What is 2-chlorobutane?

2-Chlorobutane

2-Chlorobutane is an alkyl halide with the chemical formula CH₃CH₂CH(Cl)CH₃. It is a colorless liquid at room temperature. Here's some key information about it:

• Structure: The chlorine atom is attached to the second carbon atom in the butane chain, hence the "2-" prefix in the name. This makes it a secondary alkyl halide.

• Physical Properties: Its molar mass is approximately 106.59 g/mol. It has a boiling point around 68-69 °C. It's also insoluble in water.

• Reactivity: As an alkyl halide, 2-chlorobutane can undergo several types of reactions, including:

  • Substitution Reactions: The chlorine atom can be replaced by other nucleophiles (e.g., OH⁻, CN⁻, OR⁻). These reactions can proceed via SN1 or SN2 mechanisms, depending on the reaction conditions and the nucleophile. Because the carbon bearing the chlorine is secondary, both SN1 and SN2 are possible.
  • Elimination Reactions: Under basic conditions, 2-chlorobutane can undergo elimination (E1 or E2) to form alkenes, mainly 2-butene (both cis and trans isomers) and some 1-butene. Zaitsev's rule dictates the major product in most cases.

• Preparation: 2-Chlorobutane can be synthesized by several methods, including:

  • Reaction of 2-butanol with HCl: This reaction requires a catalyst, such as zinc chloride.
  • Addition of HCl to but-2-ene: This reaction follows Markovnikov's rule.

• Uses: 2-Chlorobutane can be used as a solvent and as a reagent in organic synthesis.