Many salts, such as calcium sulfate (gypsum) and barium sulfate (barite), are found prevalently in oil well lines and water treatment systems as well as on ocean vessel shells.  These deposits are costly to oil refineries, water treatment plants, shipping companies, and the navy, as they cause operational issues and are difficult to remove.  The presence of these deposits on ocean vessels also increases pollution due to increased drag caused by the deposits.  Organic compounds have been found to inhibit the crystal growth of these salts.  Previous studies by Roger Davey investigated the effect of organic molecules as inhibitors of barium sulfate crystal growth.  However, few researchers have studied the growth inhibition of calcium sulfate crystals.  In our studies, Hollis Warren synthesized a group of potential crystal growth inhibitors (based upon Davey’s inhibitors of barite) from simple diamines (varying only in length of the carbon chain) using the Mannich Reaction.  We have synthesized hexanebis(nitrilodimethylene)tetraphosphonic acid, octanebis(nitrilodimethylene)tetraphosphonic acid, and nonanebis(nitrilodimethylene)-tetraphosphonic acid.  Currently, Karen Voelker, a new student in my lab, is working on the purification and analysis of these molecules.  She is also continuing Hollis’ preliminary work on the inhibition of calcium sulfate crystals by these molecules.  Many factors, including solution pH, concentration, and temperature, can be altered in an effort to increase the induction time once a potential inhibitor is introduced to the system.  Ideally, we hope to synthesize an inhibitor that will control growth of all the faces of calcium sulfate over the longest induction time.