Message #154508

[Jessie Phallon]

Plant production process

Union Carbide produced the pesticide, Sevin (a trademarked brand name for carbaryl), using MIC as an intermediate. Until 1979, MIC was imported from the USA.[2] Other manufacturers, such as Bayer, made carbaryl without MIC, though at greater manufacturing costs.[17]

The chemical process, or "route" used in the Bhopal plant was to react methylamine with phosgene to form MIC, which was then reacted with 1-naphthol to form the final product. This route is different from the MIC-free route used elsewhere, in which the same raw materials are used in a different manufacturing order, with phosgene first reacted with the naphthol to form a chloroformate ester, which is then reacted with methyl amine. In the early 1980s, the demand for pesticides had fallen though production continued, leading to buildup of stores of unused MIC.[2][17]