Thiophene
Thiofuran
Colorless liquid with an odor benzolartigem
Liquid
1.06 g · cm -3 ( 20 ° C)
-38 ° C
84 ° C.
80 hPa (20 ° C)
- Practically insoluble in water
- Soluble in ethanol, diethyl ether, chloroform and benzene
0.55 ( 1 ) D ( 1.8 × 10-30 C * m )
1.5289
Risk
1400 mg · kg -1 ( LD50, rat, oral)
80.2 kJ / mol
Template: Infobox chemical / molecular formula search available
Thiophene, also called thiofuran, is an organic compound with the molecular formula C4H4S and is one of the heteroaromatics. Four carbon atoms and one sulfur atom, form a five-membered ring with a six π - electrons, originating from the four double bonds and two of a free electron pair of the sulfur.
Occurs as a substituent on the thiophene ring, then this is indicated with the prefix thienyl. As Anelland he called thieno.
History
Thiophene was discovered in 1883 by Victor Meyer in crude benzene, which was obtained by distillation of coal tar. During " phen " should refer to the gaseous coking product " illuminating gas ", which at that time as town gas for lighting ( gr phainomei: shine ) in the cities served, derives " thio " sulfur ( gr theion, see also thioether ) from. The crude benzene used by Victor Meyer formed with isatin a blue dye when it was treated with sulfuric acid, the reaction Indophenin. Thus maintaining the formation of the Indophenins long time to react with benzene, until a test with pure benzene gave no color reaction.
Production
Technically from n-butane and sulfur at 560 ° C:
Instead of butane and butane derivatives, such as butenes, butadiene or 1-butanol can be used as a sulfur donor also as sulfur dioxide or carbon disulfide.
Furthermore, thiophene can be obtained by heating sodium succinate with Diphosphortrisulfid or by passing acetylene over heated pyrite.
Properties
Thiophene is a water-immiscible liquid that smells like benzene and boiling at 84 ° C at room temperature. It is flammable and highly flammable.
Because it is an aromatic compound, its properties are very different from those of conventional thioethers: So for example it is not possible to alkylate the sulfur by means of methyl iodide, while the flanking these CH groups are susceptible to electrophilic attack. As it can be easily sulfonated with sulfuric acid, the conversion into the water-soluble thiophene sulfonic acid is the basis for separation of thiophene from benzene contaminated. A separation of the mixture by distillation is hardly possible due to the differing by only 4 ° C boiling points.
Polythiophene
Polythiophenes (PT ) can be prepared by electrochemical polymerization of thiophene or derivatives thereof. The preparation of Grignard compounds of 2,5- Dihalogenthiophenen or by oxidation is possible. Polythiophenes are highly stable against heat, oxygen or moisture.
Undoped polythiophene has a low conductivity. However conductivities to 100 S / cm obtained by doping with suitable oxidizing agents. Therefore, finding doped polythiophenes as the electrode material, and semiconductor light emitters in organic light use. The polythiophenes light upon application of a voltage, wherein the respective color can be varied by the electric voltage. Since unsubstituted polythiophene is insoluble and infusible, PT derivatives are used for better handling.
Occurrence
Thiophene contained in coal tar such as benzene and can be contained as an impurity therein.