Iodination of Organic Compounds with Elemental Iodine in the Presence of Hydrogen Peroxide in Ionic Liquid Media

Jasminka Pavlinac; Kenneth K. Laali; Marko Zupan; Stojan Stavber

doi:10.1071/CH08276

RESEARCH ARTICLE

Previous Next Contents Vol 61(12)

Iodination of Organic Compounds with Elemental Iodine in the Presence of Hydrogen Peroxide in Ionic Liquid Media

Jasminka Pavlinac ^A , Kenneth K. Laali ^B ^D , Marko Zupan ^A ^C and Stojan Stavber ^A ^D

+ Author Affiliations

- Author Affiliations

^A Department of Physical and Organic Chemistry, ‘Jožef Stefan’ Institute, Jamova 39, 1000 Ljubljana, Slovenia.

^B Department of Chemistry, Kent State University, Kent, OH 44242, USA.

^C Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, 1000 Ljubljana, Slovenia.

^D Corresponding authors. Email: stojan.stavber@ijs.si; klaali@kent.edu

Australian Journal of Chemistry 61(12) 946-955 https://doi.org/10.1071/CH08276
Submitted: 30 June 2008 Accepted: Accepted without change Published: 10 December 2008

Abstract

Iodo-transformations using the reagent system I₂/H₂O₂ were studied in the water miscible ionic liquid (IL) 1-butyl-3-methyl imidazolium tetrafluoroborate (bmimBF₄) and in water immiscible IL, 1-butyl-3-methyl imidazolium hexafluorophosphate (bmimPF₆). Two different forms of H₂O₂ as mediators of iodination were investigated, namely 30% aq. H₂O₂ and urea-H₂O₂ (UHP) in solid form. The role of the oxidant during the course of a reaction could be distinguished based on the amount of reagent required for the most efficient transformation. Two types of iodo-functionalizations through an electrophilic process were observed depending on the structure of the substrates. Whereas ring iodination took place in the case of dimethoxy- and trimethoxy-benzenes, with arylalkyl ketones the alkyl group α to the carbonyl was regioselectively iodinated. The results were further evaluated in comparison with iodination using the reagent system I₂/H₂O₂ in water as medium, and under solvent-free reaction conditions, in terms of efficiency, selectivity, mechanism, and the ‘green’ aspects. The reusability/recycling of water immiscible bmimPF₆ was investigated for 1,3,5-trimethoxy benzene (1b), which required a 1/0.5/0.6 molar ratio of substrat/I₂/oxidant, and for 1,2,3-trimethoxy benzene (1f), which required a 1/1/1 ratio for complete iodine introduction. In addition, the efficiency of iodination was tested by varying the substrates, and employing the recycled hydrophobic IL bmimPF₆.

Acknowledgments

The authors thank the ‘Slovene Human Resources Development and Scholarship Fund–Ad Futura’, whose grant enabled the Ph.D. candidate Jasminka Pavlinac to spend a 3-month research visit in Professor Laali’s laboratory at the Department of Chemistry, Kent State University, Kent, OH, USA, and to the Slovenian Research Agency for financial support. The assistance of Dr Takao Okazaki (senior associate in Professor Laali’s laboratory) is also greatly appreciated.

References

Iodination of Organic Compounds with Elemental Iodine in the Presence of Hydrogen Peroxide in Ionic Liquid Media

Abstract

Acknowledgments

Subscriber Login