F Butane

R)3CH Alkanes and cydoalkanes with tertiary hydrogen atoms (e.g., f-butane, isopropyl compounds, decahydronaphthalenes)... 

An earlier report from this laboratory (7) noted that in a series of mildly extracted mordenites, the hexane cracking activity in a continuous-flow test went through a marked maximum with increasing severity of extraction, while the f-butane to n-butane ratio continuously increased. The activity and product distribution were measured after 10 min on stream. Since catalyst deactivation was rapid, it was not possible to... 

An auxiliary-directed asymmetric Simmons-Smith reaction was used by a Hoff-mann-La Roche group88 for the synthesis of an ethynyl cyclopropane that served as the A-ring precursor to Vitamin D derivatives [Scheme 2.41]. High diastereoselectivity was achieved with the aid of the dioxolane ring prepared from (/ft/f)-(-)-butane-2,3-diol. The acid conditions for hydrolysis of the dioxolane ring were mild enough to leave the cyclopropane ring unperturbed. Dia-stereoselective cyclopropanation of acetals derived from 1,2-di-O-benzyl-L-threi-tol have also been reported 90... 

In oil processing, separation of aromatic isomers Cg (ethylbenzene 7b= 136°C,p-xylene 7b= 138.3°C, m-xylene Ty, = 139.1°C, >-xylene T], = 144.4°C) is required. According to the literary data, the following isomers of hydrocarbons are separated p-xylene/m-xylene, p-xylene/o-xylene, -hexane/2,2-dimethylbutane, -hexane/3-methylpentane, and n-butane/f-butane [8,83,130-137]. Pervaporation method is the most effective for this purpose. To separate the isomers, membranes based on various polymers were used. Good separation for aU isomer mixtures was attained by the polyimide Kapton film (fip = 1.43-2.18) but parylene films and cellulose acetate also exhibited a relatively high separation factor (fip = 1.22-1.56 and /3p = 1.23-1.56, respectively). Temperatures >200°C were required to obtain a reasonable flux through the polyimide film and a pressure of about 20 atm was necessary to keep the feed stream liquid [8]. 

Zeolite monoliths have been useful for such apphcations as rotatory adsorbers for use as dehumidifiers and desiccant cooling processes [253] or in VOC treatment systems [269]. Alumina-coated sUicon carbide monoliths have also been employed as supports for B-ZSM-5 membranes [270] providing a larger surface area per unit volume, compared to traditional membrane supports. With these membranes, these authors have reported n/f-butane and H2/f-butane separation selectivities of 35 and 77, respectively [85]. Also, silicalite-1 membranes supported on stainless steel grids (Figure 10.29) have shown a good performance in the separation of n/f-butane mixtures, with separation factors as high as 53 at 63°C [255]. 

The first few plates above the reboiler show sharp changes in the concentrations of n-pentane and n-butane, similar to that shown by ethane near the tpp of the column, and this results in a maximum concentration of f-butane at plate 34. The concentration of n-pentane is nearly constant from plate 35 to the feed plate because of a pinch, and changes slowly as the temperature gradually decreases. The -butane does not show such a plateau because its volatility is about 0.8 that of i-butane, the heavy key. 

P-16 - Isomerization of /f-butane over small crystals of H-Beta and Pt-H-Beta zeolite catalysts... 

Fig. 10 Permeability measurement through a single (100 xm) crystal of silicalite (f-butane at 334 K). Note asymptotic approach to same intercept regardless of pressure. This implies that the diffusivity is independent of concentration over the relevant range. From Paravar and Hayhurst [64]...

The bridging hydroxyls in SUZ-4 are more easily accessible than those in FER. They are pardy accessible to f-butane and fully accessible to -hexane (595). 

A. Bouyermaouen and A. Bellemans,/. Chem. Phys., 108,2170 (1998). Molecular Dynamics Simulation of the Diffusion of -Butane and f-Butane in Silicalite. 

In Fig. 6, the critical p T) curves of some members of the trifluoromethane -f alkane family (with alkane = methane, ethane, hexane, octane, decane, and additionally those of tetralin and decalin), as well as those of the trifluoromethane binaries with argon, krypton, tetrafluoromethane, and nitrogen, are presented [67]. Whereas trifluoromethane -f tetrafluoromethane, -f krypton, -f methane, -f ethane, and -f hexane (as well as -f propane, -f butane, and -f pentane) exhibit class-II critical behavior, trifluoromethane -f nitrogen, -f argon, -f octane, -f decane, -f tetralin, and -f decalin belong to class III according to the classification... 

Aryl Grignards add to chiral A-alkyl (or A-aryl) benzenesulflnylimines, PhCH=NSOR/PhCH=NSOAr, in high yield and de, to give chiral diaryl amines (in protected sulfinyl form). A comparative smdy of the use of the familiar f-butane or p-toluene groups at sulfur with 2,4,6-triisopropylbenzene finds that the latter is significantly superior in yield and de and that results are somewhat better at room temperature versus -40 °C (g)... 

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