Uranium synthesis

It is possible to prepare very heavy elements in thermonuclear explosions, owing to the very intense, although brief (order of a microsecond), neutron flux furnished by the explosion (3,13). Einsteinium and fermium were first produced in this way they were discovered in the fallout materials from the first thermonuclear explosion (the "Mike" shot) staged in the Pacific in November 1952. It is possible that elements having atomic numbers greater than 100 would have been found had the debris been examined very soon after the explosion. The preparative process involved is multiple neutron capture in the uranium in the device, which is followed by a sequence of beta decays. Eor example, the synthesis of EM in the Mike explosion was via the production of from followed by a long chain of short-Hved beta decays,... 

CoF is used for the replacement of hydrogen with fluorine in halocarbons (5) for fluorination of xylylalkanes, used in vapor-phase soldering fluxes (6) formation of dibutyl decalins (7) fluorination of alkynes (8) synthesis of unsaturated or partially fluorinated compounds (9—11) and conversion of aromatic compounds to perfluorocycHc compounds (see Fluorine compounds, organic). CoF rarely causes polymerization of hydrocarbons. CoF is also used for the conversion of metal oxides to higher valency metal fluorides, eg, in the assay of uranium ore (12). It is also used in the manufacture of nitrogen fluoride, NF, from ammonia (13). 

Many challenging industrial and military applications utilize polychlorotriduoroethylene [9002-83-9] (PCTFE) where, ia addition to thermal and chemical resistance, other unique properties are requited ia a thermoplastic polymer. Such has been the destiny of the polymer siace PCTFE was initially synthesized and disclosed ia 1937 (1). The synthesis and characterization of this high molecular weight thermoplastic were researched and utilized duting the Manhattan Project (2). The unique comhination of chemical iaertness, radiation resistance, low vapor permeabiUty, electrical iasulation properties, and thermal stabiUty of this polymer filled an urgent need for a thermoplastic material for use ia the gaseous UF diffusion process for the separation of uranium isotopes (see Diffusion separation methods). 

The main technological uses for UO2 are found in the nuclear fuel cycle as the principal component for light and heavy water reactor fuels. Uranium dioxide is also a starting material for the synthesis of UF [10049-14-6] 6 (both critical for the production of pure uranium metal and... 

M. H. West, M. M. Maitinez, J. B. Nielson, D. C. Court, and Q. D. Appeit, Synthesis of Uranium Metal UsingEaser-InitiatedTeduction of Uranium Tetrafluoride by Calcium Metal, LA-12996-MS, Los Alamos National Laboiatoiy, N.M., 1995. 

One of the major advances of science in the first half of this century was the synthesis of ten elements beyond uranium. Glenn T. Seaborg participated in the discovery oj most of these, a sufficient tribute to his outstanding ability as a scientist. For the first such discoveries, those of neptunium and plutonium, he shared with Professor Edwin M. McMillan the Nobel Prize in Chemistry for 1951. 

In the usual high-vacuum apparatus I placed aluminum borohydride onto a sample of uranium tetrafluoride. I observed an immediate reaction, with formation of green crystals which could be moved about the vacuum apparatus. As it happened, on the very day I was performing the synthesis, we had a visit from Professor H. C. Urey, who was in charge of the overall study. He immediately asked us to increase our research effort and undertake to prepare uranium tetraborohydride on a relatively large scale, adequate for testing. 

This was obviously a major improvement over the original procedure, which involved many more steps, some of them quite difficult. We happily reported this improved synthesis and undertook to use it to produce uranium(IV) borohydride for large-scale testing. 

Beyond Z = 100, synthesis by neutron bombardment of uranium is no longer effective. Instead, nuclides in the Z = 95 to 99 range are bombarded with beams of light nuclei. For example, mendelevium (Z = 101) was first... 

Nickel and selenium interact with incandescence on gentle heating [1], as do also sodium and potassium, the latter mildly explosively [2], Uranium [3] and zinc [4] also incandesce when their mixtures with selenium are heated, and platinum sponge incandesces vividly [5], The particle size of cadmium and selenium must be below a critical size to prevent explosions during synthesis of cadmium selenide by heating the elements together. Similar considerations also apply to interaction of cadmium or zinc with sulfur, selenium or tellurium [6], Interaction of powdered tin and selenium at 350° C is extremely exothermic [7],... 

In order to eliminate competing reaction with the solvent, a method for generating active uranium in hydrocarbon solvents was desired. Thus a hydrocarbon soluble reducing agent [(TMEDA)Li ]9 [Nap] (Nap=naphthalene) was prepared. This complex has previously been maae from 1,4-dihydro-naphthalene(llO). We have prepared this complex from lithium, naphthalene and TMEDA in a convenient reaction which is amenable to large scale synthesis. 

We have previously documented the methodology (Marks et al., 1985a) and presented a summary of the technique (Marks et al., 1985b) at the Maastricht, The Netherlands, Seminar on Exposure to Enhanced Natural Radiation and Its Regulatory Implications. This paper represents a synthesis of the work we have conducted to date on risk assessment at uranium mill tailings vicinity properties. 

Heterojunction with intrinsic thin layer (HIT) photovoltaic cell, 23 46-47 Heteroleptic uranium complexes, 25 441 Heterologous promoters, 22 453 Heteronano interface (HNI), 23 838 Heteronium bromide, 4 359t Heteronuclear metal carbonyls, synthesis of, 26 69-71... 

Phosphorite deposits, 17 688, 691 Phosphorite uranium deposits, 17 520 Phosphorochloridate synthesis, 19 28 Phosphorodithioate DNA, 17 630 Phosphorodithioates, 17 630 Phosphorothioates, 17 629-630 synthesis of, 17 630 Phosphorous acid, 19 52 Phosphorous donor ligands, thorium and, 24 768 Phosphors... 

Uses Denaturant for ethyl alcohol solvent for paints, varnishes, cellulose acetate, nitrocellulose lacquers, resins, fats, oils, and waxes preparation of methyl amyl alcohol in hydraulic fluids and antifreeze extraction of uranium from fission products organic synthesis. 

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