CH 220 1st Edition Lecture 17 Outline of Current Lecture I. Sn2 reactionsII. The leaving groupIII. Sn1 reactionsCurrent Lecture I. Sn2 reactionsa. If you have larger neightbors around the C, it is harder for the nucleophile to react with it. The nucleophile favors small neighbors. Smallest possible neighborsare hydrogens.Reaction Substrates Solvents Nucleophile StereochemistrySn2 Methyl>1>2(never 3)Acetone or DMSONaCl, NaBr, NaI, NaCN, KCl, KBr, KI, KCNR -> SS -> RII. The leaving groupa. If a group is willing to leave, it will leave fasterb. Stable anions that are weak bases are usually excellent leaving groupsc. The more electronegative, the harder it is to leaveThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Lecture 17 III. Sn1 reactionsa. Unimolecular reaction – not concerned with nucleophile coming in, just wants to make a carbocationb. Different mechanism for each substratec. Most of the reaction begins before the nucleophile is addedd. The OH group gets protonated, allowing it to leave (OH is a bad leaving group, H2O is a good leaving group)e. The X gains an electron pair, resulting in a - chargef. The Carbon is now a carbocation (+ charge) [Transition State]g. The X attacks the carbocationReaction Substrates Solvents Nucleophile StereochemistrySn1 3 > 2never methyl or 1H2OAlcoholHCl, HBr, HI, HCN R -> R&SS -> S&RThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. CH 220 1st
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