SPECTRUM

Chemical Fact Sheet

Chemical Abstract Number (CAS #) 123386
CASRN 123-38-6
SynonymsPropionaldehyde
Analytical Methods EPA Method 554
EPA Method 8315
Molecular FormulaC3H6O

Link to the National Library of Medicine's Hazardous Substances
Database for more details on this compound.

Use Mfr of polyvinyl & other plastics; synthesis of rubber chemicals; disinfectant; preservative INTERMEDIATE IN THE MFR OF TRIMETHYLOLETHANE FOR USE IN ALKYD RESIN SYSTEMS &, IN CERTAIN CASES, IT IS OXIDIZED TO PROPIONIC ACID & REDUCED TO PROPYL ALCOHOL; IN MEDICINAL & AGRICULTURAL CHEMICAL PREPARATIONS.
Apparent Color COLORLESS LIQUID
Odor SUFFOCATING, FRUITY ; CHARACTERISTIC ODOR SIMILAR TO ACETALDEHYDE ; Pungent, unpleasant ; Choking odor
Boiling Point 49 DEG C @ 760 MM HG; 47 DEG C @ 740 MM HG; 45 DEG C @ 687 MM HG
Melting Point -81 DEG C
Molecular Weight 58.08
Density 0.8071 @ 20 DEG C/4 DEG C; 0.8432 @ 0 DEG C/4 DEG C; 0.8192 @ 9.7 DEG C/4 DEG C; 0.7898 @ 33 DEG C/4 DEG C
Odor Threshold Concentration 1 ppm.
Sensitivity Data THE VAPOR MAY CAUSE RESPIRATORY IRRITATION BUT IS NOT A STRONG ENOUGH IRRITANT OF EYES OR RESPIRATORY TRACT TO BE CONSIDERED SIGNIFICANT FACTOR IN SMOG. WHILE IT IS QUITE TOXIC BY INHALATION, IT IS ONLY MODERATELY TOXIC BY INGESTION OR ABSORPTION THROUGH SKIN.
Environmental Impact Propionaldehyde is a highly volatile compound that is emitted to air from arboreous plants. Evidence suggests that it is photolytically produced by UV irradiation of dissolved organic materials in seawater. Anthropogenic releases to the environment may occur at sites where it is produced or used as a chemical intermediate in the manufacture of propionic acid, polyvinyl and other plastics in the synthesis of rubber chemicals and as a disinfectant and preservative. Atmospheric emissions result from the combustion of wood, gasoline, diesel fuel and polyethylene. Hence, municipal waste incinerators also release it to ambient air. Effluents of alkyd resin production have been shown to contaminate surface and ground waters, and land with propionaldehyde. Photolysis, hydrolysis, adsorption and bioconcentration of propionaldehyde are not expected to be important environmental fate processes. In terrestrial and aquatic environments, propionaldehyde will biodegrade to its corresponding carboxylic acid, which then undergoes mineralization. Volatilization from soil and water is also expected to be significant. The volatilization half-lives from a model river and a model pond, the latter considers the effect of adsorption, have been estimated to be 11 hrs and 5 days, respectively. In the atmosphere, propionaldehyde exists almost entirely in the vapor-phase and reactions with photochemically generated hydroxyl radicals should be important (average half-life of 19.6 hrs). Removal by wet deposition can also occur. The most probable route of human exposure to propionaldehyde is by inhalation or ingestion. Atmospheric workplace exposures have been documented and monitoring data indicate that it is a widely occurring atmospheric pollutant. Nonoccupational exposures may occur among coffee drinkers or populations with contaminated drinking water supplies.
Environmental Fate TERRESTRIAL FATE: Direct photolysis and hydrolysis are not expected to be important fate processes of propionaldehyde in soils. Biodegradation and volatilization are expected to be the dominant removal mechanisms from terrestrial environments. Propionaldehyde biodegrades to its corresponding carboxylic acid, which then undergoes mineralization . Both the vapor pressure and Henry's Law constant indicate volatilization of propionaldehyde from soil should be significant. Adsorption should not compete with volatilization; calculated Koc values (4 to 50) indicate a very high mobility class in soil(6). AQUATIC FATE: Direct photolysis and hydrolysis of propionaldehyde in natural waters are not expected to be important fate processes. The dominant removal mechanisms of propionaldehyde from aquatic systems are expected to be biodegradation and volatilization. Propionaldehyde biodegrades to its corresponding carboxylic acid, which then undergoes mineralization . Based on a Henry's Law constant of 7.34X10-5 atm-cu m/mole at 25 deg C , the volatilization half-life from a model river has been estimated to be 11 hrs(2,SRC). The volatilization half-life from a model pond, which considers the effect of adsorption, can be estimated to be about 5 days(5,SRC). Based on estimated values of log BCF (-0.30 to 0.22) and Koc (4 to 50), propionaldehyde is not expected to bioconcentrate or partition from the water column to organic matter contained in sediments and suspended solids. ATMOSPHERIC FATE: Based on a vapor pressure of 317 mm Hg at 25 deg C , propionaldehyde is expected to exist almost entirely in the vapor phase in ambient air . Propionaldehyde weakly absorbs UV light in the environmentally significant range, >290 nm and probably will not undergo direct photolysis in the atmosphere. However, vapor phase reactions with photochemically produced hydroxyl radicals in the atmosphere should be important. A rate constant for the hydroxyl radical reaction with propionaldehyde of 1.96X10-11 cu cm/molecule-sec at 25 deg C corresponds to an atmospheric half-life of 19.6 hrs at an atmospheric concn of 5X10 5 hydroxyl radicals per cu cm. Removal by wet deposition can also occur(5-6).
Drinking Water Impact DRINKING WATER: Propionaldehyde was one of the most frequently occurring organic compounds found in drinking water supplies according to the US National Organic Reconnaissance Survey; however, levels were not reported . It was also qualitatively listed as a contaminant of drinking water supplies in the UK . SEAWATER WATER: Surface sea water samples from off the coast of Florida contained propionaldehyde at trace concns . RAINWATER: Trace quantities of propionaldehyde were detected in fog, ice fog, cloudwater and rainwater in the air of Los Angeles, CA . It was also qualitatively detected in precipitation at Hanover, Germany in 1989-90 . EFFL: Propionaldehyde is a product of wood , gasoline(1-2), diesel fuel and polyethylene combustion. Propionaldehyde was detected in the gaseous phase among the atmospheric emissions of 4 gasoline fuels upon combustion at average concentrations of 2.4, 2.8, 4.9, and 3.3 ug/km . It was also identified as a stack emission from municipal waste incinerators(7). Propionaldehyde was emitted at a rate of 0.002 g/min from burning green ash wood; it was first detected 18 min after the flames disappeared in the smolder stage of a wood stove fire . An identical test with red oak wood used as fuel emitted propionaldehyde at rates of 0.050 and 0.009 g/min for the first 2 min of burn, and thereafter, respectively . Average concentrations for various wood types were 0.15 g/kg (jack pine), 0.040 g/kg (cedar), 0.017 g/kg (red oak), 0.012 g/kg (red oak), 0.088 g/kg (red oak), 0.020 g/kg (green ash), and 0.014 g/kg (green ash) . Wastewater from an alkyd resin production facility contained propionaldehyde; accidental releases from effluent pipes contaminated the underlying soil and ground water(6).

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