The hydrophobic effect in reaction mechanism studies and in catalysis by artificial enzymes

Water is an environmentally benign solvent, easily cleaned and with a harmless vapor, so there is great interest in using water in chemical manufacturing. However, water also has important special properties as a solvent, with the hydrophobic effect promoting rapid and selective reactions in addition reactions, atom transfer reactions, and substitutions. The presence of the hydrophobic effect can be determined with the addition of prohydrophobic and antihydrophobic materials to the water solution. Using such materials, it is possible to determine the detailed geometry of transition states for a number of classical reactions, including alkylation of phenoxide ions on oxygen and carbon. The factors involved, particularly the effect of antihydrophobic agents such as ethanol in lowering the free energy of non‐polar reactants, have not been taken into account in previous well‐known mechanistic studies.