Solvent · polar protic
tert-Butanol C4H10O
Also: t-BuOH, 2-methyl-2-propanol
A polar protic alcohol used in HPLC/GC as a mobile-phase modifier and co-solvent rather than a primary eluent, because its melting point (~25-26 C) means it is solid at ambient temperature and it is highly viscous, requiring the solvent and lines to be kept warm. Uses: gradient/organic modifier and sample-solubilizing co-solvent in RP-HPLC, ion-pair and normal-phase applications, and a common co-solvent/structuring agent for lyophilization (freeze-drying) of pharmaceuticals. In GC it is both a sample solvent and an analyte of interest: tert-butyl alcohol is itself an ICH Q3C residual solvent routinely quantified by headspace GC-FID/MS. Audience: pharma/CRO residual-solvent and formulation labs.
Compiled by Hemant RawatLast reviewed July 2026How we verify
Properties
- Formula
- C4H10O
- CAS number
- 75-65-0
- UV cutoff
- 245 nm
- Snyder polarity index (P′)
- 4.1
- Selectivity group
- II
- Eluotropic strength ε° (silica)
- —
- Boiling point
- 82.4 °C
- Viscosity (25 °C)
- 4.3 cP
- Refractive index (nD²⁰)
- 1.3878
- Density
- 0.775 g/mL
- Water miscibility
- miscible
- USP <467> class
- Class 2
Safety
- flammable (GHS Flam. Liq. 2, flash point ~11 C)
- acute toxicity via inhalation (GHS Acute Tox. 4)
- eye irritant (Eye Irrit. 2)
- CNS/narcotic effects - drowsiness/dizziness (STOT SE 3)
- animal carcinogen: kidney tumors in male rats, thyroid tumors in mice (NTP); not classified as a human carcinogen
- NOT a peroxide former (tertiary alcohol, not an ether)
- solid at/below ~25 C - handling caveat (must be warmed to liquefy)
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 tert-Butanol 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 ethyl ketone, Methyl isobutyl ketone, MTBE, n-Butanol, n-Butyl acetate, n-Heptane, n-Hexane, N-Methylpyrrolidone, n-Pentane, N,N-Dimethylacetamide, N,N-Dimethylformamide, Pyridine, Tetrahydrofuran, Toluene, Triethylamine, Water.
Check any specific pair on the interactive miscibility chart.
Using tert-Butanol in HPLC/GC
A polar protic alcohol used in HPLC/GC as a mobile-phase modifier and co-solvent rather than a primary eluent, because its melting point (~25-26 C) means it is solid at ambient temperature and it is highly viscous, requiring the solvent and lines to be kept warm. Uses: gradient/organic modifier and sample-solubilizing co-solvent in RP-HPLC, ion-pair and normal-phase applications, and a common co-solvent/structuring agent for lyophilization (freeze-drying) of pharmaceuticals. In GC it is both a sample solvent and an analyte of interest: tert-butyl alcohol is itself an ICH Q3C residual solvent routinely quantified by headspace GC-FID/MS. Audience: pharma/CRO residual-solvent and formulation labs.
Its Snyder polarity index is 4.1 (selectivity group II), and its UV cutoff of 245 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.