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14 results on '"Gudimetla, Vittal B."'

3. Imidazolium-Based N-Heterocyclic Carbenes (NHCs) and Metal-Mediated Catalysis

Author

Gudimetla, Vittal B., Joy, Bony P., and Paul, Sudeep

Subjects
Science / Chemistry
Abstract

The journey of “carbenes” is more than a century old. It began with a curiosity to understand a then less familiar carbon moiety in its divalent state. It reached an important milestone in the form of 1,3-imidazolium-based N-heterocyclic carbenes (NHCs), where the quest for bottleable carbenes was achieved through simple and elegant synthetic routes. The properties of these carbenes were finely tunable through the steric and electronic factors via chemical modifications. Thus, it became one of the unique and extensively studied ligands for its properties and applications. This chapter first briefs about structural details of NHCs and different synthetic routes for the preparation of imidazolium-based NHC precursors. The later section focuses on various methods for characterizing the steric and electronic properties of these ligands and their metal intermediates, which are crucial for developing efficient catalytic processes. Finally, the chapter concludes with NHC-metal-mediated catalytic applications and its immediate challenges.

Published
2020

4. Photochemical E-Z isomerization of meta-terphenyl-protected phosphoalkenes and structural characterizations

Author

Gudimetla, Vittal B., Protasiewicz, John D., Rheingold, Arnold L., Payton, John L., Peng, Huo-Lei, and Simpson, M. Cather

Subjects
Isomerization -- Research, Alkanes -- Electric properties, Nuclear magnetic resonance spectroscopy -- Research, Chemistry
Abstract

A series of phosphoalkenes, E-ArP=C(H)Ar' are prepared by phospha-Wittig reactions and characterized. NMR spectroscopy reveals that exposure of these materials either to room light over an extended period of time (days) or to UV light (hours) produces equilibrium mixtures of the E and Z isomers.

Published
2006

7. Cost Efficient Synthesis of Diaryl Ethers Catalysed by CuI, Imidazolium Chloride and Cs2CO3.

Author

Paul, Sudeep, Joy, Bony P., Rajendran, Rajarajan, and Gudimetla, Vittal B.

Subjects
ETHER synthesis, ARYL chlorides, CHLORIDES, CESIUM iodide, ETHERS, CATALYSIS
Abstract

Synthetically versatile imidazolium chlorides, especially 1,3‐bis‐(2,6‐diisopropylphenyl)‐imidazolium chloride (IPrHCl) along with copper (I) iodide and cesium carbonate, were found to be useful to form C−O bonds via coupling of phenols and aryl/heteroaryl bromides. In this catalysis, the metal:ligand (Cu:IPr) loading was optimised to 1.0 mol%, making it an inexpensive and a simple one pot catalytic route for synthesising a variety of diaryl ethers. The catalytic cycle was probed by UV‐Vis, FT‐IR and HRMS techniques confirming involvement of a copper‐imidazolium‐carbonate complex. [ABSTRACT FROM AUTHOR]

Published
2019
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9. Phosphorus Can Also Be a “Photocopy”

Author

Washington, Marlena P., primary, Gudimetla, Vittal B., additional, Laughlin, Feng L., additional, Deligonul, Nihal, additional, He, Susan, additional, Payton, John L., additional, Simpson, M. Cather, additional, and Protasiewicz, John D., additional

Published
2010
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12. Solution Phase Photolysisof 1,2-Dithiane Alone andwith Single-Walled Carbon Nanotubes.

Author

Engel, Paul S., Gudimetla, Vittal B., Gancheff, Jorge S., and Denis, Pablo A.

Subjects
*SOLUTION (Chemistry), *PHOTOLYSIS (Chemistry), *DITHIANE, *SINGLE walled carbon nanotubes, *ACETONITRILE, *BUTANE, *ORGANOSULFUR compounds
Abstract

Photolysis of 1,2-dithiane (1) in acetonitrilewithsingle walled carbon nanotubes (SWCNTs) was earlier reported to formthiol-functionalized SWCNTs via the butane-1,4-dithiyl diradical (2). The present study shows that 2instead undergoesa facile rearrangement to thiophane-2-thiol (6). Thisphotoreaction is clean, rapid, and irreversible under 313 nm irradiation.The secondary photolysis of 6with SWCNTs at a shorterwavelength (254 nm) leads to 2-thiophanyl radicals 8,which derivatize SWCNTs by covalent attachment. Pyrolysis of the resulting“sulfurized SWCNTs” affords a mixture of organosulfurcompounds, including thiophene formed by dehydrogenation. An unknownadditional mechanism causes high TGA weight loss and a large incorporationof sulfur. [ABSTRACT FROM AUTHOR]

Published
2012
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13. metaTerphenyl Phosphaalkenes Bearing ElectronDonating and Accepting Groups

Author

Gudimetla, Vittal B., Ma, Liqing, Washington, Marlena P., Payton, John L., Cather Simpson, M., and Protasiewicz, John D.

Abstract

A set of parasubstituted metaterphenyl phosphaalkenes of the form 4X2,6Mes2C6H2P=CHC6H44X′ X = H, MeO or NMe2; X′ = H, CN, or NO2 have been synthesized to allow systematic studies of the impact of remote X and X′ substituents on the phosphaalkene unit. The new compounds were characterized by 1H and 31P NMR spectroscopy, UVVis absorption spectroscopy, single Xray crystal structures for four compounds and by electrochemical studies. The introduction of remote groups X′ on the less hindered phenyl ring generated more significant effects on the physical properties of the materials than did substituents X on the hindered metaterphenyl rings. These effects were also explored by computational methods in order to assess the influence of substituents on structures and properties. The polarization of these molecules is less than that produced for analogous alkenes, as the phosphaalkenes bear sterically demanding groups that constrain the systems to adopt conformations that are less than ideal for maximum πconjugation of the central π network

Published
2010
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14. Cost Efficient Synthesis of Diaryl Ethers Catalysed by CuI, Imidazolium Chloride and Cs2CO3.

Author

Paul, Sudeep, Joy, Bony P., Rajendran, Rajarajan, and Gudimetla, Vittal B.

Subjects
*ETHER synthesis, *ARYL chlorides, *CHLORIDES, *CESIUM iodide, *ETHERS, *CATALYSIS
Abstract

Synthetically versatile imidazolium chlorides, especially 1,3‐bis‐(2,6‐diisopropylphenyl)‐imidazolium chloride (IPrHCl) along with copper (I) iodide and cesium carbonate, were found to be useful to form C−O bonds via coupling of phenols and aryl/heteroaryl bromides. In this catalysis, the metal:ligand (Cu:IPr) loading was optimised to 1.0 mol%, making it an inexpensive and a simple one pot catalytic route for synthesising a variety of diaryl ethers. The catalytic cycle was probed by UV‐Vis, FT‐IR and HRMS techniques confirming involvement of a copper‐imidazolium‐carbonate complex. [ABSTRACT FROM AUTHOR]

Published
2019
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