1. Why are 1-bond 1H - 13C couplings usually not observed in 1H NMR spectra? 2.

ID: 529154 • Letter: 1

Question

1. Why are 1-bond 1H - 13C couplings usually not observed in 1H NMR spectra?

2. 1H has

a) one spin state, b) two spin states, c) three spin states

3. if the intensity of an M+2 peak is 4.4% of the molecular ion's intensity, what element is present?

a) sulfur, b) bromine, c) chlorine

4. A compound shows a weak molecular ion at m/z = 142 and intense fragment peak at m/z = 124. What functional group most likely is present?

a) an ester, b) a ketone, c) an alcohol

5. Mass spectrometers are run at very low pressure to

a) ensure that intermolecular colllisions do not occur, b) ionize the sample, c) pull the ions though the instrument

6. Which of the following compounds has the most exothermic heat of hydrogenation?

a) hex-1-ene, b) trans-hex-3-ene, c) (Z) -3-methylhex-3-ene

7. Simmons-Smith cyclopropanation of 1,2-distributed alkenes is

a) non-diastereoselective, b) partially diastereoselective, c) completely diastereoselective

8. Which nucleus has a higher equilirium population excess of its alpha-spin state?

a) 1H, b) 13C, c) both

9. two compounds that are regioisomeric

10. the rate-determining step in the addition of hydrogen bromide to cyclopentane

1. H1 NMR detect only proton envrionment.

2.two spin states

3. sulfur

4. Ketone

5. ensure that intermolecular colllisions do not occur

6. (Z) -3-methylhex-3-ene

7.non-diastereoselective

8.13C

9. 1-bromopropane & 2-bromopropane

10. It should be rate-determining step in the addition of hydrogen bromide to cyclopentene

answer is protonation.

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