Lithium bromide molecule

The g = h term has been considered by P. Pyykkoo and J. Linderbarg in On Nuclear Pseudoquadrupole Interactions in Lithium Fluoride and Lithium Bromide Molecules, Chem. Phys. Lett. 5, 34 (1970) and is shown to yield a very small effect. 

If 0.6 N lithium bromide is added to the solution of the polyelectrolyte and also to the solvent on the opposite side of the osmometer membrane, the lowermost set of points in Fig. 145 (lower and left scales) is observed. The anion concentration inside and outside the coil is now so similar that there is little tendency for the bromide ions belonging to the polymer to migrate outside the coil. Hence the osmotic pressure behaves normally in the sense that each poly electrolyte molecule contributes essentially only one osmotic unit. The izjc intercept is lower than that for the parent poly-(vinylpyridine) owing to the increase in molecular weight through addition of a molecule of butyl bromide to each unit. 

Bjornson worked at sufficiently high concentration (0.01m lithium bromide) to observe only the increase in specific conductance due to the addition of bromosuccinic acid to a lithium bromide-acetone solution. Lithium bromide is an ionophore and in acetone exists as lithium ions and bromide ions (conductors) in equilibrium with associated lithium bromide ion pairs (nonconductors), while bromosuccinic acid is an ionogen which exists in acetone as bromosuccinic acid molecules (nonconductors) in equilibrium with hydrogen ions and bromosucci-nate ions (conductors). In order to explain the anomalous increase in specific conductance, Bjornson proposed that when bromosuccinic acid is added to the lithium bromide-acetone solution, bromide ion from the lithium bromide combines with the hydrogen ion from the bromosuccinic acid and forms molecular hydrogen bromide (a nonconductor). This would result in a decrease in concentration of these ions however, as bromide ions and bromosuccinate ions... 

The first and as yet only molecule with conjugated Si=Si double bonds is the tetrasilabuta-1,3-diene (tetrasila-1,3-diene) 139, which was prepared as follows. The disilene 13 is treated with excess lithium to give the putative disilenyllithium species 137. In the second step of the sequence mesityl bromide was added in the expectation that the bulk of the aryl group and the poor solubility of mesityllithium would favor halogenation over the competing transarylation. Indeed, the bromodisilene 138 does appear to be formed smoothly but, like 137, it has not yet been positively identified. Intermolecular cleavage of lithium bromide from the two intermediates then furnishes the tetrasilabuta-1,3-diene 139 in 60% yield (equation 32)130. 

AjH (LlBr, g, 298.15 K) -36.8 3 kcal mol" (-153.971 13 kJ mol"" ) Is calculated from the selected enthalpy of vaporization and the enthalpy of formation for lithium bromide (t). Lithium bromide vaporizes to a mixture of monomeric and dimeric gases. (Higher polymers have been neglected In the calculation.) The enthalpies of vaporization to monomer and to dimer were chosen to satisfy (1) the total vapor pressure data measured by von Wartenberg and Schulz (1 ) and by Ruff and Mugdan (2) the partial vapor pressures of monomer and dimer derived from Miller and Kusch (3 ) In an analysis of the velocity distribution of molecules In... 

An interesting mixed tetrameric complex containing three equivalents of phenyllithium and one equiv-alent of lithium bromide, i.e. [(PhLi)3-LiBr3Et20], depicted as (116), has been characterized." In this mixed aggregate the lithium atom diagonally opposite Ae bromide in the tetramer rem s unsolvated by an ether molecule. Recall that the cyclopropyllithium lithium bromide-diethyl ether complex (44) with... 

In molten lithium bromide, although it has a larger conductivity than potassium bromide, more ions are associated to neutral LiBr molecules than are in potassium bromide to neutral KBr molecules, because Li+ is smaller than K+. In mixtures, Li+ and K+ compete in the formation of molecules LiBr and KBr, respectively, the smaller Li+ being more successful. Therefore in the mixtures, the internal mobility of lithium decreases... 

Two other papers from this laboratory should also be mentioned. Ambrose, Elliott, and Temple (1951) have studied the infrared spectrum of a single crystal of diketopeperazine and obtained excellent confirmation of the structure worked out by Corey (1938) for this molecule by X-ray methods. Of particular interest is the conclusion that the three bonds of the nitrogen atom are coplanar in this molecule. The other publication (Ambrose, Bamford, Elliott, and Hanby, 1951) concerns the spectra of silk rendered soluble in water by treatment in a concentrated solution of lithium bromide. The soluble silk appears to be in the a (folded) configuration and becomes insoluble when it (or part of it) goes over to the 3 (extended) configuration. 

Enantioposition-selective asymmetric cross-coupling has also been successfully applied to the synthesis of axially chiral biaryl molecules (Scheme 11).155],[56] Reaction of the achiral ditriflate 52 with 2 equiv of phenyhnagnesium bromide in the presence of lithium bromide and 5 mol % of PdCl2[(5)-phephos (10b)] at -30 °C for 48 h gave an 87% yield of the monophenylation product (S)-53, which is 93% ee, and a 13% yield of diphenylation product 54. The enantiomeric purity of the monophenylation product... 

Studies on the rate of hydroboration of 1-octene by several borane-Lewis base adducts indicate that the mechanism proceeds via prior dissociation of the adduct which is contrary to the direct attack mechanism proposed on the basis of ab initio calculations. Hydroboration of representative alkenes by borinane dimer in n-heptane proceeds through dissociation of the dimer followed by reaction of the monomer and alkene. Borinane shows similar behaviour to 9-BBN, both molecules differing markedly from other common monofunctional reagents. The factors that affect the stereoselectivities achieved by various hydroborating reagents have been investigated theoretically and the analysis developed into a predictive tool. The reduction of ketones and hydroboration of alkenes by catecholborane is catalysed by lithium bromide. 

Lithium bromide catalyses the decomposition of phenyldiazomethane in ether at room temperature to give stilbene (68%) consisting almost exclusively of the Z-isomer. It is postulated that this remarkable stereoselectivity results from an intermediate in which two lithium ions are sandwiched between two molecules of phenyldiazomethane. In a related study it was shown that formation of the Z-stilbene is also favoured (up to 71%) when the same decomposition is catalysed by copper perchlorate or copper bromide in acetonitrile. ... 

One way to generate carbanions is to combine an acidic molecule with one equivalent of a very strong base, such as n-butyl lithium (n-BuLi). For example, reaction of the alkyne shown below with n-BuLi leads to a carbanion of formula CsH, 02 , which then undergoes an Sn2 reaction with n-propyl bromide (n-PrBr),... 

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