Consider the following compound, which has been synthesized and characterized:(a) Assuming this molecule is entirely conjugated, do you expect it to be aromatic, antiaromatic, or nonaromatic?(b) Why was this molecule synthesized with three tert-butyl substituents? Why not makethe unsubstituted compound and study it instead?(c) Do you expect the nitrogen atom to be basic? Explain. Why doesn’t nitrogen’s lonepair overlap with the double bonds to give a total of six electrons in the pi system?(d) At room temperature, the proton NMR spectrum shows only two singlets of ratio 1:2. The smaller signal remainsunchanged at all temperatures. As the temperature is lowered to -110 °C, the larger signal broadens and separatesinto two new singlets, one on either side of the original chemical shift. At -110 °C, the spectrum consists of threeseparate singlets of areas 1:1:1. Explain what these NMR data indicate about the bonding in this molecule. How doesyour conclusion based on the NMR data agree with your prediction in part (a)?
Consider the following compound, which has been synthesized and characterized:
(a) Assuming this molecule is entirely conjugated, do you expect it to be
(b) Why was this molecule synthesized with three tert-butyl substituents? Why not make
the unsubstituted compound and study it instead?
(c) Do you expect the nitrogen atom to be basic? Explain. Why doesn’t nitrogen’s lone
pair overlap with the double bonds to give a total of six electrons in the pi system?
(d) At room temperature, the proton NMR spectrum shows only two singlets of ratio 1:2. The smaller signal remains
unchanged at all temperatures. As the temperature is lowered to -110 °C, the larger signal broadens and separates
into two new singlets, one on either side of the original chemical shift. At -110 °C, the spectrum consists of three
separate singlets of areas 1:1:1. Explain what these NMR data indicate about the bonding in this molecule. How does
your conclusion based on the NMR data agree with your prediction in part (a)?
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