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downfield signal in the spectrum is the carbonyl carbon. The CH₂ group at 63 δ is the one bonded to the of the ester. Proceeding upfield, we see the next CH₂ of the butyl group, the CH₃ bonded to the carbonyl carbon, and the final CH₂ and CH₃ of the butyl group. The compound is butyl ethanoate. 14.26 The DU = 0. The presence of a broad OH band at 3300 cm⁻¹ in the IR spectrum shows that the compound is a saturated alcohol. The singlet at in the spectrum is due to H of the hydroxy group. It is not coupled because of fast chemical exchange. The triplet (integral = 2) at 3.6 δ is due to hydrogens of a CH₂ group attached to the hydroxy group, which is also bonded to another CH₂ group. So far, the structure of the unknown can be assigned as RCH₂CH₂OH, but the rest of the is difficult to interpret. The spectrum shows the presence of seven CH₂ groups and one CH₃ group. These fragments can only be assembled into a straight chain primary alcohol. The unknown is 1-octanol. 14.27 The DU = 2. The IR spectrum shows the presence of a carbonyl group and sp³-hybridized C-H bonds. The position of the carbonyl band (1721 cm⁻¹) is characteristic of a ketone. The absence of absorptions due to =C-H and C=C bands suggests that the compound has a ring. The spectrum is complex and not very useful. However, the doublet near (integral = 3) indicates the presence of a methyl group attached to a carbon with one hydrogen, CHCH₃. The is much more useful in this case. It shows the presence of only five different carbons, indicating some symmetry in the structure. Since there is only one carbonyl carbon (near 210 δ) and one CHCH₃ (from O the spectrum), there must be two of each of the CH₂ groups to sum to the formula C₇H₁₂O. To assemble these fragments, bond a CH₂ group to each side of the carbonyl carbon. Bond another CH₂ group to each of these. Next bond these CH₂ groups to the CH group, which is also bonded to the CH₃ CH₃ group. The compound is 4-methylcyclohexanone. 223