Boronic Acids & Anhydrides
Boronic Acids & Anhydrides
Boronic acids are alkyl or aryl substituted boric acids containing a carbon-boron bond and represented by R-B(OH)2. Generally, boronic acids act as Lewis acids. Boronic acid can easily form reversible covalent complexes with sugars, amino acids, and hydroxamic acids. Owing to its low toxicity and relatively quick degradation in the environment, boronic acid is considered as a green compound. During dehydration, boronic acids give the corresponding boronic anhydrides or boroxines. A six membered heterocyclic ring comprising alternate oxygen and boron atoms is referred to as a boroxine. Boroxines are the cyclotrimeric anhydrides of boronic acids, and isoelectronic to benzene. Examples of boronic anhydrides include trimethylboroxine and triphenylboroxine. Boronic acids and their corresponding boronic anhydrides exist in equilibrium at room temperature.
