Paraffin-impregnated Silica Gel Layers

The alcohols considered here have been succesfully fractionated into groups with the same number of C atoms by impregnating 

Method. The dried silica gel G layer, after cooling to room temperature, is immersed for one minute in a 5% solution of paraffin or of silicone oil DC 550, in petroleum ether (see p. 48). The petrol ether (BP 40 to 60 C) is allowed to evaporate for 15 min with the plate horizontal and the layer then used in the normal way. Impregnation by ascending treatment with the paraffin-petrol ether solution has no advantage in this case. 

A mixture of 70 ml of analytical grade methanol and 30 ml distilled water, saturated with liquid paraffin DAB 6 or with silicone oil DC 550, is the best solvent. 

Me Sweeney [151a] has chromatographed 6 mono-, sesqui- and diterpene alcohols in like fashion on paraffin-impregnated kieselguhr layers, using acetone-water (65 + 35). Garel [70] has summarised briefly the conditions for separating alcohols of chemical interest. 

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Note Aldoses do not react or only react with greatly reduced sensitivity. The reagent can be employed with silica gel, kieselguhr and Si 50 000 layers. Paraffin-impregnated silica gel layers may also be employed [8]. 

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