5_Nucleophilic_Aromatic_Substitution

5_Nucleophilic_Aromatic_Substitution - Chem 267 Basic...

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
Prof. Dr. Xiangdong Fang University of Waterloo Chem 267 Basic Organic Chemistry II 1
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
2 Nucleophilic Aromatic Substitution Reactions 1) the S N Ar mechanism (addition-elimination) 2) benzyne mechanism (elimination-addition) 3) diazonium salts with “aryl-cation or radical” intermediate
Background image of page 2
3 Nucleophilic Aromatic Substitution Reactions “for electron-deficient aromatic rings with strong deactivator substituent(s), e.g. –NO 2
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
4 Stabilized Anionic Intermediate
Background image of page 4
5 Different Mechanism Without Electron-Withdrawing Group “go via elimination-addition mechanism Cl NaOH 350 o C, 300 atm OH Cl NaOH 350 o C, 300 atm H OH Cl OH unstable benzyne +H 2 O + NaCl OH OH sp 2 carbanion H 2 O OH H + OH elimination nucleophilic addition
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
6 side view front view benzyne sp 2 -sp 2 overlap not efficient Benzyne: a very strained cycloalkyne “extremely reactive and can not be isolated (the triple bond is very weak)”
Background image of page 6
7 Supporting Evidence for Benzyne Intermediate 1) chlorobenzene is labelled with 13 C isotope at the carbon directly bonded to Cl group; 2) 13 C isotope is scrambled evenly between two adjacent carbon atoms;
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 8
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

Page1 / 11

5_Nucleophilic_Aromatic_Substitution - Chem 267 Basic...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online