Reaction in a mixture

Scheme 3 Reactions in a mixture of PS, PE, and styrene monomer in the presence of a peroxide and the coupling agent.

Holt studied the Diels-Alder reaction in a mixture of water, 2-propanol, and toluene as microemulsions.33 The endo/exo ratio between the reaction of cyclopentadiene and methyl methacrylate was enhanced with increasing amount of water in the presence of a surfactant. 

A different dimerization takes place in formic acid (33. 34). Unlike other carboxylic acids which behave as nucleophiles, formic acid behaves as a reductant and the dimerization proceeds with partial reduction. By carrying out the reaction in a mixture of formic acid and triethylamine at 59°C using Pd(OAc)2, 1,6-octadiene (24) was obtained. 

The first involved a chemoselective 2-step sequence (1) selective O-pivaloylation of OH-6 and OH-2 2) selective oxidation at C-3 to afford the target ketone (Scheme 28). When the condensation with HSCN was carried out in refluxing ethanol, a good overall transformation yield of 83% was obtained two OZTs were formed in 22% (R = H) and 61% (R = Et) yield, respectively. Performing the reaction in a mixture of aprotic solvents (THF/DMF) afforded the target OZT (R + H) in 79% yield (Scheme 28). 

Reaction of the chloro ester 1-Me with the enol silyl ether 23 a in the presence of dimethylaluminum chloride afforded the [2-1-2] cycloadduct 20 (67% yield) (Scheme 6). Deprotection of the alcohol moiety with uBu4NF in THF gave an 83% yield of a mixture of the 5-keto ester 21a and the spiropentane derivative 22 (ratio 1 90). Upon running the reaction in a mixture of THF/water (ratio 1 1) instead of anhydrous THF, the 5-keto ester 21a was isolated exclusively [331. 

In this case, the ruthenium complex was synthesized with an ionic tag moiety that is fully compatible with the [BMIM]PF6. A minimum amount of this ionic liquid was used for the reaction in a mixture containing 90 vol% CH2CI2. The catalyst (5mol%) was selectively retained in the ionic liquid after 10 repeated uses, without significant loss of activity in tests at 50°C that lasted 3h each (Table VI). 

The observation in the gas phase of positive ion-molecule reactions which can be interpreted as a nucleophilic displacement was first reported by Holtz el al. (1970). A typical example is the tertiary ion-molecule reaction in a mixture of HCl and CH3F. Protonation of CH3F as a result of a primary ion-molecule reaction is followed by reaction (51). 

At higher temperatures, the following equilibria result from reactions in a mixture of carbon, oxygen, and their compounds ... 

Figure 2.4. Reactions in a mixture of FFAs, TAGs, and MeOH with immobilized C. antarctica lipase.

Figure 2.10. Lipase-catalyzed reaction on a mixture of FAStE and water in the presence or in the absence of MeOH. A, Hydrolysis of FA steryl ester and esterification of sterol with FFA. B, Lipase-catalyzed reactions in a mixture of FAStE, water and MeOH.

If a reaction in a mixture of solids is accompanied by the formation of gas or fluid phases (melts, solutions), solid solutions, or by the generation of defects, then, for a more strict thermodynamic forecast, it is necessary to take into account the changes of entropy and specific heat capacity during phase transitions of the components (melting, vaporization, dissolution), changes of volume and other parameters. If these factors are not taken into account, one can come across the contradictions between experimental data and thermodynamic calculations. 

Pd-promoted H4SiWi204o/Si02 is effective for this reaction in a mixture of ethene, water, and oxygen this process has been commercialized since 1997. The reaction is proposed to proceed through hydration of ethene, followed by oxidation of ethanol. The selectivity toward acetic acid reaches 86% over Pd/H4SiWi2O40 Si02. 

A part of the evidence for the mechanisms given in equations (40) and (42) is provided by the work of Lowry and co-workers (Lowry and Richards, 113 Lowry and Faulkner, 24) on the mutarotation of tetra methylglucose. In water the reaction proceeds at a measurable rate, and it is clearly catalyzed by both acids and bases. In aqueous solution pyridine is a powerful catalyst but in pure dry pyridine no reaction occurs, and likewise in pure dry re-cresol there is no reaction. Upon investigating the reaction in a mixture of pyridine and n-cresol, Lowry and Faulkner (24) found it to take place very rapidly. From these experiments Lowry drew the important conclusion that a proton cannot by itself wander from one part of the molecule to another. The transformation can occur only if the medium in which the molecule is placed has both acidic and basic properties, so that a proton can be removed from the molecule at one place and a proton added to the molecule at another place. Now these experiments furnish strong support to the mechanism of reactions (40) and (42) whereby both members of the conjugate acid-base pair play a part in the reaction. Instead of representing this mutual dependence by means of consecutive bimolecular reactions, Lowry chose to represent it by means of one trimolecular reaction... 

The reaction in a mixture of a weak acid and its salt, or a weak base and its salt. Buffer mixtures or regulators. 

With 2,4-substituted, bispidones of lower symmetry and analoguous 1,5-dicarboxylic acid esters (e.g., compounds 10-48 in Table 1) the reduction under Wolff-Kishner conditions fails, but reaction with complex hydrides leads to the corresponding bispidoles. The treatment with LiAUTj yields a 1 1 mixture of the epimeric tris alcohols, whereas reduction with NaBELj at ambient temperature in various solvents leads to the epimeric mono-alcohols in different ratios up to epimerically pure compounds (see Scheme 9) (116, 117), which can be further reduced to the tris alcohols with LiAlH4. For example, the reduction of 14 with NaBH4 in dry methanol yields 65% syn- (84b) and 35% anri-product (84a), while the reaction in a mixture of dioxane-water leads exclusively to the anti-configuration of alcohol 84a (117). 

Condensation of thiophene-3-carbaldehyde 38 with malonic acid (Doebner reaction) in a mixture of pyridine (Py) and piperidine (Hp) with heating affords ( )-3-(3-thienyl)acrylic add (42), whose treatment with thionyl chloride in Py produces 3-chlorothieno[2,3-6]thiophene-2-carboxylic add chloride (43) (72ACS2982,... 

Another useful application of Equation 2-7 is for the prediction of the direction of reaction in a mixture of any initial composition. The activity quotient (the argument of the logarithmic term) in Equation 2-7 of the mixture is calculated on the basis of the initial composition and AG evaluated. The direction of the reaction is now readily obtained using the sign of the AG as criterion. A simpler corollary of this involves comparing the value of K for the reaction with the right-hand side of 2-8, using initial values of the aetivities of all the substances involved in the reaction, which is called the activity quotient. 

Unlike the usual types of fuel cell, kinetic fuel cells do not need two gas departments hermetically sealed from each other. Cells of the kinetic type develop power from surface reaction in a mixture of fuel and air (supplied simultaneously to both electrodes, which are made of different materials). Suggest a few possible explanations for the effect. 

A solvent-free variant used octahedral CU2O nanoparticles with added PPhj ligand, which effectively catalyzed the cross-coupling reactions of various aryl and heteroaryl halides with terminal alkynes [148]. The catalyst was reusable without any observable loss of activity, but worked only at temperatures above 100 °C. Further improvements to this approach involved the elimination of the Hgand and carrying out the reaction in a mixture of DMSO, K2CO3, and catalytic amounts of CU2O nanoparticles [149]. 

Predict the products of the photochemical reactions in a mixture of ds-2-butene, frans-2-butene, and isobutene. Note that you need to consider the dimerization reaction of each reactant. 

S. Rengakuji have reported a modified sol-gel process, and insisted that sol-gel reaction in a mixture of alcohol and hydrophilic solvent like benzene affords stable solvated titanate oligomer and the resulting coating film shows higher crystallinity and excellent photocatalytic activities (Rengakuji, 2002). 

Huy et al. have recently developed an MIP-based optical sensor for clenbuterol and melamine using CdTe quantum dots (QDs) with MIP cappings and used it in the determination of the mentioned species. The preparation of the MIP-CdTe QDs was through a radical polymerization reaction in a mixture of the QDs, the template, 3-aminopro-pyltriethoxysilane and tetraethoxysilane under controlled reaction regimes. The size of the MIP-CdTe particles was controlled by means of the speed of polymerization, concentration of the template, concentration of the quantum dots, and the ratio of template, monomer and crossHnker. The LODs for clenbuterol and melamine were stated to be 0.4 and 0.6 pM [344]. Nguyen et al. introduced another MIP-based optical fiber sensor for cocaine by covalently coimecting the MIPs to the distal end of an optical fiber and reported the sensor to show fluorescence increase as the response to cocaine concentration between 0-500 pM [373]. 

Different solvents can be used for reactions with ammonium hexanitratocerate(IV) as reagent. The most popular solvents are (in decreasing order of importance) water, acetonitrile, dichloromethane, THF and methanol. Often mixtures of these solvents are used. Solvents of less importance are DMF, toluene, diethyl ether, ethanol, pyridine, acetone, benzene, ethyl acetate, hexane, acetic acid, chloroform, dioxane, DMSO, carbon tetrachloride and 1,2-dichloroethane. Other solvents have found only marginal use for this type of reactions. One report describes CAN-mediated oxidation reactions in a mixture of dichloromethane and an imidazolium ionic liquid (Bar et al., 2003). Methanol is a better solvent than ethanol for CAN (Cho and Romero, 1995) whereas methanol reacts only very slowly with CAN, the reaction between ethanol and CAN is fast. It should be mentioned that in many reactions in apolar solvents, CAN is used as a suspension thus under heterogeneous reaction conditions. Also reactions of CAN in acetic acid are often done under heterogeneous conditions. It was observed that for heterogeneous reactions of CAN in acetic acid, the nitrate/acetate ratio in the reactions mixture depends on the amount of solid CAN dispersed in acetic acid as the amount of undissolved CAN increases, the nitrate/acetate ratio increases significantly (Baciocchi et al., 1977). 

K. Hasegawa, T. Asaba, Study of the ignition reaction in a mixture of oxygen with hydrogen at relatively high pressures and low temperatures in a shock tube. Combust. Explos. Shock Waves 8(3), 317-324 (1972)... 

Notice that the multiplier of the first differential in Eq.9.4.5, the temperature, is the potentisd for heat transfer and that of the second one, the pressure, is the potential for P-V work. By analogy, the multiplier of each of the remaining differentials must be also a potential. It is indeed the potential for mass transfer from one phase to an other, or for the feasibility of chemical reactions in a mixture of compounds, and it is called, appropriately, the Chemical Potential of component . 

A pH-responsive palladium catalyst 46, prepared by immobilizing palladium nanoparticles on colloidal core-shell micro-spheres that contain a pH-responsive shell of poly(methylacryUc acid) (PMAA) segments and a coordinative core of poly[2-(acetoxy)ethyl methacrylate] (PAEMA), exhibits good activity in the Suzuki and Heck reactions in a mixture of DMF/water (1 1, v/v) or in pure water [131]. The catalyst is highly dispersed under neutral or basic conditions, behaving like a homogeneous catalyst, but heterogeneous under acidic conditions. As such, it could... 

After some modification, another fluorous paUadium-NHC complex was prepared (Scheme 7.18) [29]. To simply the catalyst recovery, the fluorous paUadium-NHC complex was immobilized on FSG. The immobilized catalyst could efHciently promote the Suzuki cross-coupling reaction in a mixture of dimethylformamide (DMF) and water. The catalyst could be recovered by simple filtration and reused three times without significant loss of catalytic activity. 

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