Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Vinylpyridine inhibitor

Cordes et al995 carried out alkaline hydrolyses of p-nitrophenylhexanoate 55 (PNPH) in the presence of poly-4-vinylpyridine partially quaternized with dodecyl-bromide and ethylbromide (QPVP). They also found that the polyelectrolytes are increasingly effective as catalysts with an increasing ratio of dodecyl to ethyl groups, and the hydrophobic interactions are important in determining the catalytic efficiency. They observed the inhibitory effects of several gegen-anions fluoride ions are the weakest inhibitor, and nitrate is the strongest (F- < Cl < S04 [Pg.159]

List C contains peroxidisable monomers, where the presence of peroxide may initiate exothermic polymerisation of the bulk of material. Precautions and procedures for storage and use of monomers with or without the presence of inhibitors are discussed in detail. Examples cited are acrylic acid, acrylonitrile, butadiene, 2-chlorobutadiene, chlorotrifluoroethylene, methyl methacrylate, styrene, tetraflu-oroethylene, vinyl acetate, vinylacetylene, vinyl chloride, vinylidene chloride and vinylpyridine [1]. [Pg.328]

The total consumption of 2-methylpyridine (a-picoline) in 1980 has been estimated at 12,000 tons [81CI(L)23]. Half is produced for the U.S. market, whereas the demand in both Western Europe and Japan lies between 2000 and 2500 tons per annum. A significant outlet for 2-methylpyridine is in the production of 2-chloro-6-(trichloromethyl)pyri-dine, which is used as a nitrification inhibitor in agricultural chemistry and in the manufacture of the defoliant 4-amino-2,5,6-trichloropicolinic acid. The major commercial outlet for 2-methylpyridine is, however, its use as a starting material for the production of 2-vinylpyridine [Eq.(7)]. [Pg.185]

It is well known that transition-metal salts and metal complexes, unlike non-Werner-type ferrocene compounds, act as inhibitors in the polymerization of vinyl monomers. For example, the radical polymerization of vinylpyridine is strongly inhibited in the presence of Cu(II) or Fe(III)32 However, vinylpyridine with Cu(I)... [Pg.21]

Vinylpyridines add to TV-alkyl- or phenyl-substituted maleimides to give unexpected 1 2 and 1 3 adducts. From the reaction of 2-vinylpyridine 99 with N-alkylmaleimides the 1 2 addition products 154, which are tetra-hydroquinoline derivatives, could be isolated in the presence of polymerization inhibitors. Furthermore, 1 3 adducts 155 are formed, representing an unusual type of cycloaddition involving the pyridine ring. On the other hand, 4-vinylpyridine 156 combines with 3 moles of dienophilic N-alkylmaleimides in the presence of polymerization inhibitors to afford the spiro compounds 157 (73HCA440). [Pg.368]

Anionic Membranes. Solutions of 4-vinylpyridine (80%) in water were used in this work. Preliminary experiments had shown that most inhibitors affect the grafting process strongly. The kinetics were therefore investigated without any additive. Most experiments were carried out at a single dose rate 28 rads/min. a few irradiations were conducted at 157 rads/min. [Pg.584]

With acrylic acid the situation is very different. For 0.1-mm. thick films /3 is independent of temperature, whereas for 0.05-mm. thick films /3 rises above 40°C. At low temperatures ft is unusually small. This effect may be ascribed to the use of a selective inhibitor to prevent homopolymerization. It was shown above that in grafting vinylpyridine the autoaccelerated character of the reaction at 20°C. vanishes in the presence of inhibitors. Moreover, with acrylic acid the autoacceleration index is lower if a more efficient inhibitor (CuCl2) is used, and f decreases as the amount of inhibitor increases (Figure 8). [Pg.587]

Butadiyne, H-CSC-C C-H, as a polymerizable monomer, has received very little attention from polymer chemists although its discovery dates back to Bayer in 1885. This structurally simple, highly reactive bifunctional molecule would be expected to have been a monomer of considerable interest in the field of polymer chemistry. Possibly, limited butadiyne stability may account for the small amount of polymerization research. The The compound is a liquified gas at room temperature (BP = 10 C), discolors slowly in sealed vessels at 20 C and may explode if heated. Storage and instability problems may be circumvented. Prevention of explosion may e accomplished by addition of an inert diluent such as butane. The monomer may also be stored in t e form of a labile complex with N-methyl-pyrrolidone. Its thermal condensation or polymerization was briefly recorded as an observation by Bayer and described in a little more detail by Miiller in 1925. Prevention of this thermal polymerization has been the subject of several patents with methylene blue, pyridine and vinylpyridine claimed as inhibitors. [Pg.399]


See other pages where Vinylpyridine inhibitor is mentioned: [Pg.66]    [Pg.966]    [Pg.654]    [Pg.588]    [Pg.373]    [Pg.66]    [Pg.75]    [Pg.184]    [Pg.1173]   
See also in sourсe #XX -- [ Pg.399 ]




SEARCH



4-Vinylpyridine

Vinylpyridines

© 2024 chempedia.info