Phenolics Titanium and

Gendler S, Groysman S, Goldschmidt Z, Shuster M, Kol M. Polymerization of 4-methylpentene and vinylcyclohex-ane by amine bis(phenolate) titanium and zirconium complexes. J Polym Sci A Polym Chem 2006 44 1136-1146. 

British Standard Code of Practice C.D. 3 003 Linings of Vessels and Equipment for Chemical Processes. Part 1 Rubber, Part 2 Glass Enamel, Part 3 Lead, Part 4 P.V.C., Part 5 Epoxy Resins, Part 6 Phenolic Resin, Part 7 Corrosion and Heat Resistant Materials, Part 8 Precious Metals, Part 9 Titanium and Part 10 Brick and Tile... 

Mn(II) > Mg(II).270 It should be underlined that titanium and zirconium alkoxides are efficient catalysts for both stages of reaction. Lanthanide compounds such as 2,2/-bipyridyl, acetylacetonate, and o-formyl phenolate complexes of Eu(III), La(III), Sm(III), Er(III), and Tb(III) appear to be even more efficient than titanium alkoxides, Ca or Mn acetates, Sb203, and their mixtures.273 Moreover, PET produced with lanthanides has been reported to exhibit better thermal and hydrolytic stability as compared to PET synthesized with the conventional Ca acetate -Sb203 catalytic system.273... 

One of the exciting results to come out of heterogeneous catalysis research since the early 1980s is the discovery and development of catalysts that employ hydrogen peroxide to selectively oxidize organic compounds at low temperatures in the liquid phase. These catalysts are based on titanium, and the important discovery was a way to isolate titanium in framework locations of the inner cavities of zeolites (molecular sieves). Thus, mild oxidations may be run in water or water-soluble solvents. Practicing organic chemists now have a way to catalytically oxidize benzene to phenols alkanes to alcohols and ketones primary alcohols to aldehydes, acids, esters, and acetals secondary alcohols to ketones primary amines to oximes secondary amines to hydroxyl-amines and tertiary amines to amine oxides. 

Most structural PMCs consist of a relatively soft matrix, such as a thermosetting plastic of polyester, phenolic, or epoxy, sometimes referred to as resin-matrix composites. Some typical polymers used as matrices in PMCs are listed in Table 1.28. The list of metals used in MMCs is much shorter. Aluminum, magnesium, titanium, and iron- and nickel-based alloys are the most common (see Table 1.29). These metals are typically utilized due to their combination of low density and good mechanical properties. Matrix materials for CMCs generally fall into fonr categories glass ceramics like lithium aluminosilicate oxide ceramics like aluminnm oxide (alnmina) and mullite nitride ceramics such as silicon nitride and carbide ceramics such as silicon carbide. 

A mixture of phenol and aluminum sulfide is rapidly converted to the phenoxide on heating with the evolution of H2S.20 Similarly, titanium and silicon phenoxides can be prepared directly from their sulfides (equation 38).119,120... 

Irradiation of powdered titanium dioxide suspended in solutions containing aromatic compounds and water under oxygen has recently been shown to induce hydroxylation of aromatic nuclei giving phenolic compounds and oxidation of side chains of the aromatic compounds (50-55). These reactions have been assumed to proceed through hydroxyl and other radical intermediates, but the mechanism for their generation, whether reactive free radicals result from oxidation of water, from reduction of oxygen, or from oxidation of the substrates on the surfaces of the excited titanium dioxide, has not been clear. 

Some undesirable impurities deteriorate the material properties of recycled plastics by reducing their stability. These contaminants consist not only of residues of polymerisation catalysts, but also of salts of metals introduced during polymer processing and exploitation [34, 35]. Metallic impurities arise from contaminated filler as well. Ions of copper and iron belong to the most dangerous species. They catalyse homolysis of hydroperoxides and increase the consumption of phenolic antioxidants or phenolic moieties of UV absorbers by their oxidation into dienoide compounds [36, 37, 38]. Residues of titanium and aluminium polymerisation catalysts can form coloured salts with phenolic antioxidants. 

Much effort has been devoted to the optimization of the polyesterification reaction. For instance, different types of monomeric precursors structurally related to succinic acid (e.g., dimethyl succinate or succinic anhydride) were used. Different kinds of catalysts (e.g., phenolates, titanium alkoxides, tin octanoates) at different concentrations were studied. Different reaction temperatures (130-190 °C) were reached and different procedures for water elimination (vacuum drying under different conditions or toluene distillation) were adopted. Experimental results obtained showed that the use of different catalysts and different monomer precursors (succinic acid derivatives) did not significantly alter the polymerization kinetics or yield, and for this reason, they were abandoned. The procedure finally adopted is summarized below. 

Besides alkoxides, acetylacetonates are also used as the starting materials for the synthesis of oxides. Titania (anatase) is obtained by decomposition of titanium oxyacetylacetonate (TiO(acac)2) in toluene at 300°C. Similarly solvothermal treatment of Fe(lll) acetylacetonate in toluene yields microcrystalline magnetite. One of the drawbacks of the use of acetylacetonate may be formation of various high boiling point organic by-products via aldol-type condensation of the acetylacetone. Actually more than 50 compounds are detected by gas chromatography-mass spectrometry (GC-MS) analysis of the supernatant of the reaction, some of which are phenolic compounds and are hardly removed from the oxide particles by washing with acetone. ... 

The photochemical destruction of ortho, meta and para-nitrophenols induced by ultra-violet light illumination of aqueous slurries of titanium dioxide has been monitored by electronic absorption spectroscopy the products are said to have been identified as dihydroxynitrobenzene isomers by coupled gas chromatography-mass spectrometry although no details are supplied. Nitrophenols have also been identified in the fog shrouding the University of Bayreuth. They are presumed to be the products of photochemical nitration and the possible precursors (phenol, cresol and nitrate) were also detected. 

Iron, titanium, and zirconium salts can be substituted for the chromium ones.146 Vegetable tannins, such as 4.20 can also be used, but they slow down the tanning process. Similar phenols can be found in the residue from tea leaves left after the manufacture of instant tea. Perhaps, they could be used in making leather to eliminate or reduce the amount of another waste product. Getting reagents to penetrate the hide is a problem. Newer methods, such as ul-trasonication and supercritical fluid extraction, may help reduce the time required to make leather, so that these alternative-tanning agents can be used instead of the chromium. 

The mordenite and titanium mordenite samples were treated with 0.5 N H2SO4 at room temperature to get protonic form. Phenol hydroxylation and benzene oxidation by H2O2 were carried out in a batch (100 ml) reactor in aqueous medium or acetone. 

The turnover numbers (TON) of phenol are 62.4 and 105.4 with a H2O2 efficiency of 28.9 wt.% and 48.9 wt.% for the Zr-Sil-2 samples A and B, respectively. A significant difference in the product distribution between these two runs is also observed. The catechol (CAT) to hydroquinone (HQ) ratios are 0.9 and 1.7 for Zr-Sil-2 (A) and (B) samples, respectively. A CAT/HQ ratio of 0.9 to 1.3 has been reported for titanium and vanadium silicate molecular sieves (TS-2 and VS-2) [13]. The samples synthesized using Zr(acac)4 show a nearly two fold activity in the reaction probably due to the smaller particle size. These results indicate that in the case of Zr-Sil-2 samples synthesized using ZrCU, the Zr " ions are well dispersed within the channels of the MEL structure while in the samples synthesized using Zr(acac)4, the hydroxylation occurs at the external surface as well, where a part of Zr species may be located. For small submicron crystals (<1 pm), external surface sites could be a significant fraction of the total surface area. If the external surface sites are catalytically either the same or more active than the intracrystalline active sites, then the shape selectivity of a zeolite could... 

In the present work, we investigated the influence of the metal precursor and of the nature of the support on the performences of ruthenium catalysts for the wet air oxidation of p-hydroxybenzoic (p-HBZ) acid chosen as a model of phenolic pollutants. Titanium and zirconium oxides were selected as supporting materials. The preparation method adopted for supports was sol-gel combined with the use of supercritical drying. The motivation of such combination is to prepare aerogel supports with high BET surface area and unique morphological and chemical properties [9,10]. 

The activation of phenol is much easier than that of benzene because of the high aromaticity of benzene and the corresponding charge delocalization. TS-1 has been used primarily as the catalyst for phenol hydroxylation, and the conditions have been thoroughly optimized (215). TS-2 (216) and Ti-MCM-41 (217) were also evaluated, but they do not perform as well as TS-1. Ramaswamy et al. (52) compared various framework metal-containing zeotype materials with MEL structure for phenol hydroxylation the incorporated metals were aluminum, tin, titanium, and vanadium. The... 

NCL Puna also developed a patented synthesis of a titanium-substituted catalyst (298) that is used for oxidation chemistry including direct hydroxylation of phenol. CleanScience (252) is offering derivatives of hydroquinone in commercial quantities that are produced via phenol hydroxylation and alkylation. 

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