CHEM 2OB3 Study Guide - Midterm Guide: Reaction Mechanism, Cyclopentane, Stoichiometry
5 Feb 2015
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This test contains 7 pages and 6 questions. Answers written in pencil will not be remarked. Guanine is one of the biological nitrogenous bases that make up dna. Note: if both rings are circled give the student the marks. Use an arrow to point to each and label each pair as inpl. [5] 2. (a) circle the most basic site on dimethylaminopyridine (dmap) and briefly explain your choice. (1) Protonation at the ring nitrogen atom results in a resonance-stabilized cation (1) Note: althought the resonance structures aid in answering the question, they are not necessary here for full marks. (b) briefly explain why cyclopentadiene is more acidic than cyclopentane. Simply stating that one compound has a lower pka than the other is not sufficient. pka = 15. 0 pka = approx. The conjugate base of cyclopentadiene is aromatic, and its formation is therefore highly favoured. This results in a lower pka value than for cyclopentane. (2)
