The compressive behavior of adamantane and its secondary monosubstituted derivatives; adamantanone, 2-methyladamantane, and 2-bromoadamantane was measured at various temperatures in a piston-cylinder apparatus. A first-order solid-solid phase transition was found under pressure in each system. The transition pressures, the equilibrium pressures, the volume changes, and the entropy changes for the transition were determined. The compression data for the low pressure phases were fitted to an equation of the form −ΔV⁄V0=a0+a1P+a2P2. The effects of substituent groups on the entropy changes of the transitions of these molecular crystals were discussed.

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The relative photochemical reactivity of α-diketones, in particular, 9,10-phenanthraquinone, 1,2-naphthoquinone, acenaphthoquinone, benzil, 4,4′-dimethylbenzil, 2,4,6-trimethylbenzil, 2,5,2′,5′-tetramethylbenzil, 2,3,5,6-tetramethylbenzil, 2,4,6,2′,4′,6′-hexamethylbenzil, phenylglyoxal, 2,5-dimethylphenylglyoxal, and 2,4,6-trimethylphenylglyoxal was investigated in hydrogen donating solvents. Type of the product and relative reactivity differ widely according to the structure of α-dike tones. Whereas 9,10-phenanthraquinone gives 1,4-adduct (V) in a hydrogen donating solvent (THF), 2,5,2′,5′-tetramethylbenzil gives 2-hydroxy-2-(2′,5′-dimethylphenyl)indanone (VII) via intramolecular hydrogen abstraction in nearly quantitative yield. No photochemical reaction of 2,4,6-trimethylbenzil or 2,3,5,6-tetramethylbenzil could be observed in the same solvent even under a long irradiation.

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Y. Yoshimura, J. Osugi, and M. Nakahara: Additivity Rule of the Partial Molal Volume etc. 25 In Fig. 5 the critical p ( T ) curves of the N,-binaries are compiled; the data are taken from the present work or from the literature. Full lines and circles are experimental results, the dashed lines are curves calculated from the Redlich-Kwong equation of state by Deiters [26, 271. Calculations The critical p ( T ) curves and some characteristic p ( x ) isotherms were calculated for both systems from a one-fluid approach using the Redlich-Kwong equation of state (Deiters and Schneider [26]; Deiters [27]; here details concerning the combining rules used and the definition of the parameters a,, , az2, , 19 and ( are also given). The adjustable parameters 19 and [ as well as the critical curve or isothermal phase equilibria were solved numerically by a computer program developed by Deiters [28]. Calculations were carried out on reproducing the critical curves interpolated from experiments as well as possible. The parameters 19 and [ were calculated using one experimental point on the critical curve. The Redlich-Kwong parameters were obtained from critical and p . V,, T data of the pure components. Some of the results are shown in Figs. 6 -8. The values for the parameters used in the calculations are given in the legends. The isothermal p(x) sections of the system N, + pentane have been calculated with the same values of the parameters as those used for correlating the critical curve. In the case of N, + pentane the fit of the parameters from experimental results was realized using a p , Vm, T data point of pure pentane additionally. This procedure has the consequence that the coordinates of the critical point of' pentane d o not equal those determined experimentally. Some difficulties for the calculation of isothermal p ( x ) sections of the system N, + ethane result from the high reduced densities of the mixtures which are outside the range of the validity of the equation of state used; such isothermal p ( x ) plots are not shown. For details see [23]. Equations of State / High Pressure / Liquids / Solutions / ThermodynamicsA critical test of the additivity rule of the partial molal or molal volume (t) at constant temperature and pressure, expressed by = an + / 3 where n is the carbon number, has been made for a wide range of n-alkanes at a variety of temperatures and pressures. In the pure liquid state the additivity rule is obeyed approximately well by the higher n-alkanes but broken by the lower ones having the boiling point close to the temperature of interest, and in solution at infinite dilution it is obeyed much more accurately by both high and low n-alkanes. These facts indicate that the