Acetaldehyde
[CAS# 75-07-0]

Identification

• Classification: Organic raw materials >> Aldehyde
• Name: Acetaldehyde
• Synonyms: Ethanal
• Molecular Formula: C₂H₄O
• Molecular Weight: 44.05
• CAS Registry Number: 75-07-0
• EC Number: 200-836-8
• FEMA: 2003
• SMILES: CC=O

Properties

• Density: 0.788
• Melting point: -123 ºC
• Boiling point: 21 ºC
• Refractive index: 1.331-1.333
• Flash point: -27 ºC
• Water solubility: > 500 g/L (20 ºC)

Safety Data

• Hazard Symbols: GHS02;GHS06;GHS08;GHS07 Danger
• Hazard Statements: H224-H350-H341-H335-H319
• Precautionary Statements: P203-P210-P233-P240-P241-P242-P243-P261-P262-P264-P264+P265-P270-P271-P272-P280-P301+P317-P302+P352-P303+P361+P353-P304+P340-P305+P351+P338-P316-P318-P319-P321-P330-P333+P317-P337+P317-P361+P364-P362+P364-P370+P378-P403+P233-P403+P235-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Flammable liquids	Flam. Liq.	1	H224
Eye irritation	Eye Irrit.	2	H319
Specific target organ toxicity - single exposure	STOT SE	3	H335
Carcinogenicity	Carc.	2	H351
Acute toxicity	Acute Tox.	4	H302
Skin sensitization	Skin Sens.	1	H317
Acute toxicity	Acute Tox.	3	H311
Germ cell mutagenicity	Muta.	2	H341
Carcinogenicity	Carc.	1B	H350
Carcinogenicity	Carc.	1B	H350i
Carcinogenicity	Carc.	1A	H350
Specific target organ toxicity - single exposure	STOT SE	3	H336
Acute toxicity	Acute Tox.	4	H332
Specific target organ toxicity - single exposure	STOT SE	2	H371
Eye irritation	Eye Irrit.	2A	H319
Chronic hazardous to the aquatic environment	Aquatic Chronic	3	H412
Carcinogenicity	Carc.	2	H350
Acute hazardous to the aquatic environment	Aquatic Acute	3	H402

• Transport Information: UN 1089

Discovory and Applicatios

Acetaldehyde, with the chemical formula C2H4O, is a volatile organic compound that plays a significant role in various industrial and biological processes. Discovered in 1774 by the Swedish chemist Karl Wilhelm Scheele, acetaldehyde was initially identified as a byproduct of the oxidation of ethanol. The name “acetaldehyde” is derived from its structure, being the aldehyde of acetic acid. Its simple structure, consisting of a two-carbon chain with a carbonyl group, underpins its diverse applications and relevance in organic chemistry.

One of the primary applications of acetaldehyde is in the production of acetic acid. The majority of acetaldehyde produced globally is converted into acetic acid through oxidation processes. This acetic acid is then utilized in the manufacture of various chemicals, including plastics, synthetic fibers, and food additives. Acetaldehyde itself is also employed as an intermediate in the synthesis of several important compounds, such as butanol, acetic anhydride, and perfumes.

In the field of organic synthesis, acetaldehyde serves as a vital building block for the production of various chemicals and pharmaceuticals. Its reactive carbonyl group allows it to undergo numerous reactions, such as nucleophilic addition and condensation, making it a valuable reagent in the synthesis of complex organic molecules. For example, it can react with amines to form imines, which are essential intermediates in the synthesis of pharmaceuticals and agrochemicals.

Acetaldehyde is also present in significant amounts in the environment as a natural product of metabolism in plants and animals. It is formed during the fermentation of sugars and is a common byproduct in the alcoholic fermentation process, where it contributes to the flavor and aroma of beverages. In humans, acetaldehyde is produced during the metabolism of ethanol and is implicated in the physiological effects associated with alcohol consumption, including hangovers and other adverse reactions.

In addition to its applications in chemical synthesis and industry, acetaldehyde is used as a flavoring agent and fragrance in the food and cosmetic industries. Its pleasant, fruity odor is often associated with fresh fruit flavors, making it a popular choice in food formulations and perfumes. However, the use of acetaldehyde in food products is regulated due to its potential toxicity and health risks, including its classification as a possible human carcinogen by the International Agency for Research on Cancer (IARC).

Despite its beneficial applications, acetaldehyde poses health and environmental concerns. Exposure to acetaldehyde can lead to irritation of the eyes, skin, and respiratory tract, and prolonged exposure is associated with more severe health risks. Consequently, industries utilizing acetaldehyde must implement appropriate safety measures and regulations to minimize exposure and environmental impact.

In summary, acetaldehyde is a versatile chemical compound with a rich history of discovery and significant applications across various fields, including industrial chemistry, organic synthesis, and the food and beverage industry. Its unique chemical properties make it an invaluable tool in both commercial applications and research, while ongoing efforts to address safety and regulatory concerns will shape its future use in various sectors.

References

1970. Ethanol-Induced Release of Acetaldehyde from Blood and its Effect on the Determination of Acetaldehyde. Quarterly Journal of Studies on Alcohol, 31(1).
DOI: 10.15288/qjsa.1970.31.001

1987. Subcellular Localization of Acetaldehyde Oxidation in Liver. Annals of the New York Academy of Sciences, 492.
DOI: 10.1111/j.1749-6632.1987.tb48650.x

1971. Preparation of 5-alkyltetrahydrofolic acids (dl-5-alkyl-5,6,7,8-tetrahydropteroyl-l-monoglutamic acids). Analytical Biochemistry, 41(2).
DOI: 10.1016/0003-2697(71)90150-3