Problem Solving for Elimination and Sub

Problem Solving for Elimination and Sub - Problem Solving...

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1 Problem Solving for Substitutions and Eliminations Use these guidelines to help you decide which reaction will predominate for a given substrate, reagent or solvent. These processes can be best understood by considering the fundamental aspects that control reaction rates, however this set of guidelines may also be useful in many cases. 1) Strong base or strong nucleophile will give second order kinetics (S N 2 or E2). This is because nucleophilic attack or proton abstraction occurs faster than carbocation formation (the energy pathway is lower for second order processes). Br CH 3 CH 2 OH S N 1 and E1 Br CH 3 CH 2 ONa S N 2 and E2 CH 3 CH 2 OH Br CH 3 CH 2 ONa CH 3 CH 2 OH E2 2) Primary substrates undergo S N 2 reactions. Primary carbocations are high energy species and are usually not formed unless special conditions are used. Nucleophilic substitution will happen by the S N 2 pathway. In the presence of strong, very hindered bases, E2 eliminations occur.
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Problem Solving for Elimination and Sub - Problem Solving...

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