Organic Chemistry Laboratory I - Chem 341

Quiz 10c

1. How might the ratio of alkenes obtained in the tert-butoxide-promoted elimination reaction change if the tert-butyl alcohol contains water? (1 pt)

Any water might react with the t-BuOK to form t-butanol and KOH. The presence of KOH would favor elimination to form 2-methyl-2-butene. Thus, the ratio of the two products would change, in this case reducing the amount of 2-methyl-1-butene formed.

2. Circle the major organic product from the following reaction. (1 pt)

3. Circle the monomer in the polymer below. (1 pt)

4. Circle the confirmation that best represents the transition state for an E2 elimination that would result in the formation of 2-methyl-1-butene (2 pts)

The leaving group (Br) and the hydrogen atom must be antiperiplaner to each other.

5. Is polystyrene synthesized by a step-growth or chain-growth mechanism? (1 pt)

Styrene is synthesized by a chain-growth mechanism. In the chain-growth mechanism an initiator is used to start the polymerization and the polymer grows out by addition of one monomer at a time until the reactive end of the chain is terminated.

6. Explain why polystyrene is soluble in toluene but insoluble in methanol. (2 pts)

Polystyrene is a nonpolar polymer, therefore it is soluble in a nonpolar solvent like toluene. Methanol is very polar, so polystyrene is not soluble in methanol.

7. Propose an arrow pushing mechanism for the bromine test. (2 pts)