Arsenic compounds preparation

Basic copper ethanoate arsenates(iii) prepared from verdigris (or other basic copper salt), sodium arsenate(m) and ethanoic acid. Used in insecticides for spraying fruit trees. Readily decomposed to soluble arsenic compounds so use is very restricted. 

Semiconductor Applications. A limited but important demand for metaUic arsenic of 99.99% and greater (exceeding 99.999 + %) purities exists in semiconductor appHcations (see Semiconductors). This high purity arsenic may be prepared by the reduction of a highly purified arsenic compound using a high purity gaseous or soHd reductant. 

Arsenlkalien, /.pi. arsenicals, arsenical compounds or preparations, arsenikalisch, a. arsenical. 

The preparation of similar precursors suitable for the deposition of metal nitrides is analogous to the preparations of phosphorus and arsenic compounds. The initial reaction of metal trialkyls MR3 (M = A1, Ga, In) with amines (NHR 2) results in the formation of oligomeric amido compounds [R2MNR 2] (n = 2 or 3) which eliminate alkanes on thermolysis. The incorporation of a proton as a substituent on the pnictide bridging ligand has been examined, and many compounds of the type [R2MNHR ]2 have been synthesized. The presence of this proton may facilitate /3-elimination, allowing lower deposition temperatures to be used. 

Arsenic trioxide is used as a starting material to prepare metallic arsenic and a number of arsenic compounds. It is also used as a decolorizer for bottle glass in pigments and ceramic enamels for preserving hides as a wood preservative as an analytical standard in oxidimetry titrations and in many rodenticide and herbicide formulations. 

Arsenic triiodide, preparation of, 7 15 Arsenic(V), C-containing compounds, 28 204-216... 

Caution All steps in the following preparations should be performed under a hood, since volatile arsenic compounds may be liberated. 

The most common structures of arsenic compounds are tetrahedral and pyramidal, which are similar when the sterically active lone pair is counted. Tetrahedral symmetry holds the potential for chirality and indeed many chiral organoarsenic compounds have been prepared. Arsenic may also use d orbitals for (d-d)n bonding and for hybridization with s2 and p3 orbitals, resulting in trigonal bipyramidal or octahedral structures. In the former the more electronegative substituents occupy the apical position. 

Sufficient to say that, of all the members of Group 5, the analogies between phosphorus and arsenic are closest. When used as coreactant with arsenic compounds, phosphorus compounds may react interchangeably. The recent preparation of P=As compounds by Escudie et a/.22 relied on this scrambling of arsenic and phosphorus reactants (equation 8). 

Laschtschenko therefore suggested that the amorphous forms may be of colloidal origin and may thus represent stages in the continuous passage from the colloidal to the crystalline state. The mode of preparation of the brown form by reduction of arsenic compounds in solution is favourable to sol formation, and the view that the various forms differed only in degree of dispersion of the particles has already been mentioned (p. 30). X-ray investigations6 show that the precipitated... 

Since this discovery a number of binuclear complexes of this type have been isolated, including the arsenic analog of the above (57) and compounds prepared from more exotic ylide precursors (58-60). A polymeric gold(I) complex was obtained by reaction of [AuCl(PMe3)] with the biden-tate ylide CH2=PMe2(CH2)6PMe2=CH2 (60). 

Arsenic triiodide has been prepared by direct union of the elements with or without a solvent,1 by the reaction of iodine with arsenic trioxide2 or sulfide,3 and by the reaction of aqueous solutions of an arsenic compound and an iodide.4 The last mentioned furnishes the most convenient method of obtaining the material in pure form. 

Probably one of the commonest reactions encountered in the template synthesis of macrocycles is the formation of imine C=N bonds from amines and carbonyl compounds. We have seen in the preceding chapters that co-ordination to a metal ion may be used to control the reactivity of the amine, the carbonyl or the imine. If we now consider that the metal ion may also play a conformational role in arranging the reactants in the correct orientation for cyclisation, it is clear that a limitless range of ligands can be prepared by metal-directed reactions of dicarbonyls with diamines. The Tt-acceptor imine functionality is also attractive to the co-ordination chemist as it gives rise to strong-field ligands which may have novel properties. All of the above renders imine formation a particularly useful tool in the arsenal of preparative co-ordination chemists. Some typical examples of the templated formation of imine macrocycles are presented in Fig. 6-12. 

The techniques used in the certification were based on hydride generation following either UV irradiation, GC or LC with ICPAES or QFAAS detection. Two techniques did not use hydride generation and were based on LC followed by QFAAS or ICPMS detection. The synthesis of pure calibrants or arsenic compounds has been necessary to enable a proper calibration to be carried out. All details on the techniques and calibrant preparation are described elsewhere (Quevauviller, 1998b). 

Wear nitrile rubber gloves, eye protection, and laboratory coat. Avoid breathing dust. In the fume hood, dissolve the arsenic compound in acidified boiling water (for 1 g of arsenic compound, use 100 mL of water containing 6 drops of concentrated hydrochloric acid). Add a solution of thioacetamide (for each 1 g of arsenic salt, use 0.2 g of thioacetamide in 20 mL of water). Boil the mixture for 20 minutes and then basify with 2 M sodium hydroxide (prepared by dissolving 8 g of NaOH in 100 mL of water). Filter the precipitate, dry, and package for disposal in a secure landfill site. ... 

Three methods for the preparation of aromatic arsonic adds are de- scribed in this review. By far the most widely applicable of these is the Bart reaction, which involves the interaction of a diazonium salt with an inorganic arsenic compound. In the original Bart process 1 and most of its modifications an alkali arsenite is used, as shown in the following equation. 

For some time, intermolecular radical additions have been an integral part of the methodological arsenal of preparative organic chemistry. However, from an ecological point of view the methods that have been used to date suffer from a number of drawbacks that present obstacles to their broad-based industrial application. This applies particularly to the commonly used organotin compounds. 

All attempts to prepare a spirocyclic hexacoordinate antimonate complex 168 and a tetracoordinate spirostibonium ion 167 or onium-ate combinations of these, according to structural and synthetic principles elaborated with corresponding phosphorus and arsenic compounds, met with failure138). When, for example,-... 

W. Goessler, J. Lintschinger, J. Szakova, P. Mader, J. Kopecky, J. Doucha, K. J. Irgolic, Chlorella sp. and arsenic compounds an attempt to prepare an algal reference material for arsenic compounds, Appl. Organomet. Chem., 11 (1997), 57-66. 

---