Also known as p-chlorobenzyl chloride. A colorless liquid or white needle-like crystals. Melting point 31℃. Boiling point 222℃ (decomposes at 210℃). Refractive index 1.5554. Soluble in organic solvents such as ether, acetone, benzene, and carbon disulfide; readily soluble in cold ethanol. Insoluble in water. Sublimes. Prepared by high-temperature chlorination of p-chlorotoluene or low-temperature chlorination of benzyl chloride, or by photochlorination of p-chlorotoluene catalyzed by azobisisobutyronitrile. In organic synthesis, it is used to produce p-chlorobenzyl alcohol, p-chlorobenzaldehyde, p-chlorobenzoic acid, and p-chlorophenoxyacetonitrile. It is an intermediate in pharmaceuticals, pesticides, insecticides, and dyes.
Preparation method: 1. Low-temperature chlorination of benzyl chloride: The chlorination reaction is carried out in the presence of sulfur and iron powder. The sulfur to iron powder ratio is 9:1, the reaction temperature is 15-17℃, and chlorination ends when the relative density of the reaction solution increases to 1.22. The crude product was obtained by vacuum distillation to obtain the final product, with a yield (based on benzyl chloride) of 80.8% and a content of 94.4%. 2. High-temperature chlorination of p-chlorotoluene: p-chlorotoluene was first added to a reactor, and chlorination was started slowly at 100℃. The temperature was then raised to approximately 115℃. The resulting crude p-chlorobenzyl chloride was washed with water, distilled under vacuum, and the fraction collected at 110-120℃ (97.325 kPa) was the final product. 3. The product was obtained by reacting chlorobenzene with hydrogen chloride, paraformaldehyde, etc. Chlorobenzene, paraformaldehyde, phosphoric acid, and zinc chloride were mixed, and hydrogen chloride was introduced to react at 40-45℃ for approximately 2 hours. Then, it was extracted with benzene, neutralized with sodium carbonate, dried, and purified to obtain the final product. Alternatively, p-chlorotoluene can be obtained by photochlorination catalyzed by azobisisobutyronitrile.
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