Vinyl pyridine N-oxide

POLY 4 VINYL PYRIDINE N-OXIDE(PVMO) fiCHa-CH) 0 CA 10 POLYSaEWES INC. (RYML.M)... 

In a recent improvement to this approach, poly(4-vinylpyridine) and poly(4-vinyl-pyridine) N-oxides were used as the catalyst carrier [81]. The MTO-catalyst obtained from 25% cross-linked poly(4-vinylpyridine) proved to efficiently catalyze the formation of even hydrolytically sensitive epoxides in the presence of aqueous hydrogen peroxide (30%). This catalyst could be recycled up to 5 times without any significant loss of activity. Attempts have been made to immobilize MTO with the use of either microencapsulation techniques, including sol-gel techniques, for the formation of silica bound rhenium compounds, and the attachment of MTO on sihca tethered with polyethers. These approaches have provided catalysts with good activity using aqueous hydrogen peroxide as the terminal oxidant [83]. In the latter case, high selectivity for epoxide formation was also obtained for very sensitive substrates (e.g., indene). 

The reactivity of a remarkable electronically unsaturated tantalum methyli-dene complex, [p-MeCgH4C(NSiMe3)2]2Ta( = CH2)CH3, has been investigated. Electrophilic addition and olefination reactions of the Ta = CH2 functionality were reported. The alkylidene complex participates in group-transfer reactions not observed in sterically similar but electronically saturated analogs. Reactions with substrates containing unsaturated C-X (X = C, N, O) bonds yield [Ta] = X compounds and vinylated organic products. Scheme 117 shows the reaction with pyridine N-oxide, which leads to formation of a tantalum 0x0 complex. ... 

Aryl- und 2-Vinyl-alkansaure-anhydride werden mit 2 bzw. 4 Molen Pyridin-N-oxid in inerten Losungsmitteln bei 80-120° zu Aldehyden bzw. Carbonsauren oxidiert93"103 ... 

For Negishi reactions in which the pyridines are nucleophiles, the pyridylzinc reagents are usually prepared from the corresponding halopyridines [6, 20, 21]. An excess of 2-chlorozincpyridine /V-oxide (26), arising from 2-bromopyridine N-oxide hydrochloride (25), was coupled with vinyl triflate 27 in the presence of Pd(Ph3p)4 to furnish adduct 28 [20]. Recently, an efficient Pd-catalyzed cyanation of 2-amino-5-bromo-6-methylpyridine (29) using zinc cyanide has been reported to afford pyridyl nitrile 30 [22]. 

Au NPs have been synthesized in polymeric micelles composed of amphiphilic block copolymers. Poly(styrene)-block-poly(2-vinylpyridine) in toluene has been used as nanocompartments loaded with a defined amount of HAuCl4 and reduced with anhydrous hydrazine. The metal ions can be reduced in such a way that exactly one Au NP is formed in each micelle, where each particle is of equal size between 1 and 15 nm [113]. In another example, the addition of HAuCfi to the triblock copolymer (PS-b-P2VP-b-PEO) (polystyrene-block-poly-2-vinyl pyridine-block-polyethylene oxide) permits the synthesis of Au N Ps using two different routes, such as the reduction of AuC14 by electron irradiation during observation or by addition of an excess of aqueous NaBH4 solution [114]. 

The standard methods of oxidation of pyridines and other heteroaromatic nitrogen compounds make use of peroxy acids or hydrogen peroxide in carboxylic acid solution. Peracetic acid, peroxymono-phthalic acid and MCPBA can all convert simple pyridines to the N-oxides. For example, the pyridine (45) was oxidized at nitrogen by MCPBA without attack on the vinyl group. Peroxymaleic acid has... 

Mn(02CCF3)2 wL (where L = pyandw = 2or4 L = pyridine-A-oxide and n = 1 or L = y-picoline and n = 1, 2, or 4) (7) have been characterized. Compound Mn(acao)2(02CCF3) aids the polymerization of methylmethacrylate and vinyl acetate and is reduced to Mn(acac)-(OgCCFg) in these processes (187, 188). 

VINYL FORMIC ACID (79-10-7) Forms explosive mixture with air (flash point 124°F/51°C). Light, heat, or peroxides can cause explosive polymerization. Incompatible with strong acids, alkalis, ammonia, amines, isocyanates, alkylene oxides, epichlorohydrin, oxidizers, toluenediamine, pyridine, methyl pyridine, n-methyl pyrrolidone, 2-methyl-6-ethyl aniline, aniline, ethylene diamine, ethyleneimine, 2-aminoethanol. Severely corrodes carbon steel and iron attacks other metals. Flow or agitation of substance may generate electrostatic charges due to low conductivity. The uninhibited vapors may form polymers in plug vents, confined spaces, or flame arresters of storage tanks. 

Amine complexes. The effect of immobilization of the Cu(II) complexes of polymeric amines has been examined and reviewed by Challa et al. ( ). The polymeric ligands were varied by using the following species polymer-bound dimethylbenzylamlne (formed by treatment of chloromethylated polystyrene with dimethylamlne), the copolymer of styrene and 4-vinyl-pyridine and the copolymer of styrene and N-vinylimidazole. The reaction examined was the Cu(II) oxidative dimerization of 2,6-disubstituted phenols (Equation 1). 

Superelectrophilic properties of nitroarenes are retained when mie of the furoxan rings in NBDF is replaced with electron-deficient isoxazole [124] or pyridine fragments [125]. As in case of NBDF, the reactions of these fused nitroarenes with ethyl vinyl ether were found to lead to the correspruiding benzoxazine N-oxides 143 and 144 condensed with heterocyclic rings (Scheme 72). 

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