General Nature of Clathrates

Once such a molecular complex with hydroquinone has been formed it may persist under conditions where it is no longer thermodynamically stable. Because the molecules of the second component are enclosed in the cavities they cannot escape without breaking a number of hydrogen bonds in the -hydroquinone lattice. This corresponds to a considerable energy of activation which may prevent the attainment of thermodynamic equilibrium. 

An example is the complex with argon which can be kept indefinitely in an ordinary bottle, although the equilibrium pressure of argon over the crystal amounts to several atmospheres at room temperature. Powell31 named these complexes clathrate compounds, which according to him are those compounds in which two or more components are associated without ordinary chemical union but through complete enclosure of one set of molecules in a suitable structure formed by another.  

Not only hydroquinone, but also phenol and a number of related substances have been reported20,21 33,44 to form clathrate compounds of a similar type. But this class of substances proves to be 

In 1810 Davy discovered chlorine hydrate when cooling a saturated solution of chlorine in water below 9°C. Research by Villard, de Forcrand and many others subsequently showed that this type of hydrate can be formed by water with a large number of gases or volatile liquids such as Cl2, Br2, H2S, C02, CH4, CHC13 and again the inert gases A, Kr, Xe. It was further established that the process 

The accurate composition of the gas hydrates for a long time remained a controversial subject, since direct analysis leads to ambiguous results owing to decomposition of the hydrate and/or inclusion of mother liquor in the crystals. Thus it was firmly believed that the nonstoichiometric compositions of gas hydrates found experimentally were all due to errors in the analysis. But more recent determinations of the composition by the indirect 

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