Molybdenum chloride catalysts

Cyclobutene, cyclopentene, and norbomene also give their polyalken-amers (64). The molecular weights are all high, and the stereochemistries are largely cis. Of these, cw-polypentenamer has also been made with molybdenum, tungsten, and rhenium halide catalysts, and cii-polynor-bomenamer (of lower molecular weight) with a molybdenum chloride catalyst, but polybutenamer made with metal halide catalysts (the metals tried were Ti, Mo, W, V, Cr, and Ru) has never been found to have more than 60% of its double bonds cis (64). 

Impurities with catalytic effects—Impurities that act as catalysts, reducing the activation energy of a process, may increase the rate of reaction significantly, even when present in small quantities. The presence of sulfuric acid, for example, increases the rate of decomposition and decreases the observed onset temperature of various isomers of ni-trobenzoic acid [28]. Also, other substances such as NaCl, FeCl3, platinum, vanadium chloride, and molybdenum chloride show catalytic effects. As a result, the decomposition temperature can be lowered as much as 100°C. Catalysts, such as rust, may also be present inadvertently. Some decomposition reactions are autocatalyzed, which means that one of more of the decomposition products will accelerate the decomposition rate of the original substance. 

Vinylsilanes react with methoxymethyl chloride, and with monothioacetals, cleaving the carbon-oxygen bond when molybdenum chloride is used as the catalyst.Vinylsilanes also react intramolecu-... 

For nitromesitylene in dichlorobenzene at 120 °C and 1 atm, k = 1.3 10, AH = 18 kcal mol and AS = - 30 cal K. Large substituents in the or//io position of the nitro compound accelerate the reaction, a situation already described in the case of some palladium and ruthenium systems [26, 38,43] (see paragraph 6.3.1. for a discussion of this effect). If other rhodium complexes were used as catalyst precursors, [Rh(CO)2(Cl)]2 was anyway formed by ligand exchange with the molybdenum chloride [207]. 

In the USA, 150,000 t benzene were used in 1976 for the production of chlorobenzene [27]. It is assumed in western Europe that 500,000 t benzene will have been used in 1979 as initial product for chloro- and nitrobenzene [3]. Based on these figures, the annual world production of chlorinated benzenes can be estimated at 600,000-800,000 t. Direct chlorination of benzene with chlorine gas is effected on a continuous basis in the presence of catalysts, such as aluminium, mercury, iron, sulphur chlorides or molybdenum chloride [32, 36, 43], following which the mixture is separated and purified by washing, chemical treatment and distillation operations. Chlorobenzene is used mainly for the production of phenol, chloronit-robenzenes, DDT, and as a solvent, o-dichlorobenzene is a solvent, whereas p-dichlorobenzene is used as an intermediate or (in addition to naphthalene) as a mothproofing agent [292]. 

Natural gas contains both organic and inorganic sulfur compounds that must be removed to protect both the reforming and downstream methanol synthesis catalysts. Hydrodesulfurization across a cobalt or nickel molybdenum—zinc oxide fixed-bed sequence is the basis for an effective purification system. For high levels of sulfur, bulk removal in a Hquid absorption—stripping system followed by fixed-bed residual clean-up is more practical (see Sulfur REMOVAL AND RECOVERY). Chlorides and mercury may also be found in natural gas, particularly from offshore reservoirs. These poisons can be removed by activated alumina or carbon beds. 

Carbonyl Compounds. Cychc ketals and acetals (dioxolanes) are produced from reaction of propylene oxide with ketones and aldehydes, respectively. Suitable catalysts iaclude stannic chloride, quaternary ammonium salts, glycol sulphites, and molybdenum acetyl acetonate or naphthenate (89—91). Lactones come from Ph4Sbl-cataly2ed reaction with ketenes (92). 

Sulfoxide adducts of chromium, molybdenum, and tungsten carbonyls have been studied as catalysts for the polymerization of monomers such as vinyl chloride (248). Simple adducts of the type [M(CO)5(Me2SO)] may be prepared by carbonyl displacement from the corresponding hexacarbonyl. Photochemical reactions are frequently necessary to cause carbonyl displacement in this manner, many carbonyl complexes of higher sulfoxides have been prepared (255, 256). Infrared (257) and mass spectral studies (154) of these complexes have appeared, and infrared data suggest that S-bonding may occur in Cr(0) sulfoxide complexes, although definitive studies have not been reported. 

The high-density polyethylene is linear and can be manufactured by (i) coordination polymerisation of monomer by triethyl aluminium and tritanium chloride, (ii) polymerisation with supported Metal Oxide Catalysts. Such as chromium or molybdenum oxides supported over alumina-silica bases. 

The solvent process involves treating phthalonitrile with any one of a number of copper salts in the presence of a solvent at 120 to 220°C [10]. Copper(I)chloride is most important. The list of suitable solvents is headed by those with a boiling point above 180°C, such as trichlorobenzene, nitrobenzene, naphthalene, and kerosene. A metallic catalyst such as molybdenum oxide or ammonium molybdate may be added to enhance the yield, to shorten the reaction time, and to reduce the necessary temperature. Other suitable catalysts are carbonyl compounds of molybdenum, titanium, or iron. The process may be accelerated by adding ammonia, urea, or tertiary organic bases such as pyridine or quinoline. As a result of improved temperature maintenance and better reaction control, the solvent method affords yields of 95% and more, even on a commercial scale. There is a certain disadvantage to the fact that the solvent reaction requires considerably more time than dry methods. 

Pentafluorocthyl iodide is of practical interest, particularly as a precursor of higher perfluoroal-kyl iodides. There are several patents for the preparation of the key compound from tetra-fluoroethene, iodine pentafluoride and iodine at 75-80 C in the presence of catalysts anti-mony(III) fluoride, titanium(lV) chloride, boron trifluoride, vanadium(V) fluoride, niobium(V) fluoride, and molybdenum(Vl) fluoride.11-13 The agents iodine monofluoride" and bromine monofluoride" can add to branched pcrfluoroalkcnes, e.g. perfluoro-2-methylbut-2-ene gives perfluoro-2-iodo-2-methylbutane.1415... 

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