Borinic acid

Borinic acid H2BOH, also known as boronous acid, is an oxyacid of boron with formula H2BOH. Borinate is the associated anion of boron with formula H2BO−, however being a lewis acid the form in basic solution is H2B(OH)−2. Borinic acid H2BOH, also known as boronous acid, is an oxyacid of boron with formula H2BOH. Borinate is the associated anion of boron with formula H2BO−, however being a lewis acid the form in basic solution is H2B(OH)−2. Borinic acid can be formed as the first step in the hydrolysis of diborane. BH3+H2O → H2BOH + H2 Borinic acid itself is unstable and only lasts for a few seconds during the hydrolysis reaction. However, by using microwave spectroscopy various properties can be determined. The B-O distance is 1.352 Å, O-H distance 0.96 Å, B-H length is probably 1.2 Å. The angle between bonds at the oxygen atom BOH = 112° and the angles at boron are cis-HBO 121°, and trans-HBO = 117°. The dipole moment is 1.506 Debye. Borinic acid can form esters such as methoxyborane. This too is unstable only lasting about ten seconds. It can be formed by heating diborane and methanol gas together. By substituting organic components instead of hydrogen, more generic borinic acids (containing RR'BOH) or borinic esters (RR'BOR') can be formed. Esters will tend to be stable in acidic conditions, but in alkaline conditions the boron atom can gain a negative charge and attach two hydroxyl groups, or two ester bonds. RR'B−(OH)2 or RR'B−(OR')2. The anionic borinate ion can very easily form esters with diols such as ethylene glycol or sugars. IUPAC naming for Borinic acid is a unique name for acid. The anhydrides are named diboroxanes, H2BOBH2, as the base compound and H being able to be substituted, e.g. tetraethyldiboroxane, as the anhydride for diethylborinic acid. Organic naming standard in the bluebook allows skeletal replacement naming where the name is shorter, 3-borapentan-3-ol versus diethyl borinic acid. The grouping -BH-O-BH2 is called diboroxanyl. Substituting sulfur for oxygen gives borinothioic acid (H2BSH). (dimethylboranyl)oxy is used for the group (CH3)2B-O− and methyl(hydroxy)boranyl for the grouping CH3B(OH)-. There are several ways to produce substituted borinic acids. Firstly borinic acids can be made from oxidising trialkyl borane starting materials with exposure to moist air, or treatment with iodine, which makes a dialkyliodoborane . Hydrolysis then results in the boronic acid (R2BOH). Trialkylborates or trialkoxyboroxine can be reduced to borinic acid by us of a Grignard reagent. Grignard reagents can also reduce a boronic ester to a borinic ester.