Synthesis catalytic

The second type of solution polymerization concept uses mixtures of supercritical ethylene and molten PE as the medium for ethylene polymerization. Some reactors previously used for free-radical ethylene polymerization in supercritical ethylene at high pressure (see Olefin POLYMERS,LOW DENSITY polyethylene) were converted for the catalytic synthesis of LLDPE. Both stirred and tubular autoclaves operating at 30—200 MPa (4,500—30,000 psig) and 170—350°C can also be used for this purpose. Residence times in these reactors are short, from 1 to 5 minutes. Three types of catalysts are used in these processes. The first type includes pseudo-homogeneous Ziegler catalysts. In this case, all catalyst components are introduced into a reactor as hquids or solutions but form soHd catalysts when combined in the reactor. Examples of such catalysts include titanium tetrachloride as well as its mixtures with vanadium oxytrichloride and a trialkyl aluminum compound (53,54). The second type of catalysts are soHd Ziegler catalysts (55). Both of these catalysts produce compositionaHy nonuniform LLDPE resins. Exxon Chemical Company uses a third type of catalysts, metallocene catalysts, in a similar solution process to produce uniformly branched ethylene copolymers with 1-butene and 1-hexene called Exact resins (56). 

Fig. 13. Schematic potential energy diagram for the catalytic synthesis and decomposition of ammonia on iron. The energies are given in kj/mol to convert...

In early times hydrogen cyanide was manufactured from beet sugar residues and recovered from coke oven gas. These methods were replaced by the Castner process in which coke and ammonia were combined with Hquid sodium to form sodium cyanide. If hydrogen cyanide was desired, the sodium cyanide was contacted with an acid, usually sulfuric acid, to Hberate hydrogen cyanide gas, which was condensed for use. This process has since been supplanted by large-scale plants, using catalytic synthesis from ammonia and hydrocarbons. 

Fe, Co or Ni is also crucial in the catalytic decomposition of hydrocarbon. In order to efficiently obtain CNT and to control its shape, it is necessary and indispensable to have enough information on chemical interaction between carbon and these metals. It is quite easy for the catalytic synthesis method to scale up the CNT production (see Chap. 12). In this sense, this method is considered to have the best possibility for mass produetion. It is important to further improve the process of catalytie synthesis and, in order to do so, clarifieation of the mechanism of CNT growth is necessary to control the synthesis. CNT can be synthesized by the chemical reaction at relatively low... 

Hernadi, H., Fonseca, A., Nagy, J. B. and Bemaerts, D., Catalytic synthesis of carbon nanotubes. In Supercarbon, Synthesis, Properties and Applications, ed. S. Yoshimura and R. P. H. Chang. Springer-Verlag, Heidelberg, 1998, pp. 75 91. 

F. Haber s catalytic synthesis of NH3 developed in collaboration with C. Bosch into a large-scale industrial process by 1913. (Hater was awarded the 1918 Nobel Prize in Chemistry for the synthesis of ammonia from its elements Bosch shared the 1931 Nobel Prize for contributions to the invention and development of chemical high-pressure methods , the Hater synthesis of NH3 being the first high-pressure industrial process.)... 

Catalytic synthesis of natural fused O- and N-heterocycles 98JHC1057. 

Dent, F. J., et al.y An Investigation into the Catalytic Synthesis of Methane... 

The catalytic synthesis of ammonia from its elements via the Haber-Bosch process is of major industrial importance. The high pressure synthesis is catalyzed by Fe promoted with K20, CaO and A1203. 

FIGURE 9.14 One of the high-pressure vessels used for the catalytic synthesis of ammonia. The vessel must be able to withstand internal pressures of greater than 250 atm. 

When the Pd bears chiral ligands, these reactions can be enantioselective. TT-Allylmolybdenum compounds behave similarly.Because palladium compounds are expensive, a catalytic synthesis, which uses much smaller amounts of the complex, was developed. That is, a substrate such as an allylic acetate, carbo-... 

Scheme 18 Reagent-induced enantioselective catalytic synthesis of 2,3-diamino esters by addition of a-amino and a-iminoester enolates to imines...

Recent research on the catalytic synthesis of methanol from CO2 and H2 over a copper catalyst has shown that the rate of reaction is first order in CO2 and 3/2 in H2. 

A chemical reactor is an apparatus of any geometric configuration in which a chemical reaction takes place. Depending on the mode of operation, process conditions, and properties of the reaction mixture, reactors can differ from each other significantly. An apparatus for the continuous catalytic synthesis of ammonia from hydrogen and nitrogen, operated at 720 K and 300 bar is completely different from a batch fermenter for the manufacture of ethanol from starch operated at 300 K and 1 bar. The mode of operation, process conditions, and physicochemical properties of the reaction mixture will be decisive in the selection of the shape and size of the reactor. 

Due to its marked atom economy, the intramolecular hydroamination of alkenes represents an attractive process for the catalytic synthesis of nitrogen-containing organic compounds. Moreover, the nitrogen heterocycles obtained by hydroamination/cyclisation processes are frequently found in numerous pharmacologically active products. The pioneering work in this area was reported by Marks et al. who have used lanthanocenes to perform hydroamination/cyclisation reactions in 1992. These reactions can be performed in an intermolecular fashion and transition metals are by far the more efficient catalysts for promotion of these transformations via activation of the... 

Simple Catalytic Synthesis of N,N -Dialkyl-N,N -di(l-deoxyglucityl)ethylenediamines, Sugar-... 

J. P. Chen, A. F. Wiese, and C. R. Penquite, CCN Enabling Catalytic Synthesis, Engelhard Corporation, October (2002). 

Methanol production, where CO is added as additive, is very a well-known reaction. The production is carried out in two steps. The first step is to convert the feedstock natural gas into a synthesis gas stream consisting of CO, CO2, H20 and hydrogen. This is usually accomplished by the catalytic reforming of feed gas and steam. The second step is the catalytic synthesis of methanol from the synthesis gas. If an external source of C02 is available, the excess hydrogen can be consumed and converted to additional methanol. 

Kumar, R., Sithambaram, S. and Suib,S.L. (2009) Cyclohexane oxidation catalyzed by manganese oxide octahedral molecular sieves - effect of acidity of the catalyst. Journal of Catalysis, 262,304—313. Sithambaram, S., Kumar, R., Son, Y. and Suib, S.L. (2008) Tandem catalysis direct catalytic synthesis of imines from alcohols using manganese octahedral molecular sieves. Journal of Catalysis, 253, 269-277. 

Borabenzene complexes of cobalt such as Co(C5H5BPh)(COD) (51) and its 5-ethyl analog show the same type of catalysis but improved activity and chemoselectivity (77). Thus, 51 as the catalyst precursor gave the hitherto best results in the catalytic synthesis of the valuable 2-vinylpyridine from C2H2 and CH2=CHCN (120°C, 51 bar, 2 hours, turnover number 2164) (77,101). Furthermore, this catalyst for the first time allowed the synthesis of pyridine from C2H2 and HCN under mild conditions (110°C, 23 bar, 60 minutes, turnover number 103) (77). 

The cyclobutenone 70 is transformed to the r/4-vinylketene complex 72 with (t/5-indenyl)Co(PPh3)2 71. The vinylketene complex 72 undergoes cyclization with alkynes to produce the corresponding phenols 73. FeCl3 oxidation of the (2-phenylvinyl)ketene complex, however, leads to the naphthol 74. A catalytic synthesis of phenols via the vinylketene intermediates 72 is achieved by the use of Ni(COD)2 as a catalyst [36]. (Scheme 26)... 

Alkylations of phenols with epichlorohydrin under PTC conditions and microwave irradiation were described twice in 1998. Subsequently, ring-opening reactions of the epoxide group were also performed using microwaves (Eqs. 20 and 21) [31, 32]. In the first catalytic synthesis of chiral glycerol sulfide ethers was described [31] in the second biologically active amino ethers were prepared [32],... 

This chapter focuses exclusively on microwave heterogeneous catalysis. Microwave homogeneous catalysis by transition metal complexes is treated in Chapt. 11, phase transfer catalysis in Chapt. 5, catalytic reactions on graphite in Chapt. 7, photocataly-tic reactions in Chapt. 14, and catalytic synthesis oflabeled compounds in Chapt. 13. 

A. Sen (ed.) Catalytic Synthesis of Alkene-Carbon Monoxide Copolymers and... 

In one approach to catalytic synthesis of 1,2,3-triazoles, copper(l) is introduced to the reaction mixture as Cul. Compounds 1109-1115 are obtained this way. As can be seen in Table 12, a tertiary amine is often added as a base. The reaction conditions are mild and yields of the products are high. In some cases, the reaction can be carried out in water (compound 1115). For the synthesis of triazole 1116, addition of Cu powder is enough to generate catalytic amounts of Cu(l). 

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