NHC-Based Mo and W Complexes as Epoxidation Catalysts
227
0
0
0
1
,1 -dibenzyl-3,3 -methylenediimidazoline-2,2 -diylidene
FCT for REDE/1517/RMN/2005. We thank MC Almeida for pro-
viding data from the Elemental Analysis Services at ITQB.
(
0.49 g, 0.85 mmol), prepared in situ by deprotonation of
t
the corresponding imidazolium salt with KOBu . The
reaction mixture was stirred for 6 h, after which the solvent
was evaporated in vacuum, and the product was recrys-
tallized from a dichloromethane/hexane mixture. The title
compound 4 was isolated as a red crystalline solid. Yield:
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.26 g, 47%. Anal. Calcd for C H N O WCl (644): C,
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Selected IR data (KBr, cm ): m(CO) 1915, 1806. H NMR
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(
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.3 Catalytic Reactions
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.3.1 Epoxidation of cis-Cyclooctene with H O2
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typical experiment, 0.14 mL (1.109 mmol) of olefin,
1
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mesitylene as internal standard were added to initiate the
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(
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.3.2 Epoxidation of cis-Cyclooctene with TBHP
2
2
2
4
The catalytic reactions were carried out under an open
atmosphere in a flask equipped with a magnetic stirrer. In a
typical experiment, 0.14 mL (1.109 mmol) of olefin,
(
6
1
0
mol% catalyst (0.011 mmol) in 2 mL of chloroform,
.66 mL of TBHP (6 M solution in decane, 3.32 mmol, 3
2
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equiv) and 0.2 mL mesitylene as internal standard were
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to 55 °C for a specific time. Samples were taken periodi-
cally and analyzed by a GC. The conversion of olefin and
the selectivity to the corresponding epoxide were calculated
using calibration curves recorded prior to the reaction.
2
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3
Acknowledgements This work was supported by FCT, POCI 2010
and FEDER through project PTDC/QUI/64458/2006. VVKM Kand-
epi and JMS Cardoso thank FCT for a postdoctoral grant (SFRH/
BPD/26944/2006) and a researcher grant, respectively. We also thank
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Appl Catal A: Gen 368:139
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123