Catalytic methods

The catalytic method provides the basis for synthesis of carbon tubules of a large variety of forms. Straight tubules, as well as bent and helically wound tubules, were observed. The latter regular helices of fullerene diameter can be of special interest from both theoretical and practical points of view. 

Devise catalytic methods where catalysts are recycled and reused. 

The inner (outer) diameter of the observed curved or coiled nanotubules produced by the catalytic method[8] varies from 20 to 100 A (150 to 200 A), which corresponds to the graphite layer order 3< <15 (Table 1). 

Doyle, M.P. McKervey, M.A. Ye, T. Modem Catalytic Methods for Organic Synthesis with Diazo Compounds, Wiley, NY, 1998. 

Doyle MP, McKervey MA, Ye T (1998) Modem catalytic methods for organic synthesis with diazo compounds. Wiley, New York 

Although enolates, their equivalents, and otherwise stabilized carbanions would be interesting candidates for ARO of weso-epoxides, no efficient catalytic method has been developed to date. Crotti reported that 20 mol% of (salen)Cr-Cl complex 2 promoted the addition of the lithium enolate of acetophenone to cyclohexene oxide with moderate ees (Scheme 7.26) [50], However, the very low yields obtained 

These optimization studies are an important step in the study of Simmons-Smith cyciopropanations since they allowed for the development of a selective, catalytic method for introduction of a simple methylene unit. However, they also provide insights into the basic mechanism of this process. Together with earlier studies regarding carbenoid structure, the true nature of the reactive carbenoid, lCH2Znl, was confirmed. On the basis of these results, a revised transition structure was proposed. Although there is no direct evidence for such a transition 

In addition to conventional thermal cracking in tubular furnaces, other thermal methods and catalytic methods to produce ethylene have been developed. None of these are as yet commercialized. 

It was found that sorbed palladium might catalyse reaction of Mn(III) reduction by Cf not only after it s removing from coal, but AC with palladium, Pd/AC, has also his own catalytic effect. On the base of dependence between characteristics of AC, chemical state of palladium on AC surface and catalytic action of Pd/AC in indicator reaction it might establish, that catalytic action concerns only to non-reduced or partly reduced palladium ions connected with chloride ions on coal surface. The presence or absence of catalytic action of Pd/AC in above-mentioned reaction may be proposed for determination of chemical state of palladium on AC surface. Catalytic effect was also used for palladium micro-amounts determination by soi ption-catalytic method. 

The sorption evaluation of Pd(II) micro-amounts by active coals, ACs, from solutions with 50-500-fold excess of accompanying metals compounds was shown [1]. From the other hand catalytic action of Pd(II) in reaction of Mn(III) reduction by Ck is used for Pd(II) micro-amounts determination by catalytic method [2]. The co-operation of soi ption and catalytic detenuination of Pd(II) in one process was investigated. 

In this study we have shown that the catalytic method—carbon deposition during hydrocarbons conversion—can be widely used for nanotubule production methods. By variation of the catalysts and reaction conditions it is possible to optimize the process towards the preferred formation of hollow 

The methods in which iodine is used as a catalyst for the reaction between ceric sulfate and nitrite or arsenite (86,87) are capable of determining smaH amounts of iodine. However, these catalytic methods are deHcate and require accurate timing, carefiH temperature control, and special apparatus. 

This reaction is illustrative of a general procedure for the alkylation of active methylene functions in the presence of concentrated aqueous alkali catalyzed by tetraalkylammonium salts. This catalytic method has been used to alkylate arylacetonitriles with monohaloalkanes,2 dihaloalkanes,3 a-chloroethers,4 chloronitriles,.5 haloacetic acid esters,6 and halonitro aromatic compounds.7 It has also been used to alkylate ketones,8 lf/ indene,9 9i/-fluorene,ll) and the Reissert compound.11 The reaction is inhibited by alcohols and by iodide ion.2 

This chiral modifier provides one of the only methods for selective cyclopropa-nation of substrates which are not simple, allylic alcohols. In contrast to the catalytic methods which will be discussed in the following section, the dioxaborolane has been shown to be effective in the cyclopropanation of a number of allylic ethers [67]. This method has also been extended to systems where the double 

Pindur U., Lutz G., Otto C. Acceleration and Selectivity Enhancement of Diels-Alder Reactions by Special and Catalytic Methods Chem. Rev. 1993 93 741 761 

Raki, a Turkish alcoholic drink was also analyzed by differential pulse polarography and copper, iron and zinc could be determined. For the arsenic content in beer a more sensitive method had to be applied. For this method a new catalytic method is established and the arsenic content was determined by using this new method. 

High Density Polyethylene. High density polyethylene (HDPE), 0.94—0.97 g/cm, is a thermoplastic prepared commercially by two catalytic methods. In one, coordination catalysts are prepared from an aluminum alkyl and titanium tetrachloride in heptane. The other method uses metal oxide catalysts supported on a carrier (see Catalysis). 

In the alternate approach, the amide formation is performed on para-nitrobenzenesulfonyl chloride (91). Reduction by either chemical or catalytic methods affords directly the desired product (90).  

The classical aza-Darzens reaction (between bromoenolates and imines) has been investigated by several groups in recent years, especially with respect to the design and execution of asymmetric variants. Both stoichiometric and catalytic methods have been studied thus, the reactions between N-Dpp imines and chiral ot-bromoenolates [49] (derived from Oppolzer s sultams Scheme 4.35) and between S-chiral sulfmylimines and achiral bromoenolates [50] (Scheme 4.36) have been reported. 

Diels-Alder reactions of conjugated cycloalkenones provide a very important method for rapidly constructing complex polycyclic molecules. Since cycloalkenones are very poorly reactive dienophiles, acceleration by special physical and catalytic methods is required in order to avoid high reaction temperatures and long reaction times which often lead to low product yields [8], 

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