Tubing removing from stoppers

Benzoates. Dissolve 0-5 g. of the amino acid in 10 ml. of 10 per cent, sodium bicarbonate solution and add 1 g. of benzoyl chloride. Shake the mixture vigorously in a stoppered test-tube remove the stopper from time to time since carbon dioxide is evolved. When the odour of benzoyl chloride has disappeared, acidify with dilute hydrochloric acid to Congo red and filter. Extract the solid with a little cold ether to remove any benzoic acid which may be present. RecrystaUise the benzoyl derivative which remains from hot water or from dilute alcohol. 

B. 2,6,6-Trimethyl-2,4-cyclohexadienone. In a nitrogen-filled dry box, 25.0 g. of lithium 2,6-dimethylphenoxide (0.195 mole) is transferred to an oven-dried, thick-walled Pyrex bomb tube (650 x 19 mm.). The bomb tube is stoppered with a rubber stopper fitted with a drying tube, removed from the dry box, and 75 ml. of methyl iodide (170 g., 1.20 moles) (freshly distilled from calcium hydride) is quickly pipetted into the bomb under a dry nitrogen stream. The bomb is cooled in a dry-ice bath and sealed with an oxygen torch. After warming to room temperature, the bomb is shaken to disperse the salt cake and placed in a bomb furnace which has been preheated to 135° (Note 7). 

Two very similar procedures have been used by the authors with similar success. The first performs the pull within 25 sec of the final heating step, such that the quartz has not completely cooled prior to the pull. The laser is turned off, the vacuum tubes removed from the capillary and the stoppers removed from the pulling sleds followed by a pull using the parameters Heat 875 Filament 2 Velocity 130 Delay 150 Pull 200. This procedure results in electrode tapers of 3-5 mm and metal disk diameters from 200 nm to 4 jm. Alternatively, the sealed capillary can be cooled to room temperature prior to executing a pull using the parameters Heat 875 Filament 2 Velocity 50 Delay 120 Pull 200. This method results in electrodes with tapers of roughly 1 cm and electrodes as small as 3 nm diameter have been fabricated. 

Surface Modification. A polydiene film (supported on a microscope slide) was immersed in a stirred, room temperature, RTD-acetonitrile solution of known concentration contained in a large glass-stoppered test tube. After a specific reaction time, the film was removed from the solution, washed with acetonitrile, water, and acetonitrile again, and dried under vacuum (Step 1). Films subsequently treated with base were immersed in aqueous solutions for 5-15 min. They were then washed with water and CH3CN, and vacuum dried (Step 2). Some films were aged in air at room temperature. 

After removing tube B from attachment A, the product is scraped, as before, into the flask. Tube B is removed, the flask is stoppered, and the stopcock closed. It is best to release any excess pressure in the flask before storage. The yield of tita-nium(IV) iodide is 25.0 g. (93% based on the titanium which reacted, 84% based on the total weight of titanium used). Anal. Calcd. for Til4 Ti, 8.62 I, 91.38. Found Ti, 8.61 I, 91.28. 

Now fit the calcium chloride tube closely to the constricted part of the combustion tube and connect the sodium hydroxide-asbestos tube to the calcium chloride tube of the aspirator. Then remove the rubber stopper from the combustion tube, push back the stand carrying the drying apparatus so as to make more room, raise the copper block with the boat to the opening of the combustion tube, with the forceps insert the boat, push it inwards 4-5 cm. up to the furnace with a clean glass rod of suitable size, taking care not to tip the boat over, insert the rubber stopper loosely into the tube, moistening the stopper if necessary with a very thin film of glycerol,... 

Observe and record the appearance of the element sample in each test tube. Observations should include physical state, color, and other characteristics such as luster and texture. CAUTION Do not remove the stoppers from the test tubes. 

Remove the stopper from receiver 2 and introduce copper shavings. Close the flask with a stopper provided with a dephlegmator and thermometer (see Fig. 20). Wrap the flask in asbestos and put it into an electrical flask heater. What is the boiling point of vanadium oxychloride Transfer the collected liquid into a weighed drawn out test tube. (Wear eye protection, seal the substance in the presence of your instructor ) Weigh the ampoule with the remaining part of the tube. Calculate the yield in per cent. 

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