Increased Yield
A difficult step in the manufacture of tenofovir is near the end, when the mixture is "like oatmeal, making it very difficult to stir," said Joseph Fortunak, who left Abbott Laboratories to teach at Howard. That slows the next reaction, a problem because the intermediary is highly unstable and decomposes, thus lowering the yield.
Fortunak's graduate student Adrian Williams tested different methods to improve this step. A catalyst, TBAB (tetrabutylammonium bromide) sped up the reaction and thinned the oatmeal-like mixture into something "like milk," Williams said. But unexpectedly, it made the product more stable, which substantially increased the yield. This lowered the cost by about 20%.
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