Examples of Safer Reactions
Compounds like hydrogen cyanide and potassium cyanide are extremely toxic, but they also happen to be very useful reagents and have been used in manufacturing for many years.
Hydrogen cyanide has commonly been used in the manufacture of weed-killers, including domestic products like "Roundup". In the event of an accident at the chemical plant, the consequences could be very serious if cyanide compounds are involved.
Monsanto, the company that makes "Roundup" has developed
an alternative manufacturing route that uses a different starting material,
a copper catalyst and cyanide is no longer needed. The old process also
involved exothermic generation of potentially unstable intermediates,
with the danger of a "runaway" reaction. The new process is
endothermic, making it even safer.
Alternative, safer routes are now available for polyurethane and polycarbonate
Water is, of course, a common solvent, but many of the compounds manufactured in the chemical industry are water insoluble. This means that reactions and product purification are often carried out in organic solvents. Paints, varnishes and other coatings also contain solvents that evaporate as the coating dries. Several of the volatile organic compounds (VOCs) used as solvents are toxic, irritants or even suspected carcinogens.
Manufacturers are now seeking to replace these with safer alternatives. There are now, for example, several water-based, low-odour paints available to the consumer, reducing emissions of VOCs when painting.
Researchers are also finding alternative solvents for manufacturing and developing processes that use no solvent at all. Supercritical carbon dioxide is already used in several processes. Ionic liquids are also receiving much attention from researchers. These have very low vapour pressure, which means they produce very little vapour, and can act as solvent and catalyst at the same time.