Yi-Chun LinPh.D.Taiwan
Laser Materials ProcessingPublished
Dec 24, 2025
Acetaldehyde (C₂H₄O)
Chemical Properties
Chemical Identity
CAS Number
75-07-0
Formula
C₂H₄O
Molecular Weight
44.05 g/mol
Exposure Limits Comparison
OSHA PEL
200 ppm
ACGIH TLV
25 ppm
Health Effects
Respiratory Irritation
Yes
Eye Irritation
Yes
Suspected Carcinogen
Yes
Narcotic Effects
Yes
Acetaldehyde (C₂H₄O) safety information
Comprehensive safety and handling requirements
Detection Monitoring
- Photoionization detector (PID)
- Electrochemical
- Infrared
- Metal oxide
- Dräger Acetaldehyde 100/a
- Gastec 92
| Sensor Types | ||||||||||
| Detection Range | 0-100 ppm typical | |||||||||
| Alarm Setpoints |
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| Colorimetric Tubes | ||||||||||
| Analytical Methods |
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| Odor Threshold | 0.05-1 ppm - provides early warning |
Environmental Impact
| Aquatic Toxicity | Toxic to aquatic life. LC50 (fish, 96h): 50-150 mg/L. | ||||
| Biodegradability | Readily biodegradable (>70% in 28 days). Oxidizes to acetic acid. | ||||
| Bioaccumulation | Does not bioaccumulate. Log Kow: -0.34. | ||||
| Soil Mobility | High mobility. Volatilizes rapidly from soil. | ||||
| Atmospheric Fate | Photolyzes rapidly. Forms peroxyacetyl nitrate (PAN). Atmospheric half-life: 9 hours. | ||||
| Ozone Depletion | false | ||||
| Reportable Releases |
|
Ppe Requirements
| Respiratory | NIOSH-approved organic vapor respirator for <25 ppm. SCBA for >25 ppm or unknown concentrations. |
| Eye Protection | Chemical safety goggles, face shield for splash hazard. |
| Skin Protection | Nitrile or butyl rubber gloves. Chemical-resistant clothing for liquid contact. |
Reactivity
- Strong acids
- Strong bases
- Oxidizers
- Halogens
- Alcohols
- Ammonia
- Hydrogen cyanide
- Phenols
- Hydrogen sulfide
- Carbon monoxide
- Carbon dioxide
- Acetic acid
- Acetaldehyde vapors
- Heat
- Light
- Air
- Acids
- Bases
- Sparks
- Flames
- Contamination
| Stability | UNSTABLE. Polymerizes readily. Must be stabilized. Oxidizes in air. |
| Polymerization | Violent exothermic polymerization with acids, bases, or contaminants. Stabilizer required. |
| Incompatible Materials | |
| Hazardous Decomposition | |
| Conditions To Avoid | |
| Reactivity Hazard | EXTREMELY REACTIVE. Polymerizes violently. Reacts violently with oxidizers. Forms explosive peroxides with air. May self-heat and ignite. |
Regulatory Classification
- Flammability
- Acute toxicity
- Carcinogenicity (probable)
- Eye irritation
| Un Number | UN1089 | ||||||
| Dot Hazard Class | 3 (Flammable liquid) | ||||||
| Dot Label | Flammable Liquid | ||||||
| Nfpa Codes |
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| Epa Hazard Categories | |||||||
| Sara Title Iii | true | ||||||
| Cercla Rq | 1000 pounds (454 kg) | ||||||
| Rcra Code | U001 |
Storage Requirements
- Acids
- Bases
- Alcohols
- Ammonia
- Halogens
- Oxidizers
- Phenols
- Hydrogen cyanide
| Temperature Range | Store below 20°C, refrigerate. Keep away from heat. |
| Ventilation | Outdoor storage strongly preferred. Indoor: explosion-proof ventilation. Gas detection mandatory. |
| Incompatibilities | |
| Container Material | Stainless steel or aluminum. Must be stabilized. Never use copper or iron containers. |
| Segregation | Separate from oxidizers and incompatibles by 20 feet. Flammable liquid storage cabinet. |
| Quantity Limits | Minimize quantities. Many facilities limit to <10 gallons. |
| Special Requirements | CRITICAL: Store with stabilizer. Check stabilizer regularly. Refrigerated storage required. Inert gas blanketing (nitrogen). Post "EXTREMELY FLAMMABLE" and "CANCER HAZARD" signs. |
Produced From Contaminants
Produced From Materials
Exposure Limits
Regulatory exposure thresholds and safe concentration levels
- Osha Pel Ppm
- 200
- Osha Pel Mg M3
- 360
- Acgih Tlv Ppm
- 25
- Acgih Tlv Mg M3
- 45
- Workplace Exposure
- Osha Peltwa_8hr: 200 ppm (360 mg/m³)stel_15min: nullceiling: nullNiosh Reltwa_8hr: nullstel_15min: nullceiling: 10 ppm (18 mg/m³) - based on carcinogenicityidlh: 2000 ppmAcgih Tlvtwa_8hr: nullstel_15min: nullceiling: 25 ppm (confirmed animal carcinogen with unknown relevance to humans)Biological Exposure Indices
Physical Properties
Physical characteristics and state information
- Boiling Point
- 20.2°C (68.4°F)
- Melting Point
- -123.5°C (-190.3°F)
- Vapor Pressure
- 740 mmHg @ 20°C
- Vapor Density
- 1.52 (Air=1)
- Specific Gravity
- 0.788 @ 20°C
- Flash Point
- -39°C (-38°F)
- Autoignition Temp
- 175°C (347°F)
- Explosive Limits
- LEL: 4%, UEL: 60%
- Appearance
- Colorless liquid, colorless gas >20°C
- Odor
- Pungent, fruity odor @ 0.05-1 ppm
Reactivity
Chemical reactivity and compatibility with other substances
- Stability
- UNSTABLE. Polymerizes readily. Must be stabilized. Oxidizes in air.
- Polymerization
- Violent exothermic polymerization with acids, bases, or contaminants. Stabilizer required.
- Incompatible Materials
- Strong acids
- Strong bases
- Oxidizers
- Halogens
- Alcohols
- Ammonia
- Hydrogen cyanide
- Phenols
- Hydrogen sulfide
- Hazardous Decomposition
- Carbon monoxide
- Carbon dioxide
- Acetic acid
- Acetaldehyde vapors
- Conditions To Avoid
- Heat
- Light
- Air
- Acids
- Bases
- Sparks
- Flames
- Contamination
- Reactivity Hazard
- EXTREMELY REACTIVE. Polymerizes violently. Reacts violently with oxidizers. Forms explosive peroxides with air. May self-heat and ignite.
Synonyms & Identifiers
Alternative names and chemical identifiers (CAS numbers)
- Synonyms
- Acetic aldehyde
- Ethanal
- Ethyl aldehyde
- CH3CHO
- Common Trade Names
- Other Identifiers
- Rtecs NumberAB1925000Ec Number200-836-8Pubchem Cid177
