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Chemistry · Glossary

What is DEPT?

Also known as: quaternary carbon

Definition 33.5 University Chemistry — Year 2 · Chapter 33 — Structure Determination: 13C NMR, MS and IR Together

DEPT (distortionless enhancement by polarisation transfer) is a set of carbon-13 experiments that give the signals of carbons with attached protons a sign or an absence depending on their number of hydrogens. A quaternary carbon carries no hydrogen (bonded to four other atoms, or a carbonyl or aromatic carbon without H); it gives no DEPT signal.

Decoupled 13C spectra (measured shifts and heights, PubChem data) with the DEPT responses (signs from , heights schematic). Butan-2-one: C=O 209.3 (absent in DEPT), CH2 36.9 (down), CH3 29.4 and 7.9 (up). Ethyl benzoate: C=O 166.5 and the ring carbon bearing the ester, 130.6, vanish; three aromatic CH (132.8, 129.6, 128.3) stay in DEPT-90; OCH2 60.9 points down.
butan-2-one
Decoupled 13C spectra (measured shifts and heights, PubChem data) with the DEPT responses (signs from , heights schematic). Butan-2-one: C=O 209.3 (absent in DEPT), CH2 36.9 (down), CH3 29.4 and 7.9 (up). Ethyl benzoate: C=O 166.5 and the ring carbon bearing the ester, 130.6, vanish; three aromatic CH (132.8, 129.6, 128.3) stay in DEPT-90; OCH2 60.9 points down.
ethyl benzoate
Decoupled X13X2213C\ce{^{13}C} spectra (measured shifts and heights, PubChem data) with the DEPT responses (signs from Proposition 33.6, heights schematic). Butan-2-one: C=O 209.3 (absent in DEPT), CHX2\ce{CH2} 36.9 (down), CHX3\ce{CH3} 29.4 and 7.9 (up). Ethyl benzoate: C=O 166.5 and the ring carbon bearing the ester, 130.6, vanish; three aromatic CH (132.8, 129.6, 128.3) stay in DEPT-90; OCHX2\ce{OCH2} 60.9 points down.
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