Toluene molecular volume

For macromolecules, it is important to distinguish between random coils (most synthetic polymers) and globular molecules (most proteins). For the former, the molecular volume is approximately proportional to the square root of the molecular weight. The diffusion coefficient of polyst n ene in toluene was estimated by Giddings et al. [19]... 

Side-chain molecular volumes are referred to the volume within van der Waals surface and are calculated for the corresponding organic compounds taken as suitable models for the amino acid side chains (e.g., p-cresol for Tyr, toluene for Phe). 

The co-solvents can be encapsnlated within the cavity of the capsular structure. The volume of the inner cavity was calculated to be 237 A. Rebek reported that a self-assembled dimeric capsule prefers to be filled by a guest with a volume occupying approximately 55% of the binding space. Accordingly, toluene is a good guest for the dimeric capsule, while the molecular volume of chloroform is too small to... 

In which the ratio m/n is close to 3. The silane was produced by free radical copolymerization of vinyltriethoxysilane with N-vinylpyrrolidone. Its number-average molecular weight evaluated by vapour-phase osmometry was 3500. Porous silica microballs with a mean pore diameter of 225 A, a specific surface area (Ssp) of 130 m2/g and a pore volume of 0.8 cm3/g were modified by the silane dissolved in dry toluene. After washings and drying, 0.55% by weight of nitrogen and 4.65% of carbon remained on the microballs. Chromatographic tests carried out with a series of proteins have proved the size-exclusion mechanism of their separation. 

Zink et al. used a blend of polystyrene (hPS) and its deuterated counterpart (dPS), both of molecular weight 1.95 x 106 (abbreviated 1.95 M). The average volume fraction (4>dPS) of deuterated polystyrene was 30%. The polymers were dissolved in toluene and spin cast on thin silicon wafers (about 10 x 10 mm), the resulting film thickness being about 300 nm. The samples were annealed at 245°C for 8 days, and the measurement of the resulting depth profiles was conducted by NRA using a monoenergetic 700 keV 3He beam. The nuclear reaction employed can be written ... 

Syntheses. Isotactic poly(methyl methacrylate) was synthesized by the method of Tsuruta et al. (9 ). Under a nitrogen atmosphere, a quantity of 6 mL (0.056 mole) of methyl methacrylate (MMA) dried over 4A molecular sieve was dissolved in 24 mL of similarly dried toluene. To the glass vial containing the reaction was added 0.65 mL of 1.6 M n-butyllithium, and the reaction was kept at -78°C in a dry ice/isopropanol bath. The polymerization was halted 24 hr later with the addition of hydrochloric acid and methanol (methanol/water 4.1 by volume). The polymer was dried in vacuo at 50°C, redissolved in methylene chloride, precipitated by being poured into water-containing methanol, and dried in vacuo at 50°C. Tacticlty and composition were verified with % NMR. Yield 47%. 

It may be assumed that the volume of the liquid phase does not change appreciably as the reaction proceeds, although, in practice there will be some departure from this assumption. If the reaction is considered complete at the stage when 1 kmol C2H2 (molecular mass = 26 kg/kmol) has been added to 1 kmol C7H8 (molecular mass = 92 kg/kmol), then per 1 kmol of toluene, the total mass in the reactor will have increased from 92 kg initially to 118 kg of product having a mass density similar to that of the original toluene. 

Figure 2. Molecular weight vs. retention volume relationships. Key I, i>-alkanes to II, toluene,...

The separation of chemical species by size exclusion chromatography is more reproducible than any other type of chromatography. Once the SEC columns, the mobile phase (most often a pure solvent like THF or toluene), and the flow rate are selected, the retention volume (or retention time assuming the flow rate does not change) is primarily a function of linear molecular size, which can be obtained from the valence bond structure if the compound is known. Some of the chemical species can interact with the solvent forming complexes with an effective linear size greater than that of the molecule. This causes the expected retention volume, based on "free" molecular structure, to shift to a lower but very reproducible retention volume. Phenols in coal liquids form 1 1 complex with THF (9,10) and carry the effective linear molecular size to increase. As a result phenolic species elute sooner than expected from their... 

The criterion of stability (R) is the constant limit value of the emulsified volume percentage at 20°C (32, 32.). It appears that 7/3 water toluene emulsions are more efficiently stabilized by star-shaped block copolymers whereas linear block copolymers give better results for 3/7 water toluene emulsions the stability of the l/l water toluene emulsions seems to be insensitive to the molecular architecture of PTBS/PO block copolymers. 

Reagent-grade toluene employed by the submitters was obtained from Mallinckrodt Chemical Works. The checkers used reagent-grade toluene purchased from Wako Pure Chemical Industries, Ltd., and dried over molecular sieves (4 A) before use. Regarding the volume of the toluene used by the checkers, see Note 3). 

The paper deals with some new data concerning the state of the metal after reduction and the catalytic functions of zeolite catalysts containing nickel and platinum. By using the molecular sieve selectivity in the hydrogenation of mesitylene it has been proved that metal (platinum) is contained in the volume of the zeolite crystal. The temperature dependence of the formation of nickel crystals was investigated. The aluminosilicate structure and the zeolite composition influence mainly the formation of the metal surface which determines the catalytic activity. In the hydrocracking of cumene and disproportionation of toluene a bifunctional action of catalysts has been established. Hydrogen retarded the reaction. 

Adsorption-desorption isotherms of toluene, p- and /n-xylene and mesitylene vapors by the sol-PILM and the modified product are compared in Figure 4. As anticipated, a decreasing tendency of uptake of each adsorbate is observed from sol-PILM to the final modified product due to the decrease in pore volume. It is also not surprised that the capacity of vapor adsorption by each sample decreases as the molecular size of the adsorbate increases, following the order ... 

The asphaltene fraction (ASTM D-893 ASTM D-2007 ASTM D-3279 ASTM D-4124 ASTM D-6560 IP 143) is the highest molecular weight and most complex fraction. In any of the methods for determination of the asphaltene content, the sample is mixed with a large excess (usually >30 volumes hydrocarbon per volume of sample) of low-boiling hydrocarbon, such as n-pentane or n-heptane. For an extremely viscous sample, a solvent such as toluene may be used prior to addition of the low-boiling hydrocarbon, but an additional amount of the hydrocarbon (usually >30 volumes hydrocarbon per volume of solvent) must be added to compensate for the presence of the solvent. After a specified time, the insoluble material (the asphaltene fraction) is separated (by filtration) and dried. The yield is reported as a percentage (% w/w) of the original sample. 

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