Chemistry 2223B- Final Exam Guide - Comprehensive Notes for the exam ( 25 pages long!)
29 Mar 2018
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Topic 3. 1: amino acids, peptides, and proteins part i. Most are -amino acids; amino group is attached to carbon that is to the carboxylic acid. All are primary amines with the exception of proline (cyclic secondary amine) All have a carbon side-chain (r) with the exception of glycine (r = h) The amide bond of polypeptides does not behave like an amide because it has resonance structure: the actual bond is an intermediate between the two resonance contributing structure. Hydrolysis of acid derivatives (i. e. amides, esters, anhydrides) In acidic conditions, the amine will become positively charged while the carboxyl is neutral. Oh- acts as the nucleophile: oh- attacks carboxyl carbon, c=o bond is lost, amino group is protonated by water, good leaving group is formed, hydroxyl group is deprotonated by base to form water. C=o bond is reformed, ejecting the leaving group. In basic conditions, the carboxyl will become negatively charged while the amine is neutral.
