Proposed Terminology for Intermolecular Hydrogen Bonds Hydrogen bonding may occur between molecules (intermolecular) or within a given molecule (intramolecular). When intermolecular hydrogen bonding involves molecules of the same species, such as water, we may read that the molecules form hydrogen bonds "among themselves." Hydrogen honds may also form between two different types of molecules. Ether molecules, for example, cannot form hydrogen bonds from one ether molecule to another but they can form hydrogen bonds with water molecules. A definition of terms may avoid a misunderstanding in the description of tendencies of compounds to form hydrogen honds. In order to avoid ambiguities, I suggest the use of the terms "homomolecular hydrogen bonds" for bonds among molecules of the same species and "heteromolecular hydrogen bonds" for honds among different molecules. H-0
homomolecular hydman bonding
CHaCH2-0-CH2CHa
hetemmnlecular hydmgen bonding
Associated liquids, such as water, would form homomolecular hydrogen bonds. Ethers, on the other hand, cannot form homomolecular hydrogen honds; they can, however, form heteromolecular hydrogen bonds with other species, such as water. The terms "homomolecular" and "heteromolecular" may also he used to identify certain organic reactions which are currently called "aldol condensations" and "crossed aldol condensations" or "Claisen condensations" and "crossed Claisen condensations," etc. Aldol condensations and Claisen condensations are examples of homomolecular condensations while crossed aldol and crossed Claisen condensations are examples of heteromolecular condensations. Norbert lsenberg University of Wiseonsin-Parkside Kenosha. WI 53141
Volume 59
Number 7
July 1982
547
