand.

How to use this appendix: treat every value as a typical range, not an exact cutoff — real spectra vary with the rest of the molecule. The Chapter 18 Common Mistake applies here too: the goal is to recognize a handful of diagnostic signals, not to memorize the entire table.

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Infrared (IR) Absorption Table

The carbonyl stretch is one of the most diagnostic IR signals, and its exact position tracks the same reactivity/resonance trend developed in Chapters 12–13…

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¹H NMR Chemical Shift Table

All values in δ (ppm), referenced to tetramethylsilane (TMS, δ = 0).

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¹³C NMR Chemical Shift Table

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Splitting Patterns (¹H NMR)

Splitting follows the n + 1 rule: a proton with n neighboring protons — equivalent to each other, but non-equivalent to the observed proton — is split into…

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Mass Spectrometry: Common Fragment Losses

Acylium ions (R–C≡O⁺, the same cationic species that drives Friedel-Crafts acylation in Appendix C) are common, stabilized fragments from ketones and…

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Cross-References