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GrignardGrignardReactionsReactions
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Dr. M. Abbas BhattiDr. M. Abbas BhattiPh.D (Scholar-BZU), M.Phil (PU),Ph.D (Scholar-BZU), M.Phil (PU), B.Pharm (PU)B.Pharm (PU)
Pharmaceutical ChemistryPharmaceutical Chemistry
Islam College of Pharmacy, Sialkot.Islam College of Pharmacy, Sialkot.
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earning ob!ecti"es
Definition of Grignard reagent and its method
of preparation.
What are the physical and chemical propertiesof grignard reagent.
arious reactions of grignard reagent and its
pharmaceutical significance.
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Grignard reagents (RMg#)
"rganomagnesium halides or alkyl magnesiumalkyl magnesiumhalideshalides are called Grignard reagent.
General formula# $ % &g % '
$(alkyl)aryl group, '(Cl, *r or I
+amples# C-!&gI, C-!&g*r
ictor Grignardictor Grignard discoered them and
deeloped their use as synthetic reagentsuse as synthetic reagents.
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0he Grignard reagents are highly reactiehighly reactie
used in the synthesissynthesis of alkanes, alkenes,alcohols, aldehydes, ketones caroylic
acids.
Pre$aration%Pre$aration% 0hey are prepared in the
laoratory y the actionaction of alky halidesalky halides on
magnesium metalmagnesium metal in the presence of dry ether dry ether
3anhydrous, C2-4"C2-45.
$ % ' 6 &g $ % &g'
C-! % I 6 &g C-! % &gI
ether ether
ether ether
reflureflu
reflureflu
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Grignard reagent is produced produced y dropping asolutionsolution of alkyl halidealkyl halide in dry ether dry ether into thereaction flask reaction flask containing magnessium rionmagnessium rion suspended in dry ether dry ether .
Diethyl ether plays t7o important roles# a)-a)- It proide mediummedium for the reaction. b)- It dissoledissole Grignard reagent through
sololysissololysis.
0etrahydrofuran0etrahydrofuran 30-85 can also e used inin place place of dry ether.
"rder of reactiity. $I&&$*r &&$Cl.
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Ph'sical $ro$ertiesP
h'sical $ro$erties%%
a)-a)- :on olatile colorlessolatile colorless solids.
b)-b)- 0hey are seldom isolatedseldom isolated in the free state ecause of their eplosie natureeplosie nature. 0herefore,al7ays preparedal7ays prepared usedused in ether ether solution.
hemical $ro$erties%hemica
l $ro$erties% 0he C;&g ond in G$s is coalentcoalent ut highlyhighly
polar polar .
0he CC atom is more electronegatiemore electronegatie than &g electrons are dra7n to7ards the C atom. <s a result, the CC atom has a partial %e partial %e &g&g
has partial 6e partial 6e charge.
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)- Reaction *ith com$o+nds containing
acti"e .
Compounds like 7ater, alcohols, amines
react 7ith Grignard reagents to form alkanesalkanes.
C-!&gI 6 -" % - C-/ 6 &gI3"-5
C-!&gI 6 C2-4" % - C-/ 6 &gI3"C2-45
C-!&gI 6 C2-4 :- % - C-/ 6 &gI3:-C2-45
ðylmegnesiumðylmegnesium
iodideiodide7ater 7ater ðaneðane
+thanol+thanol
+thylamine+thylamine
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)- Reaction *ith Al'l alides to /orm
higher alanes or alenes.
C-!&g*r 6 C-! % *r C-! % C-! 6 &g*r 2
0)- Reaction *ith 'anogen chlride to /orm
al'l nitrile. C-!&g*r 6 ClC: C-!C: 6 &g*r3Cl5
+thane+thane
ðyl nitrileðyl nitrile
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1)- Reaction *ith arbon'l com$o+nds.
Grignard reagents reactreact 7ith caronyl groupcaronyl group of
aldehydes ketones forming an additionaddition
product product, 7hich on acid hydrolysisacid hydrolysis gie
different types of alcoholsalcohols.
i)- Reaction with Formaldehyde (primaryi)- Reaction with Formaldehyde (primary
alcohol synthesis).alcohol synthesis).
8rom8rom$&g'$&g'
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ii)- Reaction with Acetaldehyd to produceii)- Reaction with Acetaldehyd to produce
secondary alcohol. secondary alcohol.
iii)- Reaction with Ketones to produce tertiaryiii)- Reaction with Ketones to produce tertiary
alcohol alcohol .
2rom2rom
RMg#RMg#
2rom2rom
RMg#RMg#
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3)- Reaction *ith 4sters
i)- Reaction with Ethyl Formate to producei)- Reaction with Ethyl Formate to produce
aldehyde.aldehyde.
ii)- Reaction with ethyl acetate to produceii)- Reaction with ethyl acetate to produce
ketonesketones.
2rom2rom
RMg#RMg#
CH3
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5)- Reaction *ith Acid hlorides to /orm etones.
6)- Reaction *ith 7 to $rod+ce carbo8'lic acid.
CH3
+ MgI(OH)
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>5; $eaction 7ith +thylene "ide to form
primary alcohol.
?5; $eaction 7ith Cyanides to produce
ketones.
CH3CH2CH2OH
1;Propanol
Primary
alcohol
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9)- Reaction *ith S+l$h+r to $rod+ce
corres$onding alcohol.
)- Reaction *ith inorganic halides to /orm
other organometalic com$o+nds.
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Re/erences
“A TEXT BOOK OF ORGANIC CHEMISTRY
BY M. YOUNAS.
Sol"ol'sis% combining o/ sol+te and sol"ent% a chemical reaction in 7hich a dissoled solute
and its solent comine to form a ne7 compound.
