Editing Methyl isocyanate (section)

== Reactions ==
Methyl isocyanate reacts readily with many substances that contain N-H or O-H groups. With water, it forms [[1,3-dimethylurea]] and [[carbon dioxide]] with the evolution of heat (1358.5 joules, or 325 calories, per gram of MIC): It is relatively slow to react at below 68&nbsp;°F, but will increase its rate with elevated temperatures or in the presence of acid or base.<ref>{{cite journal |last1=Manilla |title=Methyl isocyanate: Risk assessment, environmental, and health hazard |journal=Hazardous Gases Risk Assessment on the Environment and Human Health |date=2021 |pages=251–261}}</ref>

[[File:MIC & water to DMU & TMB.png|none]]
At 25&nbsp;°C, in excess water, half of the MIC is consumed in 9 min.;<ref>{{cite journal |vauthors=Castro EA, Moodie RB, Sansom PJ |title=The kinetics of hydrolysis of methyl and phenyl isocyanates |journal=Journal of the Chemical Society, Perkin Transactions 2 |year=1985 |volume=1985 |issue=5 |pages=737–742 |doi=10.1039/P29850000737}}</ref> if the heat is not efficiently removed from the reacting mixture, the rate of the reaction will increase and rapidly cause the MIC to boil. Such a reaction triggered the [[Bhopal disaster]] after a large amount of water was introduced to a MIC storage tank. The consequence of the out of control [[Exothermic reaction|exothermic process]] was a [[runaway reaction]] and the direct release of 42 tons of MIC to the atmosphere.

If MIC is in excess, [[Biuret|1,3,5-trimethylbiuret]] is formed along with [[carbon dioxide]].<ref name="Union Carbide 1967" /> [[Alcohols]] and [[phenols]], which contain an O-H group, react slowly with MIC, but the reaction can be catalyzed by trialkylamines or dialkyltin dicarboxylate. [[Oxime]]s, [[hydroxylamine]]s, and [[enol]]s also react with MIC to form methylcarbamates.<ref name="Union Carbide 1967" /> These reactions produce the products described below ([[#Uses|Uses]]).

[[File:MIC plus 1-naphthol to carbaryl.svg|none]]
[[Ammonia]], primary, and secondary [[amine]]s rapidly react with MIC to form substituted [[urea]]s. Other N-H compounds, such as amides and [[urea]]s, react much more slowly with MIC.<ref>{{cite book |vauthors=March J |title=Advanced Organic Chemistry |edition=3rd |publisher=John Wiley & Sons |location=New York |year=1985 |page=802}}</ref>

It also reacts with itself to form a trimer or higher-molecular-weight polymers. In the presence of [[catalysts]], MIC reacts with itself to form a solid trimer, trimethyl isocyanurate, or a higher-molecular-weight polymer:

[[File:MIC to trimer.svg|none]]
[[Alkoxide|Sodium methoxide]], [[Phosphine|triethyl phosphine]], [[ferric chloride]] and certain other metal compounds catalyze the formation of the MIC-trimer, while the high-molecular-weight polymer formation is catalyzed by certain trialkylamines. Since the formation of the MIC trimer is [[exothermic]] (1246 joules, or 298 calories, per gram of MIC), the reaction can lead to violent boiling of the MIC. The high-molecular-weight polymer hydrolyzes in hot water to form the trimethyl [[Cyanuric acid|isocyanurate]]. Since [[Catalysis|catalytic]] metal salts can be formed from impurities in commercial grade MIC and steel, this product must not be stored in steel drums or tanks.<ref name="Union Carbide 1967" />