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Another factor that process chemists must deal with is so-called green chemistry, in which they aim for energy-efficient processes that minimize or even eliminate the production of waste. Author uses an "E factor" to measure the efficiency of various chemical industries, in terms of kilograms of waste per kilogram of desired products. According to author, bulk chemicals have an E factor of less than 1 to 5, compared with 5 to greater than 50 for fine chemicals, and 25 to more than 100 for pharmaceuticals.
IN FAIRNESS to the pharmaceutical industry, author acknowledges that pharmaceutical syntheses require more steps, which push up the E value. Most of that waste (80 to 90%) is inorganic salts, which means that "organic chemists make more inorganic salts than organic compounds," he says. Ways to reduce the E factor include using catalytic processes and reactions that are atom efficient. Plus, author says, process chemists should minimize the number of different solvents they use. "Of course, the best solvent is no solvent," he notes.
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