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Pinacol is a branched alcohol which finds use in organic syntheses. It is a diol that has hydroxyl groups on vicinal carbon atoms. A white solid that melts just above room temperature, pinacol is notable for undergoing the pinacol rearrangement in the presence of acid and for being the namesake of the pinacol coupling reaction .
The reaction is named after pinacol (also known as 2,3-dimethyl-2,3-butanediol or tetramethylethylene glycol), which is the product of this reaction when done with acetone as reagent. The reaction is usually a homocoupling but intramolecular cross-coupling reactions are also possible. Pinacol was discovered by Wilhelm Rudolph Fittig in 1859.
It has the formula [(CH 3) 4 C 2 O 2 B] 2; the pinacol groups are sometimes abbreviated as "pin", so the structure is sometimes represented as B 2 pin 2. It is a colourless solid that is soluble in organic solvents. It is a commercially available reagent for making pinacol boronic esters for organic synthesis.
The reaction product he obtained instead he called paraceton which he believed to be an acetone dimer. In his second publication in 1860 he reacted paraceton with sulfuric acid (the actual pinacol rearrangement). Again Fittig was unable to assign a molecular structure to the reaction product which he assumed to be another isomer or a polymer.
A third method is by palladium catalysed reaction of aryl halides and triflates with diboronyl esters in a coupling reaction known as the Miyaura borylation reaction. An alternative to esters in this method is the use of diboronic acid or tetrahydroxydiboron ([B(OH 2)] 2). [14] [15] [16]
They reported the reaction of phenylboronic acid in water (140-150 °C) to afford the protodeboronated product, benzene, after 40 hours. Initial synthetic applications of protodeboronation were found alongside the discovery of the hydroboration reaction, in which sequential hydroboration-protodeboronation reactions were used to convert alkynes ...
This page contains tables of azeotrope data for various binary and ternary mixtures of solvents. The data include the composition of a mixture by weight (in binary azeotropes, when only one fraction is given, it is the fraction of the second component), the boiling point (b.p.) of a component, the boiling point of a mixture, and the specific gravity of the mixture.
2-Bromobenzaldehyde [1] 3-Bromobenzaldehyde [2] 4-Bromobenzaldehyde [3] [4] Structure Molecular formula: C 7 H 5 BrO (BrC 6 H 4 COH) Molar mass: 185.020 g/mol Appearance colorless liquid colorless liquid white solid CAS number [6630-33-7] [3132-99-8] [1122-91-4] Properties Density and phase: 1.585 g/ml, liquid 1.587 g/ml, liquid solid ...