Protonic salts developments

Photoinduced oxidation of 1,4-dimethoxybenzene (DMB) and tetrahydrofuran (THF) by [Au(C N N-dpp)Cl]+ in acetonitrile upon UV/Vis irradiation have been observed. The time-resolved absorption spectrum recorded 12 (xs after excitation of [Au(C N N-dpp)Cl] with a laser pulse at 35 5 nm showed the absorption band of the DMB radical cation at 460nm, whereas upon excitation at 406 nm in the presence of THF, a broad emission characteristic of the protonated salt of 2,9-diphenyl-l,10-phenanthroline (Hdpp ) developed at 500 nm. 

In addition, by-products of the initiation process may consume some of the protonic acid. The most probable by-products are furans, which could interact with the strong acid to form dark-colored resins. Polymerizations initiated with trityl or diazonium salts develop very dark colors which are not characteristic of the growing THF ion. 

Furylcarbinols with protic acids (fluoroboric acid) may merely give car-benium (furylium) salts.171 Similar cations are accessible via 2-furyldiazo-methane derivatives,172 but in many cases ring opening and prototropic shifts ensue as in Marckwald reactions (Scheme 30).173 A recent development controls solution acidity by using magnesium or zinc ions instead of protons... 

This survey focuses on recent developments in catalysts for phosphoric acid fuel cells (PAFC), proton-exchange membrane fuel cells (PEMFC), and the direct methanol fuel cell (DMFC). In PAFC, operating at 160-220°C, orthophosphoric acid is used as the electrolyte, the anode catalyst is Pt and the cathode can be a bimetallic system like Pt/Cr/Co. For this purpose, a bimetallic colloidal precursor of the composition Pt50Co30Cr20 (size 3.8 nm) was prepared by the co-reduction of the corresponding metal salts [184-186], From XRD analysis, the bimetallic particles were found alloyed in an ordered fct-structure. The elecbocatalytic performance in a standard half-cell was compared with an industrial standard catalyst (bimetallic crystallites of 5.7 nm size) manufactured by co-precipitation and subsequent annealing to 900°C. The advantage of the bimetallic colloid catalysts lies in its improved durability, which is essential for PAFC applicabons. After 22 h it was found that the potential had decayed by less than 10 mV [187],... 

Example 4 Wada et al. have been successful in developing a new class of activators dialkyl (cyanomethyl) ammonium tetrafluoroborates [21]. These activators have high proton-donating ability and a counteranion of low nu-cleophilicity. With this class of salts a remarkably efficient diastereocon-trolled synthesis of dinucleoside phosphorothioates has been devised. The power of this method lies in the fact that stereopure monomers can be ob-... 

During the course of our investigations we found that various tantalum sil-sesquioxanes are readily accessible via a versatile amide route. Commercially available tantalum diethylamide, Ta(NMe2)5, was chosen as the key starting material for the development of a salt-free route leading to tantalum silsesquioxane derivatives. Clean protonation and liberation of three equivalents of dimethylamine took place upon reaction of Ta(NMe2)5 with 3 in a 1 1 molar ratio. Pale yellow... 

New catalyst design further highlights the utility of the scaffold and functional moieties of the Cinchona alkaloids. his-Cinchona alkaloid derivative 43 was developed by Corey [49] for enantioselective dihydroxylation of olefins with OsO. The catalyst was later employed in the Strecker hydrocyanation of iV-allyl aldimines. The mechanistic logic behind the catalyst for the Strecker reaction presents a chiral ammonium salt of the catalyst 43 (in the presence of a conjugate acid) that would stabilize the aldimine already activated via hydrogen-bonding to the protonated quinuclidine moiety. Nucleophilic attack by cyanide ion to the imine would give an a-amino nitrile product (Scheme 10). 

In a related study (78CC934,79HCA2763) Lehn and coworkers incorporated guanidinium groups into macrocycles (e.g. 29). The resulting polyguanidium salts form stable complexes in water with phosphate and carboxylate anions. Unlike polyammonium anion receptors, these species remain protonated over a wide pH range and hold considerable potential in the development of anion-selective electrodes. 

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