Synthesis of palladium(II)-N-heterocyclic carbene via transmetaliation of silver(I) complex and its catalytic activity in epoxidation of alkene

A series of new silver(I)- and palladium(II)-N-heterocyclic carbene complexes of 1-benzyl-3-ethylbenzimidazolium iodide, 1-benzyl-3-(2’-nitrilebenzyl)benzimidazole bromide, 1-benzyl-3-(2’-methyl)propylbenzimidazolium bromide, 1-benzyl-(3’-methyl)butylbenzimidazolium bromide, 1-benzyl-3-hexylbenzimid...

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Main Author:	Rehman, Ghani Ur
Format:	Thesis
Language:	English
Published:	2014
Subjects:	QD Chemistry
Online Access:	http://eprints.utm.my/id/eprint/48856/25/GhaniUrRehmanMFS2014.pdf
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spelling	my-utm-ep.488562020-07-01T07:22:36Z Synthesis of palladium(II)-N-heterocyclic carbene via transmetaliation of silver(I) complex and its catalytic activity in epoxidation of alkene 2014-07 Rehman, Ghani Ur QD Chemistry A series of new silver(I)- and palladium(II)-N-heterocyclic carbene complexes of 1-benzyl-3-ethylbenzimidazolium iodide, 1-benzyl-3-(2’-nitrilebenzyl)benzimidazole bromide, 1-benzyl-3-(2’-methyl)propylbenzimidazolium bromide, 1-benzyl-(3’-methyl)butylbenzimidazolium bromide, 1-benzyl-3-hexylbenzimidazolium bromide were successfully synthesized. The respective N-heterocyclic carbene (NHC) precursors were prepared by the reaction of 1-benzylbenzimidazole with ethyl iodide, 2-bromomethylbenzonitrile, 2-methylpropylbromide, 3-methylbutyl bromide, and n-hexyl bromide in dioxane at C90? . Further, these halide salts were converted into their hexafluorophosphate counterparts by the salt metathesis reaction using KPF6 in methanol. Bis-NHC silver(I) complexes having hexafluorophosphate counterion were yielded (48.4-67.2%) by the reaction of NHC precursors with silver(I) oxide in acetonitrile/methanol at room temperature. Subsequent reactions of the silver(I) hexafluorophosphate complexes with [PdCl2(CNCH3)2] in dichloromethane/methanol afforded the bis-NHC palladium(II) complexes in good yield (48.3-76.4%) via carbene transfer method. All new complexes were fully characterized by various techniques such as CHN analysis, single crystal X-ray diffraction and spectroscopic methods such as FTIR and 1H and 13C NMR. Additionally, in case of silver(I) complex, the bis-[1-benzyl-3-(2’-nitrilebenzyl)benzimidazole] silver(I) hexafluorophosphate was characterized by single crystal X-ray diffraction technique. Preliminary catalytic studies show that the nitrile-functionalized palladium(II)-NHC complex is highly active in the oxidation of 1-octene as well as styrene in aqueous hydrogen peroxide as oxidizing agent at C70? . All the palladium(II) complexes oxidized both the aforementioned olefins efficiently to their corresponding oxidized products with 47 to 58% conversions. However, selectivity towards epoxy products was relatively low in the range of 7-10%. Major product in the oxidation of 1-octene was the 1,2-octanediol, while 2-octanone is the minor product. 2014-07 Thesis http://eprints.utm.my/id/eprint/48856/ http://eprints.utm.my/id/eprint/48856/25/GhaniUrRehmanMFS2014.pdf application/pdf en public http://dms.library.utm.my:8080/vital/access/manager/Repository/vital:85307 masters Universiti Teknologi Malaysia, Faculty of Science Faculty of Science
institution	Universiti Teknologi Malaysia
collection	UTM Institutional Repository
language	English
topic	QD Chemistry
spellingShingle	QD Chemistry Rehman, Ghani Ur Synthesis of palladium(II)-N-heterocyclic carbene via transmetaliation of silver(I) complex and its catalytic activity in epoxidation of alkene
description	A series of new silver(I)- and palladium(II)-N-heterocyclic carbene complexes of 1-benzyl-3-ethylbenzimidazolium iodide, 1-benzyl-3-(2’-nitrilebenzyl)benzimidazole bromide, 1-benzyl-3-(2’-methyl)propylbenzimidazolium bromide, 1-benzyl-(3’-methyl)butylbenzimidazolium bromide, 1-benzyl-3-hexylbenzimidazolium bromide were successfully synthesized. The respective N-heterocyclic carbene (NHC) precursors were prepared by the reaction of 1-benzylbenzimidazole with ethyl iodide, 2-bromomethylbenzonitrile, 2-methylpropylbromide, 3-methylbutyl bromide, and n-hexyl bromide in dioxane at C90? . Further, these halide salts were converted into their hexafluorophosphate counterparts by the salt metathesis reaction using KPF6 in methanol. Bis-NHC silver(I) complexes having hexafluorophosphate counterion were yielded (48.4-67.2%) by the reaction of NHC precursors with silver(I) oxide in acetonitrile/methanol at room temperature. Subsequent reactions of the silver(I) hexafluorophosphate complexes with [PdCl2(CNCH3)2] in dichloromethane/methanol afforded the bis-NHC palladium(II) complexes in good yield (48.3-76.4%) via carbene transfer method. All new complexes were fully characterized by various techniques such as CHN analysis, single crystal X-ray diffraction and spectroscopic methods such as FTIR and 1H and 13C NMR. Additionally, in case of silver(I) complex, the bis-[1-benzyl-3-(2’-nitrilebenzyl)benzimidazole] silver(I) hexafluorophosphate was characterized by single crystal X-ray diffraction technique. Preliminary catalytic studies show that the nitrile-functionalized palladium(II)-NHC complex is highly active in the oxidation of 1-octene as well as styrene in aqueous hydrogen peroxide as oxidizing agent at C70? . All the palladium(II) complexes oxidized both the aforementioned olefins efficiently to their corresponding oxidized products with 47 to 58% conversions. However, selectivity towards epoxy products was relatively low in the range of 7-10%. Major product in the oxidation of 1-octene was the 1,2-octanediol, while 2-octanone is the minor product.
format	Thesis
qualification_level	Master's degree
author	Rehman, Ghani Ur
author_facet	Rehman, Ghani Ur
author_sort	Rehman, Ghani Ur
title	Synthesis of palladium(II)-N-heterocyclic carbene via transmetaliation of silver(I) complex and its catalytic activity in epoxidation of alkene
title_short	Synthesis of palladium(II)-N-heterocyclic carbene via transmetaliation of silver(I) complex and its catalytic activity in epoxidation of alkene
title_full	Synthesis of palladium(II)-N-heterocyclic carbene via transmetaliation of silver(I) complex and its catalytic activity in epoxidation of alkene
title_fullStr	Synthesis of palladium(II)-N-heterocyclic carbene via transmetaliation of silver(I) complex and its catalytic activity in epoxidation of alkene
title_full_unstemmed	Synthesis of palladium(II)-N-heterocyclic carbene via transmetaliation of silver(I) complex and its catalytic activity in epoxidation of alkene
title_sort	synthesis of palladium(ii)-n-heterocyclic carbene via transmetaliation of silver(i) complex and its catalytic activity in epoxidation of alkene
granting_institution	Universiti Teknologi Malaysia, Faculty of Science
granting_department	Faculty of Science
publishDate	2014
url	http://eprints.utm.my/id/eprint/48856/25/GhaniUrRehmanMFS2014.pdf
_version_	1747817488435904512

Synthesis of palladium(II)-N-heterocyclic carbene via transmetaliation of silver(I) complex and its catalytic activity in epoxidation of alkene

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