Phosphorus catalyst

Prolonged heating of free isocyanates in the absence of catalysts has been reported recently to give poor yields of carbodiimides unless a slow stream of nitrogen was passed through the boiling isocyanate [18]. In the presence of phosphorus catalysts [18, 19, 27-39], aromatic carbodiimides are obtained in high yield under mild conditions from isocyanates but not isothiocyanates [18]. Aliphatic isocyanates react more slowly, but improved yields are obtained in... 

Various phosphorus catalysts have been employed in enantioselective addition of dialkylzinc reagents to sulfonylimines.123 125... 

Alternative methods to prepare and modify vanadium-phosphorus catalysts for selective oxidation of hydrocarbons. 

Quite limited information on the mixed vanadium-phosphorus catalysts siQ>ported on silica are represented in open scientific literature. For example, in [4] it was proposed the method to prepare well dispersed VPO composition over Si02 but, unfortunately, the authors did not turn out successfiflly to determine the chemical composition of the surface phase formed (siipposely VOPO4 together with VOx). In [3] a]-V0P04 as a major phase of the simflar samples was described and a-V0P04 together with unidentified compound were found to be constituents of the surface layer in [6]. 

A similar phosphorus catalyst, the dihydrobenzazaphosphole-borane complex 78 (Fig. 8), was prepared and used as catalyst for the borane reduction of acetophenone and gave (S)-2-phenylethanol with 23% ee [121]. 

There is no ambiguity in the halogenation of acids which can of course enolise n one direction only. A reliable method is bromination with red phosphorus catalyst via the acid bromide. This leads directly to a-bromo esters. 

Autoreactive spontaneously flammable substances ethylene oxide, acrylic esters, phosphorus, catalysts Single level structure, in separate fire compartments max. 50 tons per fire compartment max. 300 tons per building without storage racks max. 2 rows or 8 ft deep, one layer or 4 ft high min. 4 ft between blocks... 

Bertola, A., Cassarino, S. and Nsunda, V. (2001). US Patent 6174833 Bl, Process for the preparation of improved vanadium-phosphorus catalysts and use thereof for the production of maleic anhydride (Pantochim S.A., Feluy (BE)). 

In this work we have evaluated the catalytic properties of the molybdenum-phosphorus catalysts. For this purpose, we have prepared two Ni-Mo-P/AljOj samples following the impregnation sequences (Mo+P->Ni) and (P->Mo->Ni). These samples present the same chemical composition (15 wt% MoOj, 7.5 wtiK PjOj and 5.0 wt% NiO). The catalytic reaction was carried out in a high pressure fixed bed reactor using a vacuum gasoil under typical mild-hydrocracking conditions (T = 653K, P = 5 MPa, LHSV = 0.65 1/h, Hj/Hc = 600). 

TC. Colourless gas obtained from elements in presence of a catalyst (charcoal or Pt) or from Bra, red phosphorus, and H2O (HBr... 

Acetic acid can be chlorinated by gaseous chlorine in the presence of red phosphorus as catalyst to yield successively mono-, di-, and tri-chloroacetic acid the reaction proceeds better in bright sunlight. If the chlorination is stopped when approximately one molecule of chlorine per molecule of acetic acid is absorbed the main product is monochloroacetic acid ... 

Bromination of fatty acids in the a-position can be effected quite readily in the presence of phosphorus trichloride, red phosphorus or pyridine as catalysts or halogen carriers with acetic acid, the addition of acetic anhydride (to ensure the absence of water) improves the yield and facilitates the bromination. Examples are —... 

Hydrolysis of the azlactone leads to the acylaminooinnamic acid the latter may be be reduced catal3rtlcally (Adams PtOj catalyst 40 lb. p.s.i.) and then hydrolysed by hydrochloric acid to the amino acid. Alternatively, the azlactone (say, of a-benzylaminocinnamic acid) may undergo reduction and cleavage with phosphorus, hydriodic acid and acetic anhydride directly to the a-amino acid (d/ p phenylalanine). 

Rhenium catalysts are exceptionally resistant to poisoning from nitrogen, sulfur, and phosphorus, and are used for hydrogenation of fine chemicals. 

Common reducing agents are hydrogen in the presence of metallic or complex catalysts (e.g. Ni, Pd, Pt, Ru, Rh), hydrides (e.g. alanes, boranes, LIAIH, NaBHJ, reducing metals (e.g. Li, Na, Mg, Ca, Zn), and low-valent compounds of nitrogen (e.g. NjHj, NjHJ, phosphorus (e.g. triethyl phosphite, triphenyiphosphine), and sulfur (e.g. HO-CHj-SOjNa = SFS, sodium dithionite = Na S O. ... 

This method of a bromination of carboxylic acids is called the Hell-Volhard-Zelinsky reaction This reaction is sometimes carried out by using a small amount of phosphorus instead of phosphorus trichloride Phosphorus reacts with bromine to yield phosphorus tribromide as the active catalyst under these conditions... 

Table 5. Air-Blowing of Fluxes With and Without Ferric Chloride and Phosphorus Pentoxide Catalysts...

W. B. Williamson and co-workers. Catalyst Deactivation Due to Glac Formation from Oil-Derived Phosphorus and Zinc, SAE 841406, Society of Automotive Engineers, Warrendale, Pa., 1984. 

Diphenylmethane has been prepared with aluminum chloride as a catalyst from methylene chloride and benzene, from chloroform and benzene as a by-product in the preparation of triphenylmethane, and from benzyl chloride and benzene. It has been prepared by the reduction of benzophenone with hydriodic acid and phosphorus, or with sodium and alcohol. It has also been made by heating a solution of benzyl chloride in benzene with zinc dust, or with zinc chloride. The above method is only a slight modification of the original method of Hirst and Cohen. ... 

In catalytic incineration, there are limitations concerning the effluent streams to be treated. Waste gases with organic compound contents higher than 20% of LET (lower explosion limit) are not suitable, as the heat content released in the oxidation process increases the catalyst bed temperature above 650 °C. This is normally the maximum permissible temperature to which a catalyst bed can be continuously exposed. The problem is solved by dilution-, this method increases the furnace volume and hence the investment and operation costs. Concentrations between 2% and 20% of LET are optimal, The catalytic incinerator is not recommended without prefiltration for waste gases containing particulate matter or liquids which cannot be vaporized. The waste gas must not contain catalyst poisons, such as phosphorus, arsenic, antimony, lead, zinc, mercury, tin, sulfur, or iron oxide.(see Table 1.3.111... 

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