OHryhmä

OHryhmää is the Finnish term used in chemistry to denote the hydroxyl group, a functional group consisting of an oxygen atom bonded to a hydrogen atom, typically written as -OH. This group is found in alcohols (ROH) and phenols (ArOH) and is a key source of polarity and hydrogen bonding in organic molecules.

The presence of the OH group increases solubility in water for small molecules and raises boiling points due to hydrogen bonding. Alcohols range from methanol to tert-butanol, with increasing hydrocarbon content reducing water solubility. Phenols are more acidic than aliphatic alcohols due to resonance stabilization of the resulting phenoxide ion.

In reactivity, OH groups participate in many important transformations: esterification with carboxylic acids to form esters; oxidation of primary alcohols to aldehydes and then to carboxylic acids; oxidation of secondary alcohols to ketones; dehydration to form alkenes under acid catalysis; deprotonation with strong bases to give alkoxides.

In biology and materials science, hydroxyl groups are widespread. They occur in sugars and amino alcohols, and on mineral surfaces, where they influence adsorption and catalysis. Infrared spectroscopy detects OH groups by characteristic broad absorptions between 3200 and 3550 cm-1.

In Finnish education and chemical literature, OHryhmää is used to refer to this functional group, with OH-ryhmä as the base term and inflected forms used according to Finnish grammar.