Reactivity towards silver

Temperature-Programmed Surface Reaction (TPSR) Experiments at 800 Torr. Pretreated and preoxidized silver exhibited no reactivity toward an ethylene/argon mixture at reaction temperatures (443 - 543 K) and atmospheric pressures (750-800 torr). The desorption spectrum of a pretreated sample showed no evidence of oxygen desorption when the sample was heated in vacuo to 673 K. These... 

Gold is one of the least reactive metals in bulk form. However, in recent years a considerable amount of theoretical and experimental works have studied the reactivity of small neutral and charged Au clusters towards different molecules, like H2, O2, CO, and organic radicals " . The reactivity depends on the size and charge state of the cluster. In the previous section we have studied the reactivity towards oxygen adsorption of anionic silver and gold clusters. In this section we study the reactivity of neutral gold clusters towards molecular O2 (subsection 6.1) and CO (subsection 6.2). 

Silver(II) fluoride and potassium tetrafluoroargentate(III) have similar reactivities towards benzene,11 and appear to be slightly less reactive than cobalt(III) fluoride a similar range of products is formed. Potassium hexafluoronickelate(IV) is slightly more reactive than cobalt(III) fluoride under vapor-phase conditions18 (sec above for reactions of K2NiF6 in anhyd HF) the products are similar to those from cobalt(III) fluoride except that more unsaturates are detected, mainly the ones that predominated in the manganese(III) fluoride fluorination. 

Exercise 14-9 Arrange the following halides in order of expected increasing reactivity towards (a) sodium iodide in acetone and (b) silver nitrate in ethanol. Indicate your reasoning. 

The stabilized valence structure in the dinitramide anion results in low reactivity toward electrophiles. Only under special conditions does the anion react as a nucleophile. For example, silver dinitramide is alkylated by alkyl halides in high yields to form the covalent dinitramine [7]. 

Nonactive/slightly reactive electrode materials include metals whose reactivity toward the solution components is much lower compared with active metals, and thus there are no spontaneous reactions between them and the solution species. On the other hand, they are not noble, and hence their anodic dissolution may be the positive limit of the electrochemical windows of many nonaqueous solutions. Typical examples are mercury, silver, nickel, copper, etc. It is possible to add to this list both aluminum and iron, which by themselves may react spontaneously with nonaqueous solvent molecules or salt anions containing atoms of high oxidation states. However, they are not reactive due to passivation of the metal which, indeed, results from the formation of stable, thin anodic films that protect the metal at a wide range of potentials, and thus the electrochemical window is determined by the electroreactions of the solution components [51,52],... 

The tributyltin enolates 74 are readily prepared from the corresponding enol acetates and tributyltin methoxide in the absence of solvent [34]. The tin enolates thus obtained occur in the 0-Sn form and/or the C-Sn form, and both species can be used for the aldol reaction of this system. Although the tin enolates themselves have adequate reactivity toward aldehydes [34c], in the presence of the BINAP silver(I) catalyst the reaction proceeds much faster even at -20 °C. Optimum conditions entail the use of THF as solvent and the results employing these conditions in the catalytic enan-tioselective aldol reaction of a variety of tributyltin enolates with typical aromatic, a,/3-unsaturated, and aliphatic aldehydes are summarized in Table 2. TTie characteristic features are (i) All reactions proceed to furnish the corresponding aldol adducts 75 in moderate to high yield in the presence of 10 mol % (i )-BINAP AgOTf complex at -20 °C for 8 h, and no dehydrated aldol adduct is observed (ii) with an a,j3-unsaturated aldehyde, the 1,2-addition reaction takes place exclusively (entry 3) (iii) a bulky alkyl substituent of tin enolate increases the enantioselectivity of the aldol reaction. For instance, the highest ee (95 % ee) is obtained when the tin enolate prepared from pinacolone 77 or rert-butyl ethyl ketone 79 is added to aldehydes (entries 2, 7, and 8) (iv) addition of the cyclohexanone-derived enol tributylstannane 78 (( )-... 

Aromatic iodination [1, 497, after citation of ref. 12]. Polyalkylbenzenes having bulky groups are not reactive toward iodine alone but may react in the presence of an oxidizing agent. In a detailed study of agents used in this connection (silver perchlorate, mercuric oxide, iodic acid, potassium persulfate, etc.) Japanese investigators123 found the combination of iodine with periodic acid dihydrate to be the most satisfactory. 

The aim of this work is to extend the kinetics study of electron transfer to monitor donors of more positive redox potential than previously studied, toward silver clusters, Ag ", as acceptors and thus to approach the domain where clusters get metal-hke properties (13). The selected donor is the naphta-zarin hydroquinone, with properties similar to those of the hydroquinone used as a developer in photography. Its redox potential depends on pH, so that different monitor potentials are available through control of pH. Moreover, the reactivity of the donor may be followed by variation of absorbance when naphtazarin hydroquinone, almost transparent in the visible, is replaced by oxidized quinone with an intense absorption band. 

Clear, colorless liquid, mp +4-5. bp I28 also reported to be 131 Bruckl, Ziegler, Ber. 65, 916 (1932). Distills in vacuo without decompn. Can be stored in sealed glass ampuls. Any purple color developing is due to residual ReOv Sol in CC14. Hydrolyzed by water to HReO( and HCI. Extremely reactive toward mercury, silver and a large number of organic subetances. 

---