Alkanes density

Fisher, C. H., How to Predict n-Alkane Densities These Equations Predict Density for C20 and Heavier Alkanes. Chem. Eng., 1989 96(10), 195. 

Ivanciuc, O. (1999b) Artificial neural networks. Part 11. MolNet prediction of alkane densities. Rev. Roum. Chim., 44, 619-631. 

The mean molecular area of an amphiphile is determined foremost hy the size of the hydrophilic head group and its interactions with coimterions in the subphase and with other head groups within the plane. Once these interactions are at an energetic minimum, the alkyl chains pack to maximize hoth van der Waals interactions and alkane density. By extrapolating the steepest part of the curve before the collapse at zero pressure, a minimum cross-sectional area per molecule can be foimd. This approach was one of the original methods used in attempts to measure the size of a molecule. 

References [12-23, 30-39] are useful sourees of olefin and alkane properties. Properties of 1-olefins having two to forty carbons were published in 1953 [14] and 1959 [13]. Many of these properties are given in Tables 1-5. n-Alkane densities [36, 37, 40] and melting points (Cl to Coo) (amorphous polymethylene) [23, 31] and... 

A second method of estimating poly(l-olefin) properties consisted in creating equations correlating n-alkane properties with -alkane densities, and then using the equations with poly(l-olefin) densities to estimate poly(l-olefin) properties. 

Their boiling points and densities are higher than alkanes having the same number of carbon atoms. 

Under standard conditions of temperature and pressure (STP), the first four members of the alkane series (methane, ethane, propane, and butane) are gases. As length of the carbon increases the density of the compound increases (pentane) to C yHgg are liquids, and from C.,gH3g, the compounds exist as wax-like solids at STP. 

Alkynes resemble alkanes and aUcenes m their physical properties They share with these other hydrocarbons the properties of low density and low water solubility They are slightly more polar and generally have slightly higher boiling points than the corre spondmg alkanes and alkenes... 

After cooling of the aqueous mixture to 5-10°C an upper viscous phase is separated, which contains 45-47% alkanesulfonates and 1.0-1.3% sodium chloride, while the lower phase is a 7-8% brine with a small quantity of alkane-monosulfonates but 1.5-2.0 wt % di- and polysulfonates. The hydrotropically dissolved alkanes (neutral oil) are found entirely in the upper phase. Because of the small density differences, the separation of the two phases needs 15-20 h. The lower phase can be separated by membrane technology [13]. 

Water in its supercritical state has fascinating properties as a reaction medium and behaves very differently from water under standard conditions [771]. The density of SC-H2O as well as its viscosity, dielectric constant and the solubility of various materials can be changed continuously between gas-like and liquid-like values by varying the pressure over a range of a few bars. At ordinary temperatures this is not possible. For instance, the dielectric constant of water at the critical temperature has a value similar to that of toluene. Under these conditions, apolar compounds such as alkanes may be completely miscible with sc-H2O which behaves almost like a non-aqueous fluid. 

Three other all-atom force fields have also received much recent attention in the literature MMFF94 [36-40], AMBER94 [9] and OPLS-AA [41, 42] and are becoming widely used. The latter two force fields both use non-bonded parameters which have been adjusted in order to reproduce experimental liquid phase densities and heats of vaporisation of small organic molecules. For example, OPLS-AA includes calculations on alkanes, alkenes, alcohols. 

Previous studies have concluded that 4-, 5-, and 6-coordinate W species are present on AI2O3 and Ti02 supports [17,30] depending on surface W density and on hydration state. The present study has detected W03-like distorted octahedral domains at all surface densities and irrespective of hydration on Zr02. These species catalyze alkane isomerization reactions with much higher turnover rate and selectivity than dispersed WOx moieties on alumina or titania. 

Liquids without dipole moments (alkanes) have quite low cohesive energy densities, whereas hquids with dipole moments or hydrogen-bonding groups have high cohesive energy densities. 

If the diamond lattice itself is used for the mapping of the PE chains, each internal bead represents a methylene unit, the step length is the C-C bond length, and CxH2x 2 is represented by x beads. Typical bulk densities for n-alkane melts, which are in the range 0.7-0.8 g/cm3, are achieved with occupancy of 16-19 % of the sites on this lattice. 

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