Conversion of aldhyde or ketone to B-hydroxy ester by reacting A-haloester in the presence of zinc metal in inert solvent

1. Subject : Organic Chemistry
Module 1 : Name Reactions
Reformatskii Reaction
Author : Dr. M. T. Bachute
Dept. of Chemistry
K. B. P. Mahavidyalaya, Pandharpur

2. Reformatskii Reaction
Statement :
Aldehydes and ketones react with α-haloesters in
the presence of zinc metal in dry and inert
solvent like benzene, ether, toluene etc to form
β-hydroxyester.

3. General Statement
R
1
R
O
+ X
O
O
R
2

Aldehyde/Ketone 
Zn/benzene
R
1
OH
O
O R
2
R


-haloester -hydroxyester

4. Mechanism
For the reaction
Ph
H
O
+ Br
O
O
CH3

Benzaldehyde 
i. Zn/benzene
Ph
OH
O
O
H
CH3


-bromoacetate  hydroxyethyl- ethyl- - --phenylpropionate
ii. H 2O/H
+

5. Mechanism
Step I : Formation organo zinc compound
Br
O
O
C2H5
Zn
C6H6
Zn
O
O
C2H5
Br H2C O
O
C2H5
Br Zn
+
Organozinc compoundethyl
-

-
bromoacetate
Organozinc compound

6. Step II : Nucleophilic addition of organo zinc
compound to carbonyl group to form an
adduct.
Ph C
H
O
+ H2C O
O
C2H5
Br Zn
+
Organozinc compound
Ph C
H
OZnBr
CH2 C
O
O C2H5
AdductBenzadehyde

7. Mechanism
Step III : Hydrolysis of adduct
Ph C
H
OZnBr
CH2 C
O
O C2H5
Adduct
HCl/H 2O
Ph C
H
OH
CH2 C
O
O C2H5

-
Hydroxy ester
+ ZnBr.OH

ethyl
-

-
hydroxy
-
phenyl
-

-
propionate

8. Applications
1. To prepare β-hydroxy esters
2. To prepare β-hydroxy acids
3. To prepare α,β-unsaturated esters and acjds: β-
hydroxy esters and β-hydroxy acids can be
dehydrated to form α,β-unsaturated esters and
acids
e.g.Preparation of cinnamic acid

9. Preparation of ethyl cinnamate and
cinnamic acid
Explanation :
Ph
H
O
+ Br
O
O
CH3

Benzaldehyde 
i. Zn/benzene
Ph
OH
O
O
H
CH3


-bromoacetate  hydroxyethyl- ethyl- - --phenylpropionate
ii. H 2O/H
+
Con.H 2SO4
-H2O Ph
O
O
CH3


i. KOH,H 2O,Heat
ii.H 2O.H
+
Ph
O
O H



-

-
unsaturated ester 
-

-
unsaturated acid
Ethyl cinnamate Cinnamic acid