Water Can Copy and Reproduce the Size of Its Own Clusters and Other Molecules

Abstract Water dissolved in an organic solvent does not decompose into individual molecules, but forms clusters, the size of which can vary from a few water molecules to several hundreds. If bulk water is added to acetonitrile containing a small amount of water clusters, it will copy the size of these clusters and reproduce them in large numbers. Small clusters are much more reactive than large clusters because they contain more free hydroxyl groups. Therefore, depending on the size of the initial clusters in the solvent, the added water may turn into a large number of small active clusters, or a small number of large passive clusters. As a result, the rate of hydrolytic reactions with the same water added to acetonitrile can differ by a factor of 200. Water can also form clusters upon contact with organic molecules.