This functional group is the one of the most important functional group which naturally occurring organic compounds. All biomolecules such as carbohydrates, nucleic acids, few amino acids, and their derivatives, some terpenes, and plant pigments have hydroxyl groups. These substances play important roles in maintenance of life. One very important example is potent toxin tetrodotoxin, which is separated from Puffer fish and uses in defense from predators. Its having six different hydroxyl functions.
Physical Properties of OH group : It is less volatile, high melting point, and best water soluble due to grater polarity, but when molecular weight increases then the all properties will be decreases.
Spectroscopic Properties of OH : Hydrogen-oxygen bond gives a very good absorption band in infrared rays but all due to hydrogen bonding. In strong dilute solution of alcohol and in nonpolar solvent, hydrogen bonding is minimized. When concentration is increases, association of molecules are also increased and then intensity of infrared absorption band is also increased due to hydrogen bonding.
Basic Properties of OH : This is a base and it having similar strength to water and these are accepting proton from strong acids, such as an example reaction of methanol with hydrogen bromides to gives methyloxonium bromide.
Nucleophilic Properties of OH : By this properties its form Ether and Ester organic compounds.