1,716 research outputs found
ENTREPRENEURIALISM MEETS THE SUSTAINABLE CITY: THE CASE OF LEXINGTONâS TOWN BRANCH COMMONS
Although the idea of the entrepreneurial city is nothing new, recent research in contemporary urban geography and related disciplines indicates that the modus operandi of such entrepreneurial endeavors has shifted, as a result of an increasing recognition and acceptance of global climate change, to include and even prioritize sustainable urban development discourses and practices. While these discourses purportedly culminate in the production of the âsustainable city,â they often fail to deliver upon their promise to create a greener, more sustainable city for all. Such practices, in an effort to help cities obtain an urban sustainability fix (While et al. 2004), often lead to the selective uptake and implementation of âsustainableâ policies and projects by local governments and members of the urban elite in their efforts to positively market their respective cities to potential residents and investors. The city of Lexington, Kentuckyâs ongoing efforts to establish a new downtown park systemâthe Town Branch Commonsâalong the route of a once buried stream, is representative of how such a sustainability fix is both conceived of and ultimately produced by urban elites in the contemporary neoliberal city
Enhanced selectivity in the conversion of methanol to 2,2,3-trimethylbutane (triptane) over zinc iodide by added phosphorous or hypophosphorous acid
The yield of triptane from the reaction of methanol with zinc iodide is dramatically increased by addition of phosphorous or hypophosphorous acid, via transfer of hydride from a PâH bond to carbocationic intermediates
Synthesis and Activity of Six-Membered Cyclic Alkyl Amino CarbeneâRuthenium Olefin Metathesis Catalysts
Ruâcyclic alkyl amino carbene (RuâCAAC) olefin metathesis catalysts perform extraordinarily in metathesis macrocyclization and ethenolysis, but previous studies have been limited to the use of five-membered CAAC (CAAC-5) ligands. In this work, we synthesized a different group of ruthenium catalysts with more Ï-donating and Ï-accepting six-membered CAAC (CAAC-6) ligands, and their metathesis activity was probed through initiation studies, ring-closing metathesis (RCM), cross-metathesis, and ethenolysis. These catalysts display higher initiation rates than analogous RuâCAAC-5 complexes but demonstrate lower activity in RCM and ethenolysis
Synthesis of a Molecular Charm Bracelet via Click Cyclization and Olefin Metathesis Clipping
We describe the synthesis of a polycatenated cyclic polymer, a structure that resembles a
molecular charm bracelet. Ruthenium-catalyzed ring-opening metathesis polymerization of an aminocontaining
cyclic olefin monomer in the presence of a chain transfer agent generated an α,Ï-diazide
functionalized polyamine. Cyclization of the resulting linear polyamine using pseudo-high-dilution coppercatalyzed
click cyclization produced a cyclic polymer in 19% yield. The click reaction was then further
employed to remove linear contaminants from the cyclic polymer using azide- and alkyne-functionalized
scavenging resins, and the purified cyclic polymer product was characterized by gel permeation
chromatography, ^1H NMR spectroscopy, and IR spectroscopy. Polymer hydrogenation and conversion to
the corresponding polyammonium species enabled coordination and interlocking of diolefin polyether
fragments around the cyclic polymer backbone using ruthenium-catalyzed ring-closing olefin metathesis to
afford a molecular charm bracelet structure. This charm bracelet complex was characterized by ^1H NMR
spectroscopy, and the catenated nature of the small rings was confirmed using two-dimensional diffusion-ordered
NMR spectroscopy
Mechanism of the fluxional behaviour in (1â5-η-cycloheptadienyl)-(1â5-η-cycloheptatrienyl)iron
Evidence for a 1.2-shift mechanism of the 1-5-η-cycloheptatrienyl moiety with respect to the central iron atom of the title compound is presented together with absolute assignments of the ^(13)C n.m.r. chemical shifts of the C_(7)H_(7) ring. A low-temperature rocking motion of both rings can be frozen out at -70 °C
A Diphenylcyclopropene Complex of Tungsten, [WCl_2O(PMePh_2)_2(η^2-3,3-diphenylcyclopropene)], Precursor to a TungstenâOxoâOlefin Metathesis Catalyst
The title compound, dichlorobis(methyldiphenylphosphine-P) [(1,2-[η])-3,3-diphenylcyclopropene]oxotungsten, [WCl_2O(C_(15)H_(12))(C_(13)H_(13)P)_2], is a mononuclear complex of tungsten with an approximately octahedral environment around the metal atom. The ligand, 3,3-diphenylcyclopropene, is bonded to the W atom in a [η]^2-geometry with effectively identical metal-to-carbon bond distances [W-C1 = 2.133 (7) Ă
and W-C2 2.131 (7) Ă
]
Aerobic Palladium-Catalyzed Dioxygenation of Alkenes Enabled by Catalytic Nitrite
Catalytic nitrite was found to enable carbonâoxygen bond-forming reductive elimination from unstable alkyl palladium intermediates, providing dioxygenated products from alkenes. A variety of functional groups were tolerated, and high yields (up to 94â%) were observed with many substrates, also for a multigram-scale reaction. Nitrogen dioxide, which could form from nitrite under the reaction conditions, was demonstrated to be a potential intermediate in the catalytic cycle. Furthermore, the reductive elimination event was probed with ^(18)O-labeling experiments, which demonstrated that both oxygen atoms in the difunctionalized products were derived from one molecule of acetic acid
Selection of Ionic Liquid Solvents for Chemical Separations Based on the Abraham Model
Book chapter on the selection of ionic liquid solvents for chemical separations based on the Abraham model
- âŠ