A widely used industrial reaction that produces toxic waste could be replaced by one that yields only one by-product — water.

Chemists often use alcohols when synthesizing drugs, but the alcohol must first be ‘activated’ by the addition of other chemicals. Since 1967, that activation has often been carried out by a process called the Mitsunobu reaction, which requires two activating chemicals — one explosive — and generates two by-products, one of which is toxic.

Seeking a greener version of the Mitsunobu reaction, Ross Denton at the University of Nottingham, UK, and his colleagues used a compound called a phosphine oxide as a catalyst to jump-start the reaction. The team’s version of the reaction eliminates the explosive activator and the toxic by-product, and regenerates the second by-product to make the original catalyst, leaving behind nothing but water.

The researchers say that their catalyst provides a more environmentally friendly way of making both drugs and agrochemicals.