Propyl mercaptan (1-propanethiol) — properties & hazards overview
Boiling point
67 – 68 °C
Flash point
≈ −20 °C
Water solubility
≈ 1.9 g/L — slight
Odour threshold
≈ 0.5 ppb
Toxicity
Harmful by inhalation
Flammability
FP ≈ −20 °C
Chronic risk
CNS / respiratory
Environmental
Severe odour nuisance
| Property | Value / Note |
|---|---|
| Chemical formula | C₃H₇SH (CH₃CH₂CH₂SH) |
| Molar mass | 76.16 g/mol |
| Physical state | Volatile liquid; vapour heavier than air |
| Water solubility | Only slightly soluble — the practical difference with methyl mercaptan, and the reason a plain water or caustic stage under-performs. |
| Odour | Onion / skunk-like; perceptible below 1 ppb and very persistent on clothing and surfaces. |
| Typical sources | Slaughterhouse and rendering off-gas, onion and vegetable processing, refinery and gas odorant streams. |
| Best analytical detection | GC with sulphur-selective detection (SCD or FPD) to separate it from the other thiols; PID for continuous trending; dynamic olfactometry (EN 13725) for permit compliance. |
*Values are indicative and may vary by source. For safety and design, always consult current SDS and regulations.