Published August 1985
This report describes and evaluates the processes for making technical grade carbofuran, mancozeb, maneb, and zineb. Their formulations are not included. For carbofuran, two processes--one starting from catechol and one from o-nitrochlorobenzene--are evaluated; for the last step of production, an alternative procedure using Phosgene and methylamine instead of methyl isocyanate is evaluated for comparison. The production of mancozeb is described and evaluated in detail, with the production of maneb and zineb evaluated by analogy.
The raw materials used in making carbofuran are methyl isocyanate, methallyl chloride, catechol, and o-nitrochlorobenzene. For mancozeb, maneb, and zineb, ethylenediamine and carbon disulfide are the raw materials. Processes for all of these intermediates are evaluated. For methyl isocyanate, two versions of the phosgenation process and two nonphosgenation processes via ethylene carbonate and n-methylformamide are reviewed. For catechol, the co-production of hydroquinone is evaluated; for o-nitrochlorobenzene, the co-production of p-isomer is evaluated. For ethylenediamine, four processes are evaluated and compared: an ethylene dichloride process with extraction recovery, ethylene dichloride with evaporation recovery, the monoethanolamine process, and a monoethanolamine process starting from ethylene oxide.
Data on carbofuran, methyl isocyanate, mancozeb, carbon disulfide (especially in regard to toxicity), and on some chemicals involved in the production of carbofuran, and heat of reaction of some reactions in the processes are found in the appendices.
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