Joan Reeder

Solid + liquid phase equilibria and solid compound formation in hexafluorobenzene + benzene, + pyridine, + furan, and + thiophen

Solid + liquid phase diagrams have been obtained from cooling and warming curves for the four binary systems formed from hexafluorobenzene (C 6 F 6 ) + benzene (C 6 H 6 ), + pyridine (C 5 H 5 N), + furan (C 4 H 4 O), and + thiophen (C 4 H 4 S). A stable 1—1 addition compound forms in each system. The C 6 F 6 · C 6 H 6 and C 6 F 6 · C 4 H 4 S compounds melt congruently while the C 6 F 6 · C 5 H 5 N and C 6 F 6 · C 4 H 4 O compounds melt incongruently. The relative stability of the compounds is as expected if bonding results from charge transfer with the C 6 F 6 acting as an electron acceptor and the other component as an electron donor.

Volume changes on mixing normal alkanes with branched alkanes

Table 1. Excess Volumes, 6, at 25 O C where xi is the mole fraction of component i and ni is its chain length. The principle has been extended with some success to other homologous series (2) and has been found applicable to gaseous mixtures as well (3, 7). Theoretical justification for the principle of congruence was provided by Longuet-Higgins (4). His model for the interactions between long-chain molecules of similar type leads to a generalization of the congruence principle: “if two mixtures, each containing chain molecules of the type A(X),B, are such that the molecules of the two mixtures can be divided into identical sets of fragments by cutting the chains in suitable places, then these mixtures will have identical equations of state and identical solvent properties.” The systems n-pentane + 2,6-dimethylheptane, n-hexane + 2,5-dimethylhexane, n-heptane + 2,4-dimethylpentane, and n-octane + 2,3dimethylbutane might be expected to satisfy the

Solid + liquid phase equilibria and solid-compound formation in hexafluorobenzene + cyclic hydrocarbons containing one or two π-bonds

Abstract Solid + liquid phase diagrams have been obtained from cooling and warming curves for the binary systems formed from hexafluorobenzene (C 6 F 6 ) + 1,5-cyclo-octadiene (C 6 H 12 ) and + cyclohexene (C 6 H 10 ). An incongruently melting 1-1 addition compound forms in C 6 F 6 + C 8 H 12 . For C 6 F 6 + C 6 H 10 there is no compound formation. Exploratory measurements show the presence of a solid addition compound in C 6 F 6 + 1,3 cyclohexadiene (C 6 H 8 ). The relative stability of the compounds that form is as expected if bonding results from charge transfer with the C 6 F 6 acting as an electron acceptor and the π-bonded component as an electron donor.

Solid + liquid phase equilibria and solid-compound formation for hexafluorobenzene + p-dioxane and + each of several related ethers

Abstract Solid + liquid phase diagrams have been obtained from cooling and warming curves for hexafluorobenzene + p-dioxane and + tetrahydrofuran. An incongruently melting solid addition compound forms with p-dioxane mixtures. No compound forms with tetrahydrofuran. Exploratory measurements show that no compound forms with hexafluorobenzene + tetrahydropyran or + 1,2-dimethoxyethane. The results suggest that compound formation results from a combination of favorable packing geometry and weak eletrostatic interactions rather than from charge-transfer.

Solid/liquid phase equilibria and solid compound formation in mixtures of hexafluorobenzene with nitrogen containing compounds

Thermal methods have been used to determine with high precision the solid/liquid phase equilibria diagrams for mixtures of hexafluorobenzene with N-methylmorpholine, N-methylpiperidine and NN′-dimethylpiperazine. Solid addition compounds form in all three systems. Exploratory measurements show that hexafluorobenzene does not form solid addition compounds with triethylamine, acetonitrile or NN-dimethylacetamide. A comparison of the phase diagrams for a number of systems containing hexafluorobenzene suggests that compound formation with hexafluorobenzene results from a combination of favorable packing geometry and electrostatic interactions.

Solid/liquid phase equilibria and solid compound formation in mixtures of dimethyl sulphoxide with CCl4, CHCl3, and CCl3CHCl2

Solid/liquid phase diagrams have been obtained from time against temperature cooling and warming curves for the three binary systems formed from dimethyl sulphoxide (DMSO) with CCl4, CHCl3, and CCl3CHCl2. The CHCl3+ DMSO system forms both a stable and a metastable solid addition compound. The empirical formula for both compounds is DMSO ·(CHCl3)2. A single addition compound with the empirical formula DMSO · CCl3CHCl2 forms in the DMSO + CCl3CHCl2 system. DMSO and CCl4 form a simple eutectic system with no evidence for solid compound formation. The presence and absence of compounds in these systems is in qualitative agreement with the concept that the bonding is from hydrogen bonds formed between the DMSO oxygen and the hydrogen in the chlorinated compounds.