1-Bromo-7-chloroheptane (CAS: 68105-93-1) is a bifunctional haloalkane that is indispensable in various branches of organic synthesis. Its utility stems from the presence of two distinct halogen atoms on a seven-carbon chain, offering selective reactivity. This guide outlines common synthesis pathways, key properties, and essential handling considerations for this important chemical intermediate.

Synthesis Pathways:

Several routes can be employed to synthesize 1-bromo-7-chloroheptane, often starting from readily available precursors. A common method involves the reduction of 7-chloroheptanoic acid. This process typically begins with the reduction of the carboxylic acid functional group to a primary alcohol, 7-chloroheptan-1-ol, using strong reducing agents like lithium aluminum hydride (LiAlH4) in solvents such as tetrahydrofuran (THF). Subsequently, the alcohol is converted to the bromide via nucleophilic substitution, commonly by reacting it with hydrogen bromide (HBr) under controlled heating. This two-step process leverages the existing chlorine atom and selectively introduces the bromine atom.

Another approach involves nucleophilic substitution on a dihaloalkane precursor. For instance, reacting 1,7-dibromoheptane with a source of chloride ions, such as sodium chloride (NaCl), in a polar aprotic solvent like acetone, can lead to the formation of 1-bromo-7-chloroheptane. Careful control of reaction stoichiometry and conditions is necessary to favor monosubstitution and minimize the formation of 1,7-dichloroheptane.

Key Physical and Chemical Properties:

1-Bromo-7-chloroheptane is a colorless transparent liquid. Its molecular formula is C7H14BrCl, with a molecular weight of approximately 213.54 g/mol. The compound exhibits a density of 1.266 g/cm³ and a boiling point around 241.662°C. Chemically, its most significant feature is the differential reactivity of the carbon-bromine bond, which is more susceptible to nucleophilic attack and organometallic formation than the carbon-chlorine bond. This selectivity is crucial for its use as a versatile intermediate in synthesizing complex molecules, including pharmaceuticals, agrochemicals, and specialty chemicals.

Handling and Storage:

As with most chemical reagents, proper handling and storage practices are essential for 1-bromo-7-chloroheptane:

  • Personal Protective Equipment (PPE): Always wear appropriate PPE, including chemical-resistant gloves, safety goggles, and a lab coat, when handling this compound.
  • Ventilation: Work in a well-ventilated area, preferably a fume hood, to minimize inhalation exposure.
  • Storage Conditions: Store in a cool, dry, and well-ventilated place, away from heat sources, open flames, and strong oxidizing agents. Keep containers tightly closed to prevent moisture absorption and potential decomposition.
  • Incompatibility: Avoid contact with strong bases, strong oxidizing agents, and reactive metals, as these can lead to hazardous reactions.

When sourcing 1-bromo-7-chloroheptane, it is important to ensure high purity (typically ≥98.0% assay) from reputable manufacturers to guarantee reliable outcomes in your synthetic processes. Understanding these aspects ensures efficient and safe utilization of this key chemical intermediate.