Schlenk tube techniques

Watt and Drummond, were considered to be inert for C-C bond forming reactions. However, by the expedient of transmetallation to Cu, Ni, Zn, Li, and Al, methodologies for the stereoselective synthesis of olefins and dienes, as well as unusual heterocycles, aromatics and their ring-annulated products are now available which are beginning to make impact on material science, e. g. synthesis of pentacenes and polyphenylenes. Takahashi and Li provide evidence that, with further developments in transmetallation and handling the zirconacycles outside of the Schlenk tube techniques, synthetic utility will increase and new catalytic reactions will be developed. 

Caution. Organolithium compounds are extremely air and moisture sensitive and therefore all manipulations described here should be carried out under a dry nitrogen atmosphere using Schlenk-tube techniques.9 Solvents are dried preferably with sodium metal and distilled under nitrogen. Pure isolated organolithium compounds are pyrophoric in air. 

All reactions and manipulations should be performed under an atmosphere of dry nitrogen either in a dry box or using Schlenk tube techniques. Filtered and degassed solvents should be used for the chromatographic separations. 

All reactions were carried out following the Schlenk tube technique. All solvents were distilled under argon. 

Standard Schlenk-tube techniques for the handling of air-sensitive compounds should be employed in this preparation. 1... 

TiCl2(PR3)2, is also readily obtained. When standard Schlenk-tube techniques are used, both compounds can be prepared in 1 day or less in quantities suitable for starting materials for further research. 

This is achieved conveniently using the Schlenk tube technique. See reference 8, pp. 145 ff. 

The objective of the present chapter is to describe the combination of cannula/Schlenk tube techniques which are currently used in our own laboratories for the manipulation of air sensitive materials. These techniques are not, of course, unique to our laboratories - similar techniques have been developed in many other groups, and many of the techniques to be described were initially developed elsewhere, or are based on conversations with colleagues. 

All manipulations are carried out under a nitrogen or argon oxygen-free atmosphere using standard septum, syringe, and Schlenk tube techniques.5 Use of greaseless, Teflon-coated joints is recommended. 

All the manipulations were carried out under an efficient fume hood on a vacuum line by use of the classical Schlenk tube technique. All the solvents were dried and stored under a nitrogen atmosphere. 

Caution. The dihydridoiron complex is very oxygen-sensitive so the reduction and isolation steps described below must be carried out in a dry-box or by use of Schlenk-tube techniques.1... 

All the operations described here must be carried out under a rigorously dry, oxygen-free nitrogen atmosphere, using conventional Schlenk-tube techniques.4 Solvents should be purified by conventional methods, distilled and stored under nitrogen. 

The syntheses are performed either in a Vacuum Atmospheres Drilab or using conventional Schlenk-tube techniques under an atmosphere of dry oxygen-free argon. Tetrahydrofuran (THF), toluene, and n-hexane were distilled under nitrogen from sodium-benzophenone. [CpCr(CO)3]2 is synthesized as described previously. Silica gel used is Merck Kieselgel 60 (35/70 mesh ASTM). Convenient scales of preparation are described below, but the reaction can easily be scaled up several times if necessary. 

All manipulations are carried out under a nitrogen (or argon where stated) atmosphere using conventional Schlenk tube techniques. All the solvents used are deoxygenated (saturated with nitrogen). To achieve this, the solvent is boiled briefly at room temperature under reduced pressure and then shaken briefly with nitrogen at atmospheric pressure. This procedure is repeated twice (three times in all). 

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