Methyl Isocyanate gas, which was involved in the disaster in Bhopal in December 1984, was used in the Union Carbide factory for production of:

The Bhopal Gas Tragedy, which occurred on the night of December 2-3, 1984, involved the release of over 40 tons of methyl isocyanate (MIC) gas from the Union Carbide India Limited (UCIL) plant [3]. MIC is a highly toxic chemical used as a principal intermediate in the production of carbamate pesticides [4]. Specifically, the Bhopal facility used MIC to manufacture the pesticide Sevin (carbaryl) by reacting it with alpha-naphthol [2]. Although the plant initially imported MIC, it began on-site manufacturing of this essential pesticide production intermediary in 1980. The disaster is recognized as one of the world's worst industrial tragedies, leading to thousands of immediate deaths and long-term health disabilities for tens of thousands of residents [2]. The event subsequently prompted the enactment of the Environmental Protection Act in 1986 in India.

Sources

1. [1] https://pmc.ncbi.nlm.nih.gov/articles/PMC1142333/
2. [3] Rajiv Ahir. A Brief History of Modern India (2019 ed.). SPECTRUM. > Chapter 39: After Nehru... > Problems at the Very Outset > p. 722
3. [2] https://downloads.regulations.gov/EPA-HQ-OAR-2004-0044-0030/content.pdf
4. [4] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 12: Major Crops and Cropping Patterns in India > Environmental Laws of India > p. 87