Thiophenes for sale
Thiophene is an aromatic five-membered heterocycle containing one sulfur atom in the cycle. Thiophene is a colorless liquid with benzene smell. Thiophenes are readily soluble in hydrocarbons and in other organic solvents. It is insoluble in water. The thiophene molecule is flat. Thiophenes belong to research chemicals with excess heteroaromatic systems and exhibit aromatic properties. They enter into the electrophilic substitution reaction, particularly, the reactions of halogenation, nitration, formulation, and others, and their activity in these reactions is much stronger than benzene—for some reactions by 4 orders. These reactions are usually directed to the α-position of the cycle, and to the β-position, they are 2-3 magnitude slower orders.
The thiophene derivatives, which have 2nd position in the second order, enter substitution reactions to form 2,5-disubstituted. 2,4-isomers are synthesized using the initial reagents as complexes with strong proton or aprotic acids: this is due to a significant increase in the electron-withdrawing ability of the substituent due to complexation. Thiophene and its derivatives are less stable than benzene analogues, so many reactions in the thiophene series are accompanied by polycondensation (resinization) and destruction. Thiophene is sufficiently smoothly alkylated only under mild conditions when more active tertiary and secondary (but not primary) alkyl halides are used. Thiophene and its substituted, containing type I, very easily acylated in the SnCl4 or SnCl2 presence at benzene, which under these conditions is not acylated. The thiophene proceeds formation under the action of DMF or N-methylformanilide in the POCl3 presence; reacts with aldehydes and ketones in the presence of aprotic or protonic acids leads to the compounds formation of a number of di(2-thienyl)methane.
Thiophene and its derivatives are capable on direct metalation under the organolithium compounds action by the mechanism of so-called protophilic substitution. The reaction proceeds rapidly and practically quantitatively at room temperature in most cases with high regiospecificity with the α-metalated derivatives formation. Under very mild conditions (-70°C), the exchange reaction of a halogen atom in the thiophene-to-metal cycle also occurs under the action of C4H9Li, with halogen exchange at the α-position being preferable to β-position, and the exchange of I with Li proceeds more easily than Br. Thiophene, its homologues and some derivatives are capable of radical substitution reactions, for example aeration by the Gomberg-Bachmann-Hey reaction.