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The general structure of a boronic acid, where R is a substituent. A boronic acid is an organic compound related to boric acid (B(OH) 3) in which one of the three hydroxyl groups (−OH) is replaced by an alkyl or aryl group (represented by R in the general formula R−B(OH) 2). [1]
This protocol has proved useful in the cross-coupling of some notoriously unstable boronic acids, such as the 2-pyridine boronic acid. [ 16 ] [ 17 ] This ensures that the boronic acid concentration is low during the cross-coupling reaction, which in turn minimises the potential for side reactions.
Direct halogenation of pyridine with chlorine gas above 270 °C gives a mixture of 2-chloropyridine and 2,6-dichloropyridine. [1] 2- and 4-chloropyridine are prepared from the corresponding pyridinols using phosphoryl chloride. [1]
Phenylboronic acid or benzeneboronic acid, abbreviated as PhB(OH) 2 where Ph is the phenyl group C 6 H 5 - and B(OH) 2 is a boronic acid containing a phenyl substituent and two hydroxyl groups attached to boron. Phenylboronic acid is a white powder and is commonly used in organic synthesis.
2-Chloropyridine is produced by direct reaction of pyridine with chlorine. The initially formed 2-chloropyridine reacts further to give 2,6-dichloropyridine. [2] Alternatively, 2-chloropyridines can be conveniently synthesized in high yields from pyridine-N-oxides. [3]
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.
The latter usually have a range of molar masses (unit g mol −1), the distributions of which are indicated by dispersity (Đ). It is defined as the ratio of the mass-average molar mass ( M m ) to the number-average molar mass ( M n ) i.e. Đ = M m / M n . [ 4 ]
A pyridinecarboxylic acid is any member of a group of organic compounds which are monocarboxylic derivatives of pyridine. Pyridinecarboxylic acid comes in three isomers: Picolinic acid (2-pyridinecarboxylic acid) Nicotinic acid (3-pyridinecarboxylic acid), also known as Niacin; Isonicotinic acid (4-pyridinecarboxylic acid)