Pentane water systems

As was mentioned earlier, the three-phase data reported by Scheffer (29) for pentane - water were for a "binary" composed of water an a mixture of i-pentane and n-pentane. As shown in the figure, these data are bounded by the calculated loci of the i-pentane - water and n-pentane - water systems. 

Fig. 20. Effect of temperature driving-force on optimal column height— pentane-water system (S9).

Fig. 26. Effect of inlet and outlet temperatures on volumetric heat-transfer coefficients in three-phase spray-column heat exchanger— pentane-water system.

The interaction parameters for binary systems containing water with methane, ethane, propane, n-butane, n-pentane, n-hexane, n-octane, and benzene have been determined using data from the literature. The phase behavior of the paraffin - water systems can be represented very well using the modified procedure. However, the aromatic - water system can not be correlated satisfactorily. Possibly a differetn type of mixing rule will be required for the aromatic - water systems, although this has not as yet been explored. 

Estimate the free energy of attraction between two spheres of radius 500 nm at separation distances of 1,10, and 100 nm for the following systems (a) water-air-water (b) pentane-water-pentane (c) hexadecane-water-hexadecane (d) quartz-air-quartz (e) quartz-air-hexadecane and (f) Teflon-water-Teflon. 

Internal standard solution of 1-chloroheptane, 20 pl/1 in nanograde pentane Water, e.g. from a Millipore superpure water system Sample preparation... 

The water-soluble complex derived from [Rh(CO)2(acac)] (acac = 2,4-pentanedionate) and human serum albumin proved to be efficient in the hydroformylation of various olefins. The chemoselectivity and regioselectivity were generally higher than those obtained with the Rh/TPPTS catalyst. Styrene was converted to the corresponding aldehydes with a branched/linear ratio of 90/10 and with TOP up to 30,000 h in a H20/n-pentane biphasic system at 60°C and 7 MPa CO H2 = 1 1. Under the same conditions, 1-octene was cleanly hydro-formylated with a more than 99% aldehyde yield. The pH of the aqueous phase had a major influence on the reaction the highest rates were observed at pH 7.2 (148). 

System 1 pentane-pentane in water System 2 mica-mica in water System 3 water-air in pentane... 

Figure 2.16 Clirotnatograms of a pentane extract of a water sample containing 200 ppb of a naphtha fraction (a) sample extracted by using a continuous flow system, where a pressurized bottle was employed as the sample-delivery system (b) batch-extracted sample. Reprinted from Journal of Chromatography, A 330, J. Roeraade, Automated monitoring of organic Race components in water. I. Continuous flow exti action together with on-line capillary gas cliro-matography , pp. 263 - 274, copyrigth 1985, with permission from Elsevier Science.

Dehydropeptides were reduced (Scheme 3.9) on a preparative scale in two-phase systems with catalysts prepared in situ from [ RhCl(COD) 2] and chiral water-soluble ligands 35, 36, and 37 (Ch.2). The highest (87%) diastereoselectivity was obtained with [ RhCl(COD) 2] + tetrasuhbnated 2,4-bis(diphenylphosphino)pentane, BDPPTS, 36 [121]. 

Anotlier example of dendritic POM complexes used as recoverable oxidation catalysts was reported by Plault et al. (SS). A series of ionic polyammonium dend-rimers containing between 1 and 6 POM units were prepared and used to catalyze the epoxidation of cyclooctene in a biphasic water/CDCls system. A comparison of the homogeneous mono-, bis-, tris-, and tetra(POM) catalysts indicated that there was no dendritic effect on the reaction kinetics within this series. However, a dendritic effect was found in the recovery of the catalysts. The dendritic catalysts were precipitated from the organic phase by addition of pentane. The recovery of the tri-and tetra-(POM) catalysts was easier (80—85% and 96%, respectively) than that of the mono(POM) catalyst. 

The above processes describe the possible unimolecular reactions occurring after photoexcitation of aldehydes. For assessing the effect of solvation on the photochemistry, the following model systems have been used. Pinonic acid has been studied with one and five water molecules, and a pentanal cluster using five identical pentanal molecules has been built. 

The statistics of Norrish type I and Norrish type II reactions occurring in one pentanal molecule in the cluster (i.e., not followed by subsequent reactions) can be compared with the previously discussed statistics in the bare pentanal, in di-pinonic acid, and hydrated c/i -pinonic acid Norrish type I reaction is most pronounced in c/Y-pinonic acid, with 37% of yield, much more than for the bare pentanal (14% only). The water and the pentanal cluster reduce in both systems the percentage of Norrish type I reaction (PA-H2O - 18%, PA-(H20)5 - 24%, pentanal cluster - 9%). On the contrary, Norrish type II reaction is mostly observed in the bare pentanal (27%), compared to 10% for the bare pinonic acid. Hydration of the cA-pinonic acid further reduces the percentage of Norrish type II reactions. The existence of the pentanal cluster also decreases the percentage of Norrish type II reaction (PA-H2O - 2%, PA-(H20)5 - 3%, pentanal cluster - 1 %). 

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