Exercise 1 If structure 2' makes a more important contribution to the resonance hybrid of propenal than structure 1' does to the resonance hybrid of 1,3-butadiene, would you expect the electron density to be greater on the methylene carbon in 1,3-butadiene or the methylene carbon in propenal? 1,3-butadiene propenal
Exercise 2 The word isostructural means that two compounds have the same basic geometry, i.e. the same shape or hybridization at each comparable atom. Styrene, C6H5CH=CH2, and benzaldehyde, C6H5CH=O, are two compounds that are isostructural. What is the hybridization of the oxygen atom in benzaldehyde? sp sp2 sp3
Exercise 3 Draw the structures of these molecules:
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styrene
benzaldehyde
Exercise 4 Draw a resonance structure for styrene comparable to resonance contributor 1' in Figure 1. Draw a resonance structure for benzaldehyde comparable to resonance contributor 2' in Figure 1.
Exercise 5 Would you expect the electron density to be higher in the aromatic ring of styrene or benzaldehyde? styrene benzaldehyde
Exercise 6 Would you expect the chemical shift of the ortho protons in styrene to be higher or lower than that of the ortho protons in benzaldehyde?higher lower