Ethyl 4-Chloroacetoacetate: Properties, Safety & Lab Use Guide

Ethyl 4-Chloroacetoacetate is a versatile beta-ketoester building block widely used in pharmaceutical synthesis, agrochemical research, and fine-chemical manufacturing as a key electrophilic intermediate.

Chemical Name

Ethyl 4-chloroacetoacetate (Ethyl 4-chloro-3-oxobutanoate)

Molecular Formula

C6H9ClO3

Molecular Weight

164.59 g/mol

CAS Number

638-07-3

Appearance

Colorless to pale yellow liquid

Key Application

Pharmaceutical and agrochemical intermediate; chiral synthesis precursor

Chemical Properties and Structure

Ethyl 4-chloroacetoacetate (CAS 638-07-3) is a beta-ketoester bearing an active chloromethyl group at the 4-position. Its molecular formula is C₆H₉ClO₃ with a molecular weight of approximately 164.59 g/mol. The compound exists as a colorless to pale yellow liquid at ambient temperature.

The molecule contains three distinct reactive sites: the active methylene flanked by two carbonyl groups, the ester carbonyl susceptible to nucleophilic acyl substitution, and the primary alkyl chloride at C-4, which functions as a potent electrophile in S_N2 reactions. This combination of functional groups makes the reagent exceptionally reactive toward a wide range of nucleophiles including amines, thiols, and stabilized carbanions.

Like most beta-ketoesters, Ethyl 4-chloroacetoacetate can exist in both keto and enol tautomeric forms. The enol content is influenced by solvent polarity and temperature, a property that researchers should consider when designing reaction conditions.

Synthesis Applications and Research Uses

Ethyl 4-chloroacetoacetate is a high-value synthetic intermediate employed across multiple fields of chemistry:

• Pharmaceutical synthesis: The compound serves as a precursor in the preparation of beta-lactam antibiotics, statin side-chain intermediates, and other pharmacologically active molecules. The reactive chloro group enables efficient C–N and C–S bond formation with heterocyclic amines and thiols.
• Heterocyclic chemistry: Cyclization reactions with bifunctional nucleophiles such as hydrazines, guanidines, and urea derivatives afford pyrazoles, pyrimidines, and related N-containing rings, all of which are privileged scaffolds in medicinal chemistry.
• Chiral reduction precursor: Asymmetric ketoreduction of Ethyl 4-chloroacetoacetate using biocatalysts (e.g., ketoreductases) or chiral metal catalysts yields enantiopure ethyl (R)- or (S)-4-chloro-3-hydroxybutanoate, a critical chiral building block for carnitine and atorvastatin synthesis.
• Agrochemical research: The scaffold is used in the development of fungicides and herbicides incorporating beta-ketoester or heterocyclic pharmacophores.

When selecting a reaction pathway, researchers should carefully evaluate competing nucleophilic sites within the molecule to avoid unwanted side reactions, particularly O-alkylation versus N-alkylation in reactions with ambident nucleophiles.

Safe Handling, Storage, and Regulatory Guidance

Ethyl 4-chloroacetoacetate is a reactive lachrymator and irritant. The following precautions are mandatory for safe laboratory use:

• Personal Protective Equipment (PPE): Always wear chemically resistant gloves (nitrile or neoprene), a laboratory coat, and splash-proof safety goggles. Use a full-face shield when handling larger quantities.
• Ventilation: All operations must be conducted in a well-ventilated fume hood. Avoid inhalation of vapors; the compound has sufficient volatility to generate irritating concentrations in enclosed spaces.
• Skin and eye contact: In case of skin contact, wash immediately and thoroughly with water for at least 15 minutes. For eye exposure, irrigate with copious water and seek immediate medical attention.
• Storage: Store in a tightly sealed container in a cool, dry, well-ventilated area, away from heat sources, oxidizers, and strong bases. Recommended storage temperature is 2–8 °C or as specified on the product label. Check the product-specific SDS for exact conditions.
• Disposal: Dispose of in accordance with local, regional, and national environmental regulations. Do not pour down the drain; treat as halogenated organic waste.

Researchers should consult the current Safety Data Sheet (SDS) supplied by Aladdin Scientific for authoritative hazard classification, GHS pictograms, first-aid measures, and transport information before use.

Quality, Purity, and Specification Considerations

For reproducible experimental results, the purity and quality of Ethyl 4-chloroacetoacetate are critical parameters. Researchers and procurement teams should consider the following when evaluating this reagent:

• Purity grade: Reagent-grade material is typically ≥97% pure by GC analysis. For sensitive asymmetric synthesis or biocatalysis applications, request certificate of analysis (CoA) data confirming purity, water content, and residual impurity profiles.
• Key impurities: Common impurities include the corresponding dehalogenated compound (ethyl acetoacetate), hydrolysis products, and di-chlorinated byproducts. High impurity levels can depress enantioselectivity in enzymatic reductions and reduce yield in cyclization reactions.
• Lot-to-lot consistency: When running multi-batch studies or scale-up campaigns, request lot-specific CoA data from Aladdin Scientific to ensure consistency in purity and physical properties.
• Packaging: The reagent is typically supplied in amber glass bottles to minimize photodegradation. Once opened, the container should be purged with inert gas (N₂ or Ar) and resealed promptly.

Contact Aladdin Scientific's technical support team for custom purity grades or bulk quantity pricing on SKU E156137.

Frequently asked questions

What is Ethyl 4-Chloroacetoacetate used for in pharmaceutical synthesis?

Ethyl 4-Chloroacetoacetate is primarily used as an electrophilic building block for constructing beta-lactam antibiotics, statin intermediates, and heterocyclic scaffolds such as pyrazoles and pyrimidines. Its reactive C-4 chloro group enables efficient C–N and C–S bond formation, while asymmetric ketoreduction of the C-3 carbonyl yields enantiopure hydroxy intermediates critical for chiral drug synthesis.

How should Ethyl 4-Chloroacetoacetate be stored to maintain stability?

The compound should be stored in a tightly sealed amber glass container at 2–8 °C in a cool, dry, and well-ventilated area, away from heat, light, oxidizers, and strong bases. After opening, purge the headspace with dry inert gas (nitrogen or argon) before resealing to prevent moisture ingress and hydrolytic decomposition. Always consult the current SDS for authoritative storage conditions.

What personal protective equipment is required when handling Ethyl 4-Chloroacetoacetate?

Mandatory PPE includes chemically resistant gloves (nitrile or neoprene), a laboratory coat, and splash-proof safety goggles; a full-face shield is recommended for bulk handling. All operations must be conducted inside a fume hood to prevent vapor inhalation. In case of skin or eye contact, flush immediately with copious water and seek medical attention as appropriate.

Can Ethyl 4-Chloroacetoacetate undergo enol tautomerism, and does it affect reactions?

Yes, like all beta-ketoesters, Ethyl 4-Chloroacetoacetate exists in equilibrium between keto and enol tautomers; the ratio depends on solvent polarity, temperature, and concentration. This tautomerism can influence regioselectivity in reactions with ambident nucleophiles, leading to either O- or C-alkylated products. Researchers should optimize reaction conditions and choose appropriate solvents to control tautomeric equilibrium and achieve desired regioselectivity.

How do I verify the purity of Ethyl 4-Chloroacetoacetate from Aladdin Scientific?

Aladdin Scientific provides a Certificate of Analysis (CoA) with each lot of SKU E156137, detailing purity by GC, appearance, and other quality parameters. Customers can request lot-specific CoA documents through Aladdin Scientific's website or customer service team. For critical applications, independent verification by GC-FID or NMR spectroscopy is recommended.

References

1. March, J. Advanced Organic Chemistry: Reactions, Mechanisms, and Structure. 4th ed. Wiley-Interscience, 1992. (General beta-ketoester reactivity and tautomerism.)
2. Noyori, R.; Ohkuma, T. Asymmetric Catalysis by Architectural and Functional Molecular Engineering: Practical Chemo- and Stereoselective Hydrogenation of Ketones. Angew. Chem. Int. Ed. 2001, 40, 40–73. (Chiral reduction of beta-ketoesters context.) doi:10.1002/1521-3773(20010105)40:1<40::AID-ANIE40>3.0.CO;2-5
3. Patel, R.N. Biocatalysis: Synthesis of Chiral Intermediates for Pharmaceuticals. Curr. Opin. Drug Discov. Devel. 2003, 6, 902–920. (Biocatalytic reduction of ethyl 4-chloroacetoacetate.)

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