Chlorobenzene dimer

Chlorobenzene Dimer acid, hydrogenated Epoxy, bisphenol F N-(p-Ethoxycarbonylphenyl)-N -ethyl-N -phenylformamidine 2,2, 4,4, 5,5 -Hexachlorobiphenyl Polychlorinated biphenyls coatings, surface film Tetrahydrofuran coatings, surface lipophilic Octadecyltrichlorosilane coatings, surface PU paints Hexamethylene diisocyanate biuret Hexamethylene diisocyanate polymer coatings, surface PU varnishes Hexamethylene diisocyanate biuret Hexamethylene diisocyanate polymer coatings, surface textiles Tetrahydrofuran... 

Since the zerovalent complex Pd(PPh3)3 undergoes photoinduced oxidative addition with chlorobenzene, dimeric palladium(O) complexes are also expected to undergo such reactions. An additional feature of the dimers, however, is the presence of two metal centers that can undergo such a two-electron addition. An example of such a double addition is found in the photoreaction between... 

A calculation of the interaction energies for some prototypical dimers provides a sensitive test for a first impression of Pixel s performance. The parallel offset benzene dimer, the chlorobenzene dimer with Cl Cl encounter, and the hydrogen bond formation in benzoic acid (Scheme 12.1) will be discussed. 

Figure 12.8 shows the interaction picture for the chlorobenzene dimer. The dispersive interaction between the largely separated aromatic rings is negligible, and... 

An obvious method to investigate the formation and the nature of the catalytically active nickel species is to study the nature of products formed in the reaction of complexes such as 3 or 4 with substrate olefins. This has been investigated in some detail in the case of the catalytic dimerization of cyclooctene to 1-cyclooctylcyclooctene (17) and dicy-clooctylidene (18) [Eq. (4)] using as catalyst 7r-allylnickel acetylacetonate (11) or 7r-allylnickel bromide (1) activated by ethylaluminum sesquihalide or aluminum bromide (4). In a typical experiment, 11 in chlorobenzene was activated with excess ethylaluminum sesquichloride cyclooctene was then added at 0°C and the catalytic reaction followed by removing... 

The reaction of ethylene at -20°C and 1 atm with the phosphine-free catalyst prepared from 77-allylnickel chloride and ethylaluminum dichloride in chlorobenzene results in the rapid formation of a mixture of ethylene dimers with lesser amounts of higher oligomers. The dimer fraction consists mainly of 2-butenes and the trimer fraction of 3-methylpentenes and 2-ethyl-1-butene as well as a minor amount of hexene (97). From the composition of the products it can be concluded that the displacement reaction predominates over the insertion reaction when using the phosphine-free catalyst and that the direction of addition of both the H—Ni and C2H5—Ni species is mainly of the Ni — C2 type. 

Desulfuration-dimerization of dithioketals.1 Dithioketals when refluxed with W(CO)6 in chlorobenzene are converted into the corresponding dimeric alkenes. 

In non-polar solvents many aminolysis reactions show a third-order dependence on the amine, B. This may be explained by catalysis of leaving-group departure by hydrogen-bonded homoconjugates, BH+B. Evidence for this pathway has been adduced from studies of the reactions of some nitro-activated (9-aryl oximes (7) with pyrrolidine in benzene, chlorobenzene, and dioxane, and with piperidine and hexylamine in cyclohexane. The third-order dependence on amine of the reaction of 2,6-dinitroanisole with butylamine in toluene and toluene-octanol mixtures has been interpreted in terms of a mechanism involving attack by dimers of the nucleophile. ... 

The formation of chlorobenzene and carbon dioxide is probably coming from the decarboxylation of the ClPhCOO radical (11). This is avoided when MCPBA is reacted with Co(II) presumably because the cobalt(II) exists as a dimer which can absorb both electron equivalents of the MCPBA and avoid a radical reaction (7) ... 

The first step in this sequence is the hydroxyl radical attack on chlorobenzene (reaction 2), which likely results in the formation of chlorohydroxycy-clohexadienyl (C1HCD) radical I (Dorfman et al., 1962). This may initiate one of several possible further reactions. In the absence of strong oxidants, two predominant reactions are dimerization, to produce dichlorobiphenyls (reaction 3), and bimolecular disproportionation, to produce chlorophenol and chlorobenzene (reaction 4). Both reactions showed the stoichiometry of 2 mol... 

The intramolecular photoinduced electron transfer reaction of N-(o-chlorobenzyl)aniline 440 in the presence of sodium hydroxide in aqueous acetonitrile afforded, 9,10-dihydrophenanthridine and its dimer, which is reasonably explained by dechlorination from the radical anion of chlorobenzene chro-mophore followed by the cyclization (Scheme 130) [481], Similar photocyclization 9-(io-anilinoalkyl)-10-bromophenantherens 441 takes place to give spiro compounds, cyclized products, and reduction products dependent on the methylene chain length. The efficient intramolecular photocyclization occurs when the methylene tether is n = 3 [476] (Scheme 131). 

Cyclic conjugated earbanions have also been studied and rarely found to give an electron transfer photochemistry in the absence of an electron acceptor. One example was however found in the case of cyclooctadienyl carbanion irradiated in THF and in the presence of chlorobenzene or rrans-stilbene. Dimeric radical products and phenylated cyclooctadiene were formed in the first case while trans-cis isomerization of stilbene was observed in the second one... 

A new method using an organopalladium compound was reported by Maasarani and PfefFer (90MI1). Cationic compound 73 derived from chlo-ro-bridged dimer 72 reacted with 3-phenylpropiolate in chlorobenzene to give 6-phenylbenzo[/> ]quinolizinium salt 74 (17%). 

It was earlier discussed that 1,3-dithiolanes underwent an interesting desulfurdimerization reaction leading to dimeric olefins on treatment of metal carbonyls, such as W(CO)6 or MofCO) <1995JOC7380>. In the case of the monomeric 296, this reaction performed with W(CO)6 in refluxing chlorobenzene for 48-60 h afforded the corresponding oligophenylenevinylenes (OPVs) 297 in 67-81% yields (Equation 28) <2001JOM(1)63> . 

Even as a toluene emulsion, these complexes show catalytic activity towards ethylene and propylene which is several orders higher than that of TT-allylnickel halides. Paralleling the increase in catalytic activity, the selectivity of this catalyst is also increased—i.e., the products are mainly ethylene or propylene dimers. The most active catalytic systems for dimerizing ethylene and propylene are obtained by replacing toluene with halogenated hydrocarbons such as chlorobenzene since in these more polar solvents, the complexes XIII are soluble. 

The dimerization reaction has been carried out under two different conditions. In laboratory experiments, the reaction is conveniently carried out under 1 or less than 1 atmosphere and at a temperature of —20° to — 10°C. These relatively low temperatures are necessary to obtain a sufficient concentration of ethylene or propylene in the catalyst solution. The dimerization catalyst for laboratory experiments is usually prepared by mixing, for example, chlorobenzene solutions of a 7r-allylnickel halide and an aluminum halide (or alkylhalide) in molar ratio of at least 1 1. The phosphine-modified catalyst is obtained by simply adding 1 mole of a phosphine per mole of nickel to the solution of the catalyst. When ethylene or propylene is introduced into the catalyst solution, reaction starts immediately, as evidenced by a sudden rise in temperature. Dimerization is exothermic to the extent of about 28 kcal./mole propylene dimer. Hence, the mixture must be stirred and cooled intensively during the reaction. Under these conditions (Table V), reaction rates of about 6 kg. 

No successful attempts to observe the spectrum of the thiophenoxy radical or its unhindered substituted analogues have been reported in solution studies. Smentowski (1963) found that the p-chlorobenzene-thiolate anion reacts with nitrosobenzene to give the spectrum of the latter s radical-anion (flow system) and a high yield of the disulphide thep-chlorothiophenoxy radical is apparently formed as an intermediate but dimerizes too rapidly for spectroscopic detection. The spectra of both aromatic and aliphatic thiol radicals have, however, been observed when the species, generated by ultraviolet irradiation of the corresponding disulphides, are trapped in the solid state (Smissman and Sorensen, 1965 Windle et al., 1964). 

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