91Ó°ÊÓ

How do the IR spectra of the isomers cyclopentane and 1 -pentene differ?

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

Which of the indicated bonds absorbs at higher \(\bar{v}\) in an IR spectrum? a. \(\left(\mathrm{CH}_{2}\right)_{2} \mathrm{C}=\mathrm{O}\) or \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CH}=\mathrm{OH} \quad\) b. \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{C}=\mathrm{NCH}_{3}\) or

Propose possible structures consistent with each set of data. Assume each compound has an \(s p^{3}\) hybridized \(\mathrm{C}-\mathrm{H}\) absorption in its IR spectrum, and that other major IR absorptions above \(1500 \mathrm{~cm}^{-1}\) are listed. a. A compound having a molecular ion at 72 and an absorption in its IR spectrum at \(1725 \mathrm{~cm}^{-1}\) b. A compound having a molecular ion at 55 and an absorption in its IR spectrum at \(-2250 \mathrm{~cm}^{-1}\) c. A compound having a molecular ion of 74 and an absorption in its IR spectrum at \(3600-3200 \mathrm{~cm}^{-1}\)

Treatment of anisole \(\left(\mathrm{CH}_{3} \mathrm{OC}_{6} \mathrm{H}_{5}\right)\) with \(\mathrm{Cl}_{2}\) and \(\mathrm{FeCl}_{3}\) forms \(\mathrm{P}\), which has peaks in its mass spectrum at \(\left.\mathrm{m} / \mathrm{z}=142 \mathrm{(M}\right)\), \(144(\mathrm{M}+2), 129\), and \(127 . \mathrm{P}\) has absorptions in its IR spectrum at \(3096-2837\) (several peaks), 1582 , and \(1494 \mathrm{~cm}^{-1}\). Propose possible structures for \(\mathrm{P}\).