Ivan Keresztes
Cornell University
Organic chemistryInorganic chemistryChemistryPhotochemistryLigand
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Publications 51
#1Yuhao Xu (PV: Prairie View A&M University)
Last. Dan PhillipsH-Index: 1
view all 7 authors...
This paper reports new results about the combustion dynamics of hydroprocessed renewable jet fuel droplets derived from heterotrophic algae (AHRJ) burning under conditions that promote one-dimensional transport dynamics and near spherically symmetric burning conditions. Results are compared between Jet-A and three AHRJ/Jet-A mixtures containing 25%, 50%, and 75% AHRJ by volume. The results show that AHRJ droplets burn slightly faster than Jet-A and have a significantly reduced sooting propensity...
#1Yuhui Zhou (Cornell University)
#2Ivan Keresztes (Cornell University)H-Index: 19
Last. David B. Collum (Cornell University)H-Index: 41
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Pseudoephedrine-derived dianionic Myers enolates were generated using sodium diisopropylamide (NaDA) in THF solution. The reactivities and selectivities of the disodium salts largely mirror those of the dilithium salts but without the requisite large excesses of inorganic salts (LiCl) or mandated dilute solutions. The disodium salts require careful control of temperature to preclude deleterious aggregate aging effects traced to changes in the aggregate structure and intervening O-alkylations. St...
#1Joshua J. Gladfelder (UCSB: University of California, Santa Barbara)H-Index: 1
#2Santanu Ghosh (UCSB: University of California, Santa Barbara)H-Index: 1
Last. Armen Zakarian (UCSB: University of California, Santa Barbara)H-Index: 24
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Direct enantioselective α-alkylation of 2-alkylpyridines provides access to chiral pyridines via an operationally simple protocol that obviates the need for prefunctionalization or preactivation of the substrate. The alkylation is accomplished using chiral lithium amides as noncovalent stereodirecting auxiliaries. Crystallographic and solution NMR studies provide insight into the structure of well-defined chiral aggregates in which a lithium amide reagent directs asymmetric alkylation.
2 CitationsSource
#1Naomi E. Clayman (Stanford University)H-Index: 1
#2Lilliana S. Morris (Cornell University)H-Index: 2
Last. Geoffrey W. Coates (Cornell University)H-Index: 70
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A dual catalysis system was developed to synthesize hydrolyzable polyether–polyester copolymers from propylene oxide and cyclic esters such as γ-butyrolactone, δ-valerolactone, and e-caprolactone. A bimetallic chromium catalyst active for the enantioselective polymerisation of propylene oxide and an organocatalyst active for the ring-opening polymerisation of lactones were used in conjunction with an alcohol chain shuttling agent to create new copolymers. The monomer and alcohol ratios were vari...
#1Yuhui Zhou (Cornell University)
#2Janis Jermaks (Cornell University)H-Index: 2
Last. David B. Collum (Cornell University)H-Index: 41
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The structures and reactivities of pseudoephedrine-derived dianionic Myers enolates are examined. A combination of NMR and IR spectroscopic, crystallographic, and computational data reveal that the homoaggregated dianions form octalithiated tetramers displaying S4-symmetric Li8O8 cores and overall C2 symmetry. Computational and isotopic labeling studies reveal strong N–Li contacts in the carboxamide enolate moiety. The method of continuous variations proves deceptive, as octalithiated tetrameric...
#1Ke-Yin Ye (Cornell University)H-Index: 13
#2Gisselle Pombar (UCF: University of Central Florida)H-Index: 2
Last. Song Lin (Cornell University)H-Index: 18
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The emergence of new catalytic strategies that cleverly adopt concepts and techniques frequently used in areas such as photochemistry and electrochemistry has yielded a myriad of new organic reactions that would be challenging to achieve using orthodox methods. Herein, we discuss the strategic use of anodically coupled electrolysis, an electrochemical process that combines two parallel oxidative events, as a complementary approach to existing methods for redox organic transformations. Specifical...
49 CitationsSource
#1Janis Jermaks (Cornell University)H-Index: 2
#2Evan H. Tallmadge (Cornell University)H-Index: 4
Last. David B. Collum (Cornell University)H-Index: 41
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Building on structural and mechanistic studies of lithiated enolates derived from acylated oxazolidinones (Evans enolates) and chiral lithiated amino alkoxides, we found that amino alkoxides amplify the enantioselectivity of aldol additions. The pairing of enantiomeric series affords matched and mismatched stereoselectivities. The structures of mixed tetramers showing 2:2 and 3:1 (alkoxide-rich) stoichiometries are determined spectroscopically. Rate and computational studies provide a viable mec...
1 CitationsSource
#1Min Xiao (Cornell University)H-Index: 4
#2Joronia Chery (Cornell University)H-Index: 2
Last. Margaret W. Frey (Cornell University)H-Index: 3
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A non-acid-based, di-functional epoxide, neopentyl glycol diglycidyl ether (NPGDGE), was used to modify cotton fabrics. Direct characterization of the modified cotton was conducted by Nuclear Magnetic Resonance (NMR) without grinding the fabric into a fine powder. NaOH and MgBr2 were compared in catalyzing the reaction between the epoxide groups of NPGDGE and the hydroxyl groups of cellulose. Possible reaction routes were discussed. Scanning electron microscopy (SEM) images showed that while the...
3 CitationsSource
#1Kyle S. O’ConnorH-Index: 3
#2Jessica R. LambH-Index: 4
Last. Geoffrey W. CoatesH-Index: 70
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Nickel α-diimine catalysts have been previously shown to perform the chain straightening polymerization of α-olefins to produce materials with melting temperatures (Tm) similar to linear low density polyethylene (Tm = 100–113 °C). Branching defects due to mechanistic errors during the polymerization currently hinder access to high density polyethylene (Tm = 135 °C) from α-olefins. Understanding the intricacies of nickel α-diimine catalyzed α-olefin polymerization can lead to improved ligand desi...
15 CitationsSource
#1Katia G. Samper (Autonomous University of Barcelona)H-Index: 5
#2Sierra C. Marker (Cornell University)H-Index: 3
Last. Justin J. Wilson (Cornell University)H-Index: 17
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Abstract The syntheses of three platinum(II) complexes bearing sulfonamide- ( ( E )-2-(4-methylphenylsulfonamido)-2′,6′-difluoroazobenzene, HL1 ) and hydroxy-azo-2,6-difluorobenzene (( E )-2-((2,6-difluorophenyl)diazenyl)phenol, HL2 ) bidentate ligands is described. These complexes, [Pt( L1 )(DMSO)Cl] ( 1 ), [Pt( L2 )(DMSO)Cl] ( 2 ), and [Pt( L2 ) 2 ] ( 3 ), were characterized by multinuclear NMR spectroscopy, mass spectrometry, and X-ray crystallography. Despite bearing azobenzene functional gr...
8 CitationsSource