Marion Emmert

Nondirected, Cu-Catalyzed sp3 C–H Aminations with Hydroxylamine-Based Amination Reagents: Catalytic and Mechanistic Studies

Co-reporter:Anqi Wang, Nicholas J. Venditto, Julia W. Darcy, and Marion H. Emmert

Organometallics April 10, 2017 Volume 36(Issue 7) pp:1259-1259

Publication Date(Web):March 23, 2017

DOI:10.1021/acs.organomet.7b00003

This work demonstrates the use of hydroxylamine-based amination reagents RSO2NH-OAc for the nondirected, Cu-catalyzed amination of benzylic C–H bonds. The amination reagents can be prepared on a gram scale, are benchtop stable, and provide benzylic C–H amination products with up to 86% yield. Mechanistic studies of the established reactivity with toluene as substrate reveal a ligand-promoted, Cu-catalyzed mechanism proceeding through Ph-CH2(NTsOAc) as a major intermediate. Stoichiometric reactivity of Ph-CH2(NTsOAc) to produce Ph-CH2-NHTs suggests a two-cycle, radical pathway for C–H amination, in which the decomposition of the employed diimine ligands plays an important role.

Rare earth recovery from end-of-life motors employing green chemistry design principles

Co-reporter:H. M. Dhammika Bandara, Kathleen D. Field and Marion H. Emmert

Green Chemistry 2016 vol. 18(Issue 3) pp:753-759

Publication Date(Web):07 Sep 2015

DOI:10.1039/C5GC01255D

This manuscript describes the development of an efficient process for the recovery of rare earth elements from materials mixtures such as in motors with a recovery rate of >80%. While heat treatment is required for processing, all other steps can be performed at room temperature, thus resulting in a process designed for energy efficiency. Selective dissolution enables efficient separation of steel and copper by taking advantage of the different reduction potentials of the materials in the mixture, while selective precipitation of RE salts is the key for obtaining pure RE products. Overall, the established process applies green chemistry principles for designing a hydrometallurgical process.

Non-directed aromatic C–H amination: catalytic and mechanistic studies enabled by Pd catalyst and reagent design

Co-reporter:H. M. D. Bandara, D. Jin, M. A. Mantell, K. D. Field, A. Wang, R. P. Narayanan, N. A. Deskins and M. H. Emmert

Catalysis Science & Technology 2016 vol. 6(Issue 14) pp:5304-5310

Publication Date(Web):24 Mar 2016

DOI:10.1039/C6CY00457A

This manuscript describes the systematic development of pyridine-type ligands, which promote the Pd catalyzed, non-directed amination of benzene in combination with novel, hydroxylamine-based electrophilic amination reagents. DFT calculations and mechanistic experiments provide insights into the factors influencing the arene C–H amination protocol.

Non-directed, carbonate-mediated C–H activation and aerobic C–H oxygenation with Cp*Ir catalysts

Co-reporter:M. E. Kerr, I. Ahmed, A. Gunay, N. J. Venditto, F. Zhu, E. A. Ison and M. H. Emmert

Dalton Transactions 2016 vol. 45(Issue 24) pp:9942-9947

Publication Date(Web):08 Mar 2016

DOI:10.1039/C6DT00234J

The effect of oxidatively stable L- and X-type additives on the activity of Cp*Ir catalyst precursors in the C–H activation of arenes has been studied. Turnover numbers for C–H activation of up to 65 can thus be achieved, as determined by H/D exchange in MeOH-D4. In particular, carbonate additives are found to enhance the C–H activation reactivity of Cp*Ir(H2O)3(OTf)2 (1) more significantly than L-type ligands investigated in this study. Based on these studies, Cp*Ir/carbonate systems are developed that catalyze the aerobic Csp3–H oxygenation of alkyl arenes, employing air as oxidant.

Influence of alternative fuels on trace element content of ordinary portland cement

Co-reporter:Coleman Horsley, Marion H. Emmert, Aaron Sakulich

Fuel 2016 Volume 184() pp:481-489

Publication Date(Web):15 November 2016

DOI:10.1016/j.fuel.2016.07.038

Over the last 20 years, interest in diverting waste from landfills and recovering energy from waste materials has grown significantly. The cement industry in particular has adapted its production methods to accommodate a wide variety of waste materials as alternative fuels in order to lower both cost and environmental footprint. The incineration of waste products at existing cement plants is generally cheaper than building a new, dedicated incinerator as cement kilns generally meet the requirements for incinerating hazardous wastes. In addition to negative perception, particularly where potentially hazardous waste materials are concerned, there are a number of technical challenges in the use of alternative fuels at cement plants. This paper focuses on the incorporation of trace elements in ordinary portland cement through the use of alternative fuels, including the behavior of trace elements in the manufacturing process and their effects on final products. A brief overview of the use of waste tires, solidified sewage sludge, and meat and bone meal as alternative fuels is presented along with a discussion of challenges and opportunities facing the field.

Oxidation catalysis in air with Cp*Ir: influence of added ligands and reaction conditions on catalytic activity and stability

Co-reporter:Ahmet Gunay, Mark A. Mantell, Kathleen D. Field, Wenbo Wu, Michael Chin and Marion H. Emmert

Catalysis Science & Technology 2015 vol. 5(Issue 2) pp:1198-1205

Publication Date(Web):06 Nov 2014

DOI:10.1039/C4CY01203H

We describe the systematic evaluation of Cp*Ir catalysts for the aerobic oxidation of alcohols. Our results demonstrate turnover numbers up to 270 per [Cp*IrCl2]2 which have not been previously achieved for this reaction. Using air as the sole oxidant under base-free conditions, the effects of solvent systems and additives on the catalytic activity are documented systematically. We further elucidate the role of additives in catalyst decomposition processes and establish a novel buffer system which results in significant catalyst stabilization upon prolonged reaction times.

Iron-Catalyzed CH Oxidation of Tertiary, Aliphatic Amines to Amides under Mild Conditions

Co-reporter:Christopher J. Legacy;Anqi Wang;Brian J. O'Day ; Marion H. Emmert

Angewandte Chemie International Edition 2015 Volume 54( Issue 49) pp:14907-14910

Publication Date(Web):

DOI:10.1002/anie.201507738

Abstract

De novo syntheses of amides often generate stoichiometric amounts of waste. Thus, recent progress in the field has focused on precious metal catalyzed, oxidative protocols to generate such functionalities. However, simple tertiary alkyl amines cannot be used as starting materials in these protocols. The research described herein enables the oxidative synthesis of amides from simple, noncyclic tertiary alkyl amines under synthetically useful, mild conditions through a biologically inspired approach: Fe-catalyzed C_αH functionalization. Mechanistic investigations provide insight into reaction intermediates and allow the development of a mild C_αH cyanation method using the same catalyst system. The protocol was further applied to oxidize the drug Lidocaine, demonstrating the potential utility of the developed chemistry for metabolite synthesis.

Iron-Catalyzed CH Oxidation of Tertiary, Aliphatic Amines to Amides under Mild Conditions

Co-reporter:Christopher J. Legacy;Anqi Wang;Brian J. O'Day ; Marion H. Emmert

Angewandte Chemie 2015 Volume 127( Issue 49) pp:15120-15123

Publication Date(Web):

DOI:10.1002/ange.201507738

Abstract

De novo syntheses of amides often generate stoichiometric amounts of waste. Thus, recent progress in the field has focused on precious metal catalyzed, oxidative protocols to generate such functionalities. However, simple tertiary alkyl amines cannot be used as starting materials in these protocols. The research described herein enables the oxidative synthesis of amides from simple, noncyclic tertiary alkyl amines under synthetically useful, mild conditions through a biologically inspired approach: Fe-catalyzed C_αH functionalization. Mechanistic investigations provide insight into reaction intermediates and allow the development of a mild C_αH cyanation method using the same catalyst system. The protocol was further applied to oxidize the drug Lidocaine, demonstrating the potential utility of the developed chemistry for metabolite synthesis.

Rare Earth Recycling: Forecast of Recoverable Nd from Shredder Scrap and Influence of Recycling Rates on Price Volatility

Co-reporter:H. M. Dhammika Bandara;Mark A. Mantell

Journal of Sustainable Metallurgy 2015 Volume 1( Issue 3) pp:179-188

Publication Date(Web):2015 September

DOI:10.1007/s40831-015-0019-3

This manuscript quantifies the recoverability of the rare earth (RE) element neodymium from shredder scrap during the next two decades and provides a forecast of recycling rates until 2034 based on these calculations. In combination with this forecast, an analysis of historical price and recycling trends for several critical (i.e., platinum group metals, zinc, tantalum, cobalt, antimony, and tungsten) and non-critical materials (i.e., tin, chromium, gold, and copper) results in general conclusions for the future price volatility of REs in dependence on expected recycling rates.

Value Analysis of Neodymium Content in Shredder Feed: Toward Enabling the Feasibility of Rare Earth Magnet Recycling

Co-reporter:H. M. Dhammika Bandara, Julia W. Darcy, Diran Apelian, and Marion H. Emmert

Environmental Science & Technology 2014 Volume 48(Issue 12) pp:6553-6560

Publication Date(Web):May 21, 2014

DOI:10.1021/es405104k

In order to facilitate the development of recycling technologies for rare earth magnets from postconsumer products, we present herein an analysis of the neodymium (Nd) content in shredder scrap. This waste stream has been chosen on the basis of current business practices for the recycling of steel, aluminum, and copper from cars and household appliances, which contain significant amounts of rare earth magnets. Using approximations based on literature data, we have calculated the average Nd content in the ferrous shredder product stream to be between 0.13 and 0.29 kg per ton of ferrous scrap. A value analysis considering rare earth metal prices between 2002 and 2013 provides values between $1.32 and $145 per ton of ferrous scrap for this material, if recoverable as pure Nd metal. Furthermore, we present an analysis of the content and value of other rare earths (Pr, Dy, Tb).

Catalysts for convenient aerobic alcohol oxidations in air: systematic ligand studies in Pd/pyridine systems

Co-reporter:Lukas C. John, Ahmet Gunay, Andrew J. Wood, Marion H. Emmert

Tetrahedron 2013 69(27–28) pp: 5758-5764

Publication Date(Web):

DOI:10.1016/j.tet.2013.03.011

Oxidation catalysis in air with Cp*Ir: influence of added ligands and reaction conditions on catalytic activity and stability

Co-reporter:Ahmet Gunay, Mark A. Mantell, Kathleen D. Field, Wenbo Wu, Michael Chin and Marion H. Emmert

Catalysis Science & Technology (2011-Present) 2015 - vol. 5(Issue 2) pp:NaN1205-1205

Publication Date(Web):2014/11/06

DOI:10.1039/C4CY01203H

We describe the systematic evaluation of Cp*Ir catalysts for the aerobic oxidation of alcohols. Our results demonstrate turnover numbers up to 270 per [Cp*IrCl2]2 which have not been previously achieved for this reaction. Using air as the sole oxidant under base-free conditions, the effects of solvent systems and additives on the catalytic activity are documented systematically. We further elucidate the role of additives in catalyst decomposition processes and establish a novel buffer system which results in significant catalyst stabilization upon prolonged reaction times.

Non-directed aromatic C–H amination: catalytic and mechanistic studies enabled by Pd catalyst and reagent design

Co-reporter:H. M. D. Bandara, D. Jin, M. A. Mantell, K. D. Field, A. Wang, R. P. Narayanan, N. A. Deskins and M. H. Emmert

Catalysis Science & Technology (2011-Present) 2016 - vol. 6(Issue 14) pp:NaN5310-5310

Publication Date(Web):2016/03/24

DOI:10.1039/C6CY00457A

This manuscript describes the systematic development of pyridine-type ligands, which promote the Pd catalyzed, non-directed amination of benzene in combination with novel, hydroxylamine-based electrophilic amination reagents. DFT calculations and mechanistic experiments provide insights into the factors influencing the arene C–H amination protocol.

Non-directed, carbonate-mediated C–H activation and aerobic C–H oxygenation with Cp*Ir catalysts

Co-reporter:M. E. Kerr, I. Ahmed, A. Gunay, N. J. Venditto, F. Zhu, E. A. Ison and M. H. Emmert

Dalton Transactions 2016 - vol. 45(Issue 24) pp:NaN9947-9947

Publication Date(Web):2016/03/08

DOI:10.1039/C6DT00234J

The effect of oxidatively stable L- and X-type additives on the activity of Cp*Ir catalyst precursors in the C–H activation of arenes has been studied. Turnover numbers for C–H activation of up to 65 can thus be achieved, as determined by H/D exchange in MeOH-D4. In particular, carbonate additives are found to enhance the C–H activation reactivity of Cp*Ir(H2O)3(OTf)2 (1) more significantly than L-type ligands investigated in this study. Based on these studies, Cp*Ir/carbonate systems are developed that catalyze the aerobic Csp3–H oxygenation of alkyl arenes, employing air as oxidant.

Low temperature dehydrations of non-activated alcohols via halide catalysis

Co-reporter:X. Zhang, S. J. Desrochers, A. D. Carl, N. Geagea, K. Zielinski and M. H. Emmert

Inorganic Chemistry Frontiers 2016 - vol. 3(Issue 6) pp:NaN708-708

Publication Date(Web):2016/04/07

DOI:10.1039/C6QO00069J

Activating kinetically inert C–O bonds such as in primary alcohols is an important challenge for the transformation of biomass-derived feedstocks. The herein described methodology addresses this issue through a combination of halide and acid catalysis. The novel mechanistic pathway proposed based on detailed experimental studies enables selective olefin formation from alcohols – as opposed to ether formation – at relatively low temperatures. Suitable substrates are tertiary, secondary, and even primary alcohols. Furthermore, the observed selectivity for the Hoffman elimination product and the realization of a non-rearranging Friedel–Crafts alkylation suggest that the reaction medium with high concentrations of halide (NBu4Br) enables reaction outcomes that cannot be obtained through carbocation intermediates.

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