What Is Pentachlorothiophenol?
Pentachlorothiophenol, appearing as a white to grayish-brown powder, is known by its IUPAC name 2,3,4,5,6-pentachlorobenzenethiol or simply PCTP. In the US, it’s recognized under the Toxic Substances Control Act (TSCA) as a persistent, bioaccumulative, and toxic (PBT) substance.
Uses of Pentachlorothiophenol
Used predominantly as an embrittlement agent for rubber, PCTP enhances the efficiency of the kneading process by reducing the rubber’s molecular weight. This reduction lowers viscosity, aiding in the rubber mixing process and ensuring batch-to-batch viscosity uniformity. Despite its effectiveness, the classification of PCTP as a PBT substance has led to restrictions on its use in the US, with alternatives like bis(2-benzamidophenyl) disulfide, or BASS, being favored.
Properties of Pentachlorothiophenol
With the formula C6HCl5S and a molecular weight of 282.38, pentachlorothiophenol has a melting point of 231.5°C and a density of 1.7 g/ml. It’s flammable, emits an unpleasant odor, and is insoluble in water. Notably, it’s a metabolite of hexachlorobenzene, found in the excretions of animals exposed to the substance.
Other Information on Pentachlorothiophenol
1. Production Methods
Produced by reacting hexachlorobenzene with sodium sulfide and sulfur or through the reaction of hydrogen sulfide with pentachlorophenol, PCTP synthesis involves acidic catalysts for efficiency.
2. Handling and Storage Precautions
As a skin corrosive and irritant, proper protective clothing and immediate washing off upon contact are crucial. It should be stored in light-shielded, tightly sealed glass containers in cool, well-ventilated areas to prevent degradation by light.