Cadmium alkoxides

Te tram eric alkyl beryllium, zinc and cadmium alkoxides are formed by controlled alcoholysis of the metal dialkyls,16U62 while cubanoid thallium alkoxides are obtained by reaction of the metal with refluxing ethanol, and alcohol metathesis.163 Reaction (4) affords a tin phosphide cubane in low yield 164... 

Zinc chloride is a Lewis acid catalyst that promotes cellulose esterification. However, because of the large quantities required, this type of catalyst would be uneconomical for commercial use. Other compounds such as titanium alkoxides, eg, tetrabutoxytitanium (80), sulfate salts containing cadmium, aluminum, and ammonium ions (81), sulfamic acid, and ammonium sulfate (82) have been reported as catalysts for cellulose acetate production. In general, they require reaction temperatures above 50°C for complete esterification. Relatively small amounts (<0.5%) of sulfuric acid combined with phosphoric acid (83), sulfonic acids, eg, methanesulfonic, or alkyl phosphites (84) have been reported as good acetylation catalysts, especially at reaction temperatures above 90°C. 

The metatheis of acetates with the alkali alkoxides (method 5) can be used for the preparation of the methoxides and ethoxides of all three elements and is the only reaction leading to Hg(OR)2 [1623]. The trans-esterification of Zn(OMe)2 (method 6), according to [1121], can be carried out only in the presence of LiOR (forming soluble bimetallic complexes). The direct electrochemical synthesis on the anodic oxidation of metals in alcohols has been described for Zn(OEt)2 and a series of cadmium derivatives (Cd(OR)2 — obtained in the presence of such donor ligands as Dipy, Phen, and Dmso [98]) (method 2). 

The transesterification of DMT to BHET requires use of homogeneously dissolved metal salts, such as the acetates or alkoxides of calcium, magnesium, manganese, cobalt, zinc, sodium, lithium, lead, cerium and cadmium, and is run in the melt at 170-220 °C [18-20]. A mechanism in which the metal salt coordinates to the carbonyl oxygen of DMT, thereby enhancing the reactivity toward nucleophilic diol, is believed to occur during transesterification [21] (see Scheme 5). 

This method has been utilized for the synthesis of alkoxides of zinc and cadmium as well as the lanthanides with some specially hindered alcohols (cf. Section IV). 

Pr)2Ba(/i-0-i-Pr)2]2. This observation is intriguing in heterometallic alkoxide chemistry. The analytical as well as other physicochemical data could not have distinguished between the expected and the rather unusual actual formulation, which was established by X-ray crystallography (Fig. 37). This structure is consistent with the preferential characteristics of the two metals involved (barium and cadmium) for attaining coordination numbers 6 and 4, respectively. 

The chemical features of tin(IV) alkoxides, such as pre-existing metal-oxygen bonds in molecular units, high volatility and low decomposition temperatures make them attractive precursors for deposihon of Sn02. The heterometallic complex [Sn(dmae)2Cd(acac)2],Figures.1.2, (acac = 2,4-pentanedionato dmae = N,N -dimethylamino-ethanoate) has been decomposed in aerosol-assisted chemical vapor deposition conditions, producing amorphous tin(IV) oxide films with no detectable cadmium. ... 

The NMR spectra of normal alkoxides of heavier alkaline earth metals (Ca, Sr, Ba), beryllium as well as magnesium, zinc, cadmium and mercury do not appear to have been studied, probably owing to their highly polymeric nature and insolubility in common organic solvents. 

Table 4.22 Heterometallic alkoxides of zinc, cadmium, indium, thallium, germanium, tin, and lead... 

The ethyl derivatives of aluminum, cadmium, magnesium, and zinc yield highly crystalline polymers. Organometallic eomplexes such as magnesium diethyl cobalt chloride, which coordinate strongly with the polymer anion and the monomer, produce white crystalline PMVK. PMVK obtained by alkoxides, sodium naphthalene, and -butyllithium are intensively colored because of a partially occurring aldol condensation [292]. The mechanism of these reactions has been studied intensively. It is assumed that... 

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