substitution reaction

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TERM PAPER TERM PAPER

CHEMISTRY (CHE 101) CHEMISTRY (CHE 101)

Topic:

SUBSTITUTION REACTIONSSUBSTITUTION REACTIONS

DOA:

DOA: SEPT

SEPT 2,

2, 2010

2010

DOR:

DOR: SEPT30,

SEPT30, 2010

2010

DOS:

DOS: NOV10,

NOV10, 2010

2010

S

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Ms

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. V

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bh

hu

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a

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Mrr.

. A

Am

ma

an

nd

de

ee

ep

p S

Siin

ng

gh

h K

Kh

he

erra

a

Deptt.

Deptt. Of

Of Chemistry

Chemistry

Roll.

Roll. No.

No. RK6005A19

RK6005A19

Reg.No. 11000597

Class K6005

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ACKNOWLEDGEMENT

It acknowledges all the contributors involved in the preparation of this project. Including me, It acknowledges all the contributors involved in the preparation of this project. Including me, there is a hand of my teachers, some books and internet. I express most gratitude to my subject there is a hand of my teachers, some books and internet. I express most gratitude to my subject teacher, who guided me in the right direction. The guidelines provided by her helped me a lot in teacher, who guided me in the right direction. The guidelines provided by her helped me a lot in completing the assignment.

completing the assignment.

The books and websites I consulted helped me to describe each and every point mentioned in this The books and websites I consulted helped me to describe each and every point mentioned in this project. Help of original creativity and illustration had taken and I have explained each and every project. Help of original creativity and illustration had taken and I have explained each and every

aspect of the project precisely. aspect of the project precisely.

At last it acknowledges all the members who

At last it acknowledges all the members who are involved in the preparation are involved in the preparation of this project.of this project.

Thanks

AMANDEEP SINGH

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ABSTRACT

In

In a

a su

subs

bsti

titu

tuti

tio

on

n re

reac

acti

tion

on,

, a

a fun

fun

cti

on

al

gr

ou

p

iin

n a

a p

pa

arrti

ticu

cullar

ar chemical

chemical

compound

iis

s rrep

epla

lace

ced

d b

by

y an

ano

oth

ther

er g

grro

ou

up

p

..

In

In o

org

rgan

anic

ic ch

chem

emis

istr

try,

y, th

the

e

electrop

electrophilic and

hilic and nucleop

nucleophilic substitution reactions are

hilic substitution reactions are of

of prime importance.

prime importance.

Aft

After

er go

going

ing thr

throu

ough

gh thi

this

s on

one

e can

can eas

easily

ily un

under

derst

stand

and wh

what

at is

is su

sub

bstitution

stitution

reaction. One can account for various types of substitution reaction n there

mec

mechan

hanis

ism

m i.e

i.e.

. SN1

SN1 an

and

d SN2

SN2.

. Her

Here

e we

we wi

will

ll ta

take

ke acc

accou

ount

nt of

of su

subs

bstit

tituti

ution

on

re

react

actio

ions

ns lik

like

e nu

nucle

cleop

ophi

hilic

lic su

subs

bstit

titut

utio

ion

n an

and

d ele

electr

ctrop

ophil

hillic

lic su

subs

bstit

tituti

ution

on

re

react

actio

ions.

ns. We

We wi

will

ll tal

talk

k abo

about

ut su

subs

bstit

titut

uted

ed com

compo

poun

unds

ds,

, co

contr

ntrol

ollin

ling

g li

ligan

gand

d

substitution reactions. We will talk about use of substitution reactions in day

to day life and its importance. We will account for applications an d future

prospective of substitutions reaction and its day to day need. We will come

across how radical substitution reaction occurs n their importance. We will

come across various steps required for radical substitution.

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TABLE OF CONTENT

1. 1. IN

INTR

TROD

ODUC

UCTI

TION

ON

2. 2. NUCL

NUCLEOPH

EOPHILIC

ILIC SUBS

SUBSTIT

TITUTION

UTION

3. 3. ELECT

ELECTROPH

ROPHILIC

ILIC SUBS

SUBSTIT

TITUTIO

UTION

N

3.1

ELECTROPHILIC AROMATIC SUBSTITUTIONELECTROPHILIC AROMATIC SUBSTITUTION

3.2

ELECTROPHILIC ALIPHATIC SUBSTITUTIONELECTROPHILIC ALIPHATIC SUBSTITUTION

4. 4. RAD

RADICA

ICAL SUB

L SUBST

STITU

ITUTIO

TION

N

5. 5. SUB

SUBST

STITU

ITUTED CO

TED COMP

MPOUN

OUNDS

DS

6. 6. MEC

MECHAN

HANISM

ISM OF R

OF REAC

EACTI

TION

ON

6.1

6.1 SN

SN

11

MECHANISM

6.2

6.2 SN

SN

22

MECHANISM

7. 7. AP

APPL

PLIC

ICAT

ATIO

IONS

NS

8. 8. FUT

FUTURE

URE PRO

PROSP

SPECT

ECTIVE

IVE

9.

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INTRODUCTION

In

In a

a su

subs

bsti

titu

tuti

tion

on re

reac

acti

tion

on,

, a

a fu

func

ncti

tion

onal

al gr

grou

oup

p in

in a

a pa

part

rtic

icul

ular

ar ch

chem

emic

ical

al

compound is replaced by another group. The term substitution is derived

from the word ‘substitute’ which means putting one thing in place of other

..

In organic

In organic chemistry

chemistry,

, the electrophilic and

the electrophilic and nucleop

nucleophilic substitution reactions

hilic substitution reactions

are

are of

of pri

prime

me impo

importan

rtance.

ce. Org

Organic

anic sub

substit

stitutio

ution

n rea

reactio

ctions

ns are

are clas

classifi

sified

ed in

in

several main organic reaction types depending on whether the reagent that

brings about the substitution is considered an electrophile or a nucleophile,

whether a reactive intermediate involved in the reaction is a carbocation, a

carbanion or a free radical or whether the substrate is aliphatic or aromatic.

De

Detai

tailed

led un

unde

derst

rstand

andin

ing

g of

of a

a rea

reacti

ction

on typ

type

e hel

helps

ps to

to pr

predi

edict

ct th

the

e pr

prod

oduc

uctt

outcome in a reaction. It also is helpful for optimizing a reaction with regard

to variables such as temperature and choice of solvent.

A good example of a substitution reaction is the photochemical chlorination

of methane forming methyl chloride.

In

In th

the

e ab

abov

ove

e re

reac

acti

tio

on

n Cl

Cl

22

an

and

d CH

CH

44

ar

are

e re

reac

acta

tant

nts

s an

and

d ta

take

ke pa

part

rt in

in a

a

substitution reaction. In this reaction Cl replaces H from CH

44

in the presence

of sunlight to form CH

33

Cl.

There are various substitution reactions include –

•

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•

Electrophilic substitution

•

Radical substitution

•

Substituted compound

NUCLEOPHILIC SUBSTITUTION

In

In organicorganic andand inorinorganganic ic chemchemistristryy, , nucnucleopleophilihilic c subssubstitutitution tion is is a a funfundamedamentantal l claclassss of

of substitusubstitution tion reactionreaction in which an "electron rich"in which an "electron rich" nucleophilenucleophile selectively bonds with or selectively bonds with or attacks the positive or partially positive charge of an atom attached to a group or atom attacks the positive or partially positive charge of an atom attached to a group or atom c

caalllled ed tthhe e ggrrooupup. . TThhe e ppoosisittivive e oor r ppaartrtiaialllly y ppososititivive e aatotom m is is rrefefeerrrred ed to to aass an

an electrophileelectrophile.Nucleophilic substitution happens when the reagent is a nucleophile,.Nucleophilic substitution happens when the reagent is a nucleophile, wh

which ich memeansans, , an an atatom om or or momoleclecule ule witwith h frefree e eleelectctronrons. s. AA nucleophilenucleophile reacreacts ts witwithh an

an aliphaticaliphaticssuubbssttrraatte e iin n aa nunuclcleoeophphililic ic alipaliphahatitic c susubsbstititututitionon rereacactitionon. . ThThesesee substitutions can be produced by two different mechanisms: unimolecular nucleophilic substitutions can be produced by two different mechanisms: unimolecular nucleophilic substitut

substitution ion (SN(SN11) and bimolecular nucleophilic substitution (SN) and bimolecular nucleophilic substitution (SN22). The SN). The SN11 mechanismmechanism has two steps. In the first step, the leaving group departs, forming a carbocation. In the has two steps. In the first step, the leaving group departs, forming a carbocation. In the second step, the nucleophilic reagent attacks the carbocation and forms a

second step, the nucleophilic reagent attacks the carbocation and forms a sigma bond.sigma bond. Th

This is memechchananism ism can can reresusult lt in in eiteither her invinverersiosion n or or retretentention ion of of coconfinfigurguratationion. . AnAn SN

SN22 reaction has just one step. The attack of the reagent and the expulsion of thereaction has just one step. The attack of the reagent and the expulsion of the leaving group happen simultaneously. This mechanism always results in inversion of leaving group happen simultaneously. This mechanism always results in inversion of co

confnfigigururatatioion. n. WhWhen en ththe e susubsbstrtratate e is is anan aromaticaromatic cocompmpouound nd ththe e rereacactition on tytypepe is

is nucleophnucleophilic ilic aromatic substitutionaromatic substitution.. CarboxyCarboxylic lic acidacid derivatives react with nucleophilesderivatives react with nucleophiles in

in nuclnucleopeophilihilic c acyacyl l subssubstitutitutiontion. . ThThis is kikind nd of of rereacactition on cacan n be be ususefeful ul in in prprepeparariningg compounds.

compounds.

The most general form for the reaction may be given as The most general form for the reaction may be given as

Nuc

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The electron pair (

The electron pair (::) from the nucleophile (Nuc) attacks the substrate (R-LG) forming a) from the nucleophile (Nuc) attacks the substrate (R-LG) forming a new bond, while the leaving group (LG) departs with an electron pair. The principal new bond, while the leaving group (LG) departs with an electron pair. The principal product in this case is R-Nuc. The nucleophile may be electrically neutral or negatively product in this case is R-Nuc. The nucleophile may be electrically neutral or negatively charged, whereas the substrate is typically neutral or positively charged.

charged, whereas the substrate is typically neutral or positively charged. An example of nucleophilic substitution is the

An example of nucleophilic substitution is the hydrolysishydrolysis of anof an alkylalkyl bromidebromide,, RR-Br,-Br, under alkaline conditions, where the

under alkaline conditions, where the attacking attacking nucleophile is thenucleophile is the OHOH−−_{and the}_{and the leaving}_leaving

group group isis Br Br --_.. R-Br + OH R-Br + OH−− _{→ R-OH + Br}_{→ R-OH + Br}−−

ELECTROPHILIC SUBSTITUTION

E

Elleeccttrroopphhiilliic c ssuubbssttiittuuttiioon n rreeaaccttiioonns s aarre e cchheemmiiccaal l rreeaaccttiioonns s iin n wwhhiicchh an

an electrophileelectrophile ddiissppllaaccees s a a ggrroouup p iin n a a cocommppoouunndd, , ttyyppiiccaalllly y bbuut t nnoott always

always hydrogenhydrogen.. EElleeccttrroopphhiilliic c aarroommaattiic c ssuubbssttiittuuttiioonn iis s cchhaarraacctteerriissttiicc of

of aromaticaromatic cocompmpounounds ds anand d is is an an imimporportatant nt waway y of of intintrodroducucing ing fufunctnctionional al grgroupoupss onto

onto benzenebenzene rings. The other main reaction type isrings. The other main reaction type is electrophilic aliphatic substitutionelectrophilic aliphatic substitution..

ELECTROPHILIC AROMATIC SUBSTITUTION – ELECTROPHILIC AROMATIC SUBSTITUTION – In electrophilic substitution in

In electrophilic substitution in aromatic aromatic compouncompoundsds, an atom appended to the, an atom appended to the aromaticaromatic ring

ring, usually hydrogen is replaced by an electrophile. The most important reactions of , usually hydrogen is replaced by an electrophile. The most important reactions of tthhis is ttyype pe tthhaat t ttaakke e pplalacce e aarree aromaromatic atic nitrnitratioationn,, aromaromatic atic halohalogenagenationtion,, aromaticaromatic sulfonation

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ELECTROPHILIC ALIPHATIC SUBSTITUTION – ELECTROPHILIC ALIPHATIC SUBSTITUTION –

IIn n eelleeccttrroopphhiilliic c ssuubbssttiittuuttiioon n iinn aliphaticaliphaticccomompopounundds, s, anan electrophileelectrophile displacesdisplaces a

a functional groupfunctional group. This reaction is similar to. This reaction is similar to nucleophilic aliphatic substitutionnucleophilic aliphatic substitution where thewhere the re

reacactatant nt is is aa nucleophilenucleophile ratrather her thathan n anan electrophileelectrophile. . MeMechchananisism m is is sasame me ththat at of of n

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RADICAL SUBSTITUTION

In

In ffrree ee rraaddicicaal l hhaalologgeennatatioionn rreeaaccttiioonns s rraaddiiccaal l ssuubbssttiittuuttiioon n ttaakkees s ppllaaccee with

with halogenhalogen rereagagentents s anandd alkanealkane susubsbstrtratateses. . AnAnototheher r imimpoportrtanant t clclasass s of of raradidicacall su

substbstituitutiotions ns involinvolvevess araryyl l rradadicicalalss.. OOnne e eexxaammpplle e iis s tthhe e hhyyddrrooxxyyllaattiioonn of

of benzenebenzene byby Fenton's reagentFenton's reagent. . Many oxidatMany oxidation ion and reductiand reduction on reacreactiontions s in in orgaorganicnic chemistry have free radical

chemistry have free radical intermediatesintermediates, for example the oxidation of , for example the oxidation of aldehydesaldehydes toto carboxylic with

carboxylic with chchromromic ic aciacidd.. CouCouplinpling g reacreactiontionss cacan n alalso so be be coconsnsididerered ed raradidicacall substitutions. Certain aromatic substitution takes place by

substitutions. Certain aromatic substitution takes place by radical-nucleophilic aromaticradical-nucleophilic aromatic substitution

substitution.. Auto-oxidationAuto-oxidation is a process responsible for deterioration of paints and foodis a process responsible for deterioration of paints and food and lab hazards such as

and lab hazards such as diethyl ether peroxidediethyl ether peroxide. The reaction always involves at least. The reaction always involves at least two steps, and possibly a third. In

two steps, and possibly a third. In the first step calledthe first step called initiationinitiation aa free radicalfree radical is createdis created by

by homolysishomolysis. Homolysis can be brought about by heat or light but also by. Homolysis can be brought about by heat or light but also by radicalradical initiators

initiators such assuch as organic peroxidesorganic peroxides or or azo compoundsazo compounds. Light is used to create two free. Light is used to create two free radicals from one diatomic species. The final step is called

radicals from one diatomic species. The final step is called terminationtermination in which thein which the radical

radical recombinesrecombines with another radical species. If the reaction is not terminated, butwith another radical species. If the reaction is not terminated, but instead the radical group(s) go on to react further, the steps where new radicals are instead the radical group(s) go on to react further, the steps where new radicals are formed and then react is collectively known as

formed and then react is collectively known as propagationpropagation because a new radical isbecause a new radical is created available for secondary reactions.

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Examples Examples

SUBSTITUTED COMPOUNDS

Substituted compounds are chemical compounds where one or Substituted compounds are chemical compounds where one or more

more hydrogenhydrogen atomsatoms of a core structure have been replaced withof a core structure have been replaced with a

a functional groupfunctional group likelike alkylalkyl,, hydroxy, or hydroxy, or halogenhalogen..

For example

For example benzenebenzene is ais a simple aromatic ringsimple aromatic ring and substituted benzenes areand substituted benzenes are a

a heterogeneousheterogeneous group of chemicals with a wide spectrum of uses and properties:group of chemicals with a wide spectrum of uses and properties: Compou Compou nd nd general general formula formula general general structure structure

Benzene

C

66

H

66

Toluene

C

66

H

55

-CH

33

o

-

Xylene

C

66

H

44

(-CH

33

))

22

(11)

Mesityle

ne

C

66

H

33

(-CH

33

))

33

Phenol

C

66

H

55

-OH

J

Jusust t a a fefew w susubsbstititututeted d bebenznzenenee compounds compounds

MECHANISM OF REACTIONS

• • SS_N_N1 MECHANISM1 MECHANISM The

The SSNN1 reaction1 reaction is is aa subsubstitstitutioution n reacreactiontion in orgain organic nic chechemistmistryry. . "S"SNN" " ststanandsds for

for nucleophilic substitutionnucleophilic substitution and the "1" represents the fact that theand the "1" represents the fact that the rate-determiningrate-determining step

step is unimolecular isunimolecular . . TThhe e rereaactctiion on iinnvovolvlvees s aa carbocationcarbocation inintetermrmedediaiate te anand d isis commonly seen in reactions of secondary or tertiary

commonly seen in reactions of secondary or tertiary alkyl halidesalkyl halides under stronglyunder strongly basi

basic c condconditionitions s or, or, undeunder r strostrongly acidic ngly acidic condconditioitions, ns, withwith secosecondarndary y or or terttertiaryiary alcohols

alcohols.. A

An n eexxaammpplle e oof f a a rreeaaccttiioon n ttaakkiinng g ppllaacce e wwiitth h aan n SSNN11 reareactioction n mecmechanhanismism isis the

the hydrolysishydrolysis of tert-butyl bromide with water forming tert-butyl alcohol:of tert-butyl bromide with water forming tert-butyl alcohol:

This S

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•

• Formation of a tert-butyl carbocation by separation of aFormation of a tert-butyl carbocation by separation of a leavingleaving

group

group (a(a bromidebromide anion) from the carbon atom: this step is slow andanion) from the carbon atom: this step is slow and reversiblereversible.. [4]

[4]

•

• Nucleophilic attackNucleophilic attack: the carbocation reacts with the nucleop: the carbocation reacts with the nucleop hile. If hile. If

the nucleophile is a neutral molecule (i.e. a

the nucleophile is a neutral molecule (i.e. a solventsolvent) a third step is required) a third step is required to complete the reaction. When the solvent is water, the intermediate is to complete the reaction. When the solvent is water, the intermediate is an oxonium ion. This reaction step is fast.

an oxonium ion. This reaction step is fast.

•

• DeprotonationDeprotonation: Removal of a proton on the protonated nucleophile by: Removal of a proton on the protonated nucleophile by

water acting as a base forming the

water acting as a base forming the alcoholalcohol and a hydronium ion. Thisand a hydronium ion. This reaction step is fast.

reaction step is fast.

•

• SSNN2 MECHANISM2 MECHANISM

The S

The SNN2 reaction (also known as bimolecular nucleophilic substitution or as backside2 reaction (also known as bimolecular nucleophilic substitution or as backside a

attttaacckk) ) iis s a a ttyyppe e oof f nucnucleopleophilic hilic substitsubstitutioutionn, , wwhheerre e a a lloonne e ppaaiir r ffrroomm a

a nucnucleopleophile hile attaattacks cks an an elecelectron tron defdeficienicient t elecelectroptrophilic hilic cencenter ter andand bondsbonds tto o iitt,, expelling another group called a

expelling another group called a leaving groupleaving group. Thus the incoming group replaces. Thus the incoming group replaces the

the lealeavinving g grogroup up in in onone e ststep. ep. SinSince ce twtwo o rereacactinting g spspececies ies are are invinvolvolved ed in in thethe slow,

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name

namebimolecular nucleophilic substitutionbimolecular nucleophilic substitution, , or or S S N N 2 2 . Amo. Among ng inoinorganrganic ic chemchemistsists, , thethe S

SNN2 reaction is often known as the2 reaction is often known as the interchange mechanisminterchange mechanism.. T

Thhe e rreeaaccttiioon n mmoosst t oofftteen n ooccccuurrs s aat t aann aliphaticaliphatic spsp33 _c_ca_arrb_bo_on_{n c}_ce_en_ntte_er_{r w}_wiitth_{h a}_an_n

electronegative, stable leaving group attached to it - 'X' - frequently a halide atom. The electronegative, stable leaving group attached to it - 'X' - frequently a halide atom. The breaking of the C-X bond and the formation of the new C-Nu bond occur simultaneously breaking of the C-X bond and the formation of the new C-Nu bond occur simultaneously tto o ffoorrm m aa trtransansitiition on stastatete iin n wwhhiicch h tthhe e ccaarrbboon n uunnddeer r nnuucclleeoopphhii lilic c atattatackck is

is pentpentacoacoordiordinatenate, , and and apprapproximoximatelately y spsp22 _hybridised_hybridised._{. Th}_The_{e nu}_nucle_cleop_ophil_hile_{e att}_attack_acks_{s the}_the carbon at 180° to the

carbon at 180° to the leaving groupleaving group, since this provides the best overlap between the, since this provides the best overlap between the nucleophile's lone pair and the C-X σ* antibonding orbital. The leaving group is then nucleophile's lone pair and the C-X σ* antibonding orbital. The leaving group is then pushed off the opposite side and the product is formed.

pushed off the opposite side and the product is formed. If

If ththe e susubsbstrtratate e unundeder r nunuclcleoeophphililic ic atattatack ck is is chchiriralal, , ththis is cacan n leleadad, , alalththouough gh nonott necessarily, to an inversion of

necessarily, to an inversion of stereochemistrystereochemistry,, called thecalled the Walden inversionWalden inversion..

S

SNN2 2 reareactiction on of of brobromomoetethanhane e wiwith th hyhydrdroxoxide ide ionion. . ThThe e prprodoductucts s arare e etethahanol nol anand d aa bromide ion.

bromide ion.

IIn n aan n eexxaammpplle e oof f tthhe e SSNN2 2 rreeaactctioion, n, tthhe e atatttacack k of of OHOH−− (t(the he nunuclcleoeophphilile) e) onon a bromoetha

a bromoethane (the ne (the electrophelectrophile) ile) results inresults in ethanolethanol, with, with bromidebromide ejected as the leavingejected as the leaving group.

group. S

SNN2 2 aattttaacck k ooccccuurrs s iif f tthhe e bbaacckkssiidde e rroouutte e oof f aattttaacck k iis s nnoot t sstteerriiccaallllyy hindere

hindered by substituentd by substituents on s on thethe substratesubstrate. Therefore this. Therefore this mechanismmechanism usually occurs atusually occurs at an unhindered

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APPLICATIONS

1.

1. Total Total Synthesis Synthesis of of dl dl -Physostigmine-Physostigmine

A concise, highly efficient formal total synthesis of

A concise, highly efficient formal total synthesis of dl dl -physostigmine is described, using a-physostigmine is described, using a relatively simple method that should be adaptable to the synthesis of homologous members of relatively simple method that should be adaptable to the synthesis of homologous members of this type of alkaloid. The key step in the synthesis is a new vicarious nucleophilic substitution this type of alkaloid. The key step in the synthesis is a new vicarious nucleophilic substitution rea

reactiction on betbetweeweenn p p-n-nititroroanianisosole le anand d a a C-C-sisilylylalateted d derderivivatativive e of of N- N-methylpyrrolidinone.methylpyrrolidinone. Subsequent conversion of the initial adduct to the tricyclic framework of physostigmine Subsequent conversion of the initial adduct to the tricyclic framework of physostigmine follows a well-established protocol and provides the key intermediate

follows a well-established protocol and provides the key intermediate88 _{in high yield. The}_{in high yield. The}

vicarious nucleophilic substitution reaction has also been extended to six-membered lactams, vicarious nucleophilic substitution reaction has also been extended to six-membered lactams,

(15)

w

wiitth h eennccoouurraaggiinng g rreessuulltt..

2. 2. Nucleophilic Substitution Reactions

Nucleophilic Substitution Reactions In

In Ionic Liquids

Ionic Liquids

This paper presents a quantitative comparison of the

This paper presents a quantitative comparison of the rates of nucleophilic reactions in ionicrates of nucleophilic reactions in ionic liquids and molecular solvents. Both neutral and

liquids and molecular solvents. Both neutral and ionic nucleophiles and electrophiles were usedionic nucleophiles and electrophiles were used and the solvent effects on these

and the solvent effects on these various systems were determined using a Linear Solvationvarious systems were determined using a Linear Solvation Energy Relationship based on the Kamlet-Taft solvent scales. These

Energy Relationship based on the Kamlet-Taft solvent scales. These correlations reveal thatcorrelations reveal that different hydrogen bonding and dipolar interactions provide

different hydrogen bonding and dipolar interactions provide the dominant effects in determiningthe dominant effects in determining the rate of reaction, depending

the rate of reaction, depending upon the specific system under study. The results of this systemupon the specific system under study. The results of this system are useful for predicting nucleophilic interactions at metal centres involved

are useful for predicting nucleophilic interactions at metal centres involved in catalyticin catalytic processes.

processes.

FUTURE PROSPECTIVE FUTURE PROSPECTIVE

MICROWAVE

MICROWAVE ASSISTED SASSISTED SYNTHESIS OF AZIYNTHESIS OF AZIDES,THIOCYANATES AND SDES,THIOCYANATES AND SULFONESULFONES IN AN AQUEOUS MEDIUM

IN AN AQUEOUS MEDIUM

A practical, rapid, and efficient microwave (MW) promoted synthesis of various A practical, rapid, and efficient microwave (MW) promoted synthesis of various azides, thiocyanates, and sulfones is described in an aqueous medium. This azides, thiocyanates, and sulfones is described in an aqueous medium. This general and expeditious MW-enhanced nucleophilic substitution approach uses general and expeditious MW-enhanced nucleophilic substitution approach uses easily accessible starting materials such as halides or tosylates in reaction with easily accessible starting materials such as halides or tosylates in reaction with alkali azides, thiocyanates, or sulfinates in the absence of any phase-transfer alkali azides, thiocyanates, or sulfinates in the absence of any phase-transfer catalyst, and a variety of reactive functional groups are tolerated.