Measurements have been made over a range of temperature of the heat capacity, the coefficient of expansion a, and the adiabatic compressibility K~ of benzene, carbon tetrachloride, ethylene dichloride, acetone, chloroform, and carbon disulphide, and of a number of mixtures of the four systems named above. The corresponding heat capacities at constant volume and the isothermal compressibilities K= have been calculated. For the four binary systems, the dependence of a and K~ on composition is discussed. The variation with temperature of the volume change on mixing has been estimated, and the energy and entropy of mixing at constant volume have also been assessed.The results provide further evidence of the remarkable constancy of the quantity TV2y over a range of temperature, where T = temperature, V = molar volume, and y = c ~/ K ~. For all four systems the simple equation relating TV2y with mole fraction which Hildebrand and Carter proposed some years ago is closely obeyed, and hence in view of the different characters of these systems, obedience to this equation cannot be used as evidence of the normality or abnormality of the intermolecular force relationships between the two components. It seems that a better criterion in this respect is one based on Scatchard's relation between cohesive energy densities and the energy of mixing at constant volume.In a previous paper,l which will be referred to as part 1, we discussed the heat capacity at constant volume C, of pure liquids and of seven binary liquid mixtures. In order to evaluate C,, measurements were made of the heat capacity at constant pressure C,, the coefficient of expansion a, and the adiabatic compressibility K ~, for the pure liquids of which the seven systems were composed, and for three or four mixtures for each system. Each set of measurements of C,, a and K~ extended from room temperature to almost the boiling point. In addition to their use in estimating C,, measurements of these three quantities are of value in other connections. In considering a binary system from the standpoint of its " excess function curves ", it is necessary to know the excess Gibbs free energy G E and the heat of mixing HE a t the same temperature. Usually, however, G E has been determined at a higher temperature than HE, and knowledge of C, for the system is necessary to correct HE to the temperature of measurement of GE. Also, it isnot often that the volume change on mixing, V E , has been determined at the same temperature as the vapour pressure measurements used to establish G E , and to bridge the gap to the latter temperature requires a knowledge of a as a function of temperature and composition. Having thus found GE, HE, 5 ' '(the excess entropy of mixing at constant pressure), and Y E at the same temperature, it is interesting to enquire into the magnitude of the contribution made to HE and SE by the volume change on mixing. The corresponding quantities for constant :ohme, Ef and S,", can be readily estimated using the relations,

The microwave synthesis of several quaternary ammonium salts is described. The synthesis provides comparable or better yields than published methods with reduced reaction times and in the absence of solvent.

Measurements have been made of (i) the heat capacity at constant pressure of carbon tetrabromide from 0" to 60" C, (ii) the temperature and heat of transition of the phase change in this substance, (iii) its isothermal compressibility, coefficient of expansion, and density above and below the transition, (iv) the isothermal compressibility and the coefficient of expansion of ammonium chloride above and below the &point. The Compressibility measurements have been made over the range 1 to 50atm. For each substance, values of Cwres have been calculated above and below the transition, where Cwres is the molar heat capacity at constant volume less the contribution from intramolecular or interionic degrees of freedom. For carbon tetrabromide, Cvres does not alter at the transition, but remains almost equal to 6R, showing that the motion of the molecules at the transition does not change to rotation, but remains one of three-dimensional, simple harmonic torsional oscillations. For ammonium chloride, while the results are in agreement with the established view about the nature of the A-point, they indicate that there is an "anomalous" contribution to Cwres above the A-point. This contribution for a time actually increases with rising temperature, and at 50" above the &point amounts to about 2-6 cal/mole. Incidental to the above measurements, determinations have also been carried out of the compressibility of water at 0" and 34.8" C, and of the compressibility and coefficient of expansion of toluene between -60" and 0" C.

In the title compound, C17H24NO2 +·Br−·H2O, the pentyl group chain in the cation extends nearly perpendicular [N—C—C—C = −64.4 (3)°] to the mean plane of the indole ring with the carboxyl end group twisted such that the dihedral angle between the mean planes of the indole and carb­oxy groups measures 43.2 (4)°. Both ions in the salt form inter­molecular hydrogen bonds (O—H⋯Br and O—H⋯O) with the water mol­ecule. As a result of the Br⋯H—O—H⋯Br inter­actions, a zigzag chain is formed in the c-axis direction. The crystal packing is influenced by the collective action of the O—H⋯O and O—H⋯Br inter­molecular inter­actions as well as π–π stacking inter­molecular inter­actions between adjacent benzyl rings of the indole group [centroid–centroid distance = 3.721 (13) Å] and inter­molecular C—H⋯π inter­actions between a methyl hydrogen and the benzyl ring of the indole group. The O—H⋯Br inter­actions form a distorted tetra­hedral array about the central Br atom. A MOPAC AM1 calculation provides support to these observations.

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