endobj [23] At room temperature, acetaldehyde (CH3CH=O) is more stable than vinyl alcohol (CH2=CHOH) by 42.7 kJ/mol:[24] Overall the keto-enol tautomerization occurs slowly but is catalyzed by acids. The hydroformylation of methanol with catalysts like cobalt, nickel, or iron salts also produces acetaldehyde, although this process is of no industrial importance. %%EOF Carc and Muta Directive, Annex I - Substances, Mixtures & Processes . It is used primarily as a source of the "CH3C+H(OH)" synthon in aldol and related condensation reactions. [citation needed], It has been concluded that volatile organic compounds (VOC) such as benzene, formaldehyde, acetaldehyde, toluene, and xylenes have to be considered priority pollutants with respect to their health effects. The CAS number is assigned by the Chemical Abstracts Service to identify a specific chemical. Conjunctival irritations have been observed after a 15-minute exposure to concentrations of 25 and 50 ppm, but transient conjunctivitis and irritation of the respiratory tract have been reported after exposure to 200 ppm acetaldehyde for 15 minutes. Similarly noncompetitive, acetaldehyde arises from synthesis gas with modest selectivity.[21]. As a consequence, overall acetaldehyde consumption in China may grow slightly at 1.6% per year through 2018. Acetaldehyde is a colorless liquid with a pungent, fruity odor. The threshold limit value is 25ppm (STEL/ceiling value) and the MAK (Maximum Workplace Concentration) is 50 ppm. Occupational exposure to acetaldehyde may occur in its production, in the production of acetic acid, acetate esters and other chemicals and in other applications. below 73°F and BP below 100°F. The Centers for Disease Control and Prevention (CDC) cannot attest to the accuracy of a non-federal website. This does not mean that this substance is not harmful. 1A & 1B CMs are derived from the CLP Regulation's Table 3 of Annex VI (1272/2008/EC). Urea and acetaldehyde combine to give a useful resin. We have created a browser extension. [21] At such concentrations, the fruity odor of acetaldehyde is apparent. Scheele, C. W. (1774) "Om Brunsten eller Magnesia nigra och dess egenskaper" (On brown-stone or black magnesia [i.e., manganese ore] and its properties). endstream The living room had a mean of 18.1±17.5 μg m−3 and the bedroom was 18.2±16.9 μg m−3, whereas the outdoor air had a mean concentration of 2.3±2.6 μg m−3. �3q A combustible substance is a solid, liquid or gas that will Since then, ethylene is the dominant feedstock.[21]. The level at which an average consumer could detect acetaldehyde is still considerably lower than any toxicity. This should provide the much needed boost to the flat market, as of 2013. [Note: Prolonged contact with air may cause formation of peroxides that may explode and burst containers; easily undergoes polymerization. Acetaldehyde occurs naturally in coffee, bread, and ripe fruit,[10] and is produced by plants. Class IA Flammable Liquid: Fl.P. Traditionally, acetaldehyde was produced by the partial dehydrogenation of ethanol: In this endothermic process, ethanol vapor is passed at 260–290 °C over a copper-based catalyst. [53][54] Acetaldehyde is also the most abundant carcinogen in tobacco smoke; it is dissolved into the saliva while smoking. When taken up by the organism, acetaldehyde is metabolized rapidly in the liver to acetic acid. ;����}ݵ��s��onSMe�@��7w$���(�͕�KC�e�R�����G�وI�-�\���|stm^��A�Ȩ ��H���2�y��L��M��QN�L�#}EU�v�wu�i�a�H�K< ���4�c����yb��/��7E�r��C�#�Q���x WAYS OF REDUCING EXPOSURE * Where possible, enclose … [45], People with a genetic deficiency for the enzyme responsible for the conversion of acetaldehyde into acetic acid may have a greater risk of Alzheimer's disease. After intravenous injection, the half-life in the blood is approximately 90 seconds. As with China, the Western European acetaldehyde market is expected to increase only very slightly at 1% per year during 2012–2018. The International Agency for Research on Cancer, International Agency for Research on Cancer, National Institute for Occupational Safety and Health, "Quantitative Determination of Acetaldehyde in Foods Using Automated Digestion with Simulated Gastric Fluid Followed by Headspace Gas Chromatography", "Chemicals in the Environment: Acetaldehyde (CAS NO. Circuit Court of Appeals and the limits are not currently in force. [59], Candida albicans in patients with potentially carcinogenic oral diseases has been shown to produce acetaldehyde in quantities sufficient to cause problems. Acetaldehyde is a precursor to vinylphosphonic acid, which is used to make adhesives and ion conductive membranes. Pathways of exposure include air, water, land, or groundwater, as well as drink and smoke. The reaction is conducted at 90–95 °C, and the acetaldehyde formed is separated from water and mercury and cooled to 25–30 °C. SciFinderScholar (accessed 4 November 2009). �x~������������H�y ��Xсn2�jf�0�� `�g`0`ba�bedd*a����El���U��E0�30��3���5�#qf� Ӏ� � When taken up by the organism, acetaldehyde is metabolized rapidly in the liver to acetic acid. [43] In addition, acetaldehyde is damaging to DNA[44] and causes abnormal muscle development as it binds to proteins. 233 0 obj <>stream <>stream The drug disulfiram (Antabuse) prevents the oxidation of acetaldehyde to acetic acid. International Agency for Research on Cancer Monograph Working Group, Special Report: Policy A review of human carcinogens—Part E: tobacco, areca nut, alcohol, coal smoke, and salted fish. It is one of the most important aldehydes, occurring widely in nature and being produced on a large scale in industry. [40][41] In 1988 the International Agency for Research on Cancer stated, "There is sufficient evidence for the carcinogenicity of acetaldehyde (the major metabolite of ethanol) in experimental animals. [28] Grignard reagents and organolithium compounds react with MeCHO to give hydroxyethyl derivatives. 1-142) reveals that, at 200 ppm of acetaldehyde, all exposed persons experienced inflammation of the conjuctivae of the eyes, which manifested as redness. The synthesis sequence begins with a reaction with phosphorus trichloride:[35]. WORKPLACE EXPOSURE LIMITS No occupational limits have been established for Acetaldehyde Ammonia. [33], Three molecules of acetaldehyde condense to form "paraldehyde", a cyclic trimer containing C-O single bonds. Congratulations on this excellent venture… what a great idea! [27] In condensation reactions, acetaldehyde is prochiral. I use WIKI 2 every day and almost forgot how the original Wikipedia looks like. acetaldehyde; ethanal. Safe work practices should always be followed. Photo-induced keto-enol tautomerization is viable under atmospheric or stratospheric conditions. Acetaldehyde, derived from mucosal or microbial oxidation of ethanol, tobacco smoke, and diet, appears to act as a cumulative carcinogen in the upper digestive tract of humans. This photo-tautomerization is relevant to the earth's atmosphere, because vinyl alcohol is thought to be a precursor to carboxylic acids in the atmosphere. At 50 ppm acetaldehyde, no irritation or local tissue damage in the nasal mucosa is observed. Exposure to acetaldehyde throughthe use of hand sanitizer containing technical-grade ethanol is a very different scenario than the ones described above, with respect to the route of exposure and the amount of acetaldehyde involved.

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