Sodium-potassium Alloy Research Articles

Synthesis, properties and structures of the tris(cyclopentadienyl)thorium(III) complexes [Th{η 5-C 5H 3(SiMe 2R) 2-1,3} 3] (R=Me or tBu)

The homoleptic, dark-blue, crystalline (disubstituted-cyclopentadienyl)thorium(III) complexes [Th{η 5-C 5H 3(SiMe 2R) 2-1,3} 3] (R=Me 1 or t Bu 3) were obtained in good yield from the appropriate tris(cyclopentadienyl)thorium(IV) chloride by treatment with an excess of sodium–potassium alloy in toluene at 20–35 °C with sonication. Complex 1 was also accessible by a similar reduction of [ThCp″ 2Cl 2] [Cp″=η 5-C 5H 3(SiMe 3) 2-1,3]; with possibly a transient Th(II) cyclopentadienyl as intermediate. Complex 1 with wet toluene afforded [(ThCp″ 3) 2(μ-O)] ( 2); it was unreactive with THF, DME, CO or H 2, but with Na–K alloy in THF it afforded a green, diamagnetic, readily oxidisable cyclopentadienylthorium complex. Complexes 1 and 3 showed singlet EPR spectra in methylcyclohexane at 298 K, whence it is concluded that they have a 6d 1 rather than a 5f 1 electronic ground state. Variable temperature EPR spectra, magnetic measurements and optical spectra of 1 are described and discussed. The X-ray structures of crystalline 1 and 3 show that each has approximate D 3 h symmetry about the Th atom, which can be regarded as bound to the centroid of each of the three cyclopentadienyl rings.

Si—H Functional Polysilanes via a Homogeneous Reductive Coupling Reaction

A polysilane copolymer with reactive Si—H side groups was obtained through a homogeneous coupling reaction of dichlorodiphenylsilane with dichloromethylsilane. The reaction was carried out in a tetrahydrofuran (THF) solution of a sodium-potassium alloy complex with 18-crown-6 with a well defined composition of alkali metal ion pairs (Mt+/crown ether, Mt–) at –75°C. The product was characterized using 1H NMR, 13C NMR, FT-IR and UV/Visible spectroscopies and gel permeation chromatography. The results were compared with those obtained by the heterogeneous coupling reaction of the same monomers.

Reactions of Sodium-Potassium Alloys with Inert Gas Impurities − Potential Hazards after Oxidation

Reactions of Sodium-Potassium Alloys with Inert Gas Impurities − Potential Hazards after Oxidation

Reactions of Sodium-Potassium Alloys with Inert Gas Impurities − Potential Hazards after Oxidation

A bibliographical study of the reactions of NaK alloys with their oxides did not explain the related accidents that have occurred in the past, particularly those involving the handling of bubblers installed to remove traces of oxygen and water vapor from blanket gases of LMFR (liquid metal fast reactors). Moreover, it revealed a controversy with respect to the explosive hazard of the NaK alloys + KO2 reaction. A thermodynamic study of the reaction of a NaK alloy with oxygen as well as experimental work on mixtures containing NaK and different oxides (KO2, Na2O, Na2O2) led to the conclusion that violent reactions occurring at ambient temperature, were always linked to the presence of hydrated superoxides or hydroxides. On contact with NaK alloys, these hydrated compounds lead to the formation of hydrogen with a release of heat causing the decomposition of potassium superoxide KO2 and the simultaneous release of oxygen. The oxidation of liquid NaK alloy, by bubbling a mixture of argon and air containing traces of water vapor (H2O < 5 vpm), leads to the formation of mainly KO2, besides the hydrated compounds Na2O2·2H2O, NaOH·H2O and KOH·H2O. The gas follows preferential paths and the product obtained is highly heterogeneous in both composition and hardness (porous parts and dense parts). Hydrated superoxide and hydroxides treated under vacuum result in nearly quantitative dehydration after heating at 100 °C. For storage elements or safety valves, containing NaK that has been submitted to slow surface oxidation and hydration, the oxidized layer contains KO2, Na2O2·nH2O and hydrated hydroxides of sodium and potassium. In order to avoid any hazard due to the contact of the oxides with the residual NaK alloy during transport or under impact, it is necessary to freeze the alloy and to reheat it very slowly. Operations such as draining should also be performed slowly, after having calibrated the tanks (temperature and pressure). Therefore the use of NaK liquid alloy to purify gases is questionable; as preferential paths are established, it remains impossible to predict the period of efficiency of a bubbler. Moreover, the NaK alloy does not chemically transform all traces of water vapor; because some remains present in the form of hydrated products, leading to the formation of wastes with a potential hazard during storage or destruction. In our opinion, this method of purification should be abandoned.

Characterization of potassium and sodium–potassium alloy solutions containing metal anions and complexed cations by means of NMR and ESR techniques

The influence of a complexing agent, kind of solvent and temperature on the stability and ionic composition of potassium and sodium–potassium alloy solutions containing metal anions and complexed cations as well as solvated electrons are discussed basing on the analysis of alkali metal NMR and ESR spectra. Surprisingly it seems that the stability of metal solutions in tetrahydrofuran at ambient temperature is inversely proportional to the durability of K + complex in the case of five studied ligands. The most stable metal solutions were obtained using 15-crown-5. It was shown that the characteristic blue colour of metal solutions is not connected with the presence of solvated electrons but with metal anions.

On the Ternary System Graphite-Sodium-Potassium

The intercalation of sodium-potassium alloys into graphite leads, at room temperature, to compounds close to KC8. Graphite powder fits to large amounts of the alloy: up to compositions close to MC2, but the stable state is a mixture of KC8 and alloy excess. In spite of the presence of large quantities of free alloy, liquid at room temperature, the powder does not agglomerate and constitutes an important solid reservoir for alkali metals.

Modeling of LMR fuel pin temperature behavior using water

This paper describes the possibilities for modeling of non-uniform temperature behavior around the metal fuel pins in reactors cooled by liquid metal using water. The temperature non-uniformities arise due to nonsymmetric heat removal from the pin. The data on heat transfer to mercury, sodium-potassium alloy and water in compact pin bundles found in the State Scientific Center of Russian Federation « Institute of Physics & Power Engineering » are analyzed here. The principles of thermal similarity of fuel pins form the basis of the analysis mentioned.

Synthese und eigenschaften funktioneller Tetrasilane und Hexasilane

Abstract The methylphenylsilanes Ph2Si(SiMe3)2, SiMe3SiPh2SiPh2SiMe3, SiMe3SiPh2SiPh2SiPh2SiMe3, PhSi(SiMe3)3 and (SiMe3)2SiPhSiPh(SiMe3)2 have been prepared by dehalogenation of mixtures of Ph2SiMe2/ClSiMe3 and PhSiCl3/ClSiMe3 with sodium-potassium alloy or by reductive coupling of appropriate triflated silanes with lithium. The reactions of the silanes with HX/AlX3 (X = Cl, Br, I) as well as triflic acid have been investigated and the crystal structure of the tetrasilane Me3SiSiPh2SiPh2SiMe3 has been determined.

Contribution to the Chemistry of Boron, 232. Formation, Structure and Reactions of a P,P′‐Bi(1,3,2,4‐diphosphadiboretane)

AbstractPhotolysis of the 1,3,2,4‐diphosphadiboretane (tBuPBtmp)2 (1) in dilute toluene solution yields the bicyclic diphosphadiboretane 2. In concentrated toluene solution or in hexane, however, the P,P′‐connected bi(diphosphadiboretane) 4 is also formed implying that the radical [tBuP(Btmp)2P] 3 is the first photolysis product. On further photolysis, 3 and 4 are converted into bicyclic 2 as the final product. Reduction of 4 with sodium‐potassium alloy followed by silylation with Me3‐SiCl leads to the 1,3,2,4‐diphosphadiboretanes (tmpBP‐SiMe3)2 and [HP(Btmp)2PSiMe3]2. In contrast to many 1,3,2,4‐diboretanes, 4 in the absence of photon or thermal promotion does not react with Cr(CO)5 · THF, Fe2(CO)9, or Pd(PPh3)4. However, a mixture of Cr(CO)5 · THF and 4 on photolysis gives the known complex (tmpBP)2 · 2 Cr(CO)5.

Preparation of polycarbosilanes and polysilanes from (trimethylsilylmethyl)chlorosilanes

The one-step conversion of (Me3SiCH2)SiCl3 to polycarbosilanes by reaction with three molar equivalents of the alkali metals lithium, sodium, or sodium potassium alloy is reported. The expected network polysilanes were not isolated. Under similar conditions (Me3SiCH2)SiHCl2 gives polysilanes. The low molecular weight polymers have been characterized by elemental analyses, gpc, and FT-IR, NMR, UV-vis, and mass spectroscopies.

Synthesis, x-ray crystal structure, and phosphine-exchange reactions of the hafnium(III)-hafnium(III) dimer Hf2Cl6(PEt3)4

Reduction of HfCl 4 with sodium-potassium alloy in the presence of PEt 3 yields the dark green hafnium(III)-hafnium(III) dimer Hf 2 Cl 6 (PEt 3 ) 4 . The X-ray crystal structure shown that molecules of Hf 2 Cl 6 (PEt 3 ) 4 consist of two octahedral hafnium centers that are connected by a hafnium-hafnium bond and two bridging chloridc ligands.

Liquid Metal Flow Through a Right Angle Bend in a Strong Magnetic Field

AbstractIn designing a self-cooled liquid metal blanket based on the poloidaltoroidal flow concept, the magnitude of the MHD pressure drop and the character of the velocity distribution in the first wall coolant channels, that result from 3-dimensional MHD effects associated with the required right angle bends in the coolant flow, represent important design issues. To address these issues and to verify the relevant models used in the design, a joint MHD-experiment was conducted by Argonne National Laboratory (AND and Kernforschungszen-trum Karlsruhe (KfK). The test article was designed and built at ANL, and the experiments were performed at KfK’s MEKKA facility using a 3.6 Tesla superconducting solenoid magnet and a eutectic sodium potassium alloy working fluid. In the experiments, detailed voltage and pressure distributions on the duct walls and voltage distributions within the liquid metal were measured under a variety of Hartmann numbers and interaction parameters. Representative results from these mea...

Synthesis and NMR spectroscopy of permethylpolysilane oligomers Me(SiMe2)10Me, Me(SiMe2)16Me, and Me(Me2Si)22Me

The title compounds were synthesized by coupling a toluene solution of Me 3 SiSiMe 2 Cl and Cl(SiMe 2 ) 6 Cl with sodium-potassium alloy. The 1 H, 13 C, and 29 Si NMR spectra of Si10 were fully assigned by 2D 1 H- 13 C and 1 H- 29 Si NMR spectroscopy; the latter method is useful for obtaining Si-Si as well as Si-H connectivities. Si-Si coupling constants for Si10 were determined with use of INEPT-INADEQUATE NMR spectroscopy

An EPR study of 1-adamantylmethyl radicals

The 1-adamantylmethyl, di(1-adamantyl)methyl, and tri(1-adamantyl)methyl radicals have been prepared by photolysis of hexabutylditin in presence of the corresponding bromide, the 1-adamantylhydroxymethyl radical by photolysis of di-tert-bulyl peroxide in presence of 1-adamantylmethanol, and the di-1-adamantylketyl radical anion by photolysis of di-1-adamantyl ketone in presence of sodium–potassium alloy. The EPR 1H and 13C hyperfine coupling constants which are observed in these radicals and in the tetra-1-adamantylcyclobutadiene radical cation are discussed in terms of the structures of the radicals.The di-1-adamantylmethyl radical decays in cyclopentane at 310 K and in toluene at 180–240 K by clean pseudo first-order kinetics. The reaction is much faster in the latter solvent, implying that it involves abstraction of benzylic hydrogen. At 190 K in pentane, the decay shows second-order kinetics. The decay of the tri-1 -adamantylmethyl radical shows more complicated behaviour.

ChemInform Abstract: A Convenient One‐Pot Method for the Hydroxymethylation of Grignard Reagents.

Grignard reagents and alkynyllithiums can be hydroxymethylated in a two-step one-pot reaction by reaction of a Grignard reagent with 1-chloro-2-(chloromethoxy)ethane (1), followed by treatment with sodium-potassium alloy and aqueous workup. The reaction was found to work for primary, secondary, tertiary, benzylic, allylic and aryl Grignard reagents in yields ranging from 57-95%.

ChemInform Abstract: 9‐Diisopropylamino‐9‐borabicyclo(4.2.1)nona‐2,4,7‐triene from the Reaction of Cyclooctatetraene with Sodium‐Potassium Alloy and Dihalogeno(diisopropylamino)boranes.

ChemInformVolume 21, Issue 22 Organoelement Compounds ChemInform Abstract: 9-Diisopropylamino-9-borabicyclo(4.2.1)nona-2,4,7-triene from the Reaction of Cyclooctatetraene with Sodium-Potassium Alloy and Dihalogeno(diisopropylamino)boranes. W. MARINGGELE, W. MARINGGELE Inst. Anorg. Chem., Univ. Goettingen, D-3400 GoettingenSearch for more papers by this authorD. STALKE, D. STALKE Inst. Anorg. Chem., Univ. Goettingen, D-3400 GoettingenSearch for more papers by this authorA. HEINE, A. HEINE Inst. Anorg. Chem., Univ. Goettingen, D-3400 GoettingenSearch for more papers by this authorA. MELLER, A. MELLER Inst. Anorg. Chem., Univ. Goettingen, D-3400 GoettingenSearch for more papers by this authorG. M. SHELDRICK, G. M. SHELDRICK Inst. Anorg. Chem., Univ. Goettingen, D-3400 GoettingenSearch for more papers by this author W. MARINGGELE, W. MARINGGELE Inst. Anorg. Chem., Univ. Goettingen, D-3400 GoettingenSearch for more papers by this authorD. STALKE, D. STALKE Inst. Anorg. Chem., Univ. Goettingen, D-3400 GoettingenSearch for more papers by this authorA. HEINE, A. HEINE Inst. Anorg. Chem., Univ. Goettingen, D-3400 GoettingenSearch for more papers by this authorA. MELLER, A. MELLER Inst. Anorg. Chem., Univ. Goettingen, D-3400 GoettingenSearch for more papers by this authorG. M. SHELDRICK, G. M. SHELDRICK Inst. Anorg. Chem., Univ. Goettingen, D-3400 GoettingenSearch for more papers by this author First published: May 29, 1990 https://doi.org/10.1002/chin.199022216Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume21, Issue22May 29, 1990 RelatedInformation

Short Communication 9‐Diisopropylamino‐9‐borabicyclo[4.2.1]nona‐2,4,7‐triene from the Reaction of Cyclooctatetraene with Sodium‐Potassium Alloy and Dihalogeno(diisopropylamino)boranes

The reaction of 1,3,5,7-cyclooctatetraene with sodium-potassium alloy and dihalogeno(diisopropylamino) boranes in 1,2-dimethoxyethane gives the title compound, characterized by elemental analysis, MS(EI, FI), NMR( 1 H, 11 B, 13 C), and X-ray crystallography

Synthese und schwingungsspektren einiger Si-reicher silylarsane, -stibane und -bismuthane

Sodium-potassiumarsenide, -stibide and -bismuthide (prepared from the elements and sodium-potassium alloy in DME) react with chloropentamethyldisilane and 2-chloroheptamethyltrisilane to give silicon-rich trisilylarsanes, -stibanes and -bismuthanes. The IR and Raman spectra of the compounds were investigated using a normal coordinate analysis. The spectra of tris(trimethylsilyl)arsane and tris(trimethylsilyl)arsane-d27 are also discussed. SiAs, SiSb and SiBi force constants are reported.

Activation of aromatic CH bonds by zerovalent ruthenium complexes of bis(dimethylphosphino)methane

Reaction of [RuCl 2(PPh 3) 3] with excess bis(dimethylphosphino)methane (dmpm) in petroleum produces trans-[RuCl 2(dmpm) 2], whilst a similar reaction using [OsCl 2(PPh 3) 3] in toluene produces only [OsCl 2(dmpm) 2(PPh 3) 2] with trans-chlorine atoms or, under reflux in the presence of excess dmpm, [OsCl 2(dmpm) 3]. Reduction of [RuCl 2(dmpm) 2] with sodium-potassium alloy in benzene or toluene produces cis-[RuHR(dmpm) 2] (R = Ph or C 6H 4Me), together with small amounts of unidentified products, one of which is paramagnetic. The hydrido aryl complexes are characterized spectroscopically and the exchange of cis-[RuHPh(dmpm) 2] with C 6D 6 is described.

A Convenient One-Pot Method for the Hydroxymethylation of Grignard Reagents

Grignard reagents and alkynyllithiums can be hydroxymethylated in a two-step one-pot reaction by reaction of a Grignard reagent with 1-chloro-2-(chloromethoxy)ethane (1), followed by treatment with sodium-potassium alloy and aqueous workup. The reaction was found to work for primary, secondary, tertiary, benzylic, allylic and aryl Grignard reagents in yields ranging from 57-95%.