Acetone (systematically named propanone ) is an organic compound of formula (CH 3 ) 2 CO. It is a colorless, volatile, and flammable liquid, and is the simplest and smallest ketone.
Acetone can be mixed with water and serves as an essential solvent in itself, usually for cleaning purposes in the laboratory. About 6.7 million tonnes were produced worldwide in 2010, mainly for use as solvents and methyl methacrylate and bisphenol A. These are the common building blocks in organic chemistry. The familiar use of family acetone is the active ingredient of nail polish remover, and as a paint thinner.
Acetone is produced and discharged in the human body through a normal metabolic process. Usually present in blood and urine. Diabetics produce it in larger quantities. Reproductive toxicity tests show that it has a low potential to cause reproductive problems. Ketogenic diets that increase ketones (acetone, acids-acids, hydroxybutyrate and acetoacetic acids) in the blood are used to fight epileptic seizures in infants and children with recalcitrant refractory epilepsy.
Video Acetone
Histori
Acetone was first produced by alchemists during the late Middle Ages through the dry distillation of metallic acetates (eg, acetate tin, which produced a "spirit of Saturn" (since the alchemical symbol for lead is also an astrological symbol for the planet Saturn)).
In 1832, the French chemist Jean-Baptiste Dumas and the German chemist Justus von Liebig determined the empirical formula for acetone. In 1833, French chemist Antoine Bussy named acetone by adding a -one suffix to an appropriate acidic rod (ie, acetic acid). In 1852, the British chemist Alexander William Williamson realized that acetone was methyl acetyl; the following year, the French chemist Charles Fremont Gerhardt agreed. In 1865, German chemist August KekulÃÆ' Â © published a modern structural formula for acetone. Johann Josef Loschmidt had presented the structure of acetone in 1861, but his self-published booklet received little attention. During World War I, Chaim Weizmann developed the process for industrial production of acetone (Weizmann Process).
Maps Acetone
Metabolism
Biosynthesis
A small amount of acetone is produced in the body by decarboxylation of the ketone body. Certain dietary patterns, including low-carbohydrate and protracted high-fat diets, can produce ketosis, in which acetone forms in body tissues. Certain health conditions, such as alcoholism and diabetes, can produce ketoacidosis, an uncontrolled ketosis that leads to a sharp increase in blood acidity, and potentially fatal. Since it is a by-product of fermentation, acetone is a by-product of the refining industry.
Metabolic usage
Although some biochemical books and current research publications show that acetone can not be metabolized, there is conflicting evidence, some dating back thirty years. Acetone can be produced from the oxidation of digested isopropanol, or from spontaneous/enzymatic cleavage of acetoacetate (ketone body) in ketotic individuals. This can then be metabolized either by CYP2E1 via methylglyoxal to D -lactate and pyruvate, and finally glucose/energy, or by different pathways via propylene glycol into pyruvate, lactate, acetate (can be used for energy) and propionaldehyde.
Production
In 2010, worldwide production capacity for acetone is estimated at 6.7 million tons per year. With 1.56 million tons per year, the United States has the highest production capacity, followed by Taiwan and mainland China. The largest acetone producer is INEOS Phenol, owning 17% of the world's capacity, with significant capacity (7-8%) by Mitsui, Sunoco and Shell in 2010. INEOS Phenol also has the world's largest production site (420,000 ton/year) in Beveren (Belgium). The spot price of acetone in summer 2011 is 1100-1250 USD/ton in the United States.
Current method
Acetone is produced directly or indirectly from propylene. About 83% of acetone is produced through the cumene process; as a result, acetone production is bound to phenol production. In the cumene process, benzene is alkylated with propylene to produce cumene, which is oxidized by air to produce phenol and acetone:
Other processes involve the direct oxidation of propylene (Wacker-Hoechst process), or the hydration of propylene to give 2-propanol, which is oxidized to acetone.
The old method
Previously, acetone was produced by dry distillation of acetate, eg calcium acetate in ketonik decarboxylation. 2 -> CaO (s) CO 2 (g) (CH 3 ) 2 CO (v)
After that, during World War I, acetone was produced using acetone-butanol-ethanol fermentation with Clostridium acetobutylicum bacterium, developed by Chaim Weizmann (then the first Israeli president) to assist the British war effort, in preparation for Cordite. The acetone-butanol-ethanol fermentation is finally abandoned when newer methods with better results are found.
Usage
About one third of the world's acetone is used as a solvent, and one-fourth is consumed as acetone cyanohydrin, a methyl methacrylate precursor.
Solvent
Acetone is a good solvent for many plastics and some synthetic fibers. This is used to attenuate the polyester resin, the cleanser used with it, and dissolve the two parts epoxy and superglue before hardening. It is used as one of the volatile components of some paints and varnishes. As a heavy duty degreaser, it is useful in metal preparation before painting. It is also useful for soldering applications with high reliability to remove rosin flux after soldering is complete; this helps prevent the rusty bolt effect.
Acetone is used as a solvent by the pharmaceutical industry and as denaturant in denatured alcohol. Acetone is also present as an excipient in some pharmaceutical drugs.
Although flammable, acetone is widely used as a solvent for safe transportation and storage of acetylene, which can not be safely suppressed as a pure compound. Vessels contain the first porous material filled with acetone, followed by acetylene, which dissolves into acetone. One liter of acetone can dissolve about 250 liters of acetylene at a pressure of 10 bar.
Chemical intermediate
Acetone is used to synthesize methyl methacrylate. This starts with the initial conversion of acetone to acetone cyanohydrin:
- (CH 3 ) 2 CO HCN -> (CH 3 ) 2 C ( OH) CN
In the next step, nitriles are hydrolyzed into unsaturated amides, which are esterified: 3 2 C (OH) CN CH 3 OH -> CH 2 3 3 3
The third major use of acetone (about 20%) is to synthesize bisphenol A. Bisphenol A is a component of many polymers such as polycarbonate, polyurethane, and epoxy resin. Synthesis involves the condensation of acetone with phenol:
- (CH 3 ) 2 CO 2 C 6 H 5 OH -> (CH 3 ) 2 C (C 6 H 4 OH) 2 H 2 O
Many millions of kilograms of acetone are consumed in the production of methyl isobutyl alcohol solvents and methyl isobutyl ketones. These products appear through initial aldol condensation to provide diacetone alcohol.
Laboratory
In the laboratory, acetone is used as a polar aprotic solvent in various organic reactions, such as the S N reaction 2. The use of acetone solvents is essential for Jones oxidation. It does not form azeotropes with water (see azeotrope (data)). This is a general solvent for rinsing laboratory glasses because of its low cost and volatility. Although general use as a drying agent should, it is not effective except with mass transfer and dilution. Acetone can be cooled with dry ice to -78 Â ° C without freezing; Acrylic/dry ice baths are usually used to perform reactions at low temperatures. Acetone fluorescent under ultraviolet light, and its vapor can be used as a fluorescent tracer in fluid flow experiments.
Medical and cosmetic use
Acetone is used in a variety of general medical and cosmetic applications and is also listed as a component in food additives and food packaging as well as nail polish remover. Dermatologists use acetone with alcohol for the treatment of acne to peel dry skin.
Acetone is generally used in chemical exfoliation. The common substances used today for chemical peels are salicylic acid, glycolic acid, 30% salicylic acid in ethanol, and trichloroacetic acid (TCA). Before chemexfoliation, the skin is cleansed and excess fat is removed in a process called defatting. Acetone, Septisole, or a combination of these agents is usually used in this process.
Domestic and other niche use
Acetone is often a major component in cleaning agents such as nail polish remover. Acetone is a superglue removal component and easily removes residues from glass and porcelain. Makeup artists use acetone to remove the skin adhesive from the wig and walnut netting by soaking it in an acetone bath, then removing the residue of the softened glue with a stiff brush.
Acetone is often used for vapor impregnation of printing artifacts in 3D print models that are molded with ABS plastic. The technique, called smooth smoothing acetone acetone, involves placing a molded part in an enclosed space containing a small amount of acetone, and heating about 80 degrees Celsius for 10 minutes. This creates acetone vapor in a container. Acetone condenses evenly across parts, causing the surface to soften and melt. Surface tension then smooths semi-liquid plastic. When that part is removed from the chamber, the acetone component evaporates leaving the glass-like portion of the striation, pattern, and edges of the visible layer, a common feature of the untreated 3D mold section.
Low grade acetone is also commonly used in academic laboratory settings as a glass rinse agent to remove residues and solids prior to final washing.
Security
Flammability
The most dangerous acetone acetone is its combustible properties. At temperatures greater than the flame of acetone -20 ° C (-4 ° F), the air mixture between 2.5% and 12.8% acetone, by volume, may explode or cause a fire. Steam can flow along the surface to a remote ignition source and flash back. Static discharges can also ignite acetone vapor, although acetone has a very high initiation energy initiation point and therefore unintentional ignition is rare. Even pouring or spraying acetone on a red glowing coal will not ignite it, due to the high concentration of vapor and the cooling effect of liquid evaporation. It automatically turns on 465 ° C (869 ° F). The temperature of auto-ignition also depends on lighting time, so on some tests it is quoted as 525 ° C. Also, industrial acetone may contain less water which also inhibits ignition.
Acetone peroxide
When oxidized, acetone forms acetone peroxide as a by-product, which is a highly unstable primary explosive compound. This may be formed by accident, eg. when the waste of hydrogen peroxide is poured into a solvent containing acetone. Because of its instability, it is rarely used, although simple chemical synthesis.
Health information
Acetone has been widely studied and is generally acknowledged to have low acute and chronic toxicity if swallowed and/or inhaled. Acetone is not currently regarded as a carcinogen, mutagenic chemicals or a concern for the effects of chronic neurotoxicity.
Acetone can be found as an ingredient in a variety of consumer products ranging from cosmetics to processed and unprocessed foods. Acetone has been assessed as a substance commonly known as safe substance (GRAS) when present in beverages, baked goods, desserts, and maintains at concentrations ranging from 5 to 8 mg/L.
Acetone has been shown to have an anticonvulsant effect on epileptic animal models, in the absence of toxicity, when administered in millimolar concentrations. It has been hypothesized that a clinically used, low-carbohydrate ketogenic diet to control drug-resistant epilepsy in children works by removing acetone in the brain. Because of their higher energy needs, children have higher acetone production than most adults - and the younger the child, the higher the production is expected. This suggests that children are not uniquely susceptible to exposure to acetone. External exposure is small compared to exposures associated with ketogenic diets.
Toxicology
Acetone is believed to exhibit little toxicity in normal use, and there is no strong evidence of chronic health effects if basic precautions are followed.
Acetone is an irritant that causes mild skin irritation and moderate to severe eye irritation. At high vapor concentrations, it can suppress the central nervous system like many other solvents. In one documented case, the consumption of large amounts of acetone led to systemic toxicity, although the patient eventually recovered completely. Some sources estimate LD 50 for human consumption at 0.621 g/kg; Acute toxicity for mice with consumption (LD 50 ) was 3 g/kg and with inhalation LC 50 ) was 44 g/m 3 above 4 hours.
- EPA EPCRA Delisting (1995). The EPA removes acetone from the list of "toxic chemicals" stored under Section 313 of the Emergency Planning and Community Rights to Know Act (EPCRA). In making that decision, the EPA conducted an extensive review of the toxicity data available on acetone and found that acetone "exhibits acute toxicity only at a rate that greatly exceeds the release and exposure produced", and further that acetone "exhibits low toxicity in chronic studies".
- Genotoxicity. Acetone has been tested in more than two dozen in vitro and in vivo assays. These studies show that acetone is not genotoxic.
- Carcinogenicity. The EPA in 1995 concluded, "There is currently no evidence to indicate concern about carcinogenicity". (Review of EPCRA, described in Section 3.3). NTP scientists have recommended against the chronic toxicity/carcinogenicity test of acetone because "prechronic studies show only mild toxic responses at very high doses in rodents".
- Neurotoxicity and Developmental Neurotoxicity. The neurotoxic potential of both acetone and isopropanol, metabolic acetone precursors, has been studied extensively. These studies suggest that although exposure to high doses of acetone may cause temporary central nervous system effects, non-neurotoxic acetone. A neurotoxicity study of guideline development has been done with isopropanol, and no neurotoxic developmental effects were identified, even at the highest doses tested. (SIAR, pp.1, 25, 31).
- Environment. When the EPA released acetone from regulation as volatile organic compound (VOC) in 1995, the EPA stated that this exclusion would "contribute to the achievement of some important environmental objectives and will support EPA pollution prevention efforts". 60 Fed. Reg. 31634 (June 16, 1995). 60 Fed. Reg. 31634 (June 16, 1995). The EPA notes that acetone may be used in place of some of the compounds listed as harmful air pollutants (HAP) under section 112 of the Clean Air Act.
Environmental effects
Although acetone occurs naturally in environments in plants, trees, volcanic gases, forest fires, and as a product of damage to body fat, most of the acetone released to the environment comes from the industry. Acetone evaporates quickly, even from water and soil. Once in the atmosphere, it has a 22-day beak and is degraded by UV light through photolysis (mainly into methane and ethane.) Consumption by microorganisms contributes to the dissociation of acetone in soil, animals, or waterways. LD 50 of acetone for fish is 8.3 g/L water (or about 1%) for 96 hours, and the half life time in water is about 1 to 10 days. Acetone may pose a significant risk of oxygen depletion in aquatic systems due to microbial consumption.
Externalerrestrial Events
On July 30, 2015, the scientists reported that after the first landing of Philae landed on the surface of the comet 67P, the measurements by the COSAC and Ptolemy instruments revealed sixteen organic compounds, four of which were seen for first time on comets, including acetamide, acetone, methyl isocyanate, and propionaldehyde.
References
External links
- International Chemical Safety Card 0087
- The NIOSH Pocket Guide for Chemical Hazards
- Acetone Safety Data Sheet (SDS)
- Substance of data of hazardous substances in the national library of medicine
- SIDS Preliminary Assessment Report for Acetone from Organization for Economic Cooperation and Development (OECD)
- Vapor pressure calculation, fluid density, dynamic liquid viscosity, acetone surface tension
Source of the article : Wikipedia
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