Isopropanol
Properties
| State | Liquid (colorless with strong, characteristic alcoholic odor) |
| Color | Colorless |
| Solubility | Miscible with water in all proportions; miscible with ethanol, ether, and chloroform |
| Melting Point | -89°C |
| Boiling Point | 82.6°C |
About Isopropanol
Isopropanol is the simplest secondary alcohol — a hydroxyl group hanging off the middle carbon of propane — and it's the solvent that runs the modern electronics industry. A semiconductor fab can burn through hundreds of kilograms of high-purity (semiconductor-grade, sub-1 ppb metals) IPA per wafer lot for final rinse steps, because it wets silicon evenly, displaces water from microscopic features, and evaporates without leaving the watermarks or surfactant residue that would kill device yield. Industrially it's made by acid-catalyzed hydration of propylene over a phosphoric-acid-on-silica catalyst at 60-65°C and 2-2.5 MPa, with global production around 2 million tonnes per year. The disinfection chemistry that made IPA a household name during COVID-19 is genuinely interesting: 70% IPA outperforms 99% IPA for killing bacteria because the 30% water slows evaporation enough to give contact time, and water helps denature membrane proteins by allowing IPA to solvate them properly. Pure 99% IPA flash-coagulates the outer protein layer of a bacterium into a tough shell that protects the cytoplasm. The 60-90% range is the sweet spot, with 70% the textbook recommendation. Other working details: IPA azeotropes with water at 87.7% IPA / 12.3% water, which is why distilled product caps out around there without entrainers.
Where you'll encounter it
If you've ever wiped a smartphone screen with an alcohol pad, cleaned a keyboard between coffee spills, or watched a wafer fab tech pull silicon out of a Marangoni-style IPA dryer, you've used some form of 2-propanol. The 70% drugstore bottle is the universal cleaning solvent for electronics, optics, and lab benches because it evaporates without residue and dissolves both polar and nonpolar contaminants. During COVID-19, hand sanitizer demand pushed global IPA prices to triple their pre-pandemic level — the WHO Formulation 2 hand-rub recipe specifies 75% IPA with hydrogen peroxide and glycerol. Semiconductor fabs at TSMC and Samsung burn through hundreds of kilograms of sub-1-ppb-metals IPA per wafer lot for final rinse steps, because watermark-free drying is essential for sub-7 nm device yield. Clinical alcohol prep pads at every blood draw and IV insertion are 70% IPA-saturated nonwoven cotton.
Common Uses
- Final-rinse solvent in semiconductor wafer processing at sub-1 ppb metals
- Hand-sanitizer active ingredient at 70-75% per WHO formulation 2
- Topical disinfectant in clinical alcohol prep pads at 70% v/v
- Optical and electronics cleaning for lenses, sensors, and PCB flux residue
- Windshield washer fluid antifreeze depressing freezing to about -20°C
- Pharmaceutical recrystallization solvent and tablet-coating carrier
- Gas-chromatography internal standard and HPLC mobile-phase component
Safety Information
Flammable liquid Category 2 (flash point 12°C, autoignition 399°C) — vapors are denser than air and can travel along the floor to ignition sources. GHS H225, H319, H336. OSHA PEL 400 ppm TWA, NIOSH REL 400 ppm TWA / 500 ppm STEL. Acute oral LD50 about 5800 mg/kg in rats — toxic when ingested because metabolism by alcohol dehydrogenase produces acetone, which causes CNS depression, gastritis, and ketosis but no acidosis (unlike methanol or ethylene glycol). Always store away from oxidizers and ignition sources; ground containers when transferring to prevent static spark.
This safety summary is for educational reference only and may not be complete. It is not a substitute for Safety Data Sheets (SDS), medical advice, or professional chemical safety guidance. Always consult appropriate SDS and qualified professionals before handling chemicals.