Toluene as a solvent

Suppose laboratory results at 110°C using toluene as a solvent show the reaction to be second order with rate constant k = 5.6x 10- m /(mol-s). Suppose [N(CH3)3]o = [C3H7Br]o = 80 mol/m. ... 

The selection of the solvent can affect a reaction drastically. In the Halex process for the conversion of 2,4-dichloronitrobenzene with KF to 2,4-difluoronitrobenzene, no reaction occurs in toluene as a solvent, presumably because KF has negligible solubility in toluene. In water, in which KF is highly soluble, no reaction occurs either, due to poor solubility of 2,4-dichloronitrobenzene in water and heavy solvation of fluoride rendering it ineffective. Dimethylformamide is suitable as the solvent KF has some solubility, while the product KCl precipitates (Atherton and Jones, 1995). 

Pt/Al2C>3-cinchona alkaloid catalyst system is widely used for enantioselective hydrogenation of different prochiral substrates, such as a-ketoesters [1-2], a,p-diketones, etc. [3-5], It has been shown that in the enantioselective hydrogenation of ethyl pyruvate (Etpy) under certain reaction conditions (low cinchonidine concentration, using toluene as a solvent) achiral tertiary amines (ATAs triethylamine, quinuclidine (Q) and DABCO) as additives increase not only the reaction rate, but the enantioselectivity [6], This observation has been explained by a virtual increase of chiral modifier concentration as a result of the shift in cinchonidine monomer - dimer equilibrium by ATAs [7],... 

For this study, p-xylene and triisopropylcyclohexane (TIPcyC6) were the two molecular probes chosen, using toluene as a solvent. Their molecular dimensions were obtained from the shadow of the three-dimensional molecule projected onto a plane according to the method of Rohrbaurgh et al. [5] (Table 2). A molecular probe is considered not to penetrate into a cylindrical pore if two of its dimensions are greater than the pore diameter [6], As the free diameter of the window of the supercage of the Y zeolite is equal to 0.74 nm, it is considered that only TIPCyC6 cannot penetrate into the zeolite microporosity. 

Scheme 4.19 Use of ionic liquid-doped toluene as a solvent for microwave synthesis.

Under the action of microwave irradiation, with toluene as a solvent, cycloadduct 76 was formed in 35% yield after 15 min at 800 W [72] this is an improvement on the yields obtained by conventional heating and probably occurs because of a decrease in the reversion of the cycloaddition in the shorter period of time needed for the irradiated reaction. It is remarkable that under microwave conditions the formation of bis adducts was not observed in these reactions. 

The experimental data obtained with macrogels formed in the presence of solvents, agreed well with Eq. (5) [99,105,108]. In order to check the applicability of this equation to microgels, the experimental data reported by Hoffmann [70] are used. He prepared a series of microgels with different crosslink densities, using toluene as a solvent, at Q°° = 5. Qvwas calculated from the reported data... 

CSD [Critical solvent deashing] A process for removing insoluble material from coal before liquifaction, using toluene as a solvent under subcritical conditions. Used in the Kerr-McGee and National Coal Board processes. 

Scheme 24 shows the atom transfer radical cyclizations of unsaturated /3-keto esters 94 using MgfCKLh and chiral ligand 96. It was found that toluene as a solvent generally gave higher enantioselectivities than CH2CI2... 

Trifluoroethanol (TFE, CE3CH2OH) also demonstrates high H-bond activity. The dyad system in which a radical and electron-donor parts are linked directly undergoes intramolecular electron transfer on substitution of TEE for toluene as a solvent. The transition was interpreted as a marked effect of hydrogen bonding (or reversible protonation) of the anionic R-0 structure with TFE (Nishida et al. 2005). Scheme 5.17 depicts this transition. 

Further on, Sawamura et al. [37] investigated the influence of different counter anions on the catalytic activity of cationic silicon Lewis acids. In the studies an achiral salt was used. In previous cases [30] acetonitrile was used as a solvent, which is known to coordinate strongly the silicon cation species. Therefore, the application of toluene as a solvent was investigated with a silicon cationic species. Although even toluene coordinates a silicon cation [25, 38], an enhanced activity compared to other solvents, was found. The achiral salt was prepared in situ from triethylsilane and [Ph3C][B(CgFj) ] (17) as depicted in Scheme 10. 

Isomerically pure chlorofullerene C oClg has been reported to be the predominant product of the reaction of with an excess of iodine monochloride in benzene or toluene at room temperature (Scheme 9.11) [79], The product is very soluble in benzene, carbon disulfide and tetrachloromethane. Deep orange crystals can be obtained by recrystallization from pentane. The synthesis of CjoClg using toluene as a solvent proceeds more slowly than with benzene, indicating that radicals are involved and are scavenged by the toluene [79],... 

Commercial methods for preparing block copolymers of styrene-hutadiene-styrene utilize cyclohexane or toluene as a solvent since the polystyryl lithium is insoluble in straight chain alphatic solvents.Usually the 1,3-butadiene is added to the polystyryl lithium to produce the diblock styrene-butadienyl lithium. At this point in the reaction two processes are employed. 

A Ni based catalyst for addition polymerization can be prepared from nickel(2-ethylhexanoate), methylaluminoxane, and triethyl-borane (34). The polymerization is carried out in toluene as a solvent under pressure. 

Recently, a new rhodium recycling system was described that takes advantage of amphiphilic ligands such as Ph2ArP (Ar = 3-hydroxyphenyl, 4-carboxyphenyl). The corresponding rhodium complexes are active in the hydroformylation of 1-octene and can be separated from the products by acidic or basic extraction into water. After neutralization of the aqueous phase, the rhodium species could be extracted into a new batch of octene, with toluene as a solvent. The recovered catalyst retained only up to 87% of its activity (72). 

Table I shows some peculiarities. In contrast to what has been claimed in literature, the probabilities of forming an isotactic diad at an existing iso tactic diad (pj/j) do not always equal the probabilities of forming an isotactic diad at an existing syndiotactic diad (p8/i). The free radical polymerization of the six methacrylate monomers mentioned is thus not always Bemoullian, at least not at the temperature of — 78°C and in toluene as a solvent.

The composites were prepared from solutions of mNA and PMMA with varying loading degrees (between 30 wt % and 90 wt %), using toluene as a solvent. Thin films (30-40 fim) were cast on a glass slide and the solvent was... 

Partial benzylation with powdered potassium hydroxide as a base and toluene as a solvent was used some 50 years ago for the preparation of 1,6-anhydro-2,4-0-benzyl-P-D-glucopyranose [79]. Since that time, other solvents, such as benzene [80-82], 1,4-dioxane-toluene mixtures [83, 84], or excess benzyl chloride [82, 85] were used as well, with apparent effects on the regioselectivity. Thus, the axially oriented secondary hydroxyl group of lL-l,2,3,4-tetra-0-benzyl-c/i ro-inositol is more reactive than the equatorial one using benzyl chloride alone (ratio of 79 21), whereas the opposite is true (35 65) in benzene as a solvent [82]. Benzylation of myo-inositol derivatives in the latter solvent was also described [80, 81, 86]. 

The use of sc C02 instead of toluene as a solvent leads to some rate enhancement in these two systems, although it is clear that this activity is still not practical for most nonpolar, nonvolatile substrates. Significant improvements to the biphasic water/supercritical C02 system were accomplished by forming H20/C02 emulsions using newly developed surfactants (Jacobson et al., 1999). Three different surfactants were used that form water in C02 (w/c) or C02 in water (c/w) emulsions (1) anionic surfactant perfluoropolyether ammonium carboxylate, (2) cationic Lodyne 106A, and (3) nonionic poly(butylene oxide)-h-poly(ethylene oxide). The low interfacial tension, y, between water and C02 (17 mNm-1 at pressures above 70 bar), which is significantly lower than water/alkane systems (30-60 mNm-1),... 

Hubert et al. [101] state that accelerated solvent extraction compared to alternatives such as Soxhlet extraction, steam distillation, microwave extraction, ultrasonic extraction and, in some cases, supercritical fluid extraction is an exceptionally effective extraction technique. Hubert et al. [ 101 ] studied the effect of operating variables such as choice of solvent and temperature on the solvent extraction of a range of accelerated persistent organic pollutants in soil, including chlorobenzenes, HCH isomers, DDX, polychlorobiphenyl cogeners and polycyclic aromatic hydrocarbons. Temperatures ofbetween 20 and 180 °C were studied. The optimum extraction conditions use two extraction steps at 80 and 140 °C with static cycles (extraction time 35 minutes) using toluene as a solvent and at a pressure of 15 MPa. 

Used for the precolumn preparation of fluorescent derivatives of some primary and secondary amines using toluene as a solvent only amines with pKa > 9.33 have been successfully determined Reference 27... 

Lipase PS-30 was immobilized on Accurel PP and the immobilized enzyme was reused five times without any loss of activity or productivity in the resolution process to prepare A-(+)-(43). The enzymatic process was scaled up to a 640-liter preparative batch using immobilized lipase PS-30 at 4 g/liter racemic substrate (43) in toluene as a solvent. From the reaction mixture, i -(+)-(43) was isolated in 35 M% overall yield with 98.5% e.e. and 99.5% chemical purity. The undesired, S -(-)-acetatc (46) produced by this process was enzymatically hydrolyzed by lipase PS-30 in a biphasic system to prepare the corresponding S -(-)-alcohol (43). Thus both enantiomers of alcohol (43) were produced by the enzymatic process. 

Unbridged, bridged, substituted, and half-sandwich complexes have been used as metallocenes for ethylene polymerization (Figs. 1 and 2). To compare the activities and molecular masses, the polymerizations are carried out under the same conditions (30°C, 2 bar ethylene pressure, with toluene as a solvent) (105). Table IV shows the polymerization behavior of various met-allocene/alumoxane catalysts. Generally, zirconium-containing catalysts are... 

Good selectivity for transmetallation at the 2-position of 2,5-dibromopyridine 114 is obtained by using toluene as a solvent.96... 

The number average molecular weight of the degraded polymers was measured on an ebulliometer, using toluene as a solvent and a tristearin standard. Intrinsic viscosities of the polymers were determined using a Desreux dilution viscometer. 

We hypothesized that this polymerization proceeds by a single-site catalyst under different morphological conditions and variable monomer concentrations, i.e. polymerization in the crystalline polymer and in the amorphous polymer state. The frequency factor of the polymerization in the crystalline polymer should be lower than that in the amorphous polymer. The effect of monomer concentration on the polymerization rate is shown in Figure 17.14 using toluene as a solvent. The reaction rate is proportional to the monomer concentration. From these results, the polymerization reaction can be described by the following equations ... 

However, the analogous reaction of mesitylphosphaethyne with the diene in toluene as a solvent at 55 °C led to the isolable phosphaalkene 49. Even though the ene/[4+2] cycloaddition sequence with a second equivalent of phos-phaalkyne was slow, product 50 was isolated after 1 week as an orange oil (Scheme 17) <1998S1305>. 

Dimethylaminoethanol reacts with thionyl chloride in toluene as a solvent. The mixture is heated in the reactor at the boiling point to complete the reaction. Sulfur dioxide gas is evolved and absorbed in the scrubber. 

The last step of the process includes the reaction of 2-chloro-N,N-dimethylethylamine with 2-benzylaminopyridine in toluene as a solvent. After completion, the mixture is passed through a filter to remove the sodium chloride by-product. Tripelennamine is separated by concentrating the filtrate under reduced pressure. (Fig. 10.7). 

Regioselective dimerization of propene to 2,3-dimethylbutenes (DMBs) is currently operated by Sumitomo and BP Chemicals. Both use P(cyclohexyl)3 as the bulky ligand. In the Sumitomo process [7] very high selectivities in DMBs (up to 85 %) are obtained at 20-50 °C, thanks to a sophisticated, highly efficient, Ziegler-type catalyst system (ten times more efficient than those of conventional catalysts) and by using toluene as a solvent. Isomerization of 2,3-dimethyl-1-butene (DMB-1) into 2,3-dimethyl-2-butene (DMB-2) takes place directly in... 

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