2-Bromopyridine

Chemical Properties

light yellow oily or dark red liquid. miscible with ethanol, ether, benzene and pyridine, still soluble in water.

Uses

2-Bromopyridine is a 2-halogenated pyridine used in the preparation of a variety of biologically active compounds such as antimalarial agents and beta-adrenoceptor agonist.

Application

2-Bromopyridine can be used as:
A building block in the formation of C?N bond by various cross coupling reactions.
A reactant in Negishi cross-coupling reaction with aryl halides catalyzed by palladium.
A reactant in the synthesis of 2′-pyridyldifluoroacetate with ethyl bromodifluoroacetate in presence of copper as a catalyst.

Preparation

2-Bromopyridine is synthesized from 2-aminopyridine by bromination. In industrial production, hydrobromic acid (over 48%) is first cooled to below 0°C, 2-aminopyridine is slowly added, and then liquid bromine is added dropwise in a salt bath under freezing, and the rate of addition is to control the reaction temperature below -5°C appropriate. After adding, add sodium nitrite aqueous solution dropwise, control the reaction temperature to be below 0°C, stir for 20-30min, dropwise add 50% sodium hydroxide solution, extract the reaction solution with ether, wash with water, dry with anhydrous sodium sulfate, filter, and recover Diethyl ether, the residue was distilled under reduced pressure, and the 88°C-94°C/3333Pa fraction was collected to obtain the finished product of 2-bromopyridine with a yield of 83.8%.

Definition

ChEBI: 2-bromopyridine is a monobromopyridine.

Reactions

2-Bromopyridine reacts with butyllithium to give 2-lithiopyridine, which is a versatile reagent.Pyrithione can be prepared in a two-step synthesis from 2-bromopyridine by oxidation to the N-oxide with a suitable peracid followed by substitution using either sodium dithionite or sodium sulfide with sodium hydroxide to introduce the thiol functional group.

Flammability and Explosibility

Flammable

Purification Methods

Dry 2-bromopyridine over KOH for several days, then distil it from CaO under reduced pressure, and taking the middle fraction. [Beilstein 20/5 V 422.]