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| Names | |||
|---|---|---|---|
| Preferred IUPAC name Propan-2-ol[2] | |||
| Other names | |||
| Identifiers | |||
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3D model (JSmol) | |||
| 635639 | |||
| ChEBI | |||
| ChEMBL | |||
| ChemSpider |
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| ECHA InfoCard | 100.000.601 | ||
| 1464 | |||
| KEGG |
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| RTECS number |
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| UNII | |||
| UN number | 1219 | ||
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| Properties | |||
| C3H8O | |||
| Molar mass | 60.096 g/mol | ||
| Appearance | Colorless liquid | ||
| Odor | Pungent alcoholic odor | ||
| Density | 0.786 g/cm3 (20 °C) | ||
| Melting point | −89 °C (−128 °F; 184 K) | ||
| Boiling point | 82.6 °C (180.7 °F; 355.8 K) | ||
| Miscible with water | |||
| Solubility | Miscible withbenzene,chloroform,ethanol,diethyl ether,glycerol; soluble inacetone | ||
| logP | −0.16[3] | ||
| Acidity (pKa) | 16.5[4] | ||
| −45.794·10−6 cm3/mol | |||
Refractive index (nD) | 1.3776 | ||
| Viscosity | 2.86 cP at 15 °C 1.96 cP at 25 °C[5] 1.77 cP at 30 °C[5] | ||
| 1.66 D (gas) | |||
| Pharmacology | |||
| D08AX05 (WHO) | |||
| Hazards | |||
| Occupational safety and health (OHS/OSH): | |||
Main hazards | Flammable, mildly toxic[6] | ||
| GHS labelling: | |||
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| Danger | |||
| H225,H302,H319,H336 | |||
| P210,P261,P305+P351+P338 | |||
| NFPA 704 (fire diamond) | |||
| Flash point | Open cup: 11.7 °C (53.1 °F; 284.8 K) Closed cup: 13 °C (55 °F) | ||
| 399 °C (750 °F; 672 K) | |||
| Explosive limits | 2–12.7% | ||
Threshold limit value (TLV) | 980 mg/m3 (TWA), 1225 mg/m3 (STEL) | ||
| Lethal dose or concentration (LD, LC): | |||
LD50 (median dose) | |||
LC50 (median concentration) |
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LCLo (lowest published) |
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| NIOSH (US health exposure limits): | |||
PEL (Permissible) | TWA 400 ppm (980 mg/m3)[7] | ||
REL (Recommended) | TWA 400 ppm (980 mg/m3),ST 500 ppm (1225 mg/m3)[7] | ||
IDLH (Immediate danger) | 2000 ppm[7] | ||
| Safety data sheet (SDS) | [1] | ||
| Related compounds | |||
Relatedalcohols | 1-Propanol,ethanol,2-butanol | ||
| Supplementary data page | |||
| Isopropyl alcohol (data page) | |||
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |||
Isopropyl alcohol (IUPAC namepropan-2-ol and also calledisopropanol or2-propanol) is acolorless,flammable,organic compound with a pungent alcoholicodor.[9]
Isopropyl alcohol, an organicpolar molecule, ismiscible in water,ethanol, andchloroform, demonstrating its ability to dissolve a wide range of substances includingethyl cellulose,polyvinyl butyral, oils,alkaloids, and naturalresins. Notably, it is notmiscible with salt solutions and can be separated by addingsodium chloride in a process known assalting out. It forms anazeotrope with water, resulting in aboiling point of 80.37 °C and is characterized by its slightly bitter taste. Isopropyl alcohol becomesviscous at lower temperatures, freezing at −89.5 °C, and has significantultraviolet-visible absorbance at 205 nm. Chemically, it can be oxidized toacetone or undergo various reactions to form compounds likeisopropoxides oraluminium isopropoxide. As anisopropyl group linked to ahydroxyl group (chemical formula(CH3)2CHOH) it is the simplest example of asecondary alcohol, where thealcohol carbon atom is attached to two other carbon atoms. It is astructural isomer ofpropan-1-ol andethyl methyl ether. They all have the formulaC3H8O.
It was first synthesized in 1853 byAlexander William Williamson and later produced forcordite preparation. It is produced through hydration ofpropene orhydrogenation of acetone, with modern processes achieving anhydrous alcohol throughazeotropic distillation. Beyond its production, isopropyl alcohol serves in medical settings as arubbing alcohol andhand sanitizer, and in industrial and household applications as a solvent. It is a common ingredient in products such asantiseptics,disinfectants anddetergents. More than a million tonnes are produced worldwide annually. Despite its utility, isopropyl alcohol poses safety risks due to its flammability and potential forperoxide formation. Its ingestion or absorption leads totoxic effects includingcentral nervous system depression andcoma, primarily treated through supportive measures.
Isopropyl alcohol ismiscible in water,ethanol, andchloroform, as it is anorganicpolar molecule. It dissolvesethyl cellulose,polyvinyl butyral, many oils, alkaloids, and natural resins.[10] Unlikeethanol ormethanol, isopropyl alcohol is not miscible with salt solutions and can be separated fromaqueous solutions by adding a salt such assodium chloride. The process is colloquially calledsalting out, and causes concentrated isopropyl alcohol to separate into a distinct layer.[11]
Isopropyl alcohol forms anazeotrope with water, which gives a boiling point of 80.37 °C (176.67 °F) and a composition of 87.7% by mass (91% by volume) isopropyl alcohol. It has a slightly bitter taste, and is not safe to drink.[11][12]
Isopropyl alcohol becomes increasingly viscous with decreasing temperature and freezes at −89.5 °C (−129.1 °F).[9] Mixtures with water have higher freezing points: 99% at −89.5 °C (−129.1 °F), 91% (the azeotrope) at −75.5 °C (−103.9 °F), and 70% at −61.7 °C (−79.1 °F).[13]
Isopropyl alcohol has a maximalabsorbance at 205 nm in anultraviolet-visible spectrum.[14][15]
Isopropyl alcohol can beoxidized toacetone, which is the correspondingketone. This can be achieved using oxidizing agents such aschromic acid, or bydehydrogenation of isopropyl alcohol over a heated coppercatalyst:
Isopropyl alcohol is often used as both solvent andhydride source in theMeerwein-Ponndorf-Verley reduction and othertransfer hydrogenation reactions. Isopropyl alcohol may be converted to2-bromopropane usingphosphorus tribromide, or dehydrated topropene by heating withsulfuric acid.
Like most alcohols, isopropyl alcohol reacts with activemetals such aspotassium to formalkoxides that are calledisopropoxides. Withtitanium tetrachloride, isopropyl alcohol reacts to givetitanium isopropoxide:
This and similar reactions are often conducted in the presence of base.
The reaction withaluminium is initiated by a trace ofmercury to givealuminium isopropoxide.[16]
Isopropyl alcohol was first synthesized by the chemistAlexander William Williamson in 1853. He achieved this by heating a mixture of propene and sulfuric acid.Standard Oil produced isopropyl alcohol by hydratingpropene. Isopropyl alcohol was oxidized toacetone for the preparation ofcordite, a smokeless,low explosive propellant.[17]
In 1994, 1.5 million tonnes of isopropyl alcohol were produced in the United States, Europe, and Japan.[18] It is primarily produced by combining water andpropene in ahydration reaction or by hydrogenatingacetone.[18][19] There are two routes for the hydration process and both processes require that the isopropyl alcohol be separated from water and other by-products bydistillation. Isopropyl alcohol and water form anazeotrope, and simple distillation gives a material that is 87.9% by mass isopropyl alcohol and 12.1% by mass water.[20] Pure (anhydrous) isopropyl alcohol is made byazeotropic distillation of the wet isopropyl alcohol using eitherdiisopropyl ether orcyclohexane as azeotroping agents.[18]
Small amounts of isopropyl alcohol are produced in the body indiabetic ketoacidosis.[21]
Indirecthydration reacts propene withsulfuric acid to form a mixture of sulfate esters. This process can use low-quality propene, and is predominant in the USA. These processes give primarily isopropyl alcohol rather than 1-propanol, because adding water or sulfuric acid to propene followsMarkovnikov's rule. Subsequenthydrolysis of these esters by steam produces isopropyl alcohol, by distillation.Diisopropyl ether is a significant by-product of this process; it is recycled back to the process and hydrolyzed to give the desired product.[18]
Direct hydration reacts propene and water, either in gas or liquidphase, at high pressures in the presence of solid or supported acidiccatalysts. This type of process usually requires higher-puritypropylene (> 90%).[18] Direct hydration is more commonly used in Europe.
Isopropyl alcohol can be prepared via thehydrogenation ofacetone, but this approach involves an extra step compared to the above methods, as acetone is itself normally prepared from propene via thecumene process.[18]IPA cost is primarily driven by raw material cost, and this way is economical when acetone is cheaper than propylene as abyproduct ofphenol production (the coexistence of two ways on most markets allows them to balance the prices).
A known issue is the formation ofMIBK and other self-condensation products.Raney nickel was one of the original industrial catalysts, modern catalysts are oftensupported bimetallic materials.
In 1990, 45,000 metric tonnes of isopropyl alcohol were used in the United States, mostly as a solvent for coatings or for industrial processes. In that year, 5400 metric tonnes were used for household purposes and in personal care products. Isopropyl alcohol is popular in particular for pharmaceutical applications,[18] due to its low toxicity. Some isopropyl alcohol is used as a chemical intermediate. Isopropyl alcohol may be converted to acetone, but thecumene process is more significant.[18]
Isopropyl alcohol dissolves a wide range ofnon-polar compounds. It evaporates quickly and the typically available grades tend to not leave behind oil traces when used as a cleaning fluid unlike some other common solvents. It is also relatively non-toxic. Thus, it is used widely as a solvent and as a cleaning fluid, especially where there are oils or oil based residues which are not easily cleaned with water, conveniently evaporating and (depending on water content and other variables) posing less of a risk of corrosion or rusting than plain water. Together withethanol,n-butanol, andmethanol, it belongs to the group of alcohol solvents.
Isopropyl alcohol is commonly used for cleaningeyeglasses,electrical contacts, audio or videotape heads, DVD and otheroptical disc lenses,bongs,[22] and for removingthermal paste fromheatsinks onCPUs[23] and otherIC packages.
Isopropyl alcohol isesterified to giveisopropyl acetate, another solvent. It reacts withcarbon disulfide andsodium hydroxide to givesodium isopropylxanthate, which has use as anherbicide and anore flotation reagent.[24] Isopropyl alcohol reacts withtitanium tetrachloride andaluminium metal to givetitanium andaluminium isopropoxides, respectively, the former a catalyst, and the latter a chemical reagent.[18] This compound may serve as a chemical reagent in itself, by acting as a dihydrogen donor intransfer hydrogenation.
Rubbing alcohol,hand sanitizer, anddisinfecting pads typically contain a 60–70%solution of isopropyl alcohol orethanol inwater. Water is required to open up membrane pores of bacteria, which acts as a gateway for isopropyl alcohol. A 75%v/v solution in water may be used as a hand sanitizer.[25] Isopropyl alcohol is used as a water-drying aid for the prevention ofotitis externa, better known as swimmer's ear.[26]
Inhaled isopropyl alcohol can be used for treating nausea in some settings by placing a disinfecting pad under the nose.[27]
Although isopropyl alcohol can be used for anesthesia, its many negative attributes or drawbacks prohibit this use. Isopropyl alcohol can also be used similarly to ether as a solvent[28] or as an anesthetic by inhaling the fumes or orally. Early uses included using the solvent as general anesthetic for small mammals[29] and rodents by scientists and some veterinarians. However, it was soon discontinued, as many complications arose, including respiratory irritation, internal bleeding, and visual and hearing problems. In rare cases, respiratory failure leading to death in animals was observed.
Isopropyl alcohol is a major ingredient in "gas dryer"fuel additives. In significant quantities,water is a problem in fuel tanks, as it separates from gasoline and can freeze in the supply lines at low temperatures. Alcohol does not remove water from gasoline, but the alcoholsolubilizes water in gasoline. Oncesoluble, water does not pose the same risk as insoluble water, as it no longer accumulates in the supply lines and freezes but is dissolved within the fuel itself. Isopropyl alcohol is often sold in aerosol cans as awindshield or door lock deicer. Isopropyl alcohol is also used to removebrake fluid traces from hydraulic braking systems, so that the brake fluid (usuallyDOT 3,DOT 4, ormineral oil) does not contaminate thebrake pads and cause poor braking. Mixtures of isopropyl alcohol and water are also commonly used in homemade windshield washer fluid.
As a biological specimen preservative, isopropyl alcohol provides a comparatively non-toxic alternative toformaldehyde and other synthetic preservatives. Isopropyl alcohol solutions of 70–99% are used to preserve specimens.
Isopropyl alcohol is often used inDNA extraction. A lab worker adds it to a DNA solution to precipitate the DNA, which then forms a pellet after centrifugation. This is possible because DNA is insoluble in isopropyl alcohol.
Isopropyl alcohol is used as an additive in alkalineanisotropic etching ofmonocrystalline silicon, such as withpotassium hydroxide ortetramethylammonium hydroxide. This process is used in texturing ofsilicon solar cells and microfabrication (e.g. inMEMS devices). Isopropyl alcohol increases the anisotropy of the etch by increasing the etch rate of [100] plane relative tohigher indexed planes.[30]
Isopropyl alcohol vapor is denser than air and isflammable, with aflammability range of between 2% and 12.7% in air. It should be kept away from heat, sparks, and open flame.[31] Distillation of isopropyl alcohol over magnesium has been reported to formperoxides, which may explode upon concentration.[32][33] Isopropyl alcohol can react with air and oxygen over time to form unstable peroxides that can explode.[34]
Isopropyl alcohol, via its metabolites, is somewhat more toxic than ethanol, but considerably less toxic thanethylene glycol ormethanol. Death from ingestion or absorption of even relatively large quantities is rare. Both isopropyl alcohol and itsmetabolite,acetone, act ascentral nervous system (CNS)depressants.[35] Poisoning can occur from ingestion, inhalation, or skin absorption.[36]Symptoms of isopropyl alcohol poisoning includeflushing,headache,dizziness,CNS depression,nausea,vomiting,anesthesia,hypothermia,low blood pressure,shock,respiratory depression, andcoma.[35] Overdoses may cause a fruity odor on the breath as a result of its metabolism toacetone.[37]Isopropyl alcohol does not cause ananion gap acidosis, but it produces anosmolal gap between the calculated and measured osmolalities of serum, as do the other alcohols.[35] The findings ofacetone without acidosis leads to thesine qua non of "ketosis without acidosis."
Isopropyl alcohol is oxidized to form acetone byalcohol dehydrogenase in the liver[35] and has abiological half-life in humans between 2.5 and 8.0 hours.[35] Unlikemethanol orethylene glycol poisoning, the metabolites of isopropyl alcohol are considerably less toxic, and treatment is largely supportive. Furthermore, there is no indication for the use offomepizole, an alcohol dehydrogenase inhibitor, unless co-ingestion with methanol or ethylene glycol is suspected.[38]
Inforensic pathology, people who have died as a result ofdiabetic ketoacidosis oralcoholic ketoacidosis, with no isopropyl alcohol ingestion, usually have detectable blood concentrations of isopropyl alcohol of 1 to 40 mg/dL, while those by fatal isopropyl alcohol ingestion usually have blood concentrations of hundreds of mg/dL.[21]
Designations such as isopropanol, sec-butanol, and tert-butanol are incorrect because there are no hydrocarbons isopropane, sec-butane, and tert-butane to which the suffix "-ol" can be added; such names should be abandoned. Isopropyl alcohol, sec-butyl alcohol, and tert-butyl alcohol are, however, permissible (see Rule C-201.3) because the radicals isopropyl, sec-butyl, and tert-butyl do exist.
