2,3,5,6-Tetrachlorophenol

Chlorophenols are generally prepared by the chlorination of phenol. There are other routes of synthesis as through diazotizing p-chloroaniline or dechlorinating (by alkaline hydrolysis) 1,2,4,5-tetrachlorobenzene to yield 2,4,5-trichlorophenol (TCP). Polychlorinated dibenzo-p-dioxins can be formedduringthemanufacturingprocess of the chlorophenols. The amount formed depends on temperature and pressure process variability during production. The more notable toxic dioxin, 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD), is formed during the production of 2,4,5- TCP. Laboratory reference standards of 2,3,7,8-TCDD are prepared by heating 2,4,5-TCP under alkaline conditions. All technical and formulated products containing 2,4,5-TCP are expected to be contaminated to varying degrees by this 2,3,7,8-TCDD by-product of the manufacturing process.

純化方法Crystallise the phenol from pet ethers. The benzoate has m 136o (from EtOH). [Beilstein 6 II 182, 6 III 730, 6 IV 1025.]