Glycol

The common glycols are colorless liquids with specific gravities greater than that of water. The presence of two hydroxyl groups permits the formation of hydrogen with water, thereby favoring miscibility with the latter. Each of the glycols shown above is completely miscible with water. Intermolecular hydrogen bonding between glycol molecules gives these compounds boiling points which are higher than might otherwise have been expected; for example, ethylene glycol has a boiling point of 388.5°F (198°C).

Figure 1. Structures of common glycols. Illustration by Hans & Cassidy. Courtesy of Gale Group.

Figure 2. Laboratory preparation of a glycol. Illustration by Hans & Cassidy. Courtesy of Gale Group.

Figure 3. Industrial preparation of ethylene glycol. Illustration by Hans & Cassidy. Courtesy of Gale Group.