Chlorobenzene as solvent

A method for the polymerization of polysulfones in nondipolar aprotic solvents has been developed and reported (9,10). The method reUes on phase-transfer catalysis. Polysulfone is made in chlorobenzene as solvent with (2.2.2)cryptand as catalyst (9). Less reactive crown ethers require dichlorobenzene as solvent (10). High molecular weight polyphenylsulfone can also be made by this route in dichlorobenzene however, only low molecular weight PES is achievable by this method. Cross-linked polystyrene-bound (2.2.2)cryptand is found to be effective in these polymerizations which allow simple recovery and reuse of the catalyst. 

Note It is reported that the use of chlorobenzene as solvent is essential when the reagent is to be used to detect aromatic amines [1]. In the case of steroids, penicillins, diuretics and alkaloids the reaction should be accelerated and intensified by spraying afterwards with dimethylsulfoxide (DMSO) or dimethylformamide (DMF), indeed this step makes it possible to detect some substances when this would not otherwise be possible [5,9-11] this latter treatment can, like heating, cause color changes [5,9]. Penicillins and diuretics only exhibit weak reactions if not treated afterwards with DMF [10, 11]. Steroids alone also yield colored derivatives with DMSO [9]. Tlreatment afterwards with diluted sulfuric acid (c = 2 mol/L) also leads to an improvement in detection sensitivity in the case of a range of alkaloids. In the case of pyrrolizidine alkaloids it is possible to use o-chloranil as an alternative detection reagent however, in this case it is recommended that the plate be treated afterwards with a solution of 2 g 4-(dimethyl-amino)-benzaldehyde and 2 ml boron trifluoride etherate in 100 ml anhydrous ethanol because otherwise the colors initially produced with o-chloranil rapidly fade [12]. 

Inter- and intramolecular hetero-Diels-Alder cycloaddition reactions in a series of functionalized 2-(lH)-pyrazinones have been studied in detail by the groups of Van der Eycken and Kappe (Scheme 6.95) [195-197]. In the intramolecular series, cycloaddition of alkenyl-tethered 2-(lH)-pyrazinones required 1-2 days under conventional thermal conditions involving chlorobenzene as solvent under reflux conditions (132 °C). Switching to 1,2-dichloroethane doped with the ionic liquid l-butyl-3-methylimidazolium hexafluorophosphate (bmimPF6) and sealed-vessel microwave technology, the same transformations were completed within 8-18 min at a reaction temperature of 190 °C (Scheme 6.95 a) [195]. Without isolating the primary imidoyl chloride cycloadducts, rapid hydrolysis was achieved by the addition of small amounts of water and subjecting the reaction mixture to further microwave irradia-... 

Recently, a new and inexpensive method has been published by our group [34]. It uses Bi203 and TfOH as starting materials and anhydrous chlorobenzene as solvent, which allows the recovery of Bi(0Tf)3-xH20 (with 1 < x < 4) simply by filtration (Scheme 3). 

Tetralin Hydroperoxide. Stoichiometry of the Reaction. Initial kinetic experiments at 30°, 40°, and 50 °C. in toluene solution showed that at least 25 moles of Tetralin hydroperoxide could be decomposed by 1 mole of dilauryl thiodiproprionate. For experimental reasons the bulk of the kinetic data was obtained in the temperature region 70°-90°C. using chlorobenzene as solvent. 

Another example of commercial interest is the Fries rearrangement of the benzoate ester of resorcinol to afford 2,4-dihydroxybenzophenone, the precursor of the UV-absorbent 4-0-octyl-2-hydroxybenzophenone. Reaction of benzoic acid with one equivalent of resorcinol (see Fig. 2.22), over various solid catalysts, in chlorobenzene as solvent, with continuous removal of water, was investigated by Hoefnagel and van Bekkum [68]. H-Beta was slightly less active than the ion-ex-... 

Palchik [182] obtained nanosized amorphous iron oxide (Fe203) by the pyrolysis of iron pentacarbonyl, Fe(GO)5, in a modified domestic microwave oven in refluxing chlorobenzene as solvent under air. The reaction time was 20 min. Separate particles of iron oxide, 2-3 nm in diameter, were obtained together with aggregated spheres with a diameter of 25-40 nm. Differential scanning calorimetry measurements showed an amorphous/crystalline phase transition at about 250 °C. 

TDI (10a and 10b) is prepared from o-nitrotoluene, which is first nitrated to afford 1,4- and 1,5- dinitro isomers. These products are hydrogenated to the corresponding diamines, at 74 °C, over a palladium-on-carbon catalyst. This is the only major use of toluene diamines. On phosgenation, using chlorobenzene as solvent, at around 52 °C, the amines afford the diisocyanates. The TDI is used in the manufacture of flexible foams (upholstery, bedding, seat cushions, etc.), paints, surface coatings, elastomers and adhesives. 1,5-Diaminonaphthalene (13) is converted into naphthalene-1,5-diisocyanate (14) (Scheme 5), used in specialty polyurethanes. 

Conditions toluene (3.0mL) Ln (lOpmol) [Ph3C][B(C6F5)4] (lOpmol) TIBA (lOOpmol) Hexane as solvent Chlorobenzene as solvent... 

The synthesis of 2,4-dihydroxybenzophenone (compound 4 Eq. 5) was investigated over various solid catalysts by reacting a 1 1 molar mixture of resorcinol with benzoic acid in chlorobenzene as solvent, water resulting from ester formation being removed [3,22]. 

The rate coefficients for hydroxyperoxide decomposition to free radicals is different from that for hydroperoxides. Therefore, addition of hydroperoxide to ketone changes the rate of free radical formation. This was first found for the system cyclohexanone—t-butyl hydroperoxide [168] with chlorobenzene as solvent. The rate of initiation increases with ketone concentration at a constant concentration of hydroperoxide. The... 

The kinetic study of the acylation reaction of thiophene with acyl chlorides over dealuminated HY zeolites, in chlorobenzene as solvent, has been shown to follow a Langmuir-Hinshelwood type kinetic law. In liquid phase conditions, thiophene is slightly more adsorbed than the acyl chloride. Moreover, the study of the reaction with various substituted benzoyl chlorides X-CgH4-COCl shows that the nature of the substituent has very little influence on the initial rate. 

Dealuminated HY zeolites have been shown to be efficient catalysts for the selective preparation of 2-acyl thiophenes in the reaction nf thiophene with various acyl chlorides. The acylation reaction of thiophene with butyroyl chloride over HY (Si/Al =15) zeolite, in chlorobenzene as solvent, follows a Langmuir-Hinshelwood kinetic law, which involves the adsorption of the two reactants on identical sites of the catalyst surface. ... 

A different source of arenesulphenyl cations has been reported by Montevecchi and coworkers . They showed that the BFs-promoted reaction of 4 -nitrobenzenesulphena-nilide (35) with aryl-substituted alkynes in poorly nucleophilic solvents such as chlorobenzene generally led to bissulphides (36) and sulphimides (37) in addition to diphenyl disulphide and 4-nitroaniline. In acetonitrile as solvent, products of capture of the thiirenium ion by the solvent were also observed (equation 22). The thiirenium ion from phenylacetylene reacted even with the poorly nucleophilic solvent chlorobenzene to ( )-PhSCH=CPhC6H4Cl. With alkyl-substituted alkynes in chlorobenzene as solvent, a small amount of ( )-2-fluorovinyl sulphide PhSC(R )=CF(R ) was also detected. The yield of this sulphide could be increased when the reaction was performed in the presence of tetrabutylammonium tetrafluoroborate. Terminal alkynes gave the corresponding 2-fluorovinyl sulphides in 35-55% and internal alkynes in 65-87% yield. The procedure was unsuccessful for di-tcrt-butylacetylene and gave low yields for arylacetylenes. In acetic acid as solvent the thiirenium ion was captured as ( )-PhSC(R )=CR (OAc). 

Yang and Wu [202] showed that near-saturated concentrations of PhOQ in chlorobenzene as solvent at different temperatures were achieved after about 20 min of operation. The difference in PhOQ concentraitons at various reaction temperatures was not significant in this case. This shows that the catalytic intermediate PhOQ can be formed from tetra- -butylammonium salt reacted with PhONa in a solid-liquid system. 

Oxidations were carried out at 85 in chlorobenzene as solvent and substrate catalyst molar ratios of ca. 100 1. Cyclohexanol, and a-methylbenzyl alcohol were converted to the corresponding ketones in high selectivities using TBHP under a N2 atmosphere. The selectivity on TBHP was also > 90%. Good results were also obtained for the selective oxidations of Cyclohexanol, a-methylbenzyl alcohol, tetralol and indanol using 2 as the oxidant and 10 mol% TBHP as initiator. The catalyst could be recycled several times without any loss of activity. A mechanism is proposed for the CrAPO-5 catalyzed oxidation of alcohols. 

A composite based on single-walled carbon nanotubes and an oligo-V-vinylcarbazole (OVK) has been prepared by mixing the carbon nanotubes with the oligomer in chlorobenzene as solvent [221]. Then a sonification process follows. 

It is intermediate in selectivity between the chlorine atom and the bromine atom. The precise selectivity is solvent- and temperature-dependent, but in chlorobenzene as solvent, for example, a ratio of tert sec pri of 60 10 1 is typical. A number of examples of radical-chain halogenation that illustrate the preparative use of these reactions are given in Scheme 12.3. 

The catalytic activities were found to be well correlated with the Lewis acid-base properties. UIO-66-NH2 showed the highest catalytic activity among the investigated MOFs-based materials with a maximum of 96% Ygj, obtained at 100°C, 20 bar after 4 h in the presence of chlorobenzene as solvent. Nevertheless the contribution of homogeneous reaction cannot be excluded in this case. 

This radical is intermediate in selectivity between chlorine and bromine atoms. The selectivity is also solvent and temperature dependent. A typical ratio, in chlorobenzene as solvent, is tertiary secondary primary = 60 10 1. Scheme 12.4 (p. 690) gives a number of specific halogenation reactions that proceed by radical chain mechanisms. 

Manganese chloride, manganese malonate, and manganese acetylacetonate [138] with organoaluminum halides are reported to dimerize ethylene in chlorobenzene as solvent. The optimum aluminum to manganese ratio is 3 1. At 45 atm of ethylene pressure and 80—85°C, butenes consisting of 36.6% 1-butene, 42.2% trans-2-butene, and 21.2% cis-2-butene are formed. 

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