91Ó°ÊÓ

Question:Propose a structure consistent with each set of data.

a. a compound that contains a benzene ring and has a molecular ion at m/z= 107

b. a hydrocarbon that contains only sp3 hybridized carbons and a molecular ion at m/z= 84

c. a compound that contains a carbonyl group and gives a molecular ion at m/z= 114

d. a compound that contains C, H, N, and O and has an exact mass for the molecular ion at

101.0841

Question:A low-resolution mass spectrum of the neurotransmitter dopamine gave a molecular ion at m/z= 153. Two possible molecular formulas for this molecular ion are ${\mathbf{\text{C}}}_{\mathbf{\text{8}}}{\mathbf{\text{H}}}_{\mathbf{\text{11}}}{\mathbf{\text{NO}}}_{\mathbf{\text{2}}}$and ${\mathbf{C}}_7{\mathbf{H}}_{11}{\mathbf{N}}_3\mathbf{O}$. A high-resolution mass spectrum provided an exact mass at 153.0680. Which of the possible molecular formulas is the correct one?

Question:Primary (1°) alcohols often show a peak in their mass spectra at m/z= 31. Suggest a structure for this fragment.

Question: What molecular ions would you expect for compounds having each of the following molecular formulas: (a)${\mathbf{C}}_4{\mathbf{H}}_9\mathbf{Cl}$; (b)${\mathbf{C}}_3{\mathbf{H}}_7\mathbf{F}$; (c)${\mathbf{\text{C}}}_{\mathbf{\text{4}}}{\mathbf{\text{H}}}_{\mathbf{\text{11}}}\mathbf{\text{N}}$; (d)${\mathbf{\text{C}}}_{\mathbf{\text{4}}}{\mathbf{\text{H}}}_{\mathbf{\text{4}}}{\mathbf{\text{N}}}_{\mathbf{\text{2}}}$?

Question:Like alcohols, ethers undergo α cleavage by breaking a carbon–carbon bond between an alkyl group and the carbon bonded to the ether oxygen atom; that is, the red C–C bond in $\mathbf{R}–{\mathbf{CH}}_2\mathbf{OR}\text{'}$is broken. With this in mind, propose structures for the fragments formed by α cleavage of${\left({\mathbf{CH}}_3\right)}_2{\mathbf{CHCH}}_2{\mathbf{OCH}}_2{\mathbf{CH}}_3$. Suggest a reason why an ether fragments by α cleavage.

Question: Which of the highlighted bonds absorbs at higher $\mathbf{ν}$in an IR spectrum?

Question: What major IR absorptions are present above 1500 ${\mathbf{cm}}^{\mathbf{-}\mathbf{1}}$for each compound?

Question: How would each of the following pairs of compounds differ in their IR spectra?

Question: Morphine, heroin, and oxycodone are three addicting analgesic narcotics. How could IR spectroscopy be used to distinguish these three compounds from each other?

Question:Reduction of cyclohex-2-enone can yield cyclohexanone, cyclohex-2-enol, or cyclohexanol, depending on the reagent and reaction conditions. How could you use IR spectroscopy to distinguish the three possible products?