Furano: Diferenzas entre revisións

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=== Síntese de furanos ===
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The [[Feist–Benary synthesis]] is a classic way to synthesize furans, although many syntheses have been developed.<ref>{{cite journal| author = Hou XL, Cheung HY, Hon TY, Kwan PL, Lo TH, Tong SY, Wong HNC| year = 1998 | volume = 54 | pages = 1955–2020 | title = Regioselective syntheses of substituted furans | doi = 10.1016/S0040-4020(97)10303-9 | journal = [[Tetrahedron (journal)|Tetrahedron]]| issue = 10}}</ref> One of the simplest synthesis methods for furans is the reaction of [[ketone|1,4-diketone]]s with [[phosphorus pentoxide]] (P<sub>2</sub>O<sub>5</sub>) in the [[Paal–Knorr synthesis]]. The [[thiophene]] formation reaction of 1,4-diketones with [[Lawesson's reagent]] also forms furans as side products. Many routes exist for the synthesis of substituted furans.<ref>{{cite journal | doi = 10.3998/ark.5550190.0005.208 | title = Synthesis of 2,4-disubstituted furans and 4,6-diaryl-substituted 2,3-benzo-1,3a,6a-triazapentalenes | year = 2003 | last1 = Katritzky | first1 = Alan R. | journal = Arkivoc | volume = 2004 | issue = 2 | pages = 109}}</ref>
 
TheA [[síntese de Feist–Benary synthesis]] isé aunha classicmaneira wayclásica tode synthesizesintetizar furansfuranos, althoughaínda manyque synthesesse havedesenvolveron beenmoitas developedsínteses.<ref>{{cite journal| author = Hou XL, Cheung HY, Hon TY, Kwan PL, Lo TH, Tong SY, Wong HNC| year = 1998 | volume = 54 | pages = 1955–2020 | title = Regioselective syntheses of substituted furans | doi = 10.1016/S0040-4020(97)10303-9 | journal = [[Tetrahedron (journal)|Tetrahedron]]| issue = 10}}</ref> OneUn ofdos themétodos simplestde synthesissíntese methodsmáis forsimples furansde isfuranos theé reactiona ofreacción de [[ketonecetona|1,4-diketonedicetona]]s withcon [[phosphoruspentóxido de pentoxidefósforo]] (P<sub>2</sub>O<sub>5</sub>) in thena [[Paal–Knorrsíntese synthesisde Paal–Knorr]]. TheA reacción de formación de [[thiophenetiofeno]] formation reaction ofde 1,4-diketonesdicetonas withcon [[reactivo de Lawesson's reagent]] alsotamén formsforma furans asfuranos sidecomo productssubprodutos. ManyExisten routesmoitas existrutas forpara thea synthesissíntese ofde substitutedfuranos furanssubstituídos.<ref>{{cite journal | doi = 10.3998/ark.5550190.0005.208 | title = Synthesis of 2,4-disubstituted furans and 4,6-diaryl-substituted 2,3-benzo-1,3a,6a-triazapentalenes | year = 2003 | last1 = Katritzky | first1 = Alan R. | journal = Arkivoc | volume = 2004 | issue = 2 | pages = 109}}</ref>
==Chemistry==
 
== Química ==
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Furan is [[aromatic]] because one of the [[lone pair]]s of [[electron]]s on the oxygen atom is [[delocalized electron|delocalized]] into the ring, creating a 4''n''+2 aromatic system (see [[Hückel's rule]]) similar to [[benzene]]. Because of the aromaticity, the molecule is flat and lacks discrete [[double bond]]s. The other lone pair of electrons of the oxygen atom extends in the plane of the flat ring system. The [[Orbital hybridisation|sp<sup>2</sup> hybridization]] is to allow one of the lone pairs of oxygen to reside in a [[p orbital]] and thus allow it to interact within the [[Conjugated system|π system]].