Solvent continued yield

Hardacre et al. report the Friedel-Crafts benzoylation of anisole with benzoic anhydride to yield 4-methoxybenzophenone with various ILs and zeolite catalysts (USY, HZSM-5, H-beta, and H-mordenite). The rates of reaction were found to be significantly higher using ionic liquids compared with organic solvents.Continuous-flow studies of successful ionic liquid systems indicate that the bulk of the catalysis is due to the formation of an acid via the ion exchange of the cation with the protons of the zeolite as shown in the following reaction. Scheme 8. 

Our primary objective was to develop a computational technique which would correlate the ionization constant of a weak electrolyte (e.g., weak acid, ionic complexes) in water and the ionization constant of the same electrolyte in a mixed-aqueous solvent. Consideration of Equations 8, 22, and 28 suggested that plots of experimental pKa vs. some linear combination of the reciprocals of bulk dielectric constants of the two solvents might yield the desirable functions. However, an acceptable plot should have the following properties it should be continuous without any maximum or minimum the plot should include the pKa values of an acid for as many systems as possible and the plot should be preferably linear. The empirical equation that fits this plot would be the function sought. Furthermore, the function should be analogous to some theoretical model so that a physical interpretation of the ionization process is still possible. 

The modem commercial methods of oil extraction from oilseeds include (1) batch hydraulic pressing Oil seeds are expressed by hydraulic pressure to yield oil (2) continuous mechanical pressing Oil seeds are squeezed through a tapering outlet and oil is expressed by the increasing pressure and (3) solvent extraction Oil seeds are extracted with solvent followed by removal of solvent to yield oil. These methods are also employed in the extraction of sesame seeds with some modification. 

The trimer and tetramer are best separated by fractional crystalhzation from anhydrous f n-heptane or petroleum ether (b.p., 90 to 100°). The mixture is dissolved in sufficient hot solvent to yield a nearly saturated solution. The solution is cooled slowly as long as the characteristic flat prismatic crystals of the trimer continue to form but not until the needle-like crystals of the tetramer form. The remaining mother liquor is then removed by decantation, and the procedure is repeated with the decantate until about 70 to 75% of the trimer is recovered. Further crystallization from more dilute solutions then yields the tetramer. Both trimer and tetramer are purified by recrystallization from the same solvent, using activated charcoal to remove traces of color. The total recovery of separated trimer and tetramer depends upon how far the fractionation is carried but should amount to 90 to 95% of the original trimer-tetramer mixture. Anal. Calcd. for (PNBr2)3 or (PNBr2)4 N, 6.84. Found N, 6.87. 

Synthesis of 2-Phenylallyl-ended Poly(a-methylstyrene). Synthesis of poly(a-methylstyrene) having an end double bond was described in our previous papers(15,16). Briefly, to the reactor (100 mL flask equipped with three-way stopcock), THF (6.6 mL), sec-butyllithium (0.34 mL 0.26 mmol) and a-methylstyrene (1.18 g 10 mmol) were added in this order via a syringe at -78 C. The color of the mixture turned brownish red immediately. The reaction was allowed to continue for 20 min. For an end-modification reaction, a 2-5 times excess molar amount of the end coupling agent, 2-phenylallyl bromide, was added to the living polymer solution and allowed to react for 20 min. The resulting mixture was analyzed by GPC and then poured into a large excess of methanol. The precipitate was purified by three successive reprecipitations from THF solution into methanol. The obtained polymer was freeze-dried with benzene to remove the solvents employed. Yield of the polymer was ca. 95%. 

Diastereoselective aldol condensations continue to attract much attention. - -Alkoxyboronates add to aldehydes at room temperature in the absence of solvent to yield adducts with about 90% dia-stereoselection, dependent upon the initial stereochemistry of the boronate (Scheme 10 cf. Vol.8, p.217). Although relatively sluggish at atmospheric pressure the reactions are accelerated by the... 

In practice, surfrctant is always present during emulsification, and it is interesting to know whether coalescence then is a frequent phenomenon. To study this, a method for determining coalescence during emulsification has recently been developed in the authors laboratory. In brief, equal amounts of two OAV emulsions (I and 2) are mixed, which are the same in composition and droplet size distribution, except for the oil phases, which have different refractive indices, n, and n2-The mixture is then emulsified again. It is subsequently diluted with a solvent to yield for the continuous phase a refractive index of ( , -I- n2)/2. This dilute emulsion will have a certain turbidity if the oils 1 and 2 are unmixed, whereas turbidity will be virtually zero when the two oils have become completely mixed by... 

As it has appeared in recent years that many hmdamental aspects of elementary chemical reactions in solution can be understood on the basis of the dependence of reaction rate coefficients on solvent density [2, 3, 4 and 5], increasing attention is paid to reaction kinetics in the gas-to-liquid transition range and supercritical fluids under varying pressure. In this way, the essential differences between the regime of binary collisions in the low-pressure gas phase and tliat of a dense enviromnent with typical many-body interactions become apparent. An extremely useful approach in this respect is the investigation of rate coefficients, reaction yields and concentration-time profiles of some typical model reactions over as wide a pressure range as possible, which pemiits the continuous and well controlled variation of the physical properties of the solvent. Among these the most important are density, polarity and viscosity in a contimiiim description or collision frequency. 

Fig. 41(A) and (b), p. 65) into which the ethereal extract is allowed to run from a dropping-funnel at approximately the rate at which the solvent is distilling. When the ether has been removed, fit a capillary tube and thermometer, and continue the distillation at water-pump pressure. The diethyl ester of collidine-3,5-dicarboxylic acid (II) distils as a pale golden oil, b.p. i76 178°/i4 mm. Yield, 5 g. from 6 g. of the ester (I). 

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