secbromobutane

Sec-bromobutane, also known as 2-bromobutane, is an organobromine compound with the formula C4H9Br. It is the secondary bromide of butane and features a bromine substituent on the second carbon, giving the structure CH3-CH(Br)-CH2-CH3. The molecule is chiral at C-2, so many samples are racemic mixtures of the R and S enantiomers.

Physically, sec-bromobutane is typically a colorless liquid at room temperature. It is immiscible with water and more soluble in organic solvents. It has a higher boiling point than many smaller alkanes of similar size, reflecting the heavier bromine atom and increased molecular interactions.

Preparation and reactivity: It can be prepared by converting 2-butanol with hydrobromic acid or phosphorus tribromide, among other standard methods for forming alkyl halides from alcohols. In organic synthesis, 2-bromobutane serves as a versatile alkylating agent. It undergoes SN2 reactions with nucleophiles and can participate in E2 eliminations with bases to give butenes, notably 2-butene. It also forms the Grignard reagent sec-butylmagnesium bromide when treated with magnesium, enabling further carbon–carbon bond-forming steps after aqueous workup.

Safety and handling: Sec-bromobutane is an irritant and can affect eyes, skin, and the respiratory system. It should be used in a well-ventilated area with appropriate personal protective equipment and stored away from moisture and strong oxidizers. Like other alkyl bromides, it should be handled with care to avoid inhalation and skin contact.

See also: 1-bromobutane, tert-butyl bromide, alkyl halides.