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What is the most useful information you can get from a #C^13 NMR# spectrum?

Answer 1

The most useful information you can get from a #""^13"C"# NMR spectrum is the number of non-equivalent carbon atoms.

For example, you have the #""^13"C"# NMR spectrum of an unknown ester.

Is its structure (a) CH₃CH₂COOCH₂CH₂CH₃, (b) CH₃CH₂COOCH(CH₃)₂, or (c) CH₃COOC(CH₃)₃?

You quickly calculate that

(a) has 6 different C atoms;
(b) has two equivalent C atoms, so there only 5 different carbon environments;
(c) has three equivalent C atoms, so there only 4 different carbon environments.

The spectrum shows 5 carbon signals, so the ester must be (c) isopropyl propanoate.

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Answer 2

Jacob Anderson

A carbon-13 (C^13) NMR spectrum provides information about the types of carbon environments present in a compound. It reveals the number of different carbon environments, their chemical shifts, and indirectly gives insights into the surrounding functional groups. The spectrum helps in identifying and characterizing carbon atoms in a molecule, aiding in structural determination.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.