Standard Taper Joints

Connect a short length (12 cm.) of glass tubing equipped with a male standard-taper joint to the flask and immerse flask in a boiling water bath until the volume of the liquid is reduced to about 5 ml. Avoid prolonged heating after the alcohol has evaporated and run the next step as soon as possible. It is undesirable to hold this alcoholic solution overnight. 

For the distillation, the still head consisted of a Claisen-type adapter with a parallel side arm (24/40 standard taper joints), 21 cm. high and 10.5 cm. wide. An ordinary straight still head is attached to the parallel side arm. This large still head prevents any bumping solid from entering the condenser. 

A 100-ml. Claisen distillation flask with two 14/20 standard taper joints and a thermometer inlet is equipped with a gas inlet adapter, a... 

Fig. 1. Erlenmeyer conductance cell 24/40 standard taper joint used for solvent delivery.

In order to maintain an oxygen-free atmosphere over the solution, it is essential that all standard taper joints be adequately lubricated and that the various joints be held together with rubber bands, wire, or springs. 

Graduated cylinders of various sizes with 24/40 standard taper joints are available from Ace Glass, Inc. appropriate septa were obtained from Aldrich Chemical Company, Inc. 

A diethyl ether solution containing 20 mmoles of methyllithium is placed in a 50-mL reaction vessel equipped with a stopcock and standard taper joint. The vessel is attached to a vacuum line stopcock equipped with a mercury blow-out manometer,3 and the contents are frozen at -196° (liquid nitrogen) prior to evacuation of the vessel. 

The reaction vessels as shown in Figure 1 were cylindrical borosili-cate glass vessels, with i.d., 25 mm. and internal height, 36 mm. A standard-taper joint permitted connection to a stopcock. These two sections could be filled in a nitrogen atmosphere box. Then the sealed vessel could be connected to the vacuum system at the ball joint. 

A solution of product A (0.31 g, 0.5 mmol) and L12C03 (0.15 g, 2.0 mmol) in a mixture of 10 mL ethanol, 26 pL (0.5 mmol) acetonitrile, and 2,4-dimethylpenta-1,3-diene (Aldrich) (0.38 g, 4.0 mmol) is heated at reflux for 4 h in a 100-mL round-bottomed flask with a standard tapered joint. The solvent is evaporated under reduced pressure, and the flask is connected to a short, straight, water-cooled reflux condenser (Fig. 1). The top of the reflux condenser is attached to a high-vacuum pump, and the brown cmde product is purified by sublimation at 80°C and 10 bar. The yellow solid product is collected from the lower end of the reflux condenser. On a larger scale, it is more convenient to extract the dry brown cmde product with diethyl ether, filter the solution through a pad of alumina, evaporate the solvent, and then sublime the product. Yield 95%. 

The three-way stopcock with standard-tapered joint must be securely fastened to the neck of the flask with wire, rubber band, or springs [see Figure 1 and D. Seebach and A. K. Beck, Org. Syn., 51, 39, 76 (1971)]. 

The apparatus is shown in Fig. 2. Two 500-ml. round-bottomed flasks without standard-taper joints (which could cause diazomethane to detonate) are used. The gas inlet C is connected to a cylinder of dimethyl ether. Gas inlet C is long enough to reach near the bottom of flask A, but tubing D extends only about halfway into flask B. A calcium chloride drying tube is attached to the gas outlet E. Flask B contains a Teflon -covered stirring bar. The pieces of the apparatus are dried in an oven at 110° well-dried apparatus is essential for a good yield. 

B. Septa and Other Closures. Rubber septa may be attached in a variety of ways, as illustrated in Fig. 1.6. The flat variety is held in place by screw caps, crimped caps, or beveled holders. Various manufacturers provide apparatus with these types of septum closures.4 Of greater versatility are the sleeve septum stoppers (Fig. 1.7), which can be attached to straight tubes or standard taper joints without any special fixtures.5... 

Fig. 1.21. Typical assemblies of Schlenk ware. Commercial apparatus is illustrated similar apparatus with O-ring joints in place of standard taper joints is preferred by the authors. (

Fig. 1.26. Sublimation apparatus. Solids are introduced under inert-gas flush, and a loose plug of glass wool is introduced. The oil bath should extend above the glass wool. High vacuum may be applied through the standard taper joint. A lower vacuum may be applied through the sidearm.

G. Variations in Schlenk Ware. A large number of modifications of the basic Schlenk ware are in use. The double-ended filter is a commonly used variant of the standard Schlenk filter. The particular unit illustrated in Fig. 1.29 is equipped with O-ring joints rather than standard taper joints. (See Chapter 8 for a discussion of joints and O-ring materials.) Either conventional or modified O-ring joints, such as the Fischer and Porter Co. Solv-Seals, have several advantages over standard taper joints for Schlenk apparatus these O-joints are more resistant to solvents than the conventional standard taper ware, the O-joints are more readily clamped together, and, unlike standard taper joints, the two halves... 

A. Standard Taper and Ball Joints. These joints (Fig. 8.1) have been used for many years on vacuum and inert-atmosphere systems, and the availability of a variety of synthetic greases and waxes has extended their utility. Of the two, the ball-and-socket joint permits more flexibility in the orientation of the two halves. When this flexibility is important, this type of joint is obviously to be preferred, even though the ball joint is somewhat more prone to leak than a standard taper joint. Both metal ball joints and metal standard taper joints are available,1 and these items provide one means of joining metal and glass apparatus. 

Metal ball joints, metal standard taper joints, and O-ring joints with a step tooled into Ihe groove are available from Kontes Glass Co., P.O. Box 729, Vineland, NJ 08360. The first two items are also available from Ace Glass Co., P.O. Box 688, Vineland, NJ 08360. 

A. Vacuum Line Filtration. For their work on the diammoniate of dibo-rane. Parry, Schultz, and Girardot24 devised a versatile vacuum line filtration apparatus which is useful when small quantities of solid are handled and when the solvent is sufficiently volatile to be distilled on the vacuum line. The filter is attached to the vacuum system through a standard taper joint which allows it to be rocked or inverted (Fig. 9.21). Prior to filtration, any volatile contents are frozen down and the apparatus is thoroughly evacuated (Fig. 9.21a). By inversion of the apparatus, the solution is then poured onto the frit, and the solvent vapor pressure is employed to effect a suction filtration by closing the stopcock in the equalizing arm and cooling the lower tube (Fig. 9.21b). The precipitate is washed by distillation of the solvent from the lower receiver into the upper portion of the apparatus (with the stopcock in the sidearm open) and repetition... 

E. Miscellaneous Tubing Connectors. The variety of tubing couplers is enormous and a comprehensive list would be out of place in this book, but several additional types will be mentioned here which are useful in the laboratory. Metal standard taper and metal ball joints are available, and these will mate with corresponding ground-glass joints to provide one means of connecting parts made of dissimilar materials.4 As with glass standard taper joints, the seal is... 

A. Typical Apparatus. A simple modification which improves the utility of a one-neck still pot or solvent receiver is a sidearm, which can be used for flushing the flask. This simple modification facilitates the initial flush of the apparatus shown in Fig. 1.3. Furthermore, the sidearm provides several alternatives for the removal of solvents from a receiver, such as flushing the flask while solvent is removed through the standard taper joint, or removal of solvent through the sidearm, as illustrated in Fig. 1.4. The sidearm also permits the flask to be maintained under a constant flush of inert gas when it is attached to another piece of apparatus (Fig. 1.5). 

Fig. 1.13. Variation on the cannula technique. The glass lube with fritted filter and the glass delivery tubes are attached to the glass standard taper joints by means of plastic adaptors (e.g., Kontes K-179800). The flexible plastic tubing connecting the two parts should be impervious to solvents. Teflon tubing is best and. to prevent contamination of the filtrate, Tygon tubing should be avoided when organic solvents are used.

Fig. 8.1. Standard taper ( ) and spherical joint ( ). When the joints are lubricated with grease, they must generally be held together. Springs or rubber bands arc frequently employed on standard taper joints, while a spring-loaded clamp (illustrated here) or a screw clamp (illustrated in Fig. 8.3) is used with ball joints. The method used for specifying joint sizes in the United States is illustrated, and it is described in detail in National Bureau of Standards, Commercial Standard CS 21-39.

Fig. 9.1. Multipurpose tensimeter. Since the standard taper joint is positioned close to the manometer, the joint is close to the balance point of the apparatus. The tensimeter is best supported by clamping at the taper joint and by resting the bottom of the tensimeter on a piece of foam in a small dish which in turn is supported by a ring clamp. The brace between the left arm of the manometer and the joint is held in place with epoxy cement and adds stability to the apparatus. The tensimeter is Tilled with mercury in the same manner as a U-manometer (see Fig. 7.1 caption). To minimize the votume of mercury, capillary tubing is used for the bottom and part of the teft leg.

LC-6). Cells LC-1 and LC-2 have holdup volumes of 2.0 and 0.7 ml., respectively. In the case of LC-2 the platinum electrodes and mercury well side arms are part of a standard-taper joint assembly. Cells LC-3 and LC-4 have holdup volumes of 0.16 ml. and external copper electrode caps. Cells LC-3 and LC-4 were stacked so as to be able to shift scales during the demineralization and regeneration half cycles, but a more convenient design was achieved in the compound cells, LC-5 and LC-6, with effective holdup volumes between 0.25 and 0.55 ml. Figure 6 is a drawing of LC-4 and LC-5. By using several inputs into the recorder, a continuous record can be obtained over a wide concentration range. 

Fig. 6.1 Two-electrode assembly (A) platinum wire (B) mercury-filled glass tube (C) thermometer adapter, 10/18 standard taper joint, Teflon (D) platinum electrodes 25 mm x 30 mm. Reprinted with permission [20],...

Using the same apparatus as described above, 40 g. of freshly cut sodium and 8 g. of clean calcium turnings (or bulk calcium) are heated to approximately 850° under an argon atmosphere. After mild agitation at this temperature with the stainless-steel thermocouple well, the sodium-calcium solution is permitted to cool to room temperature. (The thermocouple well is removed before the sodium solidifies i.e., at about 100°.) Fifty milliliters of mineral oil is added to the solidified melt, and the metal mixture is then reheated to 110° and poured into 200 ml. of cold mineral oil in a 1-1. beaker. The melt may be too viscous to pour cleanly if so, the product may be removed with a spoon or spatula. The solidified product is then cut into pieces small enough to pass through a 24/40 standard taper joint and the calcium is separated by the procedure1 described in the previous synthesis. 

This preparation is divided into three steps (1) the reaction of phosphorus (V) chloride with ammonium chloride in an inert solvent, (2) the rapid distillation from the solvent and from the nondistillable, rubber-forming higher polymers, and (3) the fractionation of the trimeric and tetra-meric compounds. The reaction apparatus consists of a 5-1. three-necked flask with standard-taper joints fitted with a thermometer and a motor-driven, heavy-duty stirrer, and heated by an electric mantle. For the preliminary removal of water from the solvent a Dean and Stark trap is used at a side joint in conjunction with a long water-jacketed condenser, the latter having a calcium chloride drying tube at its upper end. 

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