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Grade 12th passOrganic Chemistry

Write a reaction in which methyl isocyanate (MIC) is formed. What products are formed when it is hydrolysed with water?

Profile image of Krishna Anilkumar
12 Years agoGrade 12th pass
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1 Answer

Profile image of Rinkoo Gupta
12 Years ago

Methyl isocyanate is usually manufactured by the reaction ofmonomethylamineandphosgene. For large scale production, it is advantageous to combine these reactants at higher temperature in the gas phase. A mixture of methyl isocyanate and two moles ofhydrogen chlorideis formed, but N-methylcarbamoyl chloride (MCC) forms as the mixture is condensed, leaving onemoleof hydrogen chloride as a gas.

MMA plus Phosgene diagram.png

The methyl isocyanate is obtained by treating the MCC with a tertiary amine, such asN,N-dimethylaniline, or withpyridine[11]or by separating it by using distillation techniques.[12]

MCC to MIC & HCl.png

Methyl isocyanate is also manufactured from N-methylformamide and air. In the latter process, it is immediately consumed in a closed-loop process to make methomyl.[13]Other manufacturing methods have been reported

Methyl isocyanate reacts readily with many substances that contain N-H or O-H groups. With water, it forms1,3-dimethylureaandcarbon dioxidewith the evolution of heat (325 calories per gram of MIC):

MIC & water to DMU & TMB.png

At 25 °C, in excess water, half of the MIC is consumed in 9 min.;[16]if the heat is not efficiently removed from the mixture, the rate of the reaction will increase and rapidly cause the MIC to boil. If MIC is in excess,1,3,5-trimethylbiuretis formed along withcarbon dioxide.[10]Alcoholsandphenols, which contain an O-H group, react slowly with MIC, but the reaction can be catalyzed by trialkylaminesor dialkyltin dicarboxylate.Oximes,hydroxylamines, andenolsalso react with MIC to form methylcarbamates.[10]These reactions produce the products described below (Uses).

MIC plus 1-naphthol to carbaryl.png

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Rinkoo Gupta
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