Purification of Organic Compounds 2.1 CRYSTALLIZATION 2.1.1 Steps Involved in Crystallization 4 7 5 6 4 8 5 4 7 6 5 6 10 1 2 3 1 2 (a) (b) 7 4 5 9 1 2 (c) 8 6 9 3 10 1 2 (d) 3 8 (e) 3 Pasteur pipette Test tube 2.2.1 Exercise on Fractional Crystallization 2.3 DISTILLATION Thermometer Condenser Adapter Pear-shaped distilling flask Air bath Receiver (Conical flask) (Centrifuge tube) (a) (Vigreux column) (b) (Dufton column) (c) (Hempel column) (d) (Pear-bulb column) Thermometer Condenser Fractionating column Adapter Receiver Distillation flask Screw clip Water Receiver Stout capillary tube To pump Claisen flask To manometer and pump Manometer Filtration flask To sink (a) To apparatus Stop cock (b) Condenser (a) (b) O H O H O N O (Intramolecular H-bonding) N O O (Intermolecular H-bonding) J H A I B G K L D M E F C To pump To pump Column Cotton wool Stop cock Receiver Purification of Organic Compounds Separatory funnel Ground glass Joint Column Buchner flask 2.13.1.1.2 Adsorbent [Column Packing Material] Purification of Organic Compounds 2.13.1.1.4 Packing of the Column [Loading of Column] Disk of filter paper Sample band Adsorbent Cotton wool Top of adsorbent Solvent front Solvent Spot Purification of Organic Compounds 2.13.1.2.4 Visualization of Spots O OH OH O (Ninhydrin) Laboratory Techniques in Organic Chemistry 2.13.1.2.5 Values R f (b) Separation of 2,4-dinitrophenylhydrazones (c) Separation of leaf pigments A B C Glass rod Lid of jar Jar Plastic staples Filter paper Solvent Solvent (a) (b) Apparatus for development of chromatogram in ascending technique Lid Hole Glass rod Trough Chromatogram Jar Apparatus for development of chromatogram in descending technique paper. The two-phase solvent system may be used in this technique, by placing the aqueous phase in the bottom of the jar and when the atmosphere becomes saturated with it, the paper to be chromatographed is then supported in the empty trough. The jar is then closed again and the paper is allowed to stand for 1-2 hours to get equilibrate with the 2.13.2.3 Visualization of spots 2.13.2.4 Rf values 2.13.2.5 Exercises on paper chromatography Laboratory Techniques in Organic Chemistry Developing solvent: Spraying agent: (a long chain hydrocarbon) O O O O (Polythene glycol) R R Si Si O R R Si O R R R Si O R Si O R R (Silicone oil) Sample Oven Gas source Injection block Column Detector Recorder Amplifier × Terminals for power supply – + Shoulder piece Cotton wool plug Paper strip holder Paper strips Center partition Holes
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