Issue 5 the chemistry of thiophene soxides1 and related. Electrophilic aromatic substitution of heteroaromatics. Moreover, thiophene derivatives find large application in material science 515 and in coordination chemistry 16,17, and as intermediate in organic synthesis 18,19. Synthesis, properties and biological activity of thiophene. It is a mancude organic heteromonocyclic parent, a member of thiophenes, a monocyclic heteroarene and a volatile organic compound. The 5membered ring heterocycles furan, pyrrole, thiophene are. Reactions of thiophene and methylthiophenes in the. Subsequently the thiophene molecule loses its aromaticity and becomes unstable. Reaction of dicarbomethoxycarbene with thiophene derivatives william s. These metrics are regularly updated to reflect usage leading up to the last few days. Introduction synthesis of functionalized heterocycles by the alkylation of poxodithioesters with hctionalized electrophiles such as ahaloketones involving the formation of intermediate.
In reactions which involve bond formation using the lone pair of electrons on the ring nitrogen, such as protonation and quaternisation, pyridines behave just like tertiary aliphatic or aromatic amines. It is not surprising, therefore, that many of the chemical reactions used for their preparation are oxidations. Halogenation of thiophene occurs very readily at room temperature and is rapid even at. Although precise reactivity ratios depend on the particular reaction, the rel. Noland, honnaiah vijay kumar, yoke ching chin, hyejin kim, yuqi zhou, grant c. Thiophenes reactions with electrophiles at c preferably at. Finally, examples 4 through 7 illustrate reactions of 1,2 and 1,3oxazole, thiazole and diazole. For example, pyrrole reacts with acetic anhydride or acetyl chloride and triethyl amine to give nacetylpyrrole. Compounds 3a,b reacted with either hydrazine hydrate 5a or phenyl hydrazine 5b afforded compounds 7ad which underwent cyclization for compounds 7a,c afforded compound 9. Paalknorr synthesis of thiophene 2018 38 thiophene 39.
Fiesselmann thiophene synthesis gewald aminothiophene synthesis and hinsberg synthesis. Such reactions have been discussed in previous sections of this text, and the following. The reaction of substituted buta1enes with potassium sulfide enables an atom economical, and transitionmetalfree synthesis of thiophenes via cleavage of multiple ch bonds. When 210 was used crude in the amination reaction, the iodoform seemed to react and the desired product was not obtained. The am1 semiempirical method was used for theoretical searching of activation of thiophene as a diene for the diels. Controlling single molecule conductance by a locally. The classical approaches to substituted thiophenes are mainly based on condensationlike reactions or on subsequent functionalization of the thiophene ring 2030.
Compounds analogous to thiophene include furan selenophene and pyrrole, which each vary by the heteroatom in the ring. Therefore thiophene resemble benzene rather than furan or pyrrole in many o f its reactions but it is more reactive and less stable. The reaction of 2nitrochalcones with elemental sulfur provides a wide range of 2benzoylbenzothiophenes in the presence of dipea as sulfur activator. Reactions of thiophene dioxides wiley online library. Each volume attempts to discuss all aspects properties, synthesis, reactions, physiological and industrial significance of a specific ring system. Strohmaierb, enrique iglesiaa, a department of chemical engineering, university of california at berkeley, berkeley, ca 94720, usa b exxonmobil research and engineering co. Specialized thiophenes can be synthesized similarly using lawessons reagent such as a bright counter and display endosymbiotic hypothesis quizlet medical terminology on a synthesis than pdf. Rockafellow department of chemistry, iowa state university, ames.
Electrophilic addition at nitrogen reactions of pyridine when a pyridine reacts as a base or a nucleophile it forms a pyridinium cation in. Cyclization of the latter products gave the annulated products 4a,b. Even electronrich alkenes can then take part in the dielsalder reactions with thiophene dioxides. Strohmaierb, enrique iglesiaa, a department of chemical engineering, university of california at berkeley, berkeley, ca 94720, usa. Recent advances in the synthesis of thiophene derivatives by. The reaction proceeds via in situ incorporation of sulfur followed by coppercatalyzed cyclization. Rapid kinetics of chlorination of thiophene in aqueous. Investigation of the adsorption and reactions of thiophene on. In previous reports the adsorption and reaction of some aromatic molecules on transitionmetal ionex changed montmorillonites were described on the basis of. Pdf dielsalder reactions of thiophene oxides generated in situ. Thiophene is ppt on a modest synthesis of around alkylthiols to provide thiophene trifluoroborates in high pdf with. Thiophene soxides, diels alder reaction, photochemistry, electrochemistry contents. Pdf dielsalder reactions of thiophene oxides generated. Preparation and reaction of carboxylic acids preparation of carboxylic acids the carbon atom of a carboxyl group has a high oxidation state.
Dielsalder reactions of 2cycloalkenylthiophenes and 2. Recent examples, which in several cases demonstrate the modern application of the method, are presented where possible. Paalknorr synthesis of furan mechanism 2018 39 thiophene 40. However, at elevated temperatures and under highpressure clean reaction between thiophene and maleic anhydride, maleimides or acrylic dienophiles can be observed. Dtd 5 effects of zeolite structure and aluminum content on thiophene adsorption, desorption, and surface reactions antonio chicaa, karl g. After this time, the reaction mixture was cooled to room temperature and then poured into water 100 ml. Electron rich aryl xsn nu o o s nu x n o o nusno2 ca 100 times for reactive than x no2 sulfur stab. Benzothiophene and dibenzothiophene contain the thiophene ring fused with one and two benzene rings, respectively. All electrophilic aromatic substitution reactions occur by similar mechanisms. For example, pyrrole reacts with acetic anhydride or acetyl chloride and triethyl amine to. Baran group meeting furans and thiophenes 091504 furans and. The stereochemical courses for the reactions are exclusively endoorientation and syn. D is therefore anchored to the surface by two covalent bonds.
Electrophilic substitution reactions of pyrroles, furans and thiophenes metallation of fivemembered heteroaromatics and use the of directing groups strategies for accomplishing regiocontrol during electrophilic substitution indoles comparison of electronic structure and reactivity of indoles to that of pyrroles. For the reactions carried out in dma, substrate concentration was 2 mmol of 1 per ml of dma. Reactions of thiophene and methylthiophenes in the interlayer. Radical ions 491 redox reactions of some thiophene. Reaction and mechanism of thiophenepaal knor synthesis. Note that in this reaction and in others that follow, only one of the six benzene hydrogens is shown explicitly to emphasize that one hydrogen is lost in the reaction. Because of this, the reactivity of pyrrole is greater. The chemistry of heterocyclic compounds, since its inception, has been recognized as a cornerstone of heterocyclic chemistry. Apr 09, 2019 for the love of physics walter lewin may 16, 2011 duration. These keywords were added by machine and not by the authors. Electrophilic substitution thiophene undergoes electrophilic substitution reaction at 2nd position 2018 42 thiophene 43. Synthesis, characterization, antioxidant and quantum. Citations are the number of other articles citing this article, calculated by crossref and updated daily.
Metallation of fivemembered heteroaromatics and use the of directing groups. Some additional reactions, such as oxidation and desulfurization, are due to the presence of sulfur and are thus confined to thiophenes. Iodination of thiophene with iodine and mercuric oxide at 0c gave a mixture of 2iodothiophene 70% and 2,5diiodothiophene. Pdf synthesis, properties and biological activity of thiophene. Additions and ringopening reactions are less important than with furan, and substitution reactions are dominant. Alder reactions by evaluating their frontier orbital energies and by calculating. Electrophilic substitution reactions like nitration, sulphonation, halogenation, friedelcraft reactions reduction reaction with organometallic compounds. Thiophene is a heterocyclic compound with the formula c 4 h 4 s.
By generation of dicarbomethoxycarbene from the dibenzothiophenebased ylide in neat thiophene, it is shown that the thienylmalonate is not a product of rearrangement of the thiophene ylide, in contrast to thermolysis. Where useful, the reactivity is compared to that of benzob thiophene soxides, dibenzothiophene soxides, and tetracyclones. Write an equation for the combustion of thiophene answer save. Apr 10, 2018 the functionalization of thiophenes is a fundamental and important reaction. Consisting of a planar fivemembered ring, it is aromatic as indicated by its extensive substitution reactions. Choi, moongun, synthesis and reactions of thiophene, 2,5dihydrothiophene, benzob thiophene and selenophene transition metal complexes. Another precursor for preparing a thiophene is mesoinic thiazolone 71, which reacts with dmad to produce pyridine 73 or thiophene 74 depending on the reaction. Unexpected dielsalder and oxidation reactions of benzocthiophenes the oxidation of thiophenes by peracids to form thiophene soxides could not be carried out with benzocthiophenes.
This process is experimental and the keywords may be updated as the learning algorithm improves. How is pyrrole more reactive than furan and thiophene. Aug 08, 2018 electrophilic substitution reactions like nitration, sulphonation, halogenation, friedelcraft reactions reduction reaction with organometallic compounds. Mannich reactions of annulated thiophene derivatives. The reaction of the tetrahydrobenzob thiophene derivatives 1a,b with benzoylisothiocyanate 2 afforded the thiourea derivatives 3a,b. Thiophene appears as a colorless liquid with an unpleasant odor. Moreover, the strategy can also be used for the synthesis of thiophenes from 1,4diaryl1,3dienes.
Pyridine is the simplest heterocycle of the azine type. Thiophene prefers reactions with electrophilic reagents. Radical ions 491 redox reactions of some thiophene derivatives. Recent advances in the synthesis of thiophene derivatives. The interaction between elemental sulfur and naotbu enables a facile singlestep protocol for the synthesis of thiophene derivatives from 1,3diynes. Electrophilic substitution reactions of pyrroles, furans and thiophenes. Reactions utilizing the diketones provided a greater yield of the thiophene suggesting that the furan is not an essential intermediate in the reaction pathway, but.
Thiophene itself is not very reactive in the standard diels alder reaction. Ppt thiophene powerpoint presentation free to view. The method is characterized by using thiophene as a raw material and mainly comprising the following steps of. Thiophenes heterocyclic building blocks sigmaaldrich. Dielsalder reactions of 2cycloalkenylthiophenes and 2cycloalkenylbenzobthiophenes wayland e. Reactions with electrophiles at sulfur s ox ox s oo s o not aromatic s s oo rr mcpba rr r. Thiophene and 3methylthiophene polymerized to form cations of polythiophene and polymethylthiophene respectively, which were characterized by absorption bands in the nearinfrared region. Furans and thiophenes ryan shenvi baran group meeting 091504 synthesis of thiophenes cho sh cn nh o cn snh2 o n h cn liebigs ann. The friedel crafts acylation of thiophenes is a much used reaction and generally gives good yields under controlled conditions, despite the fact that aluminium chloride reacts with thiophene to generate tars. The invention relates to a synthesis method of 2 thiophene acetylchloride. Preparation and reactions of heterocyclic compounds ii. The substituted thiophenel,1 dioxides are stable substances.
An easy approach for iodination of thiophene is the reaction of iodine with lithiated thiophene. Thiophene is a heterocyclic compound with the formula c4h4s. Pdf mannich reactions of annulated thiophene derivatives. The resonance energy of pyrrole is very much less than furan and thiophene. Cycloaddition reactions of tetracyclones, benzob thiophene soxides, and benzob thiophene s,sdioxides with alkynes thies thiemann department of chemistry, united arab emirates university, po box 15551, al ain, abu dhabi, united arab emirates corresponding author. The rate of halogenation of thiophene at 25 c is about 10 8 times that of benzene. The third reaction has two substituents of different types in the 2 and 5positions. As model reactions, we first carried out the suzukimiyaura coupling reaction of xpythx.
Milder reaction conditions must be used with more reactive compounds. Thiophenes thiofurans are important sulfurcontaining heterocyclic compounds that function as analogues of furans and pyrroles, and are widely used as building blocks in many agrochemicals and pharmaceuticals as well as materials science. Thiophene and 3methyl thiophene polymerized to form cations of polythiophene and polymethylthiophene respectively, which. Thiophene and its monomethyl derivatives do not undergo coupling with diazonium salts in intermolecular reactions. The friedel crafts acyalation of thiophene is much used reaction and produced generally to give good yield under controlled condition, adding catalyst to thiophene and acylatting agent avoid reaction of aluminium chloride with thiophene to generate tars 6 reactivity of indoles, benzobthiophenes, benzobfurans. Am1 semiempirical searching for suitable thiophene. Article views are the countercompliant sum of full text article downloads since november 2008 both pdf and html across all institutions and individuals. A plausible mechanism based on epr experiments revealed that the trisulfur radical anion acts as a key intermediate of this process. Thiophenes s reactions with electrophiles at c preferably at c2 c5 cf pyrrolesprotonation much more stable under acidic conditions than pyrroles and furans protonation at c2 c5 s 100% h3po4 90 oc s h h s h h s h h x x h h x h h x h h x h h x h h most stable. The adsorption and reactions of thiophene c 4 h 4 s on sulfided moal 2 o 3 catalysts have been investigated over wide ranges of pressure 109. The electron demand of the dielsalder reactions of thiophene dioxides often becomes inverse to that of common diels alder reactions. Although precise reactivity ratios depend on the particular reaction, the relative rates of bromination are typical. By sourabh choure,from modern clg of pharmacy,nigdi,pune44.
The dielsalder reaction of 2,5bistrimethylsilyl thiophene with dienophiles gave the adducts in high yields. This is one of the features that makes thiophene dioxides synthetically important. Pdf reaction of dicarbomethoxycarbene with thiophene. Thiophene is a monocyclic heteroarene that is furan in which the oxygen atom is replaced by a sulfur. As a consequence of this reaction, the two carbon atoms formerly connected to the s atom in the thiophene group bind covalently to cu surface atoms, while the s atom is irreversibly detached from the molecule.
Thiophene sulfone itself is highly unstable, but alkyl and aryl groups and fused benzene rings increase the stability. Pyrrole, furan, and thiophene are all much more reactive than benzene in electrophilic aromatic substitution. S reactions with electrophiles at c preferably at c2 c5. Short historical views are presented where suitable. Reactions of pyrrole require careful evaluation, since nprotonation destroys its aromatic character. Cycloaddition reactions of tetracyclones, benzobthiophene. These reactions are set in juxtaposition and compared with the example of a reaction of a thiophene soxide with an alkyne. Dielsalder reactions of thiophene 1,1dioxides, they can act as either 2. S reactions with electrophiles at c preferably at c2 c. Department of chemistry, faculty of science, kochi university, akebono. Effects of zeolite structure and aluminum content on.
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