Description
4-Methyl-2-pentanone has a pleasant odor. May be prepared by
hydrogenation of mesityl oxide over Ni at 160 - 190°C; also by
oxidation of methyl isobutyl carbinol.
Chemical Properties
4-Methyl-2-pentanone has a fruity, ethereal, spicy (on dilution) odor.
Chemical Properties
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 2% soluble in water by weight and with several 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 oxidizers and potassium tert-butoxide.
Physical properties
Clear, colorless, watery liquid with a mild, pleasant odor. Odor threshold concentration is 47 ppb
v
(Leonardos et al., 1969). Experimentally determined detection and recognition odor threshold
concentrations were 400 μg/m
3 (100 ppb
v) and 1.1 mg/m
3 (270 ppb
v), respectively (Hellman and
Small, 1974).
Occurrence
Reported found in orange and lemon juice, grape; vinegar, baked potato, papaya, ginger, wheat bread, cheeses,
milk, cooked egg, roast chicken, cooked beef, lamb fat, pork liver, hop oil, beer, cognac, coffee, tea, plumcot, plum brandy, mushroom, trassi, sesame seed, buckwheat, wort, elder flower, Bourbon vanilla, clary and red sage, crab, clam and Chinese quince.
Uses
In paints, glues, and cleaning agents;
used in the plastic and petrol industries
Uses
MIBK is used as a solvent for gums, resins,nitrocellulose and cellulose ethers, and various fats, oils, and waxes.
Uses
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 varnishes, methyl isobutyl ketone is used in extraction processes and as a denaturant for rubbing 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 not been found to occur naturally.
Definition
ChEBI: Methyl isobutyl ketone is a ketone.
Production Methods
Methyl isobutyl ketone can be manufactured by two processes
. The first is a mixed ketone process where MiBK,
diisobutyl ketone, and acetone are coproduced in a single
reaction using isopropanol as a starting material. The second
method is used to produce the majority of MiBK and involves
a three-step reaction sequence in which diacetone alcohol
and mesityl oxide are formed as intermediates.
Preparation
By hydrogenation of mesityl oxide over Ni at 160 to 190°C; also by oxidation of methyl isobutyl carbinol.
Aroma threshold values
Detection: 240 to 640 ppb
Taste threshold values
Taste characteristics at 25 ppm: sweet, ethereal, banana and fruity with dairy nuances
General Description
A clear colorless liquid with a pleasant odor. Flash point 73°F. Less dense than water. Vapors heavier than air.
Air & Water Reactions
Highly flammable. 4-Methyl-2-pentanone is sensitive to air (may form explosive peroxides). Slightly soluble in water.
Reactivity Profile
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 vigorously with reducing materials. .
Hazard
Flammable, dangerous fire risk, explosivelimits in air 1.4–7.5%. Avoid ingestion and inhala-tion. Upper respiratory tract irritant, dizziness, andheadache. Possible carcinogen.
Health Hazard
Vapor causes irritation of eyes and nose; high concentrations cause anesthesia and depression. Liquid dries out skin and may cause dermatitis; irritates eyes but does not injure them.
Health Hazard
MIBK exhibits low to moderate toxicity.It is more toxic than acetone. Exposureto 200 ppm can cause irritation of theeyes, mucous membranes, and skin. Prolonged skin contact can leach out fat fromthe skin. Exposure to high concentrationscan cause nausea, headache, and narcosis. Animal studies indicate that this compound could probably cause kidney damage,with symptoms of a heavier kidney, higherkidney-to-body weight ratio, and tubularnecrosis. An increase in liver weight wasnoted, too, associated with its exposure inanimal subjects. In male rats the effect wasobserved at 2000 ppm on 2 weeks’ exposure(6 hours/day) (Phillips et al. 1987). Otherthan for the male rat kidney effect, the levelsup to 1000 ppm for 14 weeks had no significant toxicological effect. In another study,exposure to 3000 ppm in rats and mice wasfound to cause increased liver and kidneyweights, decrease in food consumption, incidence of dead fetuses, and reduced fetal bodyweight (Tyl et al. 1987).
Ingestion of MIBK can result in narcosis and coma. A genetic toxicology studyof MIBK showed a negative response inthe bacterial mutation assays and the yeastmitotic gene conversion assay (Brooks et al.1988).
LD50 value, oral (rat): 2080 mg/kg
LD50 value, intraperitoneal (rat): 400 mg/kg.
Flammability and Explosibility
Highly flammable
Chemical Reactivity
Reactivity with Water No reaction; Reactivity with Common Materials: No reaction; Stability During Transport: Stable; Neutralizing Agents for Acids and Caustics: Not pertinent; Polymerization: Not pertinent; Inhibitor of Polymerization: Not pertinent.
Potential Exposure
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 lacquers; as an alcohol denaturant; as a solvent in uranium
extraction from fission products.
First aid
If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts theskin, remove contaminated clothing and wash immediatelywith soap and water. Seek medical attention immediately. Ifthis chemical has been inhaled, remove from exposure,begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR ifheart action has stopped. Transfer promptly to a medicalfacility. When this chemical has been swallowed, get medical attention. Give large quantities of water and inducevomiting. Do not make an unconscious person vomit.
Carcinogenicity
The National Toxicology Program
conducted cancer bioassays by exposing groups of
50 male and 50 female F344 rats and B6C3F1 mice to
MiBK vapor at 0, 450, 900, or 1800 ppm 6h/day, 5 days/
week for 2 years. Survival and body weight gain
were decreased in male rats at 1800 ppm. Body weight
gain was also decreased in male rats at 900 and in female
mice at 1800ppm. A higher incidence of mineralization of
the renal papilla was observed in male rats at all MiBK
exposure levels. Chronic progressive nephropathy (CPN) and
the incidences of adenoma and adenoma or carcinoma
(combined) were increased for the male 1800 ppm exposure
group. The severity of CPN and renal tubular hyperplasia was
increased in all male rat exposure groups. An uncertain
increase in mononuclear cell leukemia, adrenal medulla
hyperplasia, and a positive trend for increases in benign or
malignant pheochromocytomas (combined) were reported
for the 1800 ppm male group. The NTP considered that there
was some evidence of carcinogenic activity in male rats
based on increased incidences of renal tubule neoplasms.
None of the rodent bioassay results were considered clear
evidence of carcinogenicity by NTP.
Environmental Fate
Biological. Bridié et al. (1979) reported BOD and COD values of 2.06 and 2.16 g/g using
filtered effluent from a biological sanitary waste treatment plant. These values were determined
using a standard dilution method at 20 °C and stirred for a period of 5 d. Heukelekian and Rand
(1955) reported a 5-d BOD value of 1.51 g/g which is 55.5% of the ThOD value of 2.72 g/g.
Photolytic. When synthetic air containing gaseous nitrous acid and 4-methyl-2-pentanone was
exposed to artificial sunlight (λ = 300–450 nm), photooxidation products identified were acetone,
peroxyacetal nitrate, and methyl nitrate (Cox et al., 1980). In a subsequent experiment, the OHinitiated
photooxidation of 4-methyl-2-pentanone in a smog chamber produced acetone (90%
yield) and peroxyacetal nitrate (Cox et al., 1981). Irradiation at 3130 ? resulted in the formation of
acetone, propyldiene, and free radicals (Calvert and Pitts, 1966).
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, 1.42 x 10
-10, and 1.32 x 10
-10 cm
3/molecule?sec at 295,
299, and 300 K, respectively (Atkinson, 1985). The atmospheric lifetime was estimated to be 1–5
d (Kelly et al., 1994).
Photolytic. Cox et al. (1980) reported a rate constant of 1.24 x 10
-11 cm
3/molecule?sec for the
reaction of gaseous 4-methyl-2-pentanone with OH radicals based on a value of 8 x 10
-12
cm
3/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).
storage
Color Code—Red: Flammability Hazard: Store ina flammable liquid storage area or approved cabinet awayfrom ignition sources and corrosive and reactive materials.Prior to working with this chemical you should be trainedon its proper handling and storage. Before entering confinedspace where this chemical may be present, check to makesure that an explosive concentration does not exist. Methylisobutyl ketone must be stored to avoid contact with strongoxidizers because violent reactions occur. Store in tightlyclosed containers in a cool, well-ventilated area away fromheat, sparks, and flames. Sources of ignition, such as smoking and open flames, are prohibited where methyl isobutylketone is used, handled, or stored in a manner that couldcrate a potential fire or explosion hazard. Metal containersinvolving the transfer of 5 gallons or more of methyl isobutyl ketone should be grounded and bonded. Drums must beequipped with self-closing valves, pressure vacuum bungs,and flame arresters. Use only nonsparking tools and equipment, especially when opening and closing containers ofmethyl isobutyl ketone.
Shipping
UN1245 Methyl isobutyl ketone, Hazard Class: 3;
Labels: 3-Flammable liquid.
Purification Methods
Reflux the ketone with a little KMnO4, wash it with aqueous NaHCO3, dry with CaSO4 and distil it. Acidic impurities are removed by passage through a small column of activated alumina. [Beilstein 1 IV 3305.]
Incompatibilities
Able to form unstable and explosive peroxides on contact with air. Reacts violently with strong oxidizers, potassium tert-butoxide; strong acids; aliphatic
amines; reducing agents
Toxics Screening Level
The Initial Threshold Screening Level (ITSL) for methyl isobutyl ketone (MIBK) is 820 μg/m3 with an 8-hr averaging time.
Waste Disposal
Consult with environmental
regulatory agencies for guidance on acceptable disposal
practices. Generators of waste containing this contaminant
(≥100 kg/mo) must conform to EPA regulations governing
storage, transportation, treatment, and waste disposal.
Incineration.
