Background and Overview
Tetrahydrophiophene (THT), also known as “sulfur-containing cyclopentane” with the molecular formula C4H8S, is a five membered saturated sulfur-containing heterocyclic compound obtained by catalytic hydrogenation of thiophene. It is mainly used as an odorant for fuel gases such as city gas, liquefied petroleum gas, and natural liquefied gas, and can also be used as a raw material for pharmaceuticals and pesticides.
Nature
Tetrahydrophene is a colorless, transparent, volatile liquid with a strong unpleasant odor. Insoluble in water, miscible in ethanol, ether, benzene, and acetone. After thiophene is reduced to tetrahydrothiophene, it no longer has a conjugated system and aromaticity. Therefore, tetrahydrothiophene exhibits the properties of a typical thioether and is easily oxidized to sulfoxides and sulfones (sulfolane)
Production
Obtained by reacting 1,4-dihalogenated butane with sodium sulfide in alcohol, or by catalytic hydrogenation of thiophene. The catalytic hydrogenation of thiophene is relatively difficult, and nickel catalysts are easily poisoned by thiophene and become ineffective. When using Raney nickel as a catalyst, it often leads to desulfurization reactions, resulting in butane becoming the main product. Thiophene can only be reduced to tetrahydrothiophene in the presence of molybdenum disulfide or a significant excess of palladium carbon.
The method for producing tetrahydrothiophene from 4-chloro-1-butanol as raw material includes the following steps: first, add an aqueous solution of 4-chloro-1-butanol to a reaction vessel, heat it under stirring conditions, maintain reflux, and add initiators and sulfides in proportion. After reacting for a period of time under reflux, the reaction effluent is separated and purified, and tetrahydrothiophene is collected.
Usage
Due to its strong unpleasant odor, tetrahydrothiophene is used as a leak warning agent for gas fuels such as city gas and natural gas. It is added in small amounts to gas fuels to replace the previously used odorants such as ethanethiol. In addition, tetrahydrothiophene is also used as a raw material for organic synthesis [1].
Storage method
Tetrahydrophene is stored in a cool and ventilated warehouse. Stay away from sources of fire and heat. The storage temperature should not exceed 37 ℃. Keep the container sealed. It should be stored separately from oxidants and avoid mixing storage. Adopt explosion-proof lighting and ventilation facilities. Prohibit the use of mechanical equipment and tools that are prone to generating sparks. The storage area should be equipped with emergency response equipment for leaks and suitable containment materials.
Reference
[1] Zhu Libo, Yu Jie, Xu Nengbin, Ying Hongmei Determination of tetrahydrothiophene in ambient air by combining pre concentration system with PFPD detector. China Environmental Monitoring, 2006