Lesson28 - Nucleophilic Addition Reactions - Adding XY...

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Unformatted text preview: Nucleophilic Addition Reactions - Adding XY Across Unsaturated C=Z and C=C Bonds 1) Acid-Base - hydrogen swap 2 & 3) Oxidation & Reduction 4) Substitution- replace C’s substituent (-X) with another (-Y), neither being -H X C Y C Y + X + neither X nor Y being hydrogen Y replaces X 5) Elimination- loss of XY elements with concomitant pi bond formation 6) Addition- gain of XY elements with concomitant loss of pi bond reduction X C H C oxidation H replaces X X replaces H change in the number of C-H bonds in relation to the number of C-X bonds X C Z Z Y C + X Y elimination addition form π bond-XY break π bond +XY base H X H Y Y + X + base acid acid 7) Rearrangement- isomerization process (no atoms lost or gained); results in new bonding connectivity (one of many examples shown as there is no generic representation). R CH 3 R R stands for a generic "residue" Z = C, N, O We previously studied the electrophilic addition of “XY” across carbon-carbon multiple bonds. Here we examine the nucleophilic variations of addition. We will consider C=C and C=Z π-bonds (where Z is a heteroatom such as O or N). Nucleophilic Addition to Polarized π-Bonds: Three Examples CH 3 CH 2 MgBr O CH 3 H an aldehyde 2) H Cl / H 2 O 1) , Et 2 O a Grignard reagent H C H 3 C CH 2 CH 3 O H CH 3 O CH 3 H O H H B H H H Na NaBH 4 sodium borohydride NaB H 4 CH 3 O H C Na CN , H CN 80 ˚C C H H H C H NC H H H C O CH 3 C C O CH 3 Nucleophilic Addition to Polarized π-Bonds: Three Examples CH 3 CH 2 MgBr O CH 3 H an aldehyde 2) H Cl / H 2 O 1) , Et 2 O a Grignard reagent H C H 3 C CH 2 CH 3 O H CH 3 O CH 3 H O H H B H H H Na NaBH 4 sodium borohydride NaB H 4 CH 3 O H C Na CN , H CN 80 ˚C C H H H C H NC H H H C O CH 3 C C O CH 3 Addition Mechanisms Require a New Elementary Step: Nucleophile Addition to a C=O π-bond [Ad...
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This note was uploaded on 01/25/2012 for the course CHEM 232 taught by Professor Miller during the Spring '08 term at University of Illinois, Urbana Champaign.

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Lesson28 - Nucleophilic Addition Reactions - Adding XY...

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