# Isopropyl alcohol
**Isopropyl alcohol** (isopropanol, 2-propanol, IPA; formula (CH₃)₂CHOH) is a colorless, flammable secondary alcohol that mixes with water in all proportions and is best known as the active ingredient of rubbing alcohol and as a widely used solvent and disinfectant.[1](https://www.cdc.gov/niosh/npg/npgd0359.html/1000) It is a clear liquid with an odor resembling a mixture of ethanol and acetone, a molecular weight of 60.1, and a slight bitter taste.[1](https://www.cdc.gov/niosh/npg/npgd0359.html/1000) • [2](https://pubchem.ncbi.nlm.nih.gov/compound/Isopropanol)
| Key fact | Detail |
|---|---|
| Identification | CAS 67-63-0; synonyms include isopropanol, 2-propanol, sec-propyl alcohol, dimethyl carbinol, IPA, rubbing alcohol[1](https://www.cdc.gov/niosh/npg/npgd0359.html/1000) |
| Physical properties | Boiling point 181°F; freezing point −127°F; specific gravity 0.79; vapor pressure 33 mmHg; miscible with water[1](https://www.cdc.gov/niosh/npg/npgd0359.html/1000) |
| Fire hazard | Flash point 53°F; lower explosive limit 2.0%, upper explosive limit 12.7% at 200°F; Class IB flammable liquid[1](https://www.cdc.gov/niosh/npg/npgd0359.html/1000) |
| Exposure limits | NIOSH REL and OSHA PEL: TWA 400 ppm (980 mg/m³); NIOSH short-term limit 500 ppm (1,225 mg/m³); ACGIH TLV-TWA 200 ppm[1](https://www.cdc.gov/niosh/npg/npgd0359.html/1000) • [3](https://www.osha.gov/chemicaldata/475) |
| IDLH | 2,000 ppm, set at 10% of the lower explosive limit of 2% on safety grounds[4](https://portugues.cdc.gov/niosh/idlh/67630.html) |
| Production | Hydration of propylene, by the indirect (sulfuric acid) process or by direct catalytic hydration; also by hydrogenation of acetone[5](https://www.ncbi.nlm.nih.gov/books/NBK304434/) |
| Disinfectant use | Optimum bactericidal concentration 60%–90% (v/v) in water; does not destroy bacterial spores[6](https://www.cdc.gov/infection-control/hcp/disinfection-sterilization/chemical-disinfectants.html) |
| Metabolism | Oxidized in the liver by alcohol dehydrogenase to acetone, producing ketosis without metabolic acidosis[7](https://www.ncbi.nlm.nih.gov/books/NBK493181/) |
## Physical and chemical properties
Isopropyl alcohol is a volatile, colorless liquid that is miscible with water, alcohol, ether, acetone, benzene, and chloroform, but insoluble in salt solutions.[1](https://www.cdc.gov/niosh/npg/npgd0359.html/1000) • [2](https://pubchem.ncbi.nlm.nih.gov/compound/Isopropanol) Its vapor is denser than air (vapor density 2.07) and forms explosive mixtures with air easily; the lower explosive limit is 2.0% and the upper limit is 12.7% at 200°F.[3](https://www.osha.gov/chemicaldata/475) • [2](https://pubchem.ncbi.nlm.nih.gov/compound/isopropanol) With a flash point of 53°F and a boiling point of 181°F, it is classified as a Class IB flammable liquid.[1](https://www.cdc.gov/niosh/npg/npgd0359.html/1000) It is incompatible with strong oxidizers, acetaldehyde, chlorine, ethylene oxide, acids, and isocyanates.[1](https://www.cdc.gov/niosh/npg/npgd0359.html/1000)
## Production
Isopropyl alcohol has been called the first petrochemical.[5](https://www.ncbi.nlm.nih.gov/books/NBK304434/) It can be prepared by three routes: indirect hydration of propylene, direct hydration of propylene, and catalytic hydrogenation of acetone.[5](https://www.ncbi.nlm.nih.gov/books/NBK304434/) In the indirect, or sulfuric-acid, process, propylene is reacted with sulfuric acid to produce mono- and diisopropyl sulfates, which are then hydrolyzed to isopropanol. This was the only method used worldwide until the first commercial direct-hydration process was introduced in 1951.[5](https://www.ncbi.nlm.nih.gov/books/NBK304434/)
**Direct hydration** avoids the concentrated sulfuric acid of the older route and so reduces equipment corrosion, energy costs, and air pollution from sulfur dioxide and organic sulfur compounds, but it requires a pure propylene feed, whereas the indirect process can use a dilute refinery stream.[5](https://www.ncbi.nlm.nih.gov/books/NBK304434/) • [8](https://www.ams.usda.gov/sites/default/files/media/Isopropanol%202%20TR%202014.pdf) European manufacturers of isopropanol mostly rely on direct hydration, whereas the process sees less use among industrial producers in the United States.[8](https://www.ams.usda.gov/sites/default/files/media/Isopropanol%202%20TR%202014.pdf) In the United States, the majority of isopropyl alcohol is produced by indirect hydration of propylene.[9](https://onlinelibrary.wiley.com/doi/10.1002/0471238961.0919151612150719.a01)
## Uses
Isopropyl alcohol serves as an industrial solvent for gums, shellac, essential oils, quick-drying inks and oils, and resins; it is used in antifreeze, in denaturing ethyl alcohol, in the extraction of alkaloids, and in the manufacture of acetone, glycerol, and isopropyl acetate.[2](https://pubchem.ncbi.nlm.nih.gov/compound/Isopropanol) It also appears in body rubs, hand lotions, aftershave lotions, cosmetics, and pharmaceuticals, and acts as an antiseptic and rubefacient.[2](https://pubchem.ncbi.nlm.nih.gov/compound/Isopropanol) In electronics manufacturing, it is one of the common cleaning solvents for parts and assemblies, valued for being nonconductive and noncorrosive.[10](https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/inspection-technical-guides/evaluation-production-cleaning-processes-electronic-medical-devices-part-ii-cleaning-solvents)
**Disinfection.** In healthcare, isopropyl alcohol and ethyl alcohol are rapidly bactericidal rather than bacteriostatic against vegetative bacteria, and are also tuberculocidal, fungicidal, and virucidal, but they do not destroy bacterial spores.[6](https://www.cdc.gov/infection-control/hcp/disinfection-sterilization/chemical-disinfectants.html) Their cidal activity drops sharply when diluted below 50%, and the optimum bactericidal concentration is 60%–90% solutions in water (volume/volume); the antimicrobial action is attributed mainly to denaturation of proteins.[6](https://www.cdc.gov/infection-control/hcp/disinfection-sterilization/chemical-disinfectants.html) FDA has not cleared any liquid chemical sterilant or high-level disinfectant with alcohol as the main active ingredient.[6](https://www.cdc.gov/infection-control/hcp/disinfection-sterilization/chemical-disinfectants.html)
In a well-known experiment that Spaulding conducted with the mucin-loop method, 70% isopropyl alcohol killed 10⁴ *M. tuberculosis* within 5 minutes, while a test run at the same time using 3% phenolic needed 2–3 hours to bring about an equivalent amount of microbial destruction.[11](https://www.cdc.gov/infection-control/hcp/disinfection-sterilization/efficacy-factors.html) Isopropyl alcohol was slightly more bactericidal than ethyl alcohol against *E. coli* and *S. aureus*, but unlike ethyl alcohol it is not active against the nonlipid enteroviruses.[6](https://www.cdc.gov/infection-control/hcp/disinfection-sterilization/chemical-disinfectants.html) In practice, 60%–90% alcohol is often used to disinfect small surfaces such as rubber stoppers of medication vials and thermometers, and occasionally external surfaces of equipment like stethoscopes; because alcohol evaporates rapidly, extended contact times are difficult to achieve unless items are immersed, which precludes practical use as a large-surface disinfectant.[12](https://www.cdc.gov/infection-control/hcp/environmental-control/environmental-services.html) Prolonged and repeated use may discolor, swell, harden, and crack rubber and certain plastics.[12](https://www.cdc.gov/infection-control/hcp/environmental-control/environmental-services.html)
**Hand sanitizers.** Isopropyl alcohol is one of the two active ingredients (with ethyl alcohol) in alcohol-based hand sanitizers, which the FDA regulates as over-the-counter drugs.[13](https://www.fda.gov/consumers/consumer-updates/safely-using-hand-sanitizer) The FDA has found that some hand sanitizers contain concerningly low levels of these active ingredients and maintains a list of products consumers should not use.[14](https://www.fda.gov/drugs/drug-alerts-and-statements/fda-updates-hand-sanitizers-consumers-should-not-use)
## Toxicity and poisoning
Although ethanol is ingested more often than isopropanol, among toxic alcohols it ranks first in annual reports to American poison control centers; the American Association of Poison Control Centers logged over 20,000 cases in 2009, over 80% of them accidental.[7](https://www.ncbi.nlm.nih.gov/books/NBK493181/) [Rubbing alcohol](https://www.edgepedia.org/rubbing-alcohol), typically a 70% isopropyl alcohol solution (up to 99% in some products), is a common source, along with alcohol swabs, cleaning supplies, paint thinners, and perfumes.[15](https://medlineplus.gov/ency/article/002660.htm)
About 80% of an oral dose is absorbed within 30 minutes, and absorption is complete within 2 hours.[2](https://pubchem.ncbi.nlm.nih.gov/compound/Isopropanol) Most isopropyl alcohol is oxidized in the liver by alcohol dehydrogenase to acetone; 20%–50% of an absorbed dose is excreted unchanged.[2](https://pubchem.ncbi.nlm.nih.gov/compound/Isopropanol) The hallmark of this metabolism is marked ketonemia and ketonuria in the absence of metabolic acidosis, because acetone is a terminal, uncharged ketone in the metabolic pathway, unlike the metabolites of the other toxic alcohols.[16](https://www.mdc-berlin.de/system/files/document/cjc_40.pdf) • [7](https://www.ncbi.nlm.nih.gov/books/NBK493181/) An elevated osmolal gap (difference between measured and calculated blood solute concentration) may be present throughout the intoxication, since both isopropanol and acetone are osmotically active.[17](https://assets.contenthub.wolterskluwer.com/api/public/content/83e5ffab54d640d69c519407d3245e6b?v=74c3c2e5)
Classically, toxicity is associated with rapid inebriation followed by hemorrhagic gastritis.[7](https://www.ncbi.nlm.nih.gov/books/NBK493181/) Symptoms include altered level of consciousness, gastrointestinal irritation, and in severe cases respiratory depression and hypotension.[18](https://pmc.ncbi.nlm.nih.gov/articles/PMC12916215/) Isopropanol is more intoxicating than ethanol, producing an altered sensorium, hypotension, hypothermia, and even cardiopulmonary collapse in severe cases.[7](https://www.ncbi.nlm.nih.gov/books/NBK493181/) Unlike the other toxic alcohols, isopropanol rarely causes death, and treatment is typically supportive.[7](https://www.ncbi.nlm.nih.gov/books/NBK493181/) Fomepizole should not be administered, because inhibiting alcohol dehydrogenase prolongs isopropanol's elimination.[18](https://pmc.ncbi.nlm.nih.gov/articles/PMC12916215/) Sponge baths with isopropanol to reduce fever are dangerous for children, since it is absorbed through the skin.[15](https://medlineplus.gov/ency/article/002660.htm)
## Occupational exposure
The NIOSH recommended exposure limit is a time-weighted average of 400 ppm (980 mg/m³) with a short-term limit of 500 ppm (1,225 mg/m³), matching the OSHA permissible exposure limit of 400 ppm TWA; 1 ppm equals 2.46 mg/m³.[1](https://www.cdc.gov/niosh/npg/npgd0359.html/1000) The immediately dangerous to life or health (IDLH) concentration is 2,000 ppm, set strictly on safety considerations at 10% of the lower explosive limit.[4](https://portugues.cdc.gov/niosh/idlh/67630.html) Exposure routes are inhalation, ingestion, and skin or eye contact; symptoms of overexposure include irritation of the eyes, nose, and throat, drowsiness, dizziness, headache, and dry cracking skin, with the eyes, skin, and respiratory system as target organs.[1](https://www.cdc.gov/niosh/npg/npgd0359.html/1000) Mild irritation of the eyes, nose, and throat was induced in human subjects exposed for 3 to 5 minutes to 400 ppm.[2](https://pubchem.ncbi.nlm.nih.gov/compound/isopropanol) Isopropyl alcohol is a defatting agent that can cause dermatitis on prolonged exposure, and little absorption occurs through intact skin.[2](https://pubchem.ncbi.nlm.nih.gov/compound/Isopropanol) It is not known as a liver or kidney toxin in humans, and ACGIH documentation states it is not hepatotoxic in experimental animal studies or in human exposures.[2](https://pubchem.ncbi.nlm.nih.gov/compound/Isopropanol) Carcinogenic classifications are IARC group 3 and TLV-A4 (not classifiable as a human carcinogen).[3](https://www.osha.gov/chemicaldata/475)
## References
1. [Isopropyl alcohol, NIOSH Pocket Guide to Chemical Hazards, CDC](https://www.cdc.gov/niosh/npg/npgd0359.html/1000)
2. [Isopropanol, CID 3776, PubChem (toxicological information)](https://pubchem.ncbi.nlm.nih.gov/compound/Isopropanol)
3. [Isopropyl Alcohol (2-Propanol), OSHA Chemical Data](https://www.osha.gov/chemicaldata/475)
4. [Isopropyl alcohol – IDLH, NIOSH, CDC](https://portugues.cdc.gov/niosh/idlh/67630.html)
5. [Isopropyl Alcohol Manufacture by the Strong-Acid Process, IARC Monographs, NCBI Bookshelf](https://www.ncbi.nlm.nih.gov/books/NBK304434/)
6. [Chemical Disinfectants, Guideline for Disinfection and Sterilization in Healthcare Facilities (2008), CDC](https://www.cdc.gov/infection-control/hcp/disinfection-sterilization/chemical-disinfectants.html)
7. [Isopropanol Toxicity, StatPearls, NCBI Bookshelf](https://www.ncbi.nlm.nih.gov/books/NBK493181/)
8. [Isopropanol Technical Report, USDA](https://www.ams.usda.gov/sites/default/files/media/Isopropanol%202%20TR%202014.pdf)
9. [Isopropyl Alcohol, Kirk-Othmer Encyclopedia of Chemical Technology, Wiley](https://onlinelibrary.wiley.com/doi/10.1002/0471238961.0919151612150719.a01)
10. [Evaluation of Production Cleaning Processes for Electronic Medical Devices, Part II, FDA](https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/inspection-technical-guides/evaluation-production-cleaning-processes-electronic-medical-devices-part-ii-cleaning-solvents)
11. [Factors Affecting the Efficacy of Disinfection and Sterilization, CDC](https://www.cdc.gov/infection-control/hcp/disinfection-sterilization/efficacy-factors.html)
12. [Environmental Services, Infection Control, CDC](https://www.cdc.gov/infection-control/hcp/environmental-control/environmental-services.html)
13. [Safely Using Hand Sanitizer, FDA](https://www.fda.gov/consumers/consumer-updates/safely-using-hand-sanitizer)
14. [FDA Updates on Hand Sanitizers Consumers Should Not Use, FDA](https://www.fda.gov/drugs/drug-alerts-and-statements/fda-updates-hand-sanitizers-consumers-should-not-use)
15. [Isopropanol Alcohol Poisoning, MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/002660.htm)
16. [Isopropyl alcohol metabolism review, CJC (MDC Berlin copy)](https://www.mdc-berlin.de/system/files/document/cjc_40.pdf)
17. [Isopropanol and acetone osmolal gap, Wolters Kluwer content](https://assets.contenthub.wolterskluwer.com/api/public/content/83e5ffab54d640d69c519407d3245e6b?v=74c3c2e5)
18. [Isopropanol toxicity, CMAJ/PMC](https://pmc.ncbi.nlm.nih.gov/articles/PMC12916215/)
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*Topic: Encyclopedia › Physical world and mathematics › Chemistry › Organic substances › Alcohols, ethers, and organooxygen groups › Alcohols and polyols › Lower alkanols (C1–C4)*
*Initially written Sep 17, 2026 · Reviewed: Sep 30, 2026; Oct 15, 2026 · Edited: Sep 30, 2026; Oct 15, 2026 · Last review: Oct 15, 2026*
*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*
License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license