Cyclopentanone (CAS 120-92-3): Chemical Properties, Physical Characteristics and Industrial Safety Guide (2027)

 1. What Is Cyclopentanone?

Cyclopentanone is an organic compound belonging to the cyclic ketone family. Its molecular formula is C₅H₈O, and its molecular weight is approximately 84.12 g/mol.

It consists of a five-membered carbon ring containing a carbonyl group (C=O). This molecular structure gives Cyclopentanone its characteristic chemical identity and distinguishes it from other ketones.

Cyclopentanone is commonly identified by the following information:

Property	Information
Chemical Name	Cyclopentanone
CAS Number	120-92-3
Molecular Formula	C₅H₈O
Molecular Weight	84.12 g/mol
Chemical Family	Cyclic Ketone
Physical State	Liquid
Appearance	Clear, colorless liquid
EC Number	204-435-9

These identifiers are useful for distinguishing Cyclopentanone from other organic compounds in chemical documentation and scientific literature. 

2. Molecular Structure and Chemical Characteristics

The defining structural feature of Cyclopentanone is its five-membered carbon ring and ketone functional group.

The carbonyl group is an important structural feature in organic chemistry because it influences molecular polarity and chemical behavior.

Several characteristics help explain its chemical identity:

Cyclic structure: Its carbon framework forms a five-membered ring.

Carbonyl functionality: The C=O group is characteristic of ketones.

Molecular polarity: The carbonyl group contributes to the molecule's polar characteristics.

Chemical classification: It belongs to the broader family of cyclic ketones.

Understanding these characteristics provides a foundation for studying cyclic organic compounds and their differences in molecular structure.

3. Physical Properties of Cyclopentanone

Cyclopentanone is described as a clear, colorless liquid. Its physical properties are documented in international chemical reference databases.

Some reported properties include:

Physical Property	Reported Value
Molecular Weight	84.12 g/mol
Boiling Point	Approximately 131°C
Melting Point	Approximately -51°C
Relative Density	Approximately 0.95
Water Solubility	Poor
Flash Point	Approximately 26°C

Values may vary slightly depending on the reference source and measurement conditions. 

4. Understanding the Safety Risks of Cyclopentanone

Chemical safety is an essential part of understanding any industrial organic compound.

Cyclopentanone has several documented hazards that should be considered in professional chemical safety assessments.

Flammability

Cyclopentanone is classified as a flammable liquid. Its vapors can create fire hazards, making appropriate industrial safety management important.

Skin and Eye Irritation

Exposure may cause irritation to the skin and eyes. Contact risks should be addressed through appropriate workplace safety procedures.

Inhalation Exposure

Vapors may present respiratory exposure concerns. Workplace exposure assessments should consider ventilation and the possibility of vapor accumulation.

Chemical Stability

International Chemical Safety Cards report that Cyclopentanone may polymerize under the influence of acids.

These characteristics demonstrate why chemical hazard assessment should be an essential part of industrial chemical management. 

5. Why Is an SDS Important for Chemical Safety?

A Safety Data Sheet (SDS) is an essential document for communicating chemical hazards and safety information.

For Cyclopentanone, an SDS should be reviewed by qualified personnel before any professional handling or industrial assessment.

The standard 16-section SDS structure includes:

Identification of the substance and supplier.

Hazard identification.

Composition and ingredient information.

First-aid measures.

Firefighting measures.

Accidental release measures.

Handling and storage information.

Exposure controls and personal protection.

Physical and chemical properties.

Stability and reactivity.

Toxicological information.

Ecological information.

Disposal considerations.

Transport information.

Regulatory information.

Other relevant information.

An SDS should reflect the actual substance, formulation, applicable regulatory requirements and current supplier documentation.

6. The Importance of Reliable Chemical Information

In the global chemical industry, accurate technical information is essential for communication between manufacturers, researchers, distributors and regulatory professionals.

When evaluating chemical documentation, several aspects deserve attention:

Correct CAS number and chemical identification.

Consistency of molecular and physical property data.

Updated safety documentation.

Traceable technical references.

Compliance with applicable chemical regulations.

Reliable documentation helps reduce misunderstandings and supports responsible chemical management throughout the industrial supply chain.

7. Frequently Asked Questions About Cyclopentanone

Q1: What is the CAS number of Cyclopentanone?

Its CAS number is 120-92-3.

Q2: What is the molecular formula of Cyclopentanone?

Its molecular formula is C₅H₈O.

Q3: What chemical family does Cyclopentanone belong to?

It belongs to the cyclic ketone family.

Q4: Is Cyclopentanone a liquid or a solid?

It is generally described as a clear, colorless liquid under normal conditions.

Q5: Is Cyclopentanone hazardous?

Yes. Its documented hazards include flammability and potential skin, eye and respiratory irritation. Appropriate professional safety assessments are essential.

Q6: What is an SDS?

An SDS is a standardized document that communicates chemical hazards, health information, emergency considerations and relevant regulatory information.

8. Conclusion

Cyclopentanone  is a cyclic ketone characterized by its five-membered molecular structure and carbonyl functional group.

Understanding its molecular identity, physical characteristics and potential hazards provides an important foundation for chemical science education and responsible industrial chemical management.

Accurate chemical information, reliable technical references and appropriate safety documentation remain essential when evaluating organic chemical substances.