Organopalladiumyhdisteet Ominaisuudet ja valmistus | Lähteet | NavigointivalikkoKirja Googlen teoshaussa

OrganometalliyhdisteetPalladiumyhdisteet


organometalliyhdisteitäkovalenttinen sidospalladiuminhiilenkatalyytteinähapetusluvuillapelkistävä eliminaatio2,2′-bipyridiinitransmetallaatioreaktioillaGrignard-reagensseistaalkeeneihindieeneihinelektrofiilisenHeck-reaktioissaWacker-prosessissaaldehydeiksi







Syklopentadienyyliallyylipalladium on esimerkki organopalladiumyhdisteestä


Organopalladiumyhdisteet ovat organometalliyhdisteitä, joissa on kovalenttinen sidos palladiumin ja hiilen välillä. Organopalladiumyhdisteet ovat tärkeitä katalyytteinä ja niitä esiintyy välivaiheina useissa orgaanisen kemian reaktioissa.



Ominaisuudet ja valmistus |


Palladium esiintyy organometalliyhdisteissään hapetusluvuilla 0, +II tai +IV. Näistä tyypillisin on +II. Yksinkertaiset alkyyli- tai aryylipalladiumyhdisteet ovat suhteellisen epästabiileja ja reaktiivisia. Erityisesti palladiumin ollessa hapetusluvulla +IV on sen organometalliyhdisteille tyypillinen reaktio pelkistävä eliminaatio. Nämä yhdisteet ovat hieman stabiilimpia silloin kuin niiden lisäksi ligandina yhdisteessä on myös jokin kelatoiva ligandi esimerkiksi 2,2′-bipyridiini. Alkyyli- tai aryylipalladiumyhdisteitä voidaan valmistaa transmetallaatioreaktioilla esimerkiksi Grignard-reagensseista, palladiumkompleksien ja organohalogeenien välisillä reaktioilla ja nukleofiilien reagoidessa alkeenien ja palladiumin muodostamiin yhdisteisiin.[1][2][3][4]


Organometalliyhdisteet, joissa palladium on sitoutuneena alkeeneihin tai dieeneihin ovat alkyylipalladiumyhdisteitä stabiilimpia ja niitä tunnetaan useita. Näissä yhdisteissä palladium on hapetusluvulla +II. Palladiumin ja alkeenien muodostamat organometalliyhdisteet ovat hyvin yleisiä katalyyttejä ja välituotteita orgaanisen kemian synteeseissä. Alkeenin koordinoituminen palladiumiin tekee siitä poikkeuksellisen elektrofiilisen ja nämä yhdisteet reagoivat nukleofiilien kanssa ja ne voidaan esimerkiksi alkyloida. Näitä yhdisteitä esiintyy muun muassa välituotteina Heck-reaktioissa. Ne voidaan myös hapettaa suhteellisen helposti. Esimerkiksi Wacker-prosessissa alkenyylipalladiumyhdisteet hapetetaan aldehydeiksi.[1][2][3][4]



Lähteet |



  1. ↑ ab Christen M. Giandomenico: Platinum-Group Metals, Compounds, Kirk-Othmer Encyclopedia of Chemical Technology, John Wiley & Sons, New York, 2000. Viitattu 19.7.2017.


  2. ↑ ab N. N. Greenwood & A. Earnshaw: Chemistry of the Elements, s. 1167-1172. 2nd Edition. Butterworth Heinemann, 1997. ISBN 0-7506-3365-4. (englanniksi)


  3. ↑ ab Manfred Schlosser: Organometallics in Synthesis, s. 1125-1208. John Wiley & Sons, 2002. ISBN 0-471-98416-7. (englanniksi)


  4. ↑ ab Jiro Tsuji: Palladium Reagents and Catalysts, s. 1-24. John Wiley & Sons, 2004. ISBN 978-0-470-02119-4. Kirja Googlen teoshaussa (viitattu 19.7.2017). (englanniksi)







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