This document provides an introduction to organic synthesis via enolates. It discusses active methylene groups and compounds that contain them, such as diethyl malonate and ethyl acetoacetate. These compounds can undergo keto-enol tautomerism when treated with base, losing a hydrogen to form a carbanion which resonates into a stabilized enolate ion. The document outlines several synthetic applications of ethyl acetoacetate and diethyl malonate, such as alkylation reactions and hydrolysis to form various carboxylic acids, ketones, and heterocyclic compounds. Key concepts covered include enols, enolate ions, acidity of the alpha hydrogen, and the mechanism of

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B. Sc. Third Year
Semester-V
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CH-03:- Module-1 : Introduction of Organic Synthesis Via Enolates
Welcome
CH-03: Organic Synthesis Via Enolates
Dr. Bhimraj N. Gawade
M. Sc. CSIR-UGC-NET (JRF), Ph. D.
Assistant Professor
Department of Chemistry
Anandrao Dhonde Alias Babaji Mahavidyalaya, Kada.
Tal. Ashti. Dist. Beed - 414 202, Maharashtra, INDIA

2. 1. Active methylene group and active methylene compounds
2. Enols and enolate ions
3. Acidity of α-hydrogen
4. Ethyl Aceto Acetate (EAA) or Aceto Acetic Ester (AAE)
5. Synthesis of ethyl aceto acetate: Claisen condensation
6. Mechanism of Keto-enol tautomerism in ethyl acetoacetate (EAA)
a) Base-catalyzed keto-enol tautomerism
b) Acid-catalyzed keto-enol tautomerism
 Organic Synthesis Via Enolates Points to be studied:
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3. 7. Synthetic Applications of EAA or AAE
i. Synthesis of alkyl acetoacetic ester or EAA by alkylation
ii. Acetoacetic ester & its alkyl derivatives can undergo two types of hydrolysis with
potassium hydroxide
a) Ketonic hydrolysis
b) Acid hydrolysis
iii. Synthesis of Mono-carboxylic acid
iv. Synthesis of Dicarboxylic acid
v. Synthesis of unsaturated acid
vi. Synthesis of ketone
vii. Synthesis of 1,3-diketone
viii. Synthesis of 4-methyl uracil
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4. 8. Diethyl Malonate (Malonic ester)
9. Synthesis of Diethyl malonate
10. Synthetic Applications of Diethyl Malonate (Malonic Ester)
i. Synthesis of alkyl derivative
ii. Synthesis of Mono-carboxylic acid
iii. Synthesis of dicarboxylic acid
iv. Synthesis of α, β-unsaturated acid (Knoenvenagel reaction)
v. Synthesis of glycine (2-amino acetic acid)
vi. Synthesis of Barbituric acid
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 Active methylene group and active methylene compounds
A methylene group (-CH2-) which is situated between electron withdrawing groups (e.g. -CHO,
>C=O, -COOH, -COOR, -CN, -X etc.) attached to both sides is called as active methylene
group and compounds is called as active methylene compounds.
e.g.
C
C
C
H
H
O
O
OC2H5
OC2H5
Diethyl malonate
C
O
H3C
O
O
C2H5
Ethyl acetoacetate
H H
C
C
H
H
O
OC2H5
C N
Ethyl cyanoacetate
C
O
HO
O
OH
Malonic acid
H H
C O
O
1,3 cyclohexadione
H H

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Enols and enolate ions
Enols:- The compounds in which hydroxyl group is directly attached to a C=C bond.
C C
OH
Enolate ions:- Anions of enols are called as enolate ions.
C C
O

7. The hydrogen atoms of active methylene group are acidic in nature.
The compounds containing active methylene group when treated with base,
looses hydrogen atoms to form carbanion.
This carbanion is stabilized by another resonating structure called as enolate
ion.
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Acidity of α-hydrogen
C
C
C
H
H
O
O
OC2H5
OC2H5
Diethyl malonate
OH +
Base - H2O
C
C
C
H
O
O
OC2H5
OC2H5
Carbanion
C
C
H
O
OC2H5
C
O
OC2H5
Enolate ion

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Thank
You