| Physical Description |
Methyl isocyanate appears as a colorless low-boiling liquid (b.p. 39 °C) that is denser than water. Flash point is less than 20 °F. Very toxic by inhalation. Can be absorbed through the skin. Has a sharp odor, but the sense of smell cannot be relied upon to warn of the presence of vapors at low concentrations. Rate of onset: Immediate Persistence: Minutes to hours Odor threshold: 2.1 ppm Source/use/other hazard: Intermediate in manufacturing; reacts with H20 (don't use in fire). |
| Color/Form |
Colorless liquid |
| Odor |
Sharp, unpleasant odor |
| Boiling Point |
102 °F at 760 mmHg (EPA, 1998) |
| Melting Point |
-112 °F (EPA, 1998) |
| Flash Point |
19 °F (EPA, 1998) |
| Solubility |
Decomposes (NTP, 1992) |
| Density |
0.9599 at 68 °F (EPA, 1998) - Less dense than water; will float |
| Vapor Density |
About twice as heavy as air (EPA, 1998) (Relative to Air) |
| Vapor Pressure |
348 mmHg at 68 °F (EPA, 1998) |
| Autoignition Temperature |
995 °F (USCG, 1999) |
| Decomposition |
The substance decomposes on contact with water. The substance decomposes rapidly on contact with acids and bases producing toxic gases (hydrogen cyanide, nitrogen oxides, carbon monoxide). |
| Corrosivity |
Methyl isocyanate diffuses through polyethylene and attacks most elastomers (fluorocarbon resins are resistant). It is dangerous to use materials other than stainless steel, nickel, or glass/ceramic in contact with methyl isocyanate. In particular, do not use iron, steel, zinc, tin, copper, or their alloys. |
| Heat of Combustion |
269.4 KCAL/G MOL WT (LIQ) |
| Ionization Potential |
10.67 eV |
| Polymerization |
The substance will polymerize when pure. The substance may polymerize due to heating and under the influence of metals and catalysts. |
| Odor Threshold |
Odor Threshold Low: 2.1 [mmHg] Odor threshold from AIHA |
| Refractive Index |
Index of refraction = 1.3419 at 18 °C |
| Kovats Retention Index |
502 |
| Chemical Classes |
Toxic Gases & Vapors -> Monoisocyanates |
