Tris-sulfate, solution preparation

When A. S. Marggraf tried to prepare alum from alumina and vitriolic acid, he found that unless he added fixed alkali he obtained no crystals (19). In 1777 Lavoisier clearly stated that potash is an essential constituent of alum (18, 20). In analyzing a water containing aluminum sulfate, which the younger Cassini had sent him from Italy, Lavoisier added some potash When he evaporated the solution, he obtained crystals of alum and realized that this was a verification of the results of Marggraf and of Macquer. 

The [Cr(en)3]2+ and [Cr(pn)3]2+ salts have reflectance spectra (Table 11) resembling those of the hexaammines, and the six N donor atoms are assumed to complete tetragonally distorted octahedra around the metal. Stability constant measurements (Table 39) have shown that the ions [Cr(en)(aq)]2+ (vmax= 18 300 cm-1, e = 25 dm3 mol-1 cm-1) and [Cr(en)2(aq)]2+ (vma = 17 500 cm-1, e = 17 dm3 mol-1 cm-1) exist in aqueous solution, but that, as in the copper(II) system, the third ethylenediamine molecule is only weakly bound, and care is needed to prevent loss of en from tris(amine) complexes in the preparations. Several bis(amine) complexes, e.g. [CrBr2(en)2], have been isolated, and these are assigned trans structures because of IR spectral resemblances to the corresponding oopper(II) complexes. Since the spectrum of [Cr(S04)(en)2] also shows the presence of bidentate sulfate, this is assigned a trans octahedral structure with bridging anions. 

Hydroxoaquobis(biguanide)chromium(III) sulfate forms violet crystals which are sparingly soluble in water and do not lose any water even when heated to 120°. On treatment with hot caustic solution the substance is converted into tris(biguanidato) chromium which separates as ruby-red crystals. The chloride of the hydroxoaquo compound may be prepared as rose-red crystals by treating the sulfate with the calculated amount of barium chloride. 

Transfer buffer—We suggest that this solution be prepared fresh on the day of the experiment. Dissolve 11.6 g of Tris base, 5.86 g of glycine, and 0.038 g of sodium dodecyl sulfate in 700 ml of distilled water. Adjust pH to 9.2 with HC1 or NaOH as needed. Add 200 ml of methanol. Bring the final volume of the solution to 1 liter with distilled water. Store this solution tightly covered at room temperature. 

Tris-(2-imidazolidinethione)copper(I) acetate and sulfate have similarly been obtained by reducing the appropriate copper(II) salt with the ligand in water. They are presumably ionic since solutions of the latter gave an immediate precipitate of BaS04 when treated with BaCl2 249). Tris (0-ethylaminothioformate)copper(l) chloride 101, 299) and bromide 299) have been prepared from the copper(I) salts. 

Meyer and Schwartz, in a study of model compounds structurally related to heparin, showed that the hydrolytic release of sulfate under acid conditions from 2-amino-2-deoxy-D-glucose A -sulfate is more rapid than from D-glucose 6-0-sulfate. These workers also obtained a biologically inactive, nitroso derivative of heparin, and offered this as evidence for a sulfamic acid linkage in the molecule. Wolfrom, Shen and Summers prepared methyl 2-amino-2-deoxy-A-sulfo-tri-0-sulfo-(3-D-glucopyranoside dibarium salt, and found that, on heating a 3 X 10 M solution in 0.004 N hydrochloric acid, the A-sulfate is lost in 20 minutes and the 0-sulfate after 12 hours. 

Sulfates and sulfites. Mono- and bis-sulfate complexes of actinyl ions, An02S04 and An02(S04)2 , are generally prepared from acidic solutions. The geometry about the actinide metal center is pentagonal biypyramidal from actinyl, sulfato, and aquo oxygen atoms. A tris(sulfato) complex has been reported, but it is very weak if it does exist. Ternary hydroxo, sulfato complexes have been reported for uranyl, but they have not been structurally characterized. 

A solution of the dichlorolactone (1.5 g, 2.15 imnol) and freshly prepared tributyltin hydride (1.3 mL, 4.9 nunol) in benzene (20 inL) was heated at 78 °C for 15 min. in the presence of a catalytic amount of EtsB (0.7 inL of a 1 M solution in THF, 0.7 mmol). After evaporation of the solvent in vacuo, the residue was dissolved in ether (25 mL). The ether solution was treated with a saturated aqueous solution of potassium fluoride (25 mL). The precipitated tri-n-butyltin fluoride was filtered and washed thoroughly with ether. The combined ether layers were dried over magnesium sulfate and evaporated in vacuo. The residue was chromatographed on silica gel using a gradient of eluents (hexanes EtOAc, 20 1 to 4 1) giving 1.27 g (92%) of the lactone as a clear oil. 

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