Solvent · polar aprotic
Methyl ethyl ketone C4H8O
Also: MEK, 2-butanone
Medium-polarity ketone solvent used in GC (including as a headspace/dilution solvent) and as a strong normal-phase eluent; also an extraction/sample-prep solvent. Its high UV cutoff (~329 nm) makes it unsuitable as a low-wavelength UV-HPLC mobile phase.
Compiled by Hemant RawatLast reviewed July 2026How we verify
Properties
- Formula
- C4H8O
- CAS number
- 78-93-3
- UV cutoff
- 329 nm
- Snyder polarity index (P′)
- 4.7
- Selectivity group
- VIa
- Eluotropic strength ε° (silica)
- —
- Boiling point
- 79.64 °C
- Viscosity (25 °C)
- 0.43 cP
- Refractive index (nD²⁰)
- 1.3788
- Density
- 0.8049 g/mL
- Water miscibility
- partial
- USP <467> class
- Class 3
Safety
- highly flammable liquid and vapor
- eye irritant
- respiratory/skin irritant
- CNS depressant at high vapor concentrations
- not classified as carcinogen (IARC/NTP)
Reference only. Solvents can be flammable, toxic, or peroxide-forming. Always consult the Safety Data Sheet (SDS) and your lab's protocols before handling.
What Methyl ethyl ketone mixes with
Miscible with: 1-Propanol, 1,2-Dichloroethane, 1,4-Dioxane, 2-Propanol, Acetic acid, Acetone, Acetonitrile, Benzene, Carbon tetrachloride, Chloroform, Cyclohexane, Dichloromethane, Diethyl ether, Dimethyl sulfoxide, Ethanol, Ethyl acetate, Iso-octane, Methanol, Methyl isobutyl ketone, MTBE, n-Butanol, n-Butyl acetate, n-Heptane, n-Hexane, N-Methylpyrrolidone, n-Pentane, N,N-Dimethylacetamide, N,N-Dimethylformamide, Pyridine, tert-Butanol, Tetrahydrofuran, Toluene, Triethylamine.
Partially miscible with: Water — mix only over a limited range.
Check any specific pair on the interactive miscibility chart.
Using Methyl ethyl ketone in HPLC/GC
Medium-polarity ketone solvent used in GC (including as a headspace/dilution solvent) and as a strong normal-phase eluent; also an extraction/sample-prep solvent. Its high UV cutoff (~329 nm) makes it unsuitable as a low-wavelength UV-HPLC mobile phase.
Its Snyder polarity index is 4.7 (selectivity group VIa), and its UV cutoff of 329 nm limits low-wavelength UV detection.See what the polarity index means and the full UV cutoff table.
Sources
- University of Toronto (TRACES) — Burdick & Jackson — Solvent UV cutoff table (absorbance = 1 AU, 1 cm cell)
- Stenutz / L. R. Snyder — Solvent polarity index (P′) and selectivity groups
- NIST — Chemistry WebBook — thermophysical properties (BP, density, refractive index)
- PubChem (NIH/NLM) — Compound property records (physical constants, CAS, formula)
- USP <467> / ICH Q3C — Residual Solvents — solvent classification (Class 1/2/3)
Values are compiled from public references and were last verified July 2026. See ourmethodologyfor how we source and verify. Always confirm critical values against primary references and the SDS.