Substance profile
Methyl isothiocyanate
Methyl isothiocyanate is colorless crystals with a horseradish-like odor.
01 · Identification
What Methyl isothiocyanate is
Methyl isothiocyanate is colorless crystals with a horseradish-like odor. Its molecular formula is C2H3NS and its molecular weight is 73.12 g/mol. It boils at 119 °C, melts at 36 °C, is very soluble in water.
Under the GHS it carries the signal word Danger. It is classed as flammable agents - 3rd degree.
02 · GHS classification
Hazards and label elements
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
| Code | Hazard statement |
|---|---|
| H331 | Toxic if inhaled. |
| H301 | Toxic if swallowed. |
| H314 | Causes severe skin burns and eye damage. |
| H317 | May cause an allergic skin reaction. |
| H400 | Very toxic to aquatic life. |
| H410 | Very toxic to aquatic life with long lasting effects. |
Precautionary statements: P260, P261, P270, P271, P272, P273, P280, P301, P304, P310, P313, P330, P331, P333, P391, P501
03 · Physical and chemical properties
Methyl isothiocyanate properties
Every value is shown with the conditions it was measured under and the source it came from. Where sources disagree, all values are listed rather than one being picked — the difference is usually a different form of the substance, not an error.
| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | 119 °C (246.2 °F) | HSDB | |
| 118.89 °C (246 °F) | at 760 mmHg | CAMEO | |
| 119 °C (246.2 °F) | at 760 mmHg | DOE PAC | |
| Melting point | 36 °C (96.8 °F) | HSDB | |
| 35.56 °C (96 °F) | range, midpoint shown | CAMEO | |
| Density | 1.0691 g/cm³ | at 37 °C | HSDB |
| 1.069 g/cm³ | at 37 °C | CAMEO | |
| 0.94 g/cm³ | range, midpoint shown | JECFA | |
| Solubility | Very soluble in ethyl ether | HSDB | |
| In water, 7.6X10+3 mg/L at 25 °C | at 25 °C | HSDB | |
| Vapor pressure | 39.29 mmHg | CAMEO | |
| 19 mmHg | at 20 °C | DOE PAC | |
| 3.54 mmHg | at 25 °C | HSDB | |
| Flash point | 35 °C (95 °F) | MITC-Fume | HSDB |
| -6.67 °C (20 °F) | Haz-Map | ||
| Autoignition temperature | 370 °C (698 °F) | HSDB | |
| Lower explosive limit (LEL) | 2.5 % by volume | HSDB | |
| Product vapor forms explosive mixtures with air; prevent build-up of electrostatic charges, sparks, and open flame. | MITC-Fume | HSDB | |
| Upper explosive limit (UEL) | 30 % by volume | MITC-Fume | HSDB |
| Vapor density | 2.53 (air = 1) | HSDB | |
| Odor threshold | Odor Threshold Low: 1.7 [ppm] | Haz-Map | |
| Corrosivity | Corrosive to iron, zinc and other metals | HSDB |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
04 · Source notes
Further notes on Methyl isothiocyanate
These are descriptions rather than measured values, so they are kept out of the table above and quoted here with the source that reported them.
Solubility
Readily soluble in common organic solvents, such as ethanol, methanol, acetone, cyclohexanone, dichloromethane, chloroform, carbon tetrachloride, benzene, xylene, petroleum ether, and mineral oils.
Source: HSDB
Odor
In the olfactory threshold study, 33 individuals (16 males, 17 females) with a mean age of 25 years (range, 18 to 34 years) were tested. They were exposed to three positive control odorants, pyridine, acetic acid, and n-butyl alcohol, as well as to MITC. The technician chose the odorant and concentration level. The odorant was dispensed in double blind fashion from one of three presentation ports. The subject was responsible for identifying from which of the presentation ports the odorant was dispersed. A 30-second rest period between exposures was permitted in order to allow the subject to recover prior to the next exposure. The operator tested each subject over the range of concentrations for each odorant until he was assured that the threshold had been adequately ascertained. A standard procedure was employed in order to make this determination. The observed odor threshold for MITC ranged from 0.2 to 8 ppm with a geometric mean of 1.7 ppm. ...
Source: HSDB
05 · Handling and storage
Storing and handling Methyl isothiocyanate
Storage conditions
Store only in closed original container to prevent leakage. Store only in cool, well-ventilated, locked areas, away form food and feedstuff, out of reach of children and irresponsible persons. Avoid exposure to heat and/or direct sunlight. Do not drop container onto or slide across sharp objects. /MLPC Methylisothiocyanate (MITC)/
Source: Hazardous Substances Data Bank (HSDB)
Incompatible materials
... Can react vigorously with oxidizing materials.
Source: Hazardous Substances Data Bank (HSDB)
Reactivity
Isocyanates and thioisocyanates, such as METHYL ISOTHIOCYANATE, are incompatible with many classes of compounds, reacting exothermically to release toxic gases. Reactions with amines, aldehydes, alcohols, alkali metals, ketones, mercaptans, strong oxidizers, hydrides, phenols, and peroxides can cause vigorous releases of heat. Acids and bases initiate polymerization reactions in these materials. Some isocyanates react with water to form amines and liberate carbon dioxide. Polyurethanes are formed by the condensation reaction of diisocyanates with, for example, ethyl glycol.
Source: CAMEO Chemicals
Planning storage for a mix of chemicals? Check Methyl isothiocyanate in the storage compatibility matrix →