Hexane, molecular structure

As discussed in Sec. 4, the icomplex function of temperature, pressure, and equilibrium vapor- and hquid-phase compositions. However, for mixtures of compounds of similar molecular structure and size, the K value depends mainly on temperature and pressure. For example, several major graphical ilight-hydrocarbon systems. The easiest to use are the DePriester charts [Chem. Eng. Prog. Symp. Ser 7, 49, 1 (1953)], which cover 12 hydrocarbons (methane, ethylene, ethane, propylene, propane, isobutane, isobutylene, /i-butane, isopentane, /1-pentane, /i-hexane, and /i-heptane). These charts are a simplification of the Kellogg charts [Liquid-Vapor Equilibiia in Mixtures of Light Hydrocarbons, MWK Equilibnum Con.stants, Polyco Data, (1950)] and include additional experimental data. The Kellogg charts, and hence the DePriester charts, are based primarily on the Benedict-Webb-Rubin equation of state [Chem. Eng. Prog., 47,419 (1951) 47, 449 (1951)], which can represent both the liquid and the vapor phases and can predict K values quite accurately when the equation constants are available for the components in question. 

The Si=As bond reacts with organic isocyanides in the same way that the Si=P bond does. Thus, with mesityl isocyanide and 1,6-diisocyano-hexane 44a forms the unusual arsaalkene derivatives 53 and 54, according to Scheme 14. Their molecular structures were determined by X-ray crystallography.39,40... 

Normal-phase liquid chromatography is thus a steric-selective separation method. The molecular properties of steric isomers are not easily obtained and the molecular properties of optical isomers estimated by computational chemical calculation are the same. Therefore, the development of prediction methods for retention times in normal-phase liquid chromatography is difficult compared with reversed-phase liquid chromatography, where the hydrophobicity of the molecule is the predominant determinant of retention differences. When the molecular structure is known, the separation conditions in normal-phase LC can be estimated from Table 1.1, and from the solvent selectivity. A small-scale thin-layer liquid chromatographic separation is often a good tool to find a suitable eluent. When a silica gel column is used, the formation of a monolayer of water on the surface of the silica gel is an important technique. A water-saturated very non-polar solvent should be used as the base solvent, such as water-saturated w-hexane or isooctane. 

The reaction of l,4-bis(trimethylsilyl)-2,5,7-cyclooctatriene (37) with two equivalents of n-butyhithium in a mixture of hexane and 1,2-dunethoxyethane (DME) gives the dilithi-ated species 38 in a yield of 78% (Scheme 14) . The compound could be isolated by Edelmann and coworkers as single crystals and thus the molecular structure in the solid state could be determined. It reveals an almost planar eight-membered ring which is capped by two lithium-DME units in a /j -manner from both sides of the ring plane. 

Bis[l-(dimethylamino)-2-propanolato]copper(II) is a moisture-sensitive purple compound that is soluble in common organic solvents such as benzene, toluene, and hexane. It has a trans, square-planar molecular structure in... 

Branched-chain alkanes do not exhibit the same smooth gradation of physical properties as do the continuous-chain alkanes. Usually there is too great a variation in molecular structure for regularities to be apparent. Nevertheless, in any one set of isomeric hydrocarbons, volatility increases with increased branching. This can be seen from the data in Table 4-2, which lists the physical properties of the five hexane isomers. The most striking feature of the data is the 19° difference between the boiling points of hexane and 2,2-dimethylbutane. 

For the preparation of MIPM, the above phenol, 2,5-dimethoxyphenol was isopropylated with isopropyl bromide in methanolic KOH giving 2,5-dimethoxy-l-(i)-propoxybenzene as an oil. This formed the benzaldehyde with the standard Vilsmeier conditions, which melted at 77-78 °C from hexane and which gave a yellow malononitrile derivative melting at 171.5-173 °C. The nitrostyrene, from nitroethane in acetic acid was orange colored and melted at 100-101 °C from either methanol or hexane. This was reduced with lithium aluminum hydride in ether to give 2,5-dimethoxy-4-(i)-propoxyamphetamine hydrochloride (MIPM). The properties of the isolated salt were strange (soluble in acetone but not in water) and the microanalysis was low in the carbon value. The molecular structure had a pleasant appeal to it, with a complete reflection symmetry shown by the atoms of the amphetamine side chain and the isopropoxy side chain. But the nature of the actual product in hand had no appeal at all, and no assay was ever started. 

Compound 3a was found to react with excess water to produce a mixture of organic products including butane, ethene and ethane.17 However, when trace amounts of water were introduced into a hexane solution of 3b, the oxo complex 12 is formed. The molecular structure of 12 shows that it is formed by reaction of 2 equivalents of 3b and 1 equivalent of water ... 

The lithium benzamidinates 8 can be obtained analytically pure by recrystallization from hexane. Unsolvated 8 (R = CF3) is especially remarkable in that it sublimes readily at room temperature and dissolves freely in nonpolar solvents such as toluene or even hexane. Although the molecular structures of 8 (R = CF3) has not been determined by X-ray diffraction, it is highly likely that the 2,4,6-tris(trifluoromethyl)phenyl substituent is responsible for the remarkable properties of this particular lithium benzamidinate. It has been demonstrated that the stabilizing influence of the 2,4,6-tris(trifluoromethyl)phenyl substituent can be traced back to a combination of steric and electronic effects [42]. In addition, this ligand allows the characterization of its derivatives by 19F NMR spectroscopy. 

The conversion product tetra(carbahexa)borane 167 (molecular structure shown in Fig. 8) can be obtained from diborane 165 (Scheme 26) via a 2,5-diborabicyclo-[2,l,l]-hexane 166 and its structure have been reported by Enders et al.104 Synthesis of carbaboron compounds has also been reviewed previously.105,106... 

Treatment of a suspension of Nd(NHPh)3(KCl)3 with trimethylalumi-num in hexane yielded the heteroleptic heterobimetallic cluster [Nd[(//.2-Me)2A/Me2]2(M3-NPh)(M2-Me)AlMe 2 in low yield (Fig. 29). The formation of the cyclic byproduct (Me2AlNHPh)3 was proven by means of NMR spectroscopy and X-ray crystallography [217]. The molecular structure of the Nd2Al6 dimer revealed the presence of a doubly deprotonated imido ligand bridging each a neodymium center and two aluminum atoms. 

A number of 1,3-dithianyl-substituted 1,4-disilacyclohexanes were synthesized (98TL3197) and one molecular structure (176) was studied by X-ray diffraction (cf. Scheme 57). The two 1,3-dithianyl rings adopt strain-free chair conformations, whereas the conformation of the 1,4-disilacyclo-hexane ring was a twist-boat. The twist form was attributed to steric repulsion between the exo-cyclic C-S bonds the interaction between the silicon and the two sulfur atoms was also considered. 

Kubicki, J.D., Molecular mechanics and quantum mechanical modeling of hexane soot structure and interactions with pyrene, Geochem. Trans., 1, 41, 2000. 

Which method should you use Equation 5.1-1 and the assumption of volume additivity work best for mixtures of liquid species with similar molecular structures (e.g., all straight-chain hydrocarbons of nearly equal molecular weight, such as n-pentane, n-hexane, and n-heptane). There are no general rules for when Equation 5.1-2 works better—all we can do is rely on empirical (experimental) findings. 

Dicarbonyl( -cyclopentadienyl)( / -cyc/o-triphosphorus)molybdenum(I) is a yellow crystalline solid that may be handled briefly in air, but it should be stored in an inert atmosphere. It dissolves readily in benzene, toluene, dichloromethane, diethyl ether, and acetonitrile. The crystals are moderately soluble in pentane and hexane. The HNMR spectrum (200 MHz, QD ) shows a quartet at tms4.21 ( J,ph = 0-5Hz). The P H NMR spectrum (CjHg, 85% H3PO4 as reference) shows a singlet at —351.1. The IR spectrum (CgHg) shows v,-o = 1995 and 1938 cm . The molecular structure has been determined by X-ray diffraction studies. ... 

More work is required in order to clarify the molecular structure of these fascinating molecular assemblies which seem to be on the borderline between fluid and solid micellar rods. Their formation develops through a certain type of precipitation, also typical for solid micellar fibres. However, the binding forces between the head group molecules (tetraalkylammonium and phenol) are weak, meaning that the fibres are not as stiff and uniform as the crystalline fibres described later. Aqueous suspensions of the described fibres dissolve massive amounts of small hydrocarbon molecules, e.g. 20 mol % of hexane, but the dissolving of hydrophobic porphyrins in them has not yet been achieved. 

I THF crystallizes from hexane as a dimer. The central four membered ring is formed by the two lithium atoms and two metallated carbon atoms. The carbon atoms show two lithium contacts. Similarly, the lithium atoms have two carbon contacts. An intramolecular coordination of the piperidino nitrogen and the oxygen of the THF molecule complete the coordination sphere of lithium. A ball and stick drawing of the molecular structure of I THF and selected bond distances and angles are given in Fig. 1. 

Evans et al. also reported the synthesis of the divalent lanthanide COT complexes [Zr2(OPr )9Ln]2(COT) (Ln = Yb, Sm) from [Zr2(OPr )9LnI]2 and K2COT (Scheme 226). The monoanionic [Zr2(OPr )9]- unit is used as a cyclopentadienyl analog. X-ray diffraction studies show the bimetallic Ln(ll) complexes with the Sm centers coordinated to the bridging COT ligand in an -fashion.264 [Zr2(OPr )9Sm]2(COT) reacts with 1,3,5,7-COT to form the hexane-soluble Sm(m) complex [Zr2(OPr )9]Sm(COT), in a manner analogous to the reduction of COT by Cp Sm(COT). The molecular structure shows the monomeric complex with one -coordinated COT ligand and the monoanionic [Zr2(OPr )9]- unit attached to the Sm in a tetradentate fashion.2... 

Addition of TiCl4 to a solution of trimethylsiloxyphenylisocyanide in //-hexane yields the air sensitive octahedral diisocyanide complex TiCl4(CNR)2 (Scheme 114). This complex crystallizes with one molecule of //-hexane. Its molecular structure has been determined by X-ray crystallography.227 The formations of isocyanide titanium complexes are studied as species related with the Passerini reaction assisted by TiCl4. Three classes of compounds were identified and exemplified by isolated complexes (Scheme 115).228... 

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