Silver salts initiators

The electrocyclic opening of cyclopropane derivatives containing internal nucleophilic groups provides a new route to vinyl lactones, tetrahydropyrans, and tetra-hydrofurans (Danheiser et al. 1981). The silver salt initiates the opening of the ring... 

Dye release may relate either directly or inversely to the image-related reduction of silver halide. Release of the dye or dye precursor may be accomphshed or initiated by the oxidized developing agent or the unoxidized developing agent or by alkali or silver salts. 

With respect to the initiation of cationic chain polymerizations, the reaction of chlorine-terminated azo compounds with various silver salts has been thoroughly studied. ACPC, a compound often used in condensation type reactions discussed previously, was reacted with Ag X , X, being BF4 [10,61] or SbFa [11,62]. This reaction resulted in two oxocarbenium cations, being very suitable initiating sites for cationic polymerization. Thus, poly(tetrahydrofuran) with Mn between 3 x 10 and 4 x lO containing exactly one central azo group per molecule was synthesized [62a]. Furthermore, N-... 

Block or graft copolymem can be obtained by cationic polymerization of THF with macromolecular initiators. The recommended groups for the initiation are the dioxolenium cation, the acyl cation and the super acid ester, each of which can be introduced into the backbone polymer by reaction with silver salts of strong acids. Introduction of the dioxolenium group into polystyrene was carried out by the following route32 ... 

During pyrolysis to silver (via silver dicyanamide), initial heating must be slow to avoid explosion [1], High intensity illumination will also cause explosive decomposition of a confined sample [2], Safety precautions for preparation and subsequent use of the explosive salt are detailed [3],... 

Initial attempts at carbocydization of the enyne 82 with Wilkinson s catalyst under an atmosphere of 1,3-butadiene in refluxing toluene furnished only trace amounts of product, which was attributed to the preference for the enyne to undergo homodimerization in a highly stereoselective manner (Tab. 12.8, entry 1 ds 19 1) [38]. Nonetheless, the coordinatively unsaturated (AgOTf-modified) catalyst furnished the [4-i-2-1-2] product in excellent yield (entry 2). The ability to alter the product distribution in this manner prompted further examination of various other silver salts. 

Both the reactions are essentially the additions of iodine carboxylate (formed in situ) to an alkene, i.e., the reaction of an alkene with iodine and silver salt. The Prevost procedure employs iodine and silver carboxylate under dry conditions. The initially formed transiodocarboxylate (b) from a cyclic iodonium ion (a) undergoes internal displacement to a common intermediate acylium ion (c). The formation of the diester (d) with retention of configuration provides an example of neighbouring group participation. The diester on subsequent hydrolysis gives a trans-glycol. 

The mercuration of thiophene, which presumably goes by way of a coordination compound, gives an initial attack in the 2 position as expected from the reactions of thiophene itself (67). The bromination (or chlorination) of indazole or its silver salt also leads to the same products (82). 

Metal deposition or stripping and capacitance under constant current, (a) What is the potential transient in the case of metal deposition under constant current (/ = 10 mA/cm ) Derive its transition time x. Consider silver deposition on a silver substrate as an example ( Ag = 0.799 V, DAg - 1.65 x 10-5 cm2/s at room temperature), (b) If this process is reversed (i.e., silver is stripped from the silver substrate electrode), what should the expression be Suppose the initial solution does not contain silver salt, (c) What will the potential be at t = 0 ... 

Harris [25] isolated this substance by the action of anhydrous hydrogen chloride on the solution of the silver salt of nitrocyanamide in acetonitrile. It has explosive properties but it is of no practical value due to the difficulty of preparing it. On the other hand its salts may be of practical value. These salts and their preparation will be discussed in the chapters dealing with initiating explosives (p. 211). 

The same author et al. (McKay, Hatton, G. W. Taylor [38]) prepared a number of nitrocyanamide salts by the action of the chlorides of various metals on the silver salt in suitable solvents or the by reaction of the carbonates of various metals with a solution of nitrocyanamide in acetonitrile, and found that some of these salts have initiating properties. The majority, however, cannot be recommended for practical use, their sensitiveness to impact being too low (they are not exploded by a 5 kg weight falling from a height of 300 cm). 

Its silver salt, C7H3N4OftAg, N 27.89% and Ag 26.98%, brownish-yel solid, is a powerful explosive (Ref 2, p 64). Its copper salt (greenish powder) and lead salt (golden-yel powd) are not as powerful explosives Note None of these salts was recommended by Stolle for use as igniting or initiating agents in blasting caps or detonators Refs l)Beil—not found 2)R.Stolle et al,... 

Alkylations of NH azapentalenes are carried out not on the neutral molecule, but on the corresponding anion. Methylations are usually performed with iodomethane or methyl sulfate on the silver salt,61 or, more frequently, on the sodium salt. Methylations with diazomethane may also be included since Gompper404 has shown that initial proton abstraction to give the methylating agent CH3N is involved. Scheme 16... 

The reaction of melamine with formaldehyde is a useful one, as the initial product (39) forms a resin on heating. Such condensates are very important polymers (see Section 2.20.6.3 and Chapter 1.11). Melamine and other amino-1,3,5-triazines form salts with aqueous acids. In addition, the amino-1,3,5-triazines form potassium and silver salts (58CRV131). 

Similar products were obtained in the decomposition of the silver salt of 2.4.6-trichlorophenol, however, in this case higher temperature (60° C) was necessary and ethyl iodide did not initiate the reaction. Polymers were also obtained from several other trihalophenols. 

The cyclofunctionalization of 4-alkynoic and 5-alkynoic acids generates y-alkylidene-y-lactones and 5-alkylidene-S-lactones, respectively (equation 76 and Table 22). The initial products from the reactions catalyzed by mercury or silver salts undergo protiodemetallation under the reaction conditions. The vi-nylpalladium intermediates undergo either protiodemetallation or coupling with an added allyl halide. The palladium(II)-catalyzed cyclization of 3-alkynoic acids proceeds by 5-endo closure to give 3-buten-4-olides (Table 22, entry 2).50 190... 

Infra-red spectra of the sodium, 1,1r lead, and l,r silver salts of 5,5 -azotetrazole are included] 4) A.T. Thomas R.J. Wiliiams, Fuse Heads , USP 3763783 (1973) CA 80, 17084 (1974) (Electrically initiated (by resistance-wired bridges) fuse heads contg Pb-Azo-tetrazole are claimed in this patent. Thus, typically, sufficient wet Pb-Azotetrazole particles 6—10 microns long and 1—2 microns wide to give 8.08g of dry Pb-Azotetrazole, adjusted to include 2.0g w and 5cc of an aq suspension contg 5% methyl cellulose, is mixed to give a smooth paste. Bridge wires are then immersed in the paste, withdrawn, and the fuse heads so formed are allowed to dry]... 

Properties of Ag-salts of 1-(iV-nitramino)-, 2-(Wnitramino)-, 5-(W-nitramino)tetrazole, and l-methyl-5-(fV-nitramino)-tetrazole have been examined. The initiation power of these salts was estimated from minimal blasting charge in RDX. Silver salts of l-(W-nitramino)- and 2-(iV-nitramino)tetrazole have a DDT (deflagration-to-detonation transition) period shorter than the salts of 5-(W-nitramino)tetrazole and l-methyl-5-(W-nitramino)tetrazole. The salt of 2-(fV-nitramino)te-trazole is a more powerful initiative explosive than lead azide <2006MI39>. 

Strained or bridged cycles substituted by at least one halide could be rearranged on treatment with silver salts. On the other hand, strained a bonds directly interact with silver ions, leading to bond breakage and thus initiating rearrangement. 

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