Hydrogenation in Water

30 August 2003

Many compounds have sufficient solubility in water (e.g. as salts) to enable them to be reduced using water as solvent, and this may seem an environmentally friendly way to proceed. Remember, however, that the solubility of hydrogen in water at 20oC is low, and to achieve the same dissolved hydrogen concentration as, for example, in methanol, you would need to increase the pressure by approx 5 times.

Not only the rate of reaction, but also the selectivity of the reaction can be influenced by the dissolved hydrogen concentration.

For more on this topic see Aqueous Organometallic Catalysis by Ferenc Joó (Kluwer, 2001, ISBN 1-4020-0195-9).