Standard taper

The interchangeability of joints is ensured by the use of a standard taper of 1 in 10 on the diameter (i.e., a cone of semi-angle 2° 51 45 ) and limited tolerances on the cone semi-angles and the dimensions of the joints. The specifications for joints in Great Britain and the U.S.A. differ. It will accordingly be necessary to treat each separately. 

Class A conforms to specifications in ASTM E694 for standard taper stopcocks and to ASTM E287 for Teflon or poly-tetrafluoroethylene stopcock plugs. The 10-mL size meets the requirements for ASTM D664. ... 

Apparatus.—The unit shown in Fig. i is constructed of Pyrex glass, and the following is a summary of satisfactory dimensions for the various tubings (outer diameters) and of other specifications A, 32-mm. tubing B, 500-cc. flask C, 7-mm. tubing D, 8-mm. tubing E, No. 35 standard taper... 

A. 3-Amino-2,4,6-tribromohenzoic acid. The bromination apparatus consists of a 2-1. three-necked standard-taper flask A, equipped with a Trubore stirrer and attached by rubber stoppers and glass tubing to two filter flasks, B and C, as shown... 

A 125-ml standard taper Erlenmeyer flask is equipped for magnetic stirring and charged with 50 g (0.37 mole) of tetrahydrodicyclopentadiene (Chapter 5, Section I). A standard taper inner joint or a short condenser is greased and inserted into the flask... 

The benzene strip or extract solutions are evaporated nearly to dryness in 500-ml. standard-taper Erlenmeyer flasks on 3 units of a 6-unit variable heat extraction apparatus hot plate (see Figure 1). Evaporation is hastened by directing a jet of air at the surface of the benzene, gentle enough to avoid spattering when maintained 0.5 inch above the surface of the liquid. The benzene vapors are removed through a manifold connected to the house vacuum. On this apparatus 250 ml. of sample can be reduced to a volume of about 5 ml. in 10 minutes. 

Transfer an aliquot of the filtrate containing between 5 and 50 micrograms of methoxychlor to a 125-ml. standard-taper Erlenmeyer flask. 

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. 

The apparatus for distillation of solids in vacuum described in Organic Syntheses is satisfactory, as is a combination of standard taper flasks, short column, and adaptors. 

The following procedure is carried out in a ventilated hood. Finely powdered dry sodium cyanide (29.4 g., 0.60 mol) and 180 ml. of dimethylformamide (DMF) are placed into a 1-1., three-necked, standard-taper round-bottomed flask equipped with a reflux condenser, dropping funnel, and Hirshberg stirrer connected to a high-speed stirring motor. External cooling is provided by a cold-water or ice-water bath. Carbon disulfide... 

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 round-bottomed, standard-taper flask with a Claisen head carrying an ebullition capillary and a thermometer and attached to a two-necked flask with one neck for vacuum takeoff is satisfactory. It is important that the setup allow for heating by either flame or infrared lamp to melt the solid distillate and prevent its clogging the vapor passage. 

Using standard taper jointware you can connect glassware without rubber stoppers, corks, or tubing. Pieces are joined by glass connections built into the apparatus (Fig. 17). They are manufactured in standard sizes, and you ll probably use T19/22. 

The symbol T means standard taper. The first number is the size of the joint at the widest point, in millimeters. The second number is the length of the joint, in millimeters. This is simple enough. Unfortunately, life is not all that simple, except for the mind that thought up this next devious little trick. 

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... 

C. 3-Chloro-2-(chloromethyl)-1-propene. Tris(chloromethyl)acetic acid (205 g, 1.00 mol) is transferred to a 500-mL, two-necked, round-bottomed flask. On top of the powdery acid, which nearly fills the flask, is placed a football magnetic stir bar (1.25 x 0.5 in.). The neck of the flask to be clamped is wrapped well with aluminum foil and is fitted with a glass stopper. A standard taper 24/40 short path still head, to which is attached a Drierite drying tube, is attached at the second neck. The upper flask and short path column are wrapped with aluminum foil, and the flask is immersed in a high temperature oil bath (Note 14) that has been preheated to a stable 210°C. As the solid melts, the reaction mixture becomes yellow, and the oil bath temperature drops (IQ-... 

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

The lower part of the barrel of the dropping funnel should be bent in such a way as to offset it from the path of the thermocouple to permit adjustment of the latter. The checkers used a 8-mm. glass tube bent for offset and fitted at the upper end with a nitrogen inlet and a standard-taper ground joint to permit at-tachment of funnels of various sizes. 

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. 

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