Grubbsin katalyytti

Ensimmäisen sukupolven Grubbsin katalyytti

Grubbsin katalyytit ovat ruteniumin ja karbeenien komplekseja, jotka katalysoivat alkeenien metateesiä. Grubbsin katalyytit ovat nykyisin käytetyimpiä kaupallisia siirtymämetallikatalyyttejä ja niiden kehitys toi Robert H. Grubbsille Nobelin kemianpalkinnon vuonna 2005.[1][2][3][4][5]

Grubbsin katalyyttien historiaa

Grubbsin katalyytit sisältävät keskusatominaan ruteniumin, bentsylideenikarbeenin ja labiileja, korvattavissa olevia ligandeja. Ensimmäinen Robert Grubbsin vuonna 1992 kehittämä ruteenikatalyytti oli bentsylideenibis(trifenyylifosfiini)diklororutenium. Tämä kompleksi ei kuitenkaan ole katalyyttisesti erityisen aktiivinen ja katalysoi ainoastaan erittäin jännittyneiden alkeenien kuten norborneenin metateesia. Vuonna 1995 Grubbs julkaisi niin kutsutun ensimmäisen sukupolven Grubbsin katalyytin, jossa ligandeina olivat trifenyylifosfiinien tilalla trisykloheksyylifosfiinit. Emäksisemmän trisykloheksyylifosfiiniligandit tekivät katalyytistä aktiivisemman. Ensimmäisen sukupolven Grubbsin katalyytti on ulkomuodoltaan violettia kitestä ainetta. Useista muista siirtymämetallikatalyyteistä poiketen tämä katalyytti on stabiili ilman vaikutuksille useiden kuukausien ajan. Parannuksena aikaisempiin alkeenien metateesin katalyytteihin on myös se, että Grubbsin katalyyttiä käytettäessä alkeenissa voi olla myös muita reaktiivisia ryhmiä kuten amino- tai hydroksyyliryhmiä. Ensimmäisen sukupolven Grubbsin katalyyttiä valmistetaan diklorotris(trifenyylifosfiini)rutenium(II)-kompleksista ja fenyylidiatsometaanista. Yhdiste reagoi trisykloheksyylifosfiinin kanssa ligandinvaihtoreaktiolla muodostaen Grubbsin katalyyttiä.[1][2][3][4][5][6]

Vuonna 1999 Grubbs ryhminen esitteli niin kutsutun toisen sukupolven Grubbsin katalyytin, jossa karbeeniosana on hyvin stabiili typpiheterosyklinen karbeeni. Käytetyimpiä ovat Grubbsin katalyytit, joissa karbeeniosa on 1,3-bis(2,4,6-trimetyylifenyyli)-4,5-dihydroimidatsol-2-ylideeni. Nämä toisen sukupolven katalyytti ovat ensimmäisen sukupolven Grubbsin katalyyttejä aktiivisempia.[1][2][3][4][5][6]

Hoveyda–Grubbs-katalyytit

Ensimmäisen sukupolven Hoveyda–Grubbs-katalyytti
Toisen sukupolven Hoveyda–Grubbs-katalyytti

Hoveyda–Grubbs-katalyyteissä bentsylideenikarbeeniosassa on mukana kelatoiva isopropoksyyliryhmä. Ensimmäisen sukupolven tämänkaltaisen katalyytin julkaisi Amir H. Hoveyda ryhmineen vuonna 1997. Tunnetaan myös toisen sukupolven Hoveyda–Grubbs-katalyyttejä, jotka muistuttavat toisen sukupolven Grubbsin katalyyttejä.[1][2][3][5]

Lähteet

  1. ↑ a b c d Jonathan Clayden, Nick Greeves, Stuart Warren: Organic Chemistry, s. 1023–1025. Oxford University Press, 2012. ISBN 978-0-19-927029-3 (englanniksi)
  2. ↑ a b c d Lionel Delaude & Alfred F. Noels:Metathesis, Kirk-Othmer Encyclopedia of Chemical Technology, John Wiley & Sons, New York, 2005. Viitattu 20.9.2016
  3. ↑ a b c d Arno Behr: Catalysis, Homogeneous, Ullmann's Encyclopedia of Industrial Chemistry, John Wiley & Sons, New York, 2010. Viitattu 20.9.2016
  4. ↑ a b c Christoph Elsenbroich: Organometallics, s. 684. Wiley-VCH, 2006. ISBN 978-3-527-29390-2 (englanniksi)
  5. ↑ a b c d John Hartwig: Organotransition Metal Chemistry, s. 1017–1020. University Science Books, 2010. ISBN 978-1-891389-53-5 (englanniksi)
  6. ↑ a b Didier Astruc: Organometallic Chemistry and Catalysis, s. 205. Springer, 2007. ISBN 978-3-540-46128-9 Kirja Googlen teoshaussa Viitattu 20.9.2016. (englanniksi)

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