Problem Set (PS) K3 – 13C–NMR Spectroscopy & Mass Spec Smith Sections A & C (15 points)

Other Problems – Gradable

1. Draw all possible constitutional isomers of C5H11Br and for each indicate how many different kinds of carbons (unique carbons) are present in each structure. [Hint: There should be at least 8 constitutional isomers.)

2. Explain in detail how you would distinguish between the following set of constitutional isomers using 13C–NMR.

3. Compound UWT–S (C8H16) reacts with one mole of bromine to form product C8H16Br2. Compound UWT–S has the broadband proton–decoupled 13C–NMR spectrum shown below. The number of protons attached to each carbon, as determined by DEPT, is in the boxes next to each peak. Propose a structure for UWT–S.

4. In the mass spectrum of 2,6–dimethyl–4–heptanol there are prominent peaks at m/z =87, 111, and 126.
a). At what m/z value would you find the molecular ion for this compound?
b) Propose reasonable structures for the fragment ions observed.