Oil drying agents for compounds that speed up the hardening of oils, often used in painting. Activated alumina ¹ is a very porous form of aluminum oxide of high surface area which adsorbs liquids and gases without any change in form. Activated alumina will not soften or disintegrate when immersed in liquids.
There are various ways of removing water and other impurities from a solution. This can become a major task once the exploited reagents are also excitable towards water e.g. Grignard reagents or enolates. If water is one of the products, it also experiences a detrimental effect on-duty the concede and/or reaction rate. Activated alumina may be regenerated to its original adsorption efficiency by heating to a temperature between (177-316°C ).
The drying agents commonly used in the organic laboratories are calcium chloride (CaCl2), sodium sulfate (Na2SO4) Calcium sulfate (CaSO4, as Drierite (R)) and magnesium sulfate (MgSO4), all in their anhydrous form. In those cases, drying agents like activated alumina¹, calcium hydride (CaH2), sodium metal (in combination with benzophenone which forms a dark blue ketyl radical), lithium aluminum hydride (LiAlH4) or phosphorous pentoxide (P4O10) are used to chemically destroy the water.
A good rule of thumb for predicting solubility in water is to assume that any molecule having six or more carbons and 0-1 functional group will be insoluble in water. Molecules having the described structural characteristics have physical properties that reflect the dominance of the hydrophobic hydrocarbon portion of the molecule.
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