1. A hydrocarbon with six carbon atoms exhibits a proton NMR spectrum with sever
ID: 843128 • Letter: 1
Question
1. A hydrocarbon with six carbon atoms exhibits a proton NMR spectrum with several peaks in the 1.0 - 2.0 ppm chemical shift range in addition to several peaks in the 6.0 ppm chemical shift range. What is most likely the identity of this molecule?
a. 4-methylpent-1-yne
b. hexane
c. 3-methylpent-2-ene
d. hexyne
2. The gas phase IR spectrum of butan-1-ol exhibits a sharp band at approximately 3500 cm-1, while in the liquid phase the same molecular vibration exhibits a broad band at approximately 3000-3400 cm-1. The best explanation for this observation is:
a. Butan-1-ol has a lower temperature in the liquid phase compared to the gas phase.
b. Hydrogen bonding interactions in the liquid phase result in a broad range of vibrational frequencies for the -OH stretch mode.
c. The higher density of molecules in the liquid phase compared to the gas phase cause the IR band to broaden.
d. Butan-1-ol isomerises to butan-2-ol in the liquid phase.
3. How many unique chemical environments can be identified using proton NMR spectroscopy for the hydrogen atoms in pentan-2-one?
Explanation / Answer
1.4-methyl pent1-yne
2.b due to hydrogen bonding
3. if pentene 2one gives 4 types of signal
if pentanone only 2 tpes of peaks observed
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