Glassware drying

Commercial grades of anhydrous ether and benzene which have been allowed to stand over sodium are satisfactory. Dry glassware should be used for transferring the solvents. 

Precautions were taken whilst azeotroping the catalyst with toluene thus the use of freshly dried toluene and flame-dried glassware were necessary to ensure anhydrous conditions. 

Procedure After having maintained the various experimental parameters stated above for gas chromatography and using throughout absolutely dry glassware which may be siliconized, inject 1 pl of solution (1) through solution 4 sequentially and obtain the chromatogram. 

Note All operations must be carried out in oven-dried glassware using Schlenk techniques under an atmosphere of argon and conducted in an efficient fume cupboard. 

Fill washed and dried glassware with sterile filtered water, sonicate for 5 minutes and test with a particle counter. 

Triphenylphosphine was purchased from Aldrich Chemical Company, Inc. Use of a considerable excess of triphenylphosphine ensures complete reaction and obviates the need for rigorously dried glassware and reagents. Hydrochloric acid, generated by the reaction of dichlorotriphenylphosphorane and water, can react with the epoxide to produce a trans -chlorohydrin rrans-chloro-hydrins, however, are converted to cis-dichlorides by dichloro-tripbenylphnsphnrane under the conditions of the reaction. 

Under an atmosphere of dry nitrogen gas, the dropping funnel is replaced by a fractional distillation apparatus provided with a 10-cm Vigreux column and a 5-cm water-cooled condenser. The system is heat-dried under a flow of nitrogen gas with an electric heat gun or may be assembled from oven-dried glassware. The mixture is then heated over a period of 20-30 min until the silicone oil bath reaches 130-140 °C. During this time, the initial yellow precipitate is partially dissolved and the mixture refluxes smoothly. The silicone oil bath is maintained at this temperature for an additional 30 min. Heating is then increased over the period of 1 h to achieve distillation of the product the final oil temperature reaches 200 to 215 °C. 

Because of the sensitivity of the reagents toward moisture, both procedures A and B should be carried out in oven-dried glassware under dry and inert conditions. 

Dry equipment is required for most processes carried out in biochemistry laboratory. When you needed dry glassware in organic laboratory, you probably rinsed the piece of equipment with acetone, which rapidly evaporated, leaving a dry surface. Unfortunately, that surface is coated with an organic residue consisting of nonvolatile contaminants in the acetone. Since... 

Unless otherwise stated, all operations are carried out in flame-dried glassware under an inert gas atmosphere using standard Schlenk techniques.6... 

Unless otherwise stated, all operations are carried out in flame-dried glassware under an inert gas atmosphere using standard Schlenk techniques.7 Solvents were dried over sodium (light petroleum, bp 40-60°C) or sodium benzophenone (diethyl ether, THF) or calcium hydride (acetonitrile). Li[BHEt3] in THF (Superhydride ) and sodium bis(trimethylsilyl)amide were used as purchased (Aldrich). 

Dry glassware, syringe needles, and a stirring bar in a drying oven ( 120°C) for several hours before use. 

Coat the clean, dry glassware with Repelcote (Hopkins and Williams Ltd.), dimethylchlorosilane (British Drugs Houses) or similar reagent. 

Whereas carbonyl chloride itself is very moisture sensitive and requires the corresponding precautions such as efficiently dried glassware and solvents, the Box derivative is very stable and can be analysed by high performance liquid chromatography (HPLC) with ultra violet (UV) detection at 270 nm. Quantification is achieved by the standard addition procedure spiking carbonyl chloride into the test polymer solution. However, since Box is a commercially available chemical, it is advisable to work also with Box standards, especially when the method is used for the first time and when problems are experienced in the HPLC determination or the derivation procedure. The standards of the carbonyl chloride derivative are particularly useful to establish the analytical system and to check linearity of detector response as well as for the recovery check. 

All reactions should be carried out in dry glassware under a nitrogen atmosphere. 

In this section, representative experimental details of the synthesis and photochemical study of the [(Ti -C5H5)Fe(CO)2] (Fp) disilanes and the Fp- and [( T] -C5H5)Fe( T] -C5H4)] (Fc)-substituted polysilanes are presented. All manipulations were performed under dry nitrogen or argon atmosphere in oven-dried glassware with dry solvents. 

All vessels used in SPPS should be silanized to minimize the tendency of resin beads to stick to the vessel walls. Do not sUanize with water-soluble sUanizing agents. Treat dry glassware for 15 min with a 10% solution of trimethylsilyl chloride in an anhydrous solvent (toluene, CH2CI2, THF) rinse with dry solvent. 

These can be used instead of Bunsen burners or microbumers provided that the temperature required is not too high. The main uses of hot-air guns are for drying glassware and as a heat source for distillation of liquids at relatively moderate temperatures up to about 120 °C. 

During your laboratory course it will be necessary to dry glassware, analytical standard compounds (see p. 144), chemicals you have synthesized, crucibles used in gravimetric analysis (see p. 139) and solvents. Drying solvents is described on p. 127. 

---