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14.10 The chemical shifts for carbons are approximately 20 times larger than the chemical shifts for the hydrogens attached to that carbon. The signals are shifted downfield by nearby electron withdrawing groups, just as was the case for hydrogens. O 209.7 a) CH₃CH₂CH₂CH₂OH b) 41.9 26.6 13.6 19.1 35.0 61.4 24.6 O CH 14.11 a) The DU for this compound is 5. There are 5 different types of carbons in this molecule. The signal around 190 δ is due to a carbonyl carbon bonded to one H, so it is an aldehyde. The four signals in the 140 -120 δ region are due aromatic carbons. To have only four different aromatic carbons, the two CI substituents must be para. b) This compound has a DU of 1, and contains five different carbons. The signal at ~147 δ is an alkene CH₃CH₂ carbon that is not bonded to any hydrogens and the C CH₂ one at ~110 δ is an alkene type carbon that is bonded CH₃ to two hydrogens. The alkene accounts for the DU of 1. The only way to attach one CH₂ group and two CH₃ groups is to add an ethyl and a methyl group to the double bond. c) The compound has a DU of 2. It must have symmetry because the spectrum shows the presence of only three different types of carbons. There are probably two of each type because this sums to the correct formula, C₆H₁₀. The signal at ~128 δ is due to an alkene carbon (actually two of them) that is bonded to one hydrogen. This accounts for one C=C and for one DU, so the other DU must be due to a ring. The other C's are two sets of two identical CH₂ groups. Putting these carbons together gives the structure, cyclohexene. 215