Correlation of melting points of inositols with hydrogen bonding patterns

Abstract

The melting points of seven inositol isomers cover a range of 180–350 °C although the only difference between them is the ratio of axially/equatorially orientated hydroxyl groups. All seven isomers feature infinite and finite hydrogen bond patterns and the type and occurrence of these patterns are explored as useful criteria for the prediction of melting points. All the patterns are classified into chain and ring motifs and atomistic and quantum chemical calculations are employed to evaluate the strength of interaction between pairs of molecules contributing to a pattern. There are four types of hydrogen bonded chains with three different types of molecular interactions—one strong and two weak ones. All high melting inositols (scyllo-, neo- and epi-inositol) possess infinite hydrogen bonded double chains with strong links and the number of chains per molecule correlates with their melting points. The lowest melting isomer (allo-inositol) shows no such double chains and only two single hydrogen bonded chains.