Copper group, separation

In routine analysis arsenic is precipitated from acid solution as sulphide and with antimony, molybdenum and tin is separated from the copper group by dissolution in yellow ammonium sulphide. The sulphides are reprecipitated from this solution by acidifying, and on treatment with concentrated hydrochloric acid all the sulphides, except arsenic, redissolve. The latter dissolves in aqua regia and arsenic may be identified in the solution by applying one of the tests described in the sequel.1... 

Many schemes oF qualitative analysis involve separation of the copper-group sulfides (PbS, CuS, CdS) horn the tin-group sulfides (HgS,... 

Separation of lead from other members of the silver group or copper group has been achieved by Komlev and Tslmballsta (K2) by precipitation on a column packed with either AlgO or synthetic resin well grovmid with the precipitant. The Ions to be separated were either poured onto a 3- n>m diameter column packed with 4-5 cm of the dry charge or In some cases it was found beneficial to moisten the packed column mixture with a solution of the precipitant before use. 

For separation of silver,- lead and mercury a moist column of AlgO and potassium Iodide was used. Separate zones of Agl, Hggig and Pbig appeared. With the copper group (Cu, Cd, Pb, Bl), AlgOg moistened with saturated NagS or 2N (NH )gS solution was used (K2). 

Sequential group separations using a niimber of different com-plexlng agents in conjunction. with Dowex-50 resin has also been described by Blaedel, Olsen and Buchanan (B9). In this scheme lead Is removed from the resin with 2 per cent citric acid at pH 3.0 along with sixteen other elements. The notable separations appear to be from copper, zinc, cadmium, strontium barium and thallium which adsorb on the resin In this medium. 

Discovered in 1803 by Wollaston, Palladium is found with platinum and other metals of the platinum group in placer deposits of Russia, South America, North America, Ethiopia, and Australia. It is also found associated with the nickel-copper deposits of South Africa and Ontario. Palladium s separation from the platinum metals depends upon the type of ore in which it is found. 

Forma n dyes bear a formal resemblance to a2o dyes, since they contain an a2o group but have sufficient stmctural dissimilarities to be considered as a separate class of dyes. The most important forma2an dyes are the metal complexes, particularly copper complexes, of tetradentate forma2ans. They are used as reactive dyes for cotton (81) is a representative example. 

Polyhydric Alcohols. (Polyols). An alcohol with three or more hydroxyl groups, each attached to a different carbon atom. They are w-sol and of sweetish taste, which tends to intensify with increasing hydroxyl content. Examples of polyols of ordn interest are listed below. Polyvinyl alcohol is considered in a separate entry as a polymer although it is defined as a polyhydric alcohol. Polyols, when nitrated, make excellent expls, proplnt binders, plasticizers, etc. Prepn can follow the procedure of Lenth DuPuis (Ref 3) which uses a methanol suspension of either sucrose or dextrose and a special Cu-Al oxide catalyst to yield 60-65% distillable polyols at 240° and 1500psi Refs 1) Beil — refs found under individual compds 2) CA, under Alcohols, Polyhydric for compds of current ordn interest 3) C.W. Lenth R.N. DuPuis, "Polyhydric Alcohol Production by Hydrogenolysis of Sugars in the Presence of Copper-Aluminum Oxide , IEC 37, 152-57 (1945) CA 39, 1391 (1945)... 

Concave curvatures are always found with calcium while straight lines are obtained in presence of copper. In Figures 3 and 4 the polymer concentration was expressed in mole of carboxyl groups in order to take into account the difference in the charge density between the samples. With copper (Figure 3) all the experimental phase separation points fall almost on a same line that is to say that the total concentration of copper required for precipitation depends only on... 

The first copper(I) complex of tris(hydroxymethyl)phosphine ((760) tetrahedral) has been reported by Samuelson and co-workers. This group addressed the question of anion-controlled nuclearity and metal-metal distances in copper(I)-bis(diphenylphosphino)methane complexes, and in this endeavor they reported the structures of complexes (761) (Cu-Cu separation 3.005-3.128 A), (762) (Cu-Cu separation 3.165 A) and (763) (tetrahedral Cu-Cu 3.293 A). 6 They synthesized and provided structural evidence of oxy anion- encapsulated copper(I) complexes of this ligand. The complexes (764) (distorted tetrahedral Cu-Cu 3.143 A), (765) (distorted tetrahedral Cu-Cu 3.424A), (766) (distorted trigonal Cu-Cu 3.170A), and (767) (Cu-Cu 3.032-3.077A) were reported. They studied solid-state emission spectra of these complexes.567 During this pursuit they... 

The macrocyclic ligands utilized for incorporation of copper generally contain four nitrogens separated by ethylene or propylene groups. The overall size of the macrocycle, thus, extends to fourteen atoms in the case of 4-[(l,4,8,ll-tetraazacyclotetradec-l-yl)methyl]benzoic acid (PCBA) (Figure 8).112... 

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