Liquor free surface

The effect of free surface liquor content in a bulk material, as opposed to bound moisture or water of composition, is to alter the physical and geometric structure of the mass. Water is a common component of liquor/solids mixtures and can be present in a wide range of proportions, categorized by descriptions that reflect increasing moisture content as ... 

Bound moisture This is moisture retained within the solid such that it exerts a vapour pressure less than that of free solvent (Figure 4.24). Such solvent may be adsorbed on the surface, retained in capillaries or within cells or occlusions of liquor. The latter can be difficult to remove without resorting to high temperatures, which may damage the crystals. 

Cool the reaction mixture in an ice bath. If crystallization does not occur, withdraw a drop of solution on a stirring rod and rub it against the inside surface of the flask to induce crystallization. Collect the product by suction filtration and wash it free of yellow mother liquor with a 1 1 mixture of 95% ethanol and water. The product should be colorless and of sufficient purity (mp 134-135°C) to use in subsequent reactions usual yield is 10-12 g. If desired, the moist product can be recrystallized from 95% ethanol (8 mL per g). 

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