Hydroquinone acetonitrile clathrate

In the acetonitrile clathrate of hydroquinone, the only authenticated Type III system, a further reduction in space group symmetry from R3 (in Type II) to P3 occurs. There are now three distinct clathration cavities in the shape of prolate spheroids. The three symmetry-independent MeCN molecules fit snugly inside these cavities, one guest molecule being aligned in the opposite sense to the other two. ... 

C20H21NO6, Hydroquinone - acetonitrile (3 1) clathrate, 44B, 571 C2oH44BrP 32 H2O, Tetraisoamyl phosphonium bromide hydrate, 45B,... 

Previously we showed that the dipole-dipole interaction between the guest molecules has an appropriate magnitude to explain the phase transitions in the hydroquinone clathrate compounds [14,17]. We have now two more substances to compare with the model the phase transition in the hydrogen sulphide compound and the ordered structure of the acetonitrile compound. A Monte Carlo calculation showed that no phase tran-... 

Figure 4 shows the transition temperature of the hydroquinone clathrate compound plotted against the square of the dipole moment of the guest molecule. The data on the hydrogen sulphide, methanol and hydrogen cyanide compounds are those of the heat capacity anomalies. The transition temperature of the acetonitrile compound, if it exists, lies above the room temperature. One finds a good proportionality between the transition temperature and the square of the dipole moment. 

Figure 6. The solubility isotherm in the hydroquinone - HCOOH - CH3CN system (a) b - the variation of the total (y) and the constituent degree of the clathrate framework filling (yi - for acetonitrile, y2 -formic acid).

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