IONIC HYDROGEN BOND. 2. INTRAMOLECULAR AND PARTIAL BONDS. PROTONATION OF POLYETHERS, CROWN ETHERS, AND DIKETONES.

Article abstract of DOI:10.1021/ja00353a011

The relation between molecular structure and intramolecular hydrogen bonding was observed in polyfunctional oxonium ions in terms of the enthalpy and entropy of the internal bond; the thermal stability of the bond as reflected by the bond opening temperature, the bond weakening factor, and the entropy of 'cyclization' per single C-C, C-O, or C-N bond incorporated into the ring. It was found that in the smallest compounds the 'cyclic' structure may amount only to a stabilized cis conformation, while in the largest compounds the hydrogen bond approaches its full intermolecular strength. Together with previous results, the present data show that intramolecular bonding is prevalent in complex organic ions.