Calcium cyclic carboxylates as structural models for calcium carbonate scale inhibitors

Abstract

Cyclic oligocarboxylic acids are the most commonly explored phosphate-free inhibitors for calcium carbonate scale deposition. The structural chemistry of calcium complexes of candidate inhibitors has the potential to give insight into inhibitor mode of action and design. We report a series of calcium compounds of cyclic oligocarboxylic acids of (1α,3α,5α)-1,3,5,-cyclohexanetricarboxylic acid (CHTCA); cyclohexane-1,2,4,5-tetracarboxylic acid (CHTTCA); 1,2,3,4,5,6-cyclohexanehexacarboxylic acid (CHHCA); 1,1-cyclohexandiacetic acid (CHDAA) and cis,cis,cis,cis-1,2,3,4-cyclopentanetetracarboxylic acid (CPTCA) to understand the relationship between ligand stereochemistry and calcium ion coordination mode.