Technology utilization workshop subjects study, supplement 1

Aerospace technology utilization and information dissemination for industry and commerc

Land use classification in Bolivia

The Bolivian LANDSAT Program is an integrated, multidisciplinary project designed to provide thematic analysis of LANDSAT, Skylab, and other remotely sensed data for natural resource management and development in Bolivia, is discussed. Among the first requirements in the program is the development of a legend, and appropriate methodologies, for the analysis and classification of present land use based on landscape cover. The land use legend for Bolivia consists of approximately 80 categories in a hierarchical organization which may be collapsed for generalization, or expanded for greater detail. The categories, and their definitions, provide for both a graphic and textual description of the complex and diverse landscapes found in Bolivia, and are designed for analysis from LANDSAT and other remotely sensed data at scales of 1:1,000,000 and 1:250,000. Procedures and example products developed are described and illustrated, for the systematic analysis and mapping of present land use for all of Bolivia

Application of ERTS-1 data to integrated state planning in the state of Maryland

There are no author-identified significant results in this report

Synthesis of the Oxidative Metabolites of Di(2-ethylhexyl) phthalate and Analysis of Metabolite Binding with Peroxisome Proliferator-Activated Receptors

Di(2-ethylhexyl) phthalate (DEHP) is a persistent organic pollutant that is added to increase the flexibility of soft plastics, such as polyvinyl chloride (PVC). Since DEHP is not bound to the polymer, it leaches into the environment, leading to human exposure. When DEHP is metabolized by the body, it is cleaved into mono-(2-ethylhexyl) phthalate (MEHP). MEHP is then oxidized to produce the secondary-oxidized metabolites mono-(2-ethyl-5-carboxypentyl)phthalate (5cx-MEPP), mono-(2-ethyl-5-oxohexyl)phthalate (5oxo-MEHP), and mono-[2-(carboxymethyl)hexyl]phthalate (2cx-MMHP). DEHP and its metabolites interact with peroxisome proliferator-activated receptors (PPARs), which can alter lipid metabolism. To synthesize 5cx-MEHP, an enolate alkylation was performed with ethyl butyrate to form ethyl 2-ethyl-6-heptenoate. A reduction with LiAlH4 was performed to produce 2-ethyl-6-hepten-1-ol. The alcohol was esterified with phthalic anhydride and subsequently oxidized to produce 5cx-MEHP. This procedure was then repeated to synthesize 2cx-MMHP and 5oxo-MEPP, replacing the enolate alkylation with a malonic ester alkylation and modifying the final oxidation. Binding of the metabolites of DEHP to PPARγ can be assessed using a thermal shift assay. A protocol for the thermal shift assay was developed using the binding of PPARγ and rosiglitazone, a known PPARγ ligand. The information gained surrounding the binding of DEHP and its metabolites to PPARγ may explain the endocrine-disrupting effects seen from exposure to phthalate plasticizers by addressing the fundamental question of their cellular targets

Mechanistic Studies of pi-Activation Catalysis by Cationic Gold(I) and Brønsted-acid

<p>Soluble gold(I) complexes are highly efficient catalysts for the functionalization of C-C multiple bonds through the addition of carbon- or heteroatom-nucleophiles across &pi;-bonds or cycloisomerizations of enynes and related &pi;-systems. Mechanisms involving outer-sphere attack of a nucleophile on the electrophilic &pi;-ligand of a cationic gold &pi;-complex are typically invoked for gold(I)-catalyzed hydrofunctionalization and cycloisomerization processes, but direct experimental evidence for this mechanism is limited. </p><p>As an extension of the pioneering research in the Widenhoefer lab on the synthesis and characterization of gold(I) &pi;-complexes, a diverse family of 15 gold(I) &pi;-complexes in three distinct series are reported herein. First, the synthesis, characterization, and solution behavior of a series of seven gold(I) &pi;-diene complexes is reported. In each case, gold binds preferentially to the less substituted C&#9552;C bond of the diene, but intermolecular exchange of the complexed and uncomplexed C&#9552;C is facile. The gold-alkene interaction is stabilized via substitution-dependant donation of electron density from the uncomplexed C&#9552;C bond to the complexed C&#9552;C bond of the diene.</p><p>In addition, a pair of axially chiral dicationic, bis(gold) &pi;-alkene complexes that contain a 2,2&#8242;-bis(phosphino)biphenyl ligand are reported. The complexes show no intramolecular Au-Au interactions or facial selectivity for complexation, but solution analyses suggest that the environment about one gold center affects the behavior of the proximal gold center through a yet unknown mechanism. Gold(I) &pi;-alkene, alkyne, diene, and allene complexes that bear a triphenylphosphine supporting ligand have also been synthesized and characterized in situ. The &pi;-ligands in the triphenylphosphine gold complexes were considerably more labile than those bearing bulky, electron rich phosphine or N-heterocyclic carbene ligands, and the complexes decomposed in solution above -20 °C.</p><p>Mechanistic investigation of the gold-catalyzed cycloisomerization of a 7-aryl-1,6-enyne led to characterization of the first organometallic complex directly observed in the course of an enyne cycloisomerization. The complex is best described as a gold &pi;-(bicyclo[3.2.0]heptane) complex with a domination metallacyclopropane binding interaction and undergoes an acid-catalyzed rearrangement to yield a stable bicyclo[3.2.0]heptane product which can further isomerize in the presence of Ag+. In a further effort to understand the reactive species in catalytic cycloisomerizations, the first example of a gold cyclopropyl carbene was synthesized and fully characterized. </p><p>Finally, in an effort understand the mechanistic distinctions between electrophilic metal-catalyzed hydrofunctionalization and similar Brønsted acid-catalyzed additions, the kinetics and stereochemistry of intramolucar acid-catalyzed hydrofunctionalizion were studied. In all cases, the transformations were > 95 % selective for <italic>anti</italic>-addition and displayed rate laws similar to those expected for metal-catalyzed variants. A concerted C-H, C-X bond forming mechanism for addition is proposed.</p>Dissertatio

An element through the looking glass: Exploring the Au-C, Au-H and Au-O energy landscape

Gold, the archetypal “noble metal”, used to be considered of little interest in catalysis. It is now clear that this was a misconception, and a multitude of gold-catalysed transformations has been reported. However, one consequence of the long-held view of gold as inert metal is that its organometallic chemistry contains many “unknowns”, and catalytic cycles devised to explain gold's reactivity draw largely on analogies with other transition metals. How realistic are such mechanistic assumptions? In the last few years a number of key compound classes have been discovered that can provide some answers. This Perspective attempts to summarise these developments, with particular emphasis on recently discovered gold(III) complexes with bonds to hydrogen, oxygen, alkenes and CO ligands

Dispersion, solvent and metal effects in the binding of gold cations to alkynyl ligands: implications for Au(i) catalysis.

The coordination modes of the [Au(PPh3)](+) cation to metal alkynyl complexes have been investigated. On addition to ruthenium, a vinylidene complex, [Ru(η(5)-C5H5)(PPh3)2([double bond, length as m-dash]C[double bond, length as m-dash]CPh{AuPPh3})](+), is obtained while addition to a gold(iii) compound gives di- and trinuclear gold complexes depending on the conditions employed. In the trinuclear species, a gold(i) cation is sandwiched between two gold(iii) alkynyl complexes, suggesting that coordination of multiple C-C triple bonds to gold is facile

Preparation of Tremorine and Gemini Surfactant Precursors with Cationic Ethynyl-Bridged Digold Catalysts

[EN] Tremorine and precursors of gemini surfactants were synthesised in a one-pot, three-step, double-catalytic A3 coupling reaction and characterised by structural and spectroscopic methods. The cationic [Au-I(L1)]SbF6 complex is a more active catalyst compared to neutral L2- and L3-Au-I bis(trifluoromethanesulfonyl) imidate complexes (L1, L2= Buchwald-type biaryl phosphane; L3= triphenylphosphine) in promoting the double A(3) coupling of ethynyltrimethylsilane, secondary amines (cyclic, aliphatic, or aromatic) and formaldehyde. The solvent influences the catalytic performance by desilylation of silyl acetylene or deactivation of the catalyst by a halide anion. Acetylide-bridged cationic di-gold(I) L1 and L2 complexes were isolated and characterised by means of single-crystal X-ray structure analysis and their spectroscopic properties. Iodine in the acetylene reagent deactivates the AuI catalyst by formation of the less active iodido-bridged cationic digold(I) L1 complex, which was fully characterised by single-crystal X-ray crystal structure analysis and spectroscopy. The nature of the phosphine ligand of the gold complexes used as catalyst affects the stability and activity of the formed cationic ethynyl-bridged Au-2(I)-L intermediates, isolation of which lends support to the proposed double A(3) coupling mechanism.Financial support by the Spanish Ministry of Economy and Competitiveness (Severo Ochoa and CTQ2015-69153-CO2-R1) and Generalidad Valenciana (Prometeo 2013-014) is gratefully acknowledged.Grirrane, A.; Alvarez-González, E.; García Gómez, H.; Corma Canós, A. (2017). Preparation of Tremorine and Gemini Surfactant Precursors with Cationic Ethynyl-Bridged Digold Catalysts. Chemistry - A European Journal. 23(12):2792-2801. https://doi.org/10.1002/chem.201605269S27922801231

Disclosing the multi-faceted world of weakly interacting inorganic systems by means of NMR spectroscopy

The potential of NMR spectroscopy to investigate inorganic systems assembled by, or whose reactivity is affected by, non-covalent interactions is described. Subjects that have received particular attention in recent years (halogen bonding and Frustrated Lewis Pairs) and more classical subjects that remain under-explored (self-aggregation of ion pairs in low polar solvents, behavior of MAO containing metallocenium ion pairs, and hydrogen bonding/ion pairing effects in Au(I) catalysis) are considered, using an innovative approach, always focusing on the crucial information that can be provided by NMR