Calcium, bis

Examples Ca[PFg]2, calcium bis(hexalluorophosphate) and (CioH2i)3P04, tris(decyl) phosphate instead of tridecyl which is (Cj3H27—). 

Lhuintre JP, Moore ND, Saligaut C, et ah Ability of calcium bis acetyl homotaurinate, a GABA agonist, to prevent relapse in weaned alcoholics. Lancet 1 1014-1016, 1985... 

C5HgN04,Ca-4 H20 Calcium bis(2-amino-2,3,4-trideoxy-L-gfi/cero-pentarate) (calcium di-L-glutamate), tetrahydrate5... 

Calcium bis(2-amino-2,3,4-trideoxy-L-gZycero-pentarate) (calcium di-L-glutamate), tetrahydrate D-Arabinono-1,4-lactone Calcium L-arabinonate, pentahydrate Strontium L-arabinonate, pentahydrate Barium D-ribose 5-phosphate, pentahydrate 2-Deoxy-D-en/thro-pentose j8-DL-Arabinopyranose... 

Amino-3-methylisoxazole, 1502 2-Amino-4-methyloxazole, 1500 5-Amino-3-methylthio-l,2,4-oxadiazole, 1192 Ammonium A-nitrosophenylaminooxide, 2399 2-Aza-l,3-dioxolanium perchlorate, 0898 Azoformaldoxime, 0815 Bis(l-benzo[d]triazolyl) carbonate, 3598 Bis(l-benzo[d]triazolyl) oxalate, 3629 Bis(trifluoromethyl) nitroxide, 0638 2-/er/-Buty 1-3 -phenyloxaziridine, 3406 Calcium bis(O-hydroxylamide). 3930 Calcium hydroxide O-hydroxylamide, 3929... 

SILICON AND SILICON ALLOYS - CHEMICAL AND METALLURGICAL] (Vol 21) Calcium bis [O-ethyl (3,5-di-tert-butyl-4-hydroxybenzyl)phosphonate] [65140-91-2]... 

Insertion reactions of calcium atoms into M14—M14 bonds yield symmetrical or unsym-metrical M14—Ca compounds according to Scheme 144 and equation 6989. A trimethylsi-lyl trimethylstannyl calcium was also characterized chemically in the cocondensation of calcium with trimethylsilyl trimethylstannane90. Calcium bis(stannide) (equation 69) crystallizes in the form of colorless cuboids in a centrosymmetric space group PI. The calcium atom lies on the crystallographic center of inversion in the middle of the linear Sn—Ca—Sn chain. The calcium atom is coordinated in a distorted octahedral fashion by two tin atoms... 

The tetrahydroborate salts of alkali metals, M[BH4] (M = Li, Na, K),1 are important because they serve as starting materials for the preparation of other boron hydrides2,3 and because they are used frequently as reducing agents.4 The lithium and sodium salts are prepared on a technical scale.5 9 The tetrahydroborate salts of the alkaline earth metals, M[BH4]2 (M = Mg, Ca, Sr, Ba), have not as yet been used extensively however, calcium bis[tetrahydroborate(l-)], Ca(BH4)2,10 is very soluble in tetrahydrofuran (THF) and it therefore has considerable potential application as a substitute for the lithium and sodium salts. 

Calcium bis[tetrahydroborate(l-)] may be prepared from sodium tetra-hydroborate( 1 -) and calcium dichloride by cation exchange11 in a suitable solvent such as dimethylformamide,12 an amine13,14 or an alcohol.13,14 A particularly good preparation of very pure Ca[BH4]2 involves the reaction of calcium dihydride with the triethylamine-borane adduct.15,16 This method may also be used for the preparation of other tetrahydroborates of alkali and alkaline earth metals. The triethylamine-borane adduct17 may be synthesized in a variety of ways, e.g., from triethylamine, sodium tetrahydro-borate(l —), and trichloroborane 18 from a trialkoxyborane, aluminum metal, and hydrogen in the presence of triethylamine 19 or by hydrogenation under pressure of a mixture of triethylborane and triethylamine.20 The triethylamine-borane adduct is a colorless liquid (mp — 2°). It is stable to air and moisture at room temperature and it is easily purified by vacuum distillation (bp 95-96°/12 torr). 

The preparation of calcium bis[tetrahydroborate(l —)] described here is recommended because high yields of pure product are usually obtained without difficulty. If the material should be contaminated by impurities from the calcium hydride, then it may be extracted with THF. Needles of Ca[BH4]-2THF11,21,22 may be obtained from this solution. The THF can then be readily removed by heating and pumping. 

Caution. Calcium dihydride and calcium bis[tetrahydroborate( 1 —)] react vigorously with water, alcohols, and other compounds which contain acidic hydrogen atoms, sometimes with spontaneous ignition. The reaction should be carried out in an efficient hood and the reagents and products should be handled under an inert gas. 

Calcium bis[tetrahydroborate(l —)] is obtained as a fine powder which must be stored in well-sealed containers. It is stable in dry air at room temperature but traces of moisture decompose it with liberation of hydrogen. The gas evolution is quantitative when dilute hydrochloric acid is added. The compound decomposes at ca. 260°. The solvate Ca[BH4]2 -2THF loses THF on heating to 240° in vacuo. Calcium bis[tetra-hydroborate(l —)] dissolves exothermally in THF and crystalline Ca[BH4]2 -2THF may be isolated from the solution. The Ca[BH4]2 2THF is very soluble in dimethyl sulfoxide, in hexamethylphosphoric triamide, and in bis(2-methoxyethyl) ether (diglyme). 

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