MS 912 - Benzyl Position and Aromaticity

MS 912 - Benzyl Position and Aromaticity

Textbook and Chapter: Carey and Giuliano 8th Ed. (2010), Chapter 11

Keywords: aromaticity, benzylic position, heteroaromatic compounds

Description: Goes over benzene, aromaticity, and the benzyl position (1 carbon away from benzene).
Lots of aromatic resonance practice.

Total Problems: 5

  1. Problem # 580

    Draw all resonance forms for each species.

    For the anion and cation species, used curved arrows. For the radical species, use hooks.

  2. Problem # 581

    Draw all products for the two reactions below.

    The allylic alkene gives two products- the 1,2 product, and the 1,4 product. 

    However, the benzylic alkene only gives the one product (analogous to the 1,2 product), instead of multiple products (like the 1,4 product, 1,6 product, and 1,8 product). Why is this the case?

  3. Problem # 582

    Rationalize the follwing pKa values. Explain your answer in terms of the stabilites of the conjugates bases of each acid.

    Note: the lower the pKa, the stronger the acid.

  4. Problem # 583

    Pyrrole is an example of a heteroaromatic compound: it contains a heteroatom (atom that is not carbon or hydrogen, such as N, O, S, etc.), and is aromatic.

    Because pyrrole is aromatic, we should be able to draw many resonance forms- usually as many resonance forms as sides (in this case, five sides, so five resonane forms).

    Draw all resonance forms for pyrrole. (I've started you off.)

  5. Problem # 584

    Imidazole (shown below) has two nitrogen atoms, N-1 and N-3. Which nitrogen is more basic?

    To answer this problem, draw the product after each nitrogen protonates, and compare their stabilities. Explain your reasoning.