Sulfolene

Last updated
Sulfolene [1]
Sulfolene.png
Sulfolene-3D-balls.png
Names
Preferred IUPAC name
2,5-Dihydro-1H-1λ6-thiophene-1,1-dione
Other names
2,5-Dihydrothiophene 1,1-dioxide
Butadiene sulfone
3-Sulfolene
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.000.964 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 201-059-7
PubChem CID
UNII
  • InChI=1S/C4H6O2S/c5-7(6)3-1-2-4-7/h1-2H,3-4H2
    Key: MBDNRNMVTZADMQ-UHFFFAOYSA-N
  • C1C=CCS1(=O)=O
Properties
C4H6O2S
Molar mass 118.15 g·mol−1
Melting point 65 to 66 °C (149 to 151 °F; 338 to 339 K)
Hazards
GHS labelling: [2]
GHS-pictogram-acid.svg GHS-pictogram-exclam.svg
Danger
H318
P264+P265, P280, P305+P351+P338, P305+P354+P338, P317, P337+P317
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Sulfolene, or butadiene sulfone is a cyclic organic chemical with a sulfone functional group. It is a white, odorless, crystalline, indefinitely storable solid, which dissolves in water and many organic solvents. [3] The compound is used as a source of butadiene. [4]

Contents

Production

Synthesis of sulfolene 3-Sulfolen Synthese.svg
Synthesis of sulfolene

Sulfolene is formed by the cheletropic reaction between butadiene and sulfur dioxide. The reaction is typically conducted in an autoclave. Small amounts of hydroquinone or pyrogallol are added to inhibit polymerization of the diene. The reaction proceeds at room temperature over the course of days. At 130 °C, only 30 minutes are required. [5] An analogous procedure gives the isoprene-derived sulfone. [6]

Reactions

Acid-base reactivity

The compound is unaffected by acids. It can even be recrystallized from conc. HNO3. [7] [8]

The protons in the 2- and 5-positions rapidly exchange with deuterium oxide under alkaline conditions. [9] Sodium cyanide catalyzes this reaction. [10]

3-Sulfolen Deuteriumaustausch.svg

Isomerization to 2-sulfolene

In the presence of base or cyanide, 3-sulfolene isomerizes to a mixture of 2-sulfolene and 3-sulfolene. [10]

Isomerisierung von Sulfolen.svg

At 50 °C an equilibrium mixture is obtained containing 42% 3-sulfolene and 58% 2-sulfolene. [11] The thermodynamically more stable 2-sulfolene can be isolated from the mixture of isomers as pure substance in the form of white plates (m.p. 48-49 °C) by heating for several days at 100 °C, because of the thermal decomposition of the 3-sulfolene at temperatures above 80 °C. [12]

Hydrogenation

Catalytic hydrogenation yields sulfolane, a solvent used in the petrochemical industry for the extraction of aromatics from hydrocarbon streams. The hydrogenation of 3-sulfolene over Raney nickel at approx. 20 bar and 60 °C gives sulfolane in yields of up to 65% only because of the poisoning of the catalyst by sulfur compounds. [13]

3-Sulfolen Hydrierung.svg

Halogenation

3-Sulfolene reacts in aqueous solution with bromine to give 3,4-dibromotetrohydrothiophene-1,1-dioxide, which can be dehydrobrominated to thiophene-1,1-dioxide with silver carbonate. [7] Thiophene-1,1-dioxide, a highly reactive species, is also accessible via the formation of 3,4-bis(dimethylamino)tetrahydrothiophene-1,1-dioxide and successive double quaternization with methyl iodide and Hofmann elimination with silver hydroxide. [12]

A less cumbersome two-step synthesis is the two-fold dehydrobromination of 3,4-dibromotetrohydrothiophene-1,1-dioxide with either powdered sodium hydroxide in tetrahydrofuran (THF) [14] or with ultrasonically dispersed metallic potassium. [15]

Thiophen-1,1-dioxid Synthese.svg

Diels-Alder reactions

3-sulfolene is mainly valued as a stand-in for butadiene. [3] [4] The in situ production and immediate consumption of 1,3-butadiene largely avoids contact with the diene, which is a gas at room temperature. One potential drawback, aside from expense, is that the evolved sulfur dioxide can cause side reactions with acid-sensitive substrates.

D-A-Addukte mit Butadien und Cyclopentadien.svg

Diels-Alder reaction between 1,3-butadiene and dienophiles of low reactivity usually requires prolonged heating above 100 °C. Such procedures are rather dangerous. If neat butadiene is used, special equipment for work under elevated pressure is required. With sulfolene no buildup of butadiene pressure could be expected as the liberated diene is consumed in the cycloaddition, and therefore the equilibrium of the reversible extrusion reaction acts as an internal "safety valve". [16]

Diels-Alder reaction with sulfolene.svg

3-Sulfolene reacts with maleic anhydride in boiling xylene to cis-4-cyclohexene-1,2-dicarboxylic anhydride, obtaining yields of up to 90%. [4]

3-Sulfolen Reaktion mit MA.svg

3-Sulfolene reacts also with dienophiles in trans configuration (such as diethyl fumarate) at 110 °C with SO2 elimination in 66–73% yield to the trans-4-cyclohexene-1,2-dicarboxylic diethyl ester. [17]

3-Sulfolen Reaktion mit Diethylfumarat.svg

6,7-Dibromo-1,4-epoxy-1,4-dihydronaphthalene (6,7-Dibromonaphthalene-1,4-endoxide, accessible after debromination from 1,2,4,5-tetrabromobenzene using an equivalent of n-butyllithium and Diels-Alder reaction in furan in 70% yield [18] ) reacts with 3-sulfolene in boiling xylene to give a tricyclic adduct. This precursor yields, after treatment with perchloric acid, a dibromo dihydroanthracene which is dehydrogenated in the last step with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) to 2,3-dibromoanthracene. [19]

Synthese von 2,3-Dibromanthracen.svg

1,3-Butadiene (formed in the retro-cheletrophic reaction of 3-sulfolene) reacts with dehydrobenzene (benzyne, obtained by thermal decomposition of benzenediazonium-2-carboxylate) in a Diels-Alder reaction in 9% yield to give 1,4-dihydronaphthalene. [20]

3-Sulfolen Reaktion mit Arin.svg

2- and 3-Sulfolenes as a dienophile

In the presence of very reactive dienes (for example 1,3-diphenylisobenzofuran) butadienesulfone behaves as a dienophile and forms the corresponding Diels-Alder adduct. [21]

D-A-Addukt mit 1,3-Diphenylisobenzofuran.svg

As early as 1938, Kurt Alder and co-workers reported Diels-Alder adducts from the isomeric 2-sulfolene with 1,3-butadiene and 2-sulfolene with cyclopentadiene. [22]

Other cycloadditions

The base-catalyzed reaction of 3-sulfolene with carbon dioxide at 3 bar pressure produces 3-sulfolene-3-carboxylic acid in 45% yield. [23]

3-Sulfolen-3-carbonsaure Synthese.svg

With diazomethane, 3-sulfolene forms in a 1,3-dipolar cycloadduct: [24]

3-Sulfolen Reaktion mit Diazomethan.svg

Polymerization

In 1935, H. Staudinger and co-workers found that the reaction of butadiene and SO2 at room temperature gives a second product in addition to 3-sulfolene. This second product is an amorphous solid polymer. By free-radical polymerization of 3-sulfolene in peroxide-containing diethyl ether, up to 50% insoluble high-molecular-weight poly-sulfolene was obtained. The polymer resists degradation by sulfuric and nitric acids. [8]

In subsequent investigations, polymerization of 3-sulfolene was initiated above 100 °C with the radical initiator azobis(isobutyronitrile) (AIBN). [25] 3-sulfolene does not copolymerize with vinyl compounds, however. On the other hand, 2-sulfolene does not homopolymerize, but forms copolymers with vinyl compounds, e.g. acrylonitrile and vinyl acetate.

3-Sulfolene as a recyclable solvent

The reversibility of the interconversion of 3-sulfolene with buta-1,3-diene and sulfur dioxide suggests the use of sulfolene as a recyclable aprotic dipolar solvent, in replacement for dimethyl sulfoxide (DMSO), which is often used but difficult to separate and poorly reusable. [26] As a model reaction, the reaction of benzyl azide with 4-toluenesulfonic acid cyanide forming 1-benzyl-5-(4-toluenesulfonyl)tetrazole was investigated. The formation of the tetrazole can also be carried out as a one-pot reaction without the isolation of the benzyl azide with 72% overall yield.

Tetrazolbildung in 3-Sulfolen.svg

After the reaction, the solvent 3-sulfolene is decomposed at 135 °C and the volatile butadiene (b.p. −4.4 °C) and sulfur dioxide (b.p. −10.1 °C) are deposited in a cooling trap at −76 °C charged with excess sulfur dioxide. After the addition of hydroquinone as polymerization inhibition, 3-sulfoles is formed again quantitatively upon heating to room temperature. It appears questionable though, if 3-sulfolene with a useful liquid phase range of only 64 to a maximum of about 100 °C can be used as DMSO substitutes (easy handling, low cost, environmental compatibility) in industrial practice.

Uses

Aside from its synthetic versatility (see above), sulfolene is used as an additive in electrochemical fluorination. It can increase the yield of perfluorooctanesulfonyl fluoride by about 70%. [27] It is "highly soluble in anhydrous HF and increases the conductivity of the electrolyte solution". [27] In this application, it undergoes a ring opening and is fluorinated to form perfluorobutanesulfonyl fluoride.

Further reading

Related Research Articles

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In organic chemistry, a diene ; also diolefin, dy-OH-lə-fin) or alkadiene) is a covalent compound that contains two double bonds, usually among carbon atoms. They thus contain two alkene units, with the standard prefix di of systematic nomenclature. As a subunit of more complex molecules, dienes occur in naturally occurring and synthetic chemicals and are used in organic synthesis. Conjugated dienes are widely used as monomers in the polymer industry. Polyunsaturated fats are of interest to nutrition.

<span class="mw-page-title-main">Diels–Alder reaction</span> Chemical reaction

In organic chemistry, the Diels–Alder reaction is a chemical reaction between a conjugated diene and a substituted alkene, commonly termed the dienophile, to form a substituted cyclohexene derivative. It is the prototypical example of a pericyclic reaction with a concerted mechanism. More specifically, it is classified as a thermally allowed [4+2] cycloaddition with Woodward–Hoffmann symbol [π4s + π2s]. It was first described by Otto Diels and Kurt Alder in 1928. For the discovery of this reaction, they were awarded the Nobel Prize in Chemistry in 1950. Through the simultaneous construction of two new carbon–carbon bonds, the Diels–Alder reaction provides a reliable way to form six-membered rings with good control over the regio- and stereochemical outcomes. Consequently, it has served as a powerful and widely applied tool for the introduction of chemical complexity in the synthesis of natural products and new materials. The underlying concept has also been applied to π-systems involving heteroatoms, such as carbonyls and imines, which furnish the corresponding heterocycles; this variant is known as the hetero-Diels–Alder reaction. The reaction has also been generalized to other ring sizes, although none of these generalizations have matched the formation of six-membered rings in terms of scope or versatility. Because of the negative values of ΔH° and ΔS° for a typical Diels–Alder reaction, the microscopic reverse of a Diels–Alder reaction becomes favorable at high temperatures, although this is of synthetic importance for only a limited range of Diels–Alder adducts, generally with some special structural features; this reverse reaction is known as the retro-Diels–Alder reaction.

<span class="mw-page-title-main">Butadiene</span> Chemical compound

1,3-Butadiene is the organic compound with the formula CH2=CH-CH=CH2. It is a colorless gas that is easily condensed to a liquid. It is important industrially as a precursor to synthetic rubber. The molecule can be viewed as the union of two vinyl groups. It is the simplest conjugated diene.

In organic chemistry, an electrocyclic reaction is a type of pericyclic, rearrangement reaction where the net result is one pi bond being converted into one sigma bond or vice versa. These reactions are usually categorized by the following criteria:

<span class="mw-page-title-main">Michael addition reaction</span> Reaction in organic chemistry

In organic chemistry, the Michael reaction or Michael 1,4 addition is a reaction between a Michael donor and a Michael acceptor to produce a Michael adduct by creating a carbon-carbon bond at the acceptor's β-carbon. It belongs to the larger class of conjugate additions and is widely used for the mild formation of carbon-carbon bonds.

<span class="mw-page-title-main">Cheletropic reaction</span> Chemical reaction in which a ring is formed/broken by adding/removing a single atom

In organic chemistry, cheletropic reactions, also known as chelotropic reactions, are a type of pericyclic reaction. Specifically, cheletropic reactions are a subclass of cycloadditions. The key distinguishing feature of cheletropic reactions is that on one of the reagents, both new bonds are being made to the same atom.

<span class="mw-page-title-main">Sulfone</span> Organosulfur compound of the form >S(=O)2

In organic chemistry, a sulfone is a organosulfur compound containing a sulfonyl functional group attached to two carbon atoms. The central hexavalent sulfur atom is double-bonded to each of two oxygen atoms and has a single bond to each of two carbon atoms, usually in two separate hydrocarbon substituents.

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<span class="mw-page-title-main">1,4-Dioxin</span> Chemical compound

1,4-Dioxin (also referred as dioxin or p-dioxin) is a heterocyclic, organic, non-aromatic compound with the chemical formula C4H4O2. There is an isomeric form of 1,4-dioxin, 1,2-dioxin (or o-dioxin). 1,2-Dioxin is very unstable due to its peroxide-like characteristics.

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<span class="mw-page-title-main">Xylylene</span>

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References

  1. ↑ Sulfolene at Sigma-Aldrich
  2. ↑ "3-Sulfolene". pubchem.ncbi.nlm.nih.gov.
  3. 1 2 J. M. McIntosh (2001). "3-Sulfolene". E-EROS Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rs130. ISBN   0471936235.
  4. 1 2 3 Sample, Thomas E.; Hatch, Lewis F. (Jan 1968). "3-Sulfolene: A Butadiene Source for a Diels-Alder Synthesis". Journal of Chemical Education. 45 (1): 55. doi:10.1021/ed045p55.
  5. ↑ Houben-Weyl (1955). Volume IX: Sulfur, Selenium, Tellurium Compounds. Methods of Organic Chemistry (4th ed.). Stuttgart: Georg Thieme Verlag. p. 237. ISBN   978-3-13-208104-8.
  6. ↑ Robert L. Frank, Raymond P. Seven (1949). "Isoprene Cyclic Sulfone". Organic Syntheses. 29: 59. doi:10.15227/orgsyn.029.0059.
  7. 1 2 DE 506839,H. Staudinger,"Verfahren zur Darstellung von monomolekularen Reaktionsprodukten von ungesättigten Kohlenwasserstoffen der Butadienreihe mit Schwefeldioxyd",published 1930-8-28, assigned to H. Staudinger
  8. 1 2 H. Staudinger; B. Ritzenthaler (1935). "Über hochmolekulare Verbindungen, 104. Mitteil.: Über die Anlagerung von Schwefeldioxyd an Äthylen-Derivate". Chemische Berichte (in German). 68 (3): 455–471. doi:10.1002/cber.19350680317.
  9. ↑ J. Leonard; A. B. Hague; J. A. Knight (1998). "6. Preparation of substituted 3-sulfolenes and their use as precursors for Diels-Alder dienes". Organosulfur Chemistry. Vol. 2 (4th ed.). San Diego: Academic Press, Inc. p. 241. ISBN   0-12-543562-2.
  10. 1 2 US 4187231,R. L. Cobb,"Cyanide-catalyzed isomerization and deuterium exchange with alpha- and beta-sulfolenes",published 1980-02-05, assigned to Phillips Petroleum Co.
  11. ↑ C. D. Broaddus (1968). "Equilibria and base-catalyzed exchange of substituted olefins". Accounts of Chemical Research . 1 (8): 231–238. doi:10.1021/ar50008a002.
  12. 1 2 W. J. Bailey; E. W. Cummins (1954). "Cyclic dienes. III. The synthesis of thiophene-1,1-dioxide". Journal of the American Chemical Society . 76 (7): 1932–1936. doi:10.1021/ja01636a058.
  13. ↑ US 4286099,M. E. Nash, E. E. Huxley,"Sulfolene hydrogenation",published 1981-08-25, assigned to Phillips Petroleum Co.
  14. ↑ D. M. Lemal; G. D. Goldman (1988). "Synthesis of azulene, a blue hydrocarbon". Journal of Chemical Education . 65 (10): 923. Bibcode:1988JChEd..65..923L. doi:10.1021/ed065p923.
  15. ↑ T.-S. Chou; M.-M. Chen (1987). "Chemoselective reactions of ultrasonically dispersed potassium with some brominated hydrothiophene-S,S-dioxides". Heterocycles. 26 (11): 2829–2834. doi: 10.3987/R-1987-11-2829 .
  16. ↑ M. A. Filatov; S. Baluschev; I. Z. Ilieva; V. Enkelmann; T. Miteva; K. Landfester; S. E. Aleshchenkov; A. V. Cheprakov (2012). "Tetraaryltetraanthra[2,3]porphyrins: Synthesis, Structure, and Optical Properties". The Journal of Organic Chemistry. 77 (24): 11119–11131. doi:10.1021/jo302135q. PMID   23205621.
  17. ↑ "Diethyl trans-Δ4-tetrahydrophthalate". Organic Syntheses . 50. doi:10.15227/orgsyn.050.0043 .
  18. ↑ H. Hart, A. Bashir-Hashemi, J. Luo, M. A. Meador (1986). "Iptycenes: Extended Triptycenes". Tetrahedron. 42: 1641–1654. doi:10.1016/S0040-4020(01)87581-5.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  19. ↑ C.-T. Lin, T.-C. Chou (1988). "Synthesis of 2,3-dibromoanthracene". Synthesis. 1988 (8): 628–630. doi:10.1055/s-1988-27659. S2CID   93109532.
  20. ↑ L. F. Hatch, D. Peter (1968). "Reaction of benzyne with butadiene". Chemical Communications. 23 (23): 1499. doi:10.1039/C19680001499.
  21. ↑ M. P. Cava, J. P. VanMeter (1969). "Condensed cyclobutane aromatic compounds. XXX. Synthesis of some unusual 2,3-naphthoquinonoid heterocycles. A synthetic route to derivatives of naphtho[2,3-b]biphenylene and anthra[b]cyclobutene". The Journal of Organic Chemistry . 34 (3): 538–545. doi:10.1021/jo01255a012.
  22. ↑ K. Alder; H. F. Rickert; E. Windemuth (1938). "Zur Kenntnis der Dien-Synthese, X. Mitteil.: Über die Dien-Synthese mit α, β-ungesättigten Nitrokörpern, Sulfonen und Thio-Äthern". Chemische Berichte. 71 (12): 2451–2461. doi:10.1002/cber.19380711206.
  23. ↑ G. S. Andrade; et al. (2003). "The one-pot synthesis and Diels-Alder Reactivity of 2,5-dihydrothiophene-1,1-dioxide-3-carboxylic acid". Synthetic Communications . 33 (20): 3643–3650. doi:10.1081/SCC-120024845. S2CID   98504228.
  24. ↑ M. E. Brant; J. E. Wulff (2016). "3-Sulfolenes and their derivatives: Synthesis and applications". Synthesis . 48 (1): 1–17. doi:10.1055/s-0035-1560351. S2CID   196826278.
  25. ↑ E. J. Goethals (1967). "On the polymerization and copolymerization of sulfolenes". Macromolecular Chemistry and Physics. 109 (1): 132–142. doi:10.1002/macp.1967.021090113.
  26. ↑ Y. Huang; et al. (2015). "Butadiene sulfone as 'volatile', recyclable dipolar, aprotic solvent for conducting substitution and cycloaddition reactions". Sustainable Chemical Processes. 3 (13). doi: 10.1186/s40508-015-0040-7 .
  27. 1 2 Lehmler HJ (March 2005). "Synthesis of environmentally relevant fluorinated surfactants—a review". Chemosphere. 58 (11): 1471–96. Bibcode:2005Chmsp..58.1471L. doi:10.1016/j.chemosphere.2004.11.078. PMID   15694468.
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