Lubrication of ground glass joints

Locating an organic compound, 1128 Lubrication of ground glass joints, 225 Lucas test, 261 reagent, 261 ... 

Assemble a setup as shown in Fig. 100. Lubricate the ground-glass joints with phosphoric acid. Displace the air from the setup with dry carbon dioxide. Pour 50 ml of absolute benzene into 250-ml... 

Lubricate the ground-glass joints in the apparatus with a concentrated sulphuric acid solution. Clean a piece of metallic aluminium with emery paper, make 10-12 g of shavings from it, and put it into flask 1. Pour 30 ml of dry bromine into dropping funnel 2. This amount of bromine is not sufficient for the aluminium to enter into the reaction completely (why is excess aluminium taken )... 

All reactions are carried out using conventional vacuum-line techniques. Teflon-in-glass stopcocks and a silicone lubricant for ground-glass joints should be used because of the marked solubility of germanes in hydrocarbon greases. 

Lubricate all ground-glass joints in the apparatus carefully and mate them tightly to prevent the escape of diethyl ether during the reaction. 

Make sure your glassware is dry, lubricate the ground-glass joints of the apparatus carefully, and be certain that the joints are intimately mated. Otherwise, noxious gases will escape. 

It is often advisable to lubricate ground-glass joint surfaces with an extremely thin film of vaseline. This applies particularly to joints employed in assemblies for distillation under reduced pressure. For distillations under greatly reduced pressures or at very high temperatures it is essential to employ a special lubricant, e.g., silicone grease. 

Some simple apparatus, suitable for high vacuum distillation, are collected in Figs. 11, 26, 1-4. Fig. 11, 26, 1 represents an apparatus, which is particularly well adapted for solids the ground glass joint must be lubricated with a grease of negligible vapour pressure. Hickman s vacuum still is shown in Fig. 11, 26, 2 it is about 60 mm. in diameter. 

The mercury-cup seals may be replaced by ground-glass joints lubricated with a very small amount of 85% phosphoric acid. If ground-glass connections are used the inlet and outlet... 

The reaction can be carried out in a round-bottomed glass flask fitted with a still head, the arm of which is attached to a trap immersed in a cooling bath of ice. Owing to the reactivity of arsenic(III) fluoride, the apparatus should be well dried, and the use of rubber or cork stoppers must be avoided. A thermometer can be inserted into the still head by means of a ground-glass joint lightly lubricated with Apiezon grease L, which reacts only very slowly with the vapor.3... 

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