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Palladium Catalyzed Coupling Reactions: Mechanism of Reductive Elimination. Progress Report, June 1, 1978-September 30, 1979

Description: The coupling reaction of benzyl halides and organolithium, organotin, or Grignard Reagents is catalyzed by palladium. The sequence of events in the catalytic cycle is oxidative addition of the benzyl halide to palladium(0), methathesis by the organometallic reagent to give a benzyl methyl palladium(II) complex, oxidative addition of the benzyl halide to give a palladium(IV) complex, and reductive elimination of benzyl and methyl to give ethylbenzene. The reductive elimination from palladium bearing an optically active ..cap alpha..-deuteriobenzyl group takes place with retention of configuration at carbon, and is therefore concerted or nearly concerted. Since rho is positive in the catalytic reaction with substituted aryl halides, an oxidative addition, probably during the Pd(II) to Pd(IV) reaction, is the slow step in the catalytic cycle. The intermediate diorganopalladium species can be isolated when the two groups attached to palladium are both methyl or methyl and either cis or trans-..beta..-styryl. The decomposition of these species can be followed by NMR. In the case of methylstyrylpalladium(II) complexes, the reductive elimination gives propenyl benzene with stereospecific retention of double bond geometry. Cis-dimethylbis(diphenylmethylphosphine)palladium(II) does not undergo isomerization to the more stable trans isomer in an inert solvent, and is stable toward reductive elimination up to 50/sup 0/. In the presence of added phosphine, or in a coordinating solvent, rapid cis to trans isomerization and reductive elimination to give ethane is observed. An associative mechanism is apparently operative in this case.
Date: September 1, 1979
Creator: Stille, J. K.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department

Overburden Characterization and Post-Burn Study of the Hanna Iv, Underground Coal Gasification Site, Wyoming, and Comparison to Other Wyoming Ucg Sites

Description: Analysis of 21 post-burn cores taken from the Hanna IV UCG site allows 96 m (315 ft) of overburden to be subdivided into four local stratigraphic units. The 7.6 m (25 ft) thick Hanna No. 1 coal seam is overlain by a laterally discontinuous, 3.3 m (11 ft) thick shaley mudstone (Unit A') in part of the Hanna IV site. A more widespread, 30 m (90 ft) thick well-indurated sandstone (Unit A) overlies the A' unit. Unit A is the roof rock for both of the Hanna IV cavities. Overlying Unit A is a 33 m (108 ft) thick sequence of mudstone and claystone (Unit B), and the uppermost unit at the Hanna IV site (Unit C) is a coarse-grained sandstone that ranges in thickness from 40 to 67 m (131 to 220 ft). Two elliptical cavities were formed during the two phases of the Hanna IV experiment. The larger cavity, Hanna IVa, is 45 x 15 m in plan and has a maximum height of 18 m (59 ft) from the base of the coal seam to the top of the cavity; the Hanna IVb cavity is 40 x 15 m in plan and has a maximum height of 11 m (36 ft) from the base of the coal seam to the top of the cavity. Geotechnical tests indicated that the Hanna IV overburden rocks were moderately strong to strong, based on the empirical classification of Broch and Franklin (1972), and a positive, linear correlation exists between rock strength and volume percent calcite cement. There is an inverse linear correlation between rock strength and porosity for the Hanna IV overburden rocks. 28 refs., 34 figs., 13 tabs..
Date: November 1, 1984
Creator: Marcouiller, B.A.; Burns, L.K. & Ethridge, F.G.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department

Diosmacycloalkanes as models for the formation of hydrocarbons from surface methylenes

Description: We have obtained a neutron diffraction data set for Os{sub 2}(CO){sub 8}({mu}-C{sub 2}H{sub 4}). While the structure is still being solved, it is already clear that the hybridization at both of the ethylene carbons is sp{sup 3}. Our first interpretation of our liquid crystal NMR results had suggested a very acute H-C-H angle. We have also obtained {sup 13}C liquid crystal data for Os{sub 2}(CO){sub 8}({mu}-C{sub 2}H{sub 4}). Liquid crystal NMR ({sup 13}C as well as {sup 1}H) spectra have been obtained for Os(CO){sub 4}(C{sub 2}H{sub 4}) and its solution structure determined, in order to test our methodology on a molecule with a rigid structure. The normal modes of Os(CO){sub 4}({mu}-C{sub 2}H{sub 4}) and its deuterated and {sup 13}C-labelled isotopomers have been completely assigned. A partial vibrational analysis of Os{sub 2}(CO){sub 8}({mu}-propene), Os{sub 2}(CO){sub 8}(trans-2-butene), and Os{sub 2}(CO){sub 8}(1-butene) has been completed. We have prepared Os(CO){sub 4}({mu}-CH{sub 2}CH{sub 2}CH{sub 2}) and its 3,3-dideuterio analog. In the course of this work the reaction of Na{sub 2}Os(CO){sub 4} with a number of 1,3-propanediol derivatives has been examined. 1,3-Propanediol ditosylate afforded much better yields of the osmacycle than did either the ditriflate or diiodide. 2,2-Dideutero-1,3-propanediol ditosylate was used to prepare the deuterium-labelled osmacyclobutane.
Date: January 1, 1989
Creator: Norton, J.R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department

Lead-Zinc-Silver in the Poughkeepsie District and Part of the Upper Uncompahgre and Mineral Point Districts, Ouray and San Juan Counties, Colorado

Description: Report issued by the Bureau of Mines over mining districts in Colorado. As noted in the introduction, "in this report the physical features, climate, and ore deposits of the districts are described, and a brief history of mining and production of lead, zinc, and silver is given" (p. 4). This report includes tables, illustrations, and maps.
Date: September 1949
Creator: Hazen, Scott W., Jr.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department

Corners of Texas

Description: This volume contains popular folklore of Texas, including information about folk music, folk arts and crafts, history of Texas, prominent Texas writers, and other miscellaneous folklore. The index begins on page 285.
Date: 1993
Creator: Abernethy, Francis Edward
Item Type: Refine your search to only Book
Partner: UNT Press

Development of a Mobile Compressor and Utility Station

Description: Report issued by the U.S. Bureau of Mines on the development of a mobile compressor and utility station in the oil-shale mine near Rifle, Colorado during 1949. The report includes photographs and illustrations of the mobile station.
Date: July 1950
Creator: Wright, Fred D. & Ballinger, Homer J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department

Effect of Oil-Base Drilling Fluid Filtrate on Analysis of Cores from South Coles Levee, California, and Rangely, Colorado Fields

Description: Report issued by the U.S. Bureau of Mines on the study of contamination of cores obtained with conventional core barrels. The effect of the oil-based drilling fluid and analysis of the cores are presented. The report includes tables, graphs, and illustrations.
Date: August 1950
Creator: Gates, Gates L.; Morris, Frank C. & Caraway, W. Hodge
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department

Green River Formation Lithology and Oil Shale Correlations in the Piceance Creek Basin, Colorado

Description: Report issued by the Bureau of Mines discussing the oil-shale formations of the Green River in the Piceance Creek Basin. Detailed descriptions of oil-shale samples taken from the Green River formation are presented. This report includes tables, maps, illustrations, and a photograph.
Date: 1970
Creator: Trudell, Laurence G.; Beard, Thomas N. & Smith, John Ward
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department

Role of Polycrystallinity in Cdte and Cuinse Sub 2 Photovoltaic Cells

Description: The polycrystalline nature of thin-film CdTe and CuInSe{sub 2} solar cells continues to be a major factor in several individual losses that limit overall cell efficiency. This report describes progress in the quantitative separation of these losses, including both measurement and analysis procedures. It also applies these techniques to several individual cells to help document the overall progress with CdTe and CuInSe{sub 2} cells. Notably, CdTe cells from Photon Energy have reduced window photocurrent losses to 1 mA/Cm{sup 2}; those from the University of South Florida have achieved a maximum power voltage of 693 mV; and CuInSe{sub 2} cells from International Solar Electric Technology have shown a hole density as high as 7 {times} 10{sup 16} cm{sup {minus}3}, implying a significant reduction in compensation. 9 refs.
Date: January 1, 1991
Creator: Sites, J.R. (Colorado State Univ., Fort Collins, CO (United States))
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department

Mineral Facts and Problems, 1956

Description: Report issued by the Bureau of Mines over mineral characteristics, uses, and problems. Descriptions of common minerals and their uses are presented and discussed. This report includes tables, maps, and illustrations.
Date: 1956
Creator: United States. Bureau of Mines.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department

Comparative Performance of Two Types of Evacuated Tube Solar Collectors in a Residential Heating and Cooling System - The Progress Report

Description: Two types of evacuated tube solar collectors have been operated in space heating, cooling and domestic hot water heating systems in Colorado State University Solar House I. An experimental collector from Corning Glass Works supplied heat to the system from January 1977 through February 1978, and an experimental collector from Philips Research Laboratory, Aachen, which is currently in use, has been operating since August 1978. A flat absorber plate inside a single-walled glass tube is used in the Corning design, whereas heat is conducted through a single glass wall to an external heat exchanger plate in the Philips collector. In comparison with conventional flat-plate collectors, both types show reduced heat losses and improved efficiency. For space heating and hot water supply in winter, the solar delivery efficiency of the Corning collector ranged from 49% to 60% of the incident solar energy. The portion of the space heating and domestic hot water load carried by solar energy through fall and winter ranged from 50% to 74%, with a four-month contribution of 61% of the total requirements. Data on the Philips collector are currently being analyzed.
Date: January 1, 1979
Creator: Conway, T.M.; Duff, W.S.; Lof, G.O.G. & Pratt, R.G.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department

Mean and Peak Wind Load Reduction on Heliostats

Description: This report presents the results of wind-tunnel tests supported through the Solar Energy Research Institute (SERI) by the Office of Solar Thermal Technology of the US Department of Energy as part of the SERI research effort on innovative concentrators. As gravity loads on drive mechanisms are reduced through stretched-membrane technology, the wind-load contribution of the required drive capacity increases in percentage. Reduction of wind loads can provide economy in support structure and heliostat drive. Wind-tunnel tests have been directed at finding methods to reduce wind loads on heliostats. The tests investigated both mean and peak forces, and moments. A significant increase in ability to predict heliostat wind loads and their reduction within a heliostat field was achieved. In addition, a preliminary review of wind loads on parabolic dish collectors was conducted, resulting in a recommended research program for these type collectors. 42 refs., 38 figs., 1 tab.
Date: September 1, 1987
Creator: Peterka, J. A.; Tan, L.; Bienkiewcz, B. & Cermak, J. E.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department

Comparison of the Response of a Nai Scintillation Crystal With a Pressurized Ionization Chamber as a Function of Altitude, Radiation Level and RA-226 Concentration

Description: The Grand Junction Uranium Mill Tailings Remedial Action-Radiological Survey Activities Group (UMTRA-RASA) program employs a screening method in which external exposure rates are used to determine if a property contaminated with uranium mill tailings is eligible for remedial action. Portable NaI detectors are used by survey technicians to locate contaminated areas and determine exposure rates. The exposure rate is calculated using a regression equation derived from paired measurements made with a pressurized ionization chamber (PIC) and a NaI detector. During July of 1985 extensive measurements were taken using a PIC and a NaI scintillator with both analogue and digital readout for a wide range of exposure rates and at a variety of elevations. The surface soil was sampled at most of these locations and analyzed for /sup 226/Ra. The response of the NaI detectors was shown to be highly correlated to radiation level but not to /sup 226/Ra concentration or elevation.
Date: January 1, 1986
Creator: Provencher, R.; Smith, G.; Borak, T.B. & Kearney, P.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department

Southwestern Lore

Description: Collection of a miscellany of Texas and Mexican folklore, including folk stories about treasure hunters, cowboys, Native Americans, and razorback hogs, as well as myths, customs and other superstitions. The index of song material begins on page 192 and the general index begins on page 193.
Date: 1931
Creator: Dobie, J. Frank (James Frank), 1888-1964
Item Type: Refine your search to only Book
Partner: UNT Press

Cloche

Description: Cloche hat of royal blue velvet and silver lace. The cylindrical crown is of royal blue velvet, slightly domed and slightly "crushed". The top panel of the crown is of silver lace over a dark fabric. Around the sides of the crown, nearer the top than the base, is a horizontal band of the same silver lace. The shallow brim is constructed of the royal blue velvet and overlaid with the silver lace, which extends beyond the edge of the velvet. The crown is lined in a cream/iridescent satin; most of the underside of the brim is lined with blue velvet. Maker's label embroidered to center inner lining panel of crown: [pseudo coat of arms] "The Denver Dry Goods Co. / Paris New York / Denver", with small embroidered "FRONT" indicating the front of the hat. Retailer's label sewn to inner side of crown: "Parisian / Abilene, Tex."
Date: 1920/1925
Creator: The Denver Dry Goods Co. (Denver, Colorado)
Item Type: Refine your search to only Physical Object
Partner: UNT College of Visual Arts + Design
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