Methyl isothiocyanate

Methyl isothiocyanate is the organosulfur compound with the formula CH3N=C=S. This low melting colorless solid is a powerful lachrymator. As a precursor to a variety of valuable bioactive compounds, it is the most important organic isothiocyanate in industry.[1]

Methyl isothiocyanate
Names
IUPAC name
Methylisothiocyanate
Other names
MITC
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.008.303
KEGG
UNII
Properties
C2H3NS
Molar mass 73.12
Appearance colourless solid
Density 1.07 g cm−3
Melting point 31 °C (88 °F; 304 K)
Boiling point 117 °C (243 °F; 390 K)
8.2g/L
Hazards
Safety data sheet ACC# 07204
NFPA 704 (fire diamond)
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilHealth code 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasReactivity code 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazards (white): no code
1
3
1
Structure
3.528 D
Related compounds
Related compounds
 Methyl isocyanate
Methyl thiocyanate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

Synthesis

It is prepared industrially by two routes. Annual production in 1993 was estimated to be 4M kg. The main method involves the thermal rearrangement of methyl thiocyanate:[1]

CH3S-C≡N → CH3N=C=S

It is also prepared via with the reaction of methylamine with carbon disulfide followed by oxidation of the resulting dithiocarbamate with hydrogen peroxide. A related method is useful to prepare this compound in the laboratory.[2]

MITC forms naturally upon the enzymatic degradation of glucocapparin, a modified sugar found in capers.

Reactions

A characteristic reaction is with amines to give methyl thioureas:

CH3NCS + R2NH → R2NC(S)NHCH3

Other nucleophiles add similarly.

Applications

Solutions of MITC are used in agriculture as soil fumigants, mainly for protection against fungi and nematodes.

MITC is a building block for the synthesis of 1,3,4-thiadiazoles, which are heterocyclic compounds used as herbicides. Commercial products include "Spike", "Ustilan," and "Erbotan."

Well known pharmaceuticals prepared using MITC include Zantac and Tagamet. Suritozole is a third example.

MITC is used in the Etasuline patent (Ex2[3]), although the compound is question (Ex6) is with EITC.

Safety

MITC is a dangerous lachrymator as well as being poisonous.

See also

References
  1. Romanowski, F.; Klenk, H. "Thiocyanates and Isothiocyanates, Organic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a26_749.CS1 maint: multiple names: authors list (link)
  2. Moore, M. L.; Crossley, F. S. (1941). "Methyl Isothiocyanate". Organic Syntheses. 21: 81.CS1 maint: multiple names: authors list (link); Collective Volume, 3, p. 599
  3. U.S. Patent 3,417,085
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