TYPICAL GROUND GLASS JOINT ASSEMBLIES FOR STANDARD REACTION PROCEDURES

15 TYPICAL GROUND GLASS JOINT ASSEMBLIES FOR STANDARD REACTION PROCEDURES 

Some typical assemblies are collated in the following diagrams, which represent most of the basic reaction procedures which are adopted in the later experimental sections. 

An assembly for heating a reaction mixture under reflux is illustrated in Fig. 2.54. The precise design of condenser depends upon the volatility of the reaction liquid, low boiling liquids ( 60°C) require the use of a double surface condenser. Additionally a calcium chloride tube may be inserted at the end of the condenser if the reaction mixture contains moisture-sensitive components. It is 

Where the addition of solid is required to a reaction mixture, which is being heated under reflux with stirring, either of these devices may be attached to the upper socket of the reflux condenser, which must, of course, be of the Liebig type. In these circumstances a second reflux condenser must be fitted with a guard-tube or with a nitrogen inlet system (cf. Fig. 2.60) to allow for equilibration of pressure within the apparatus. 

The addition of a gas to a reaction mixture (commonly the hydrogen halides, fluorine, chlorine, phosgene, boron trifluoride, carbon dioxide, ammonia, gaseous unsaturated hydrocarbons, ethylene oxide) requires the provision of safety precautions which may not be immediately apparent. Some of these gases may be generated in situ (e.g. diborane in hydroboration reactions), some may be commercially available in cylinders, and some may be generated by chemical or other means (e.g. carbon dioxide, ozone). An individual description of the convenient sources of these gases will be found under Section 4.2. 

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