Docsity
Docsity

Prepare for your exams
Prepare for your exams

Study with the several resources on Docsity


Earn points to download
Earn points to download

Earn points by helping other students or get them with a premium plan


Guidelines and tips
Guidelines and tips

Nucleophilic Aromatic Substitution, Lecture notes of Organic Chemistry

Benzyne Mechanism, Nucleophilic Aromatic Substitution for Hydrogen.

Typology: Lecture notes

2020/2021

Uploaded on 06/21/2021

salim
salim 🇺🇸

4.4

(24)

243 documents

1 / 15

Toggle sidebar

This page cannot be seen from the preview

Don't miss anything!

bg1
A Green Chemistry Module
Nucleophilic Aromatic Substitution
Presidential Green Chemistry Challenge Award
Elimination of Chlorine in the Synthesis of 4-Aminodiphenylamine.
A New Process Which Utilizes Nucleophilic Aromatic Substitution
for Hydrogen
pf3
pf4
pf5
pf8
pf9
pfa
pfd
pfe
pff

Partial preview of the text

Download Nucleophilic Aromatic Substitution and more Lecture notes Organic Chemistry in PDF only on Docsity!

A Green Chemistry Module

Nucleophilic Aromatic Substitution

Presidential Green Chemistry Challenge Award

Elimination of Chlorine in the Synthesis of 4-Aminodiphenylamine.

A New Process Which Utilizes Nucleophilic Aromatic Substitution

for Hydrogen

LG

Nu

LG

Nu

Nu

slow^ RDS fast LG

Meisenheimer Complex Resonance Stabilized

ADDITION ELIMINATION

SNAr Mechanism - addition / elimination

CF 3 , CN, CHO, COR, COOH, Br, Cl, I Common Activating Groups for NAS

LG Nu

LG Nu (^) Nu

LG

Resonance Stabilization of the Intermediate Anion[The Meisenheimer Complex]

C

O

O

N H 3

C

O

O

N N

O D i e l s / A l d e r

O

B E N Z Y N E

Dienophile Diene A d d u c t

Evidence for the Benzyne Mechanism

Trapping in Diels/Alder Reaction

LG

Substituent Substituent Base No Reaction

Substrate Modification – absence of α hydrogens

LG

H

Nu Nu

Isotopic Labeling

SN1 Mechanism

N N

slow

Nu Nu

Aryl Cation

N 2 RDS

Brown Chemistry Route to 4-ADPA

Cl (^2) c a t a l y s t

Cl HNO (^3)

Cl

NO (^2)

Cl

P N C B

E l e c t r o p h i l i c A r o ma t i c S u b s t i t u t i o n NO 2

Cl

NO 2

N (^) H

O C H

K 2 CO 3 N

H NO 2 KCl CO CO 2 4 - NDPA H 2 Catalyst

N

H NH 2 4 - ADPA

Nucleophilic Aromatic Substitution

PNCB

various organics

Atom Economy of the Traditional Chemistry

Cl 2

Cl HNO 3

Cl NO 2

Cl

30% 70% NO 2 N

H CO H N^ H NO 2 K^2 CO^3 H 2 N

H NH 2

1

(^2 )

(^54) 6

Reagent formula Reagent FW Utilized Atoms Wt Unutilized Atoms Wt 1 C 6 H 6 78 6C ,4H 53 2 H 2 2 Cl 2 70 ------------ 0 2 Cl 70 3 HNO 3 63 1 N 14 1 H, 3 O 49 4 C 7 H 7 NO 121 6 C, 6 H, 1 N 92 1 C, 1 O, 1 H 29 5 K 2 CO 3 98 ------------ 0 2 K, 1 C, 3 O 98 6 H 2 2 2 H 2 -------------- 0 TOTAL^432 12C ,12H, 2N^161 2C ,4H, 2C ,2K, 7O^248

H

NO 2

Nu: H^ Nu

N O O

H Nu

N O O

Nu

N O O

Nucleophilic Aromatic Substitution for Hydrogen

General Mechanism

NO 2

H NH 2

Base N

H

N

O

H O

Base-Promoted Coupling Reaction

Flexsys Route to 4-ADPA

Base-Promoted Coupling Reaction

Flexsys - Intermolecular Oxidation Pathway

Atom Economy of the Flexsys Chemistry

HNO 3

NO 2 NHH

N NO 2

H

H 2

N NH 2

H

Reagent Formula Reagent FW Utilized Atoms^ Wt Unutilized Atoms Wt 1 C 6 H 6 78 6 C, 4 H 76 2 H 2 2 HNO 3 63 1 N 14 1 H, 3 O 49 3 C 6 H 7 N 93 6 C, 6 H, N 92 1 H 1 4 H 2 2 2 H 2 ----------- 0 TOTAL 236 12C, 12 h, 2 n 184 4H, 3O 52