Chemistry of Organophosphonate Scale Growth Inhibitors: 2. Structural Aspects of 2-Phosphonobutane-1,2,4-Tricarboxylic Acid Monohydrate (PBTC.H2O)

摘要

Industrial water systems often suffer from undesirable inorganic deposits, such as calcium carbonate,calcium phosphate(s), magnesium silicate, and others. Synthetic water additives such as phosphonates andphosphonocarboxylates are the most important and widely utilized scale inhibitors in a plethora of industrialapplications. The design of efficient and cost-effective inhibitors, as well as the study of their structure andfunction at the molecular level are important areas of research. This study reports the crystal and molecularstructure of PBTC (PBTC = 2-phosphonobutane-1,2,4-tricarboxylic acid), one of the most widely used scaleinhibitors in the cooling water treatment industry. Triclinic PBTC monohydrate crystallizes in the P 1 spacegroup with cell dimesions, a =7.671(1) ?, b = 8.680(1) ?, c = 9.886(1) ?, α = 65.518(2) deg, β = 71.683(2) deg, γ = 76.173(2) deg, V = 564.20(11) ?3, and Z = 2. Bond distances in the -PO3moiety are 1.4928(10) ? for the P=O double bond and 1.5294(10) ? and 1.5578(10) ? for the two -P-O(H) groups. P-C and C-O bond lengths fall in the normal range. A network of hydrogen bonds are formed between the water molecule of crystallization, the -P-OH and the -COOH groups.