4-Methyl-2-pentanone has a pleasant odor. It can be prepared by hydrogenation of mesityl oxide on Ni at 160–190 °C; also by oxidation of methyl isobutyl carbinol.
4-Methyl-2-pentanone has a fruity, ethereal, and spicy odor (when diluted).
4-Methyl-2-pentanone, also known as methyl isobutyl ketone (MIBK), is a colorless liquid with a pleasant, sweet, fruity odor. The odor threshold can be as low as 0.10 ppm. It is soluble to 2% by weight in water and various other organic solvents. The lower explosive limit is 1.2% and the upper explosive limit is 8.0% at 200°F. Methyl Isobutyl Ketone may be incompatible with strong oxidizing agents and potassium tert-butoxide.
Clear, colorless aqueous liquid with a mild, pleasant odor. Odor threshold concentration is 47 ppbv(Leonardos et al., 1969). Experimentally determined threshold odor concentrations for perception and recognition were 400 µg/m3(100ppbv) y 1,1 mg/m3(270ppbv), o (Hellman y Small, 1974).
Reported in Orange and Lemon Juice, Grape; Vinegar, Baked potato, Papaya, Ginger, Wheat bread, Cheese, Milk, Boiled egg, Fried chicken, Boiled beef, Mutton fat, Pig liver, Hop oil, Beer, Cognac, Coffee, Tea, Prunes, Plum Brandy, Mushrooms, Trassi, Sesame Seeds, Buckwheat, Seasonings, Elderflower, Bourbon Vanilla, Clary Sage and Red Sage, Crayfish, Clam and Chinese Quince.
In paints, adhesives and cleaning products; Used in the plastics and gasoline industries.
MIBK is used as a solvent for gums, resins, nitrocellulose and cellulose ethers, and various fats, oils, and waxes.
Methyl isobutyl ketone (hexone, isobutyl methyl ketone, 4-methyl-2-pentanone) is an organic solvent similar in structure and use to methyl butyl ketone. In addition to its use as a solvent for paints, lacquers, and lacquers, methyl isobutyl ketone is used in extraction processes and as a denaturant for isopropyl alcohol. Methyl isobutyl ketone is also used as a synthetic flavoring in some varieties of rum, candy, and cheese. Unlike methyl butyl ketone, methyl isobutyl ketone has been found not to occur naturally.
Methyl isobutyl ketone can be produced by two methods. The first is a mixed ketone process in which MiBK, diisobutylketone, and acetone are co-produced in a single reaction using isopropanol as the starting material. The second method is used to produce the majority of MiBK and involves a three-step reaction sequence that forms diacetone alcohol and mesityl oxide as intermediate products.
By hydrogenation of mesityl oxide on Ni from 160 to 190°C; also by oxidation of methyl isobutyl carbinol.
Detection: 240 to 640 ppb
Flavor characteristics at 25ppm: sweet, ethereal, banana and fruity with hints of milk
Journal of the American Chemical Society, 100, p. 5437, 1978DOI: 10.1021/ja00485a031
Tetrahedron Letters, 36, p. 2285, 1995DOI: 10.1016/0040-4039(95)00191-E
Tetrahedron, 37, p. 3073 ,DOI: 10.1016/S0040-4020(01)98839-8
Transparent, colorless liquid with a pleasant odor. Flash point 73°F. Less dense than water. Vapors heavier than air.
air and water reactions
Extremely flammable. 4-Methyl-2-pentanone is sensitive to air (may form explosive peroxides). Easily soluble in water.
4-Methyl-2-pentanone is incompatible with caustic soda and other strong alkalis, hydrochloric acid, sulfuric acid, and other strong inorganic acids, amines, and oxidizing agents such as hydrogen peroxide, nitric acid, perchloric acid, and chromium trioxide. 4-Methyl-2-pentanone reacts violently with potassium tert-butoxide. 4-Methyl-2-pentanone reacts violently with reducing substances. .
Flammable, Fire Hazard Hazardous, Explosive Limits in Air 1.4-7.5%. Avoid swallowing and inhaling. Upper respiratory tract irritation, dizziness and headache. Possible carcinogen.
Vapors cause eye and nose irritation; high concentrations cause anesthesia and depression. The liquid dries out the skin and can cause dermatitis; it irritates the eyes but does not damage them.
MIBK has low to moderate toxicity. It is more toxic than acetone. Exposure to 200 ppm may irritate eyes, mucous membranes, and skin. Prolonged skin contact can leach oil from the skin. Exposure to high concentrations can cause nausea, headache, and narcosis. Animal studies suggest that this compound could likely cause kidney damage, with symptoms of a heavier kidney, a higher kidney-to-body weight ratio, and tubular necrosis. An increase in liver weight was also found in relation to exposure in animals. In male rats, the effects were observed after exposure to 2000 ppm for 2 weeks (6 hours/day) (Phillips et al. 1987). Other than effects on the kidneys in male rats, concentrations up to 1000 ppm had no significant toxicological effect for 14 weeks. In another study, exposure to 3000 ppm in rats and mice was found to cause increased liver and kidney weights, reduced food intake, fetal deaths, and reduced fetal body weight (Tyl et al. 1987).
Taking MIBK can lead to anesthesia and coma. A genetic toxicology study of MIBK showed a negative reaction in bacterial mutation assays and the yeast mitotic gene conversion assay (Brooks et al., 1988).
Valor LD50, oral (rata): 2080 mg/kg
Valor LD50, intraperitoneal (rata): 400 mg/kg.
Flammability and explosivity
Reactivity with water No reaction; Reactivity with Common Materials: No reaction; Transport stability: Stable; Acid and base neutralizers: Not applicable; Polymerization: Not relevant; Polymerization inhibitor: Not applicable.
MIBK is used as a solvent; a denaturant; and as an extractant; in the manufacture of methyl amyl alcohol; as a solvent in paints, varnishes and varnishes; as an alcohol denaturant; as a solvent in the extraction of uranium from fission products.
The National Toxicology Program performed cancer bioassays by subjecting groups of 50 male and 50 female F344 rats and B6C3F1 mice to MiBK vapor at 0, 450, 900, or 1800 ppm 6 h/day, 5 days/week for 2 years off. Survival and body weight gain were reduced in male rats at 1800 ppm. Body weight gain was also reduced in male rats at 900 ppm and in female mice at 1800 ppm. In male rats, increased renal papilla mineralization was observed at all levels of MiBK exposure. Chronic progressive kidney disease (CPN) and the incidence of adenomas and adenomas or carcinomas (combined) were increased in males exposed to 1800 ppm. The severity of NPC and renal tubular hyperplasia was increased in all exposure groups of male rats. For the male group at 1800 ppm, an uncertain increase in mononuclear cell leukemia, adrenal medulla hyperplasia, and a positive trend of increased benign or malignant (combined) pheochromocytomas were reported. The NTP considered that there was some evidence of carcinogenic activity in male rats due to the increased incidence of renal tubular neoplasms.
None of the results from the rodent bioassays were considered to provide clear evidence of carcinogenicity of NTP.
Biological.Bridie et al. (1979) reported BOD and COD values of 2.06 and 2.16 g/g using filtered effluents from a biological wastewater treatment plant. These values were determined using a standard dilution method at 20°C and shaking for 5 days. Heukelekian and Rand (1955) reported a 5-day BOD value of 1.51 g/g, which is 55.5% of the ThOD value of 2.72 g/g.
PhotolithismWhen synthetic air containing gaseous nitrous acid and 4-methyl-2-pentanone was exposed to artificial sunlight (λ = 300-450 nm), acetone, peroxyacetal nitrate and methyl nitrate were identified as products of photooxidation (Cox et al., 1980). In a later experiment, OH-initiated photooxidation of 4-methyl-2-pentanone in a smog chamber produced acetone (90% yield) and peroxyacetal nitrate (Cox et al., 1981). Irradiation at 3130 ? led to the formation of acetone, propyldiene, and free radicals (Calvert and Pitts, 1966).
The second order photooxidation rate constants for the reaction of 4-methyl-2-butanone and OH radicals in the atmosphere are 1.4 x 10-10, 1,42x10-10y 1.32x10-10cm3/molecule?sec at 295,299 and 300 K, respectively (Atkinson, 1985). The atmospheric lifetime has been estimated at 1-5 days (Kelly et al., 1994).
PhotolithismCox et al. (1980) reported a rate constant of 1.24 x 10-11cm3/molecule?sec for the reaction of 4-methyl-2-pentanone gas with OH radicals based on a value of 8 x 10-12cm3/molecule?sec for the reaction of ethylene with OH radicals.
Chemical/Physical.4-Methyl-2-pentanone will not hydrolyze in water because it does not contain a hydrolyzable functional group (Kollig, 1993).
UN1245 Methylisobutylketone, Hazard class: 3 Labels: 3-Flammable liquid.
Reflux the ketone with some KMnO4, wash with aq. NaHCO3, dry over CaSO4, and distill. Acidic contaminants are removed by passing them through a small column of activated alumina. [Beilstein 1 IV 3305.]
May form unstable and explosive peroxides in contact with air. Reacts violently with strong oxidants, potassium tert-butoxide; strong acids; aliphaticamines; reducing agent
Contact environmental authorities for guidance on acceptable disposal practices. Producers of waste containing this contaminant (≥100 kg/month) must comply with EPA standards for waste storage, transportation, treatment, and disposal. Combustion.