CHM136H1 Lecture Notes - Lecture 27: Rate-Determining Step, Nucleophilic Addition, Bromomethane
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CHM136H1 Full Course Notes
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Things are good nucleophiles for other reasons other than being a strong base. It isn"t necessarily easy to predict the nucleophilicity of atoms. Example is iodine vs hydroxide reacting with bromomethane. More basic nucleophiles of same func group reacts faster. Assuming affinity of atom is same as carbon. Better nucleophiles are lower in a column of a periodic table. A good leaving group reduces barrier to reaction. Could react backwards to make an equilibrium if stronger. If a group is very basic or very small, it requires more energy to break bond. Thus, these are called poor leaving groups bc they stay. Occurs in two steps with a carbocation intermediate. Equilibrium can occur between reactant and carbocation intermediate. If the carbocation can"t be formed, only sn2 occurs. The rate determining step is the formation of the carbocation. This is the highest energy peak shown in the graph. The highest peak is always the rate determining step, forward and backward.
