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Question: Tell how IR spectroscopy could be used to determine when each reaction is complete.

Question: Match each compound to its IR spectrum.

Question: Propose possible structure consistent with each set of data. Assume each compound has ${\mathbf{sp}}^{\mathbf{3}}$hybridized C-H absorption in its IR spectrum, and that other major IR absorption above 1500${\mathbf{cm}}^{\mathbf{-}\mathbf{1}}$are list.

1. A compound having a molecular ion at 72 and an absorption in its IR spectrum at 1725 ${\mathbf{cm}}^{\mathbf{-}\mathbf{1}}$.
2. A compound having a molecular ion at 55 and an absorption in its IR spectrum at 2250 ${\mathbf{cm}}^{\mathbf{-}\mathbf{1}}$.
3. A compound having a molecular ion at 74 and an absorption in its IR spectrum at 3600-3200 ${\mathbf{cm}}^{\mathbf{-}\mathbf{1}}$.

Question: A chiral hydrocarbon X exhibits a molecular ion at 82 in its massspectrum. The IR spectrum of X shows peaks at 3300, 3000–2850, and 2250 cm^-1. Propose a structure for X.

Question: What molecular ions would you expect for the compound depicted in the ball-and-stick model?

Question:A chiral compound Y has a strong absorption at 2970–2840 ${\mathbf{cm}}^{\mathbf{-}\mathbf{1}}$in its IR spectrum and gives the following mass spectrum. Propose a structure for Y.

Question: Treatment of benzaldehyde (${\mathbf{C}}_{\mathbf{6}}{\mathbf{H}}_{\mathbf{5}}\mathbf{CHO}$) with Zn(Hg) in aqueous HCl forms a compound Z that has a molecular ion at 92 in its mass spectrum. Z shows absorptions at 3150–2950, 1605, and 1496 cm^-1 in its IR spectrum. Give a possible structure for Z.

Question: Reaction of tert-butyl pentyl ether $\mathbf{}\mathbf{\left[}{\mathbf{CH}}_{\mathbf{3}}{\mathbf{CH}}_{\mathbf{2}}{\mathbf{CH}}_{\mathbf{2}}{\mathbf{CH}}_{\mathbf{2}}{\mathbf{CH}}_{\mathbf{2}}\mathbf{OC}{\mathbf{\left(}{\mathbf{CH}}_{\mathbf{3}}\mathbf{\right)}}_{\mathbf{3}}\mathbf{\right]}$with HBr forms 1-bromopentane$\mathbf{\left(}{\mathbf{CH}}_{\mathbf{3}}{\mathbf{CH}}_{\mathbf{2}}{\mathbf{CH}}_{\mathbf{2}}{\mathbf{CH}}_{\mathbf{2}}{\mathbf{CH}}_{\mathbf{2}}\mathbf{Br}\mathbf{\right)}$ and compound B. B has a molecular ion in its mass spectrum at 56 and gives peaks in its IR spectrum at 3150–3000, 3000–2850, and 1650 cm^-1. Propose a structure for B and draw a stepwise mechanism that accounts for its formation.

Question:Reaction of pentanoyl chloride $\left({\mathbf{CH}}_3{\mathbf{CH}}_2{\mathbf{CH}}_2{\mathbf{CH}}_2\mathbf{COCl}\right)$ with lithium dimethyl cuprate $\left[\mathbf{LiCu}{\left({\mathbf{CH}}_3\right)}_2\right]$forms a compound J that has a molecular ion in its mass spectrum at 100, as well as fragments at m/z= 85, 57, and 43 (base). The IR spectrum of J has strong peaks at 2962 and 1718 cm–1. Propose a structure for J.

Question:Benzonitrile (C₆H₅CN) is reduced to two different products depending on the reducing agent used. Treatment with lithium aluminum hydride followed by water forms K, which has a molecular ion in its mass spectrum at 107 and the following IR absorptions: 3373, 3290, 3062, 2920, and 1600 cm^-1. Treatment with a milder reducing agent forms L, which has a molecular ion in its mass spectrum at 106 and the following IR absorptions: 3086, 2820, 2736, 1703, and 1600 cm^-1. L shows fragments in its mass spectrum at m/z= 105 and 77. Propose structures for K and L and explain how you arrived at your conclusions.