Silver salts, use

Uses Most important silver salt used in photography emulsion making intensification etc. Caution Stains on fingers can be removed by rubbing with tincture of iodine followed by a strong solution of hypo. 

This observation is not related to traces of base or acid from the silver salts used since control experiments mled out this possibility. It was known from the literature that the 5-exo-dig versus 6-endo-dig cyclization mode could depend on the nature of the carbonyl group,56 57 of the alkyne substituent,58 59 and of the nature60 61 and oxidation state62 of the metallic source used. Also, work from Yamamoto25 demonstrated the importance of both a- and Jt-Lewis acidity properties of silver(I) complexes. Therefore, depending on the silver salt used, two mechanistic pathways were proposed (pathways A and B, Scheme 5.15). 

A synthesis of lapachol using reaction conditions better than those used by Fieser was carried out by Fridman et al [149].They used the lithium salt of 2-hydroxy-1,4-naphthoquinone prepared in situ instead of the silver salt used for Fieser [150]. The lithium salt was prepared in situ by addition of lithium hydride to the frozen solution of the quinone in dimethyl sulfoxide, Fig. (14). As the solution thawed, the lithium quinone was slowly formed and was then alkylated with 3,3-dimethylallyl bromide. Lapachol was thus obtained in 40% yield. 

Uses manufacture of indelible inks and silver salts, used for resilvering mirror snrfaces... 

The method given here employs the commercially available ammonium (4-)-ff-bromocamphor-7t-sulfonate instead of the more expensive silver salt used by Werner, and it gives higher yields of enantiomers. - The chloride, bromide, and ni trate of the ( + ) series can be prepared from the precipitated (+)(+)-bro-mocamphorsulfonate diastereoisomer by metathesis with the appropriate concentrated acid, whereas the chloride, bromide, and nitrate of the (—)-series can be prepared by treatment with the appropriate concentrated acid of the (—)-dithionate precipitated from the diastereoisomer filtrate. 

Cyclization. The modes of Ag(I)-catalyzed cycUzation of 2-alkynyl-3-formyl-quinolines in MeOH have been correlated with tbe pKa values of tbe silver salts used. Both 5-exo-dig and 6-endo-dig pathways are equally favored in the presence of AgOAc, products arising from the former pathway predominate in using more basic silver salts (e.g., Ag20, AgO). 

Thus, the use of dicarbonylrhodium(I) 3-trifluroacetylcamphorate as an active stationary phase component has the following advantages over the use of silver salts used for the same purpose (l) stronger interaction with the compounds to be separated, which permits a better separation of saturated from unsaturated hydrocarbons to be obtained ... 

The primary use of silver nitrate is in the production of other silvers salts used in the production of photographic film. Compounds such as silver bromide (AgBr) and silver iodide (AgD decompose when exposed to light, forming free silver ... 

Their silver salts become increasingly covalent from AgF to Agl. A test for aqueous halides is the precipitation of the silver salt using silver nitrate solution. The general ionic equation is... 

In certain cases the stereoselectivity of the cyclization reaction is rigorously influenced by the addition of silver salts using the same enantiomer of BINAP both enantiomers of a spiroannelated indole could be selectively obtained depending on the presence or absence of silver salts (Scheme 7). 

Sunflower oil-based hyperbranched and linear thermoplastic polyure-thane/silver nanocomposites have also been prepared by the in situ catalytic reduction of silver salt, using a catalytic amount of organic tin compound. The virgin polymer and its nanocomposites are entirely thermoplastic as... 

Because of the previously mentioned problems with in situ activation of gold chlorides, alternative catalysts that did not require any kind of activation were developed. As a starting point, attempts were made to isolate the actual catalyti-cally active species that are formed after the addition of the silver salts to the gold chlorides. However, the isolated compounds appeared to be as hygroscopic as the silver salts used with noncoordinating anions and are therefore difficult to... 

D.i.d. Diquinanes. The successful execution of AHRs for the formation of 6,6- and 6,5-ring systems from prochiral substrates clearly suggested an extension of the method to the formation of 5,5-systems, which form the backbone of a large number of natural products. The use of prochiral cyclopentadienyl systems, however, involves the generation of a rr-allylpalladium species, which must then be trapped with a suitable nucleophile. " The greater reactivity of the 1,3-diene substrate toward the silver salts used in the reactions and the propensity for undesirable side reactions such as Diels-Alder cycloadditions must also be borne in mind. The former problem, in fact, figures prominently in the first example of an AHR-based diquinane synthesis to be published (Scheme... 

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