Ethyl acetoacetate

Preparation, properties and synthetic uses of EAA

1. Presented by: Pranjal Protim Dutta B.Sc 4 th sem Roll no:14 Active methylene compound-Ethyl acetoacetate

2. CONTENTS

3. The class of compounds containing a methylene (>CH ₂) group directly bonded to two electron withdrawing groups are called active methylene compounds. Ethyl acetoacetate(EAA) and diethyl malonate falls in this class. Now we shall discuss about preparation, properties and uses of EAA. The structure of EAA is: CH₃ C CH₂ C OC₂H₅ INTRODUCTION O O

4. Claisen Condensation: 2CH ₃COOC₂H₅ CH₃COCH₂COOC₂H₅ Let us discuss the mechanism of this reaction PREPARATION NaOEt -C ₂H₅OH

5. Mechanism:

6. Ethyl acetoacetate is a colourless, pleasant smelling liquid with b.p 180.4 °C and density 1.0282. It is sparingly soluble in water but freely soluble in organic solvents. PHYSICAL PROPERTIES

7. As the methylene hydrogen is acidic in nature, hence it can be easily replaced by some other groups. Hence from ethyl acetoacetate we can synthesize large number of compounds. Now why the methylene hydrogen is acidic in nature? CHEMICAL PROPERTIES

8. Acidity of methylene hydrogen It is attributed to two factors: Inductive effect

9. Resonance effect

10. Salt formation Alkylation

11. Hydrolysis There are two types of hydrokysis : Ketonic hydrolysis:

12. Acidic hydrolysis

13. Aldehydes, ketones and some other compounds undergo this special type of tautomerism . It involves the migration of a proton from ἀ -carbon to the carbonyl oxygen. KETO-ENOL TAUTOMERISM

14. Due to the greater strength of π -bond of C=O group as compared to that of C=C group, the keto form is more stable then enol form. In simple aldehydes and ketones the amount of enol form is negligible (<1%). However the percentage of enol form increases in case of 1,3-dicarbonyl compounds. It is because of the formation of intramolecular H-bonding. STABILITY OF KETO FORM

15. Ethyl acetoacetate exist as a tautomeric mixture of keto and enol form. KETO-ENOL TAUTOMERISM IN EAA

16. Facts in favor of keto form: EAA forms a bisulphite compound with sodium hydrogen sulphite . EAA forms a cyanohydrin with hydrogen cyanide. EAA forms an oxime with hydroxylamine and phenylhydrazone with phenylhydrazine . On reduction with sodium amalgum or by using LiAlH ₄ in pyridine, EAA gives ß- hydroxybutyric ester containing a secondary alcohol group.

17. When EAA is hydrolysed with dil.NaOH solution in cold followed by acidification, it forms acetoacetic acid. This on heating yields acetone thereby showing that acetoacetic acid is a ß- ketoacid and ethyl acetoacetate is a ß- ketoester .

18. Facts in favor of enol form: EAA reacts with sodium metal to form sodium derivative and hydrogen gas is evolved. This indicates the presence of –OH group. EAA forms an acetyl derivative with acetyl chloride which shows the presence of –OH group. When EAA is treated with alcoholic bromine solution, the brown color of the later is discharged. This indicates the presence of C=C bond . EAA forms a reddish violet color when treated with FeCl ₃. This indicates the presence of C=C-OH structural unit as in phenol.

19. EAA is used for the synthesis of various compounds such as: Mono and dicarboxyllic acid. α, ß -unsaturated acids. Ketones . 4-Methyl uracil Antipyrine SYNTHETIC USES OF EAA

20. From the above discussion we can conclude that: Ethyl acetoacetate is the ethyl ester of acetoacetic acid. It is used for the synthesis of large number of compounds. It is also as flavouring for food. CONCLUSION

21. Advanced Organic Chemistry- Arun Bahl , B.S Bahl Organic Chemistry- Mukherji,Singh,Kapoor REFERENCES

22. At the point of completion of my presentation, I would like to pay my sincere thanks to our honorable teacher Dr . Porinita Borah mam for her valuable guidance . Pranjal Protim Dutta ACKNOWLEDGEMENT