Zhenzhong Hu , Fran M. Kerton*
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Zhenzhong Hu <[email protected]>, Fran M. Kerton*<[email protected]> Department of Chemistry, Memorial University of Newfoundland, St. John’s, NL, Canada, A1B 3X7 Efficient aerobic oxidation of alcohols using CuBr Efficient aerobic oxidation of alcohols using CuBr 2 2 and and a a series of series of α- α- pyridyl-imine terminated pyridyl-imine terminated polydimethylsiloxane ligands polydimethylsiloxane ligands Introduction Introduction From the point of view of Green Chemistry, polymer-based catalysts are very environmentally friendly. These catalysts can be used and recycled in green solvents such as liquid polymers and supercritical carbon dioxide. They can also be very selective. In our recent studies, a series of α- pyridyl-imine terminated polydimethylsiloxane ligands have been synthesized and characterized. It is interesting that these carbon dioxide miscible ligands form metallocyclic complexes when coordinated with copper(I) salt. Meanwhile, they provide perfect binding sites for copper (II) ions which then work as catalysts for more efficient aerobic oxidations of primary and secondary alcohols. Cloud point data for L1 ( ) and [Cu(L2)](PF 6 ) (▲) in carbon dioxide. L2 is miscible in liquid CO 2 . [Cu(L1)] (PF 6 ) is insoluble at Ts and Ps studied. [C u(C H 3 CN) 4 ](PF 6 ) + L [C u( L)](PF 6 ) Aerobic oxidation of selected Aerobic oxidation of selected alcohols with in situ made alcohols with in situ made TEMPO/[Cu]/L1 system TEMPO/[Cu]/L1 system 5 m ol% CuBr 2 ,2.5 m ol% L1 5 m ol% TEM PO ,5 m ol% t -BuO K CH 3 CN /H 2 O (2:1),air,25 º C R 1 R 2 OH R 1 R 2 O [a] GC conversion, selectivity > 99%; [b] Reaction temperature = 45 o C, using compressed air; [c] Reaction time = 48 h Summary Summary • α- Pyridyl-imine terminated PDMS compounds have been prepared and characterised. • Coordination chemistry with Cu(I) shows the formation of [1+1] metallocycles. • The TEMPO/[CuBr 2 ]/L1 catalytic system is very effective for the aerobic oxidation of alcohols. • Future studies will involve the study of catalytic reaction mechanism and the recycling of the catalyst. • Attempts will also be made to obtain Acknowledgements; Acknowledgements; Prof. Christopher M. Kozak; Green Chemistry and Catalysis Group; Dr. Celine Schneider ; C-CART (Brent, Linda & Julie); Chemistry Department, Memorial University Coordination Chemistry Coordination Chemistry • L2 titrated with Cu(I) reagent (L1 behaves similarly) • MLCT band max. intensity reached at a ratio C M /C P = 1 • Metallocyclopolymer is characterised by NMR, FT-IR, GPC, CHN, MALDI-TOF MS Ligand Ligand Synthesis Synthesis Solubility in Supercritical CO Solubility in Supercritical CO 2 2
description
Cloud point data for L1 ( ) and [Cu( L2 )](PF 6 ) (▲) in carbon dioxide. L2 is miscible in liquid CO 2 . [Cu( L1 )](PF 6 ) is insoluble at Ts and Ps studied. L2 titrated with Cu(I) reagent (L1 behaves similarly) MLCT band max. intensity reached at a ratio C M /C P = 1 - PowerPoint PPT Presentation
Transcript of Zhenzhong Hu , Fran M. Kerton*
Zhenzhong Hu<[email protected]>, Fran M. Kerton*<[email protected]> Department of Chemistry, Memorial University of Newfoundland,
St. John’s, NL, Canada, A1B 3X7
Efficient aerobic oxidation of alcohols using CuBrEfficient aerobic oxidation of alcohols using CuBr22 and and a a series of series of α-α- pyridyl-imine terminated pyridyl-imine terminated
polydimethylsiloxane ligandspolydimethylsiloxane ligands
IntroductionIntroductionFrom the point of view of Green Chemistry, polymer-
based catalysts are very environmentally friendly. These
catalysts can be used and recycled in green solvents
such as liquid polymers and supercritical carbon dioxide.
They can also be very selective.
In our recent studies, a series of α- pyridyl-imine
terminated polydimethylsiloxane ligands have been
synthesized and characterized. It is interesting that these
carbon dioxide miscible ligands form metallocyclic
complexes when coordinated with copper(I) salt.
Meanwhile, they provide perfect binding sites for copper
(II) ions which then work as catalysts for more efficient
aerobic oxidations of primary and secondary alcohols.
Cloud point data for L1 ( ) and [Cu(L2)](PF6) (▲) in carbon dioxide. L2 is miscible in liquid CO2. [Cu(L1)](PF6) is insoluble at Ts and Ps studied.
[Cu(CH3CN)4](PF6) + L [Cu(L)](PF6)
Aerobic oxidation of selected alcohols with Aerobic oxidation of selected alcohols with in situ made TEMPO/[Cu]/L1 systemin situ made TEMPO/[Cu]/L1 system
5 mol% CuBr2, 2.5 mol% L15 mol% TEMPO, 5 mol% t-BuOK
CH3CN/H2O (2:1), air, 25 ºCR1 R2
OH
R1 R2
O
[a] GC conversion, selectivity > 99%; [b] Reaction temperature = 45 oC, using compressed air; [c] Reaction time = 48 h
SummarySummary• α-Pyridyl-imine terminated PDMS compounds have
been prepared and characterised.• Coordination chemistry with Cu(I) shows the formation
of [1+1] metallocycles.
• The TEMPO/[CuBr2]/L1 catalytic system is very
effective for the aerobic oxidation of alcohols.• Future studies will involve the study of catalytic
reaction mechanism and the recycling of the catalyst.• Attempts will also be made to obtain further evidence
for the structures of these metallocyclic polymers.
Acknowledgements; Acknowledgements; Prof. Christopher M. Kozak; Green Chemistry and Catalysis Group; Dr. Celine Schneider ; C-CART (Brent, Linda & Julie); Chemistry Department, Memorial University
Coordination ChemistryCoordination Chemistry
• L2 titrated with Cu(I) reagent (L1 behaves similarly)
• MLCT band max. intensity reached at a ratio CM/CP= 1
• Metallocyclopolymer is characterised by NMR, FT-IR, GPC, CHN, MALDI-TOF MS
LigandLigandSynthesisSynthesis
Solubility in Supercritical COSolubility in Supercritical CO22
![ContentsTensor Standard-Form FullForm p m p m LTensor[p, m] g m g m LTensor[DiracG, m] g mn g m,n LTensor[MetricG, m, n] mnr„ ¶ m,n,r,„ LTensor[LeviCivitaE,m,n,r,„] Table 1:](https://static.fdocument.org/doc/165x107/60037b10ad260b1621260c6c/contents-tensor-standard-form-fullform-p-m-p-m-ltensorp-m-g-m-g-m-ltensordiracg.jpg)
