Nitrogen clamp

Novel Synthesis of a 1,3,5-Trioxazatriquinan Skeleton Using a Nitrogen Clamp [87] 215... 

It is sometimes cliflicult to detect nitrogen by the sodium test. The result should not be regarded as conclusive, especially if the substance is volatile, unless it has been dropped in small quantities at a time into the melted metal, which should be heated in a hard-glas.s tube clamped in a retort-.stand. Special care must be used with nitro compounds, which may explode and shatter the Lube. 

The epoxide and the nitrogen compound were mixed and stirred in a 250 1 reactor fitted for reflux and protected by a rupture disk. After addition of the catalyst, subsequent heating to the required temperature seems to have been effected by direct application of steam to the jacket, rather than the usual hot water. The too-rapid heating led to a violently exothermic reaction which ruptured the disk and stretched the lid clamping bolts. 

The apparatus shown in Fig. 16 is set up in the fume hood. The equipment is flushed with dry nitrogen, then a 200-ml. portion (314.8 g., 2.29 mols) of phosphorus trichloride is placed in the 2-1. reaction flask. The flask is partially immersed in the Dry Ice-isopropyl alcohol bath the clamp to the alkylamine container is opened and a stream of dry nitrogen is passed through the system at a rate of about 30 cc./minute measured at S.T.P. The nitrogen stream sweeps the anhydrous amine (200 g.) from the bottle into the reactor. The amine usually condenses on one of the two cold fingers of the reactor and drips into the chilled stirred phosphorus trichloride solution. Finely divided dimethylammonium chloride precipitates immediately. 

ChiU the freezing chuck by dipping it briefly into freezing solution, either 2-methyl-butane with added dry ice or liquid nitrogen. Use a clamp or other device to hold chuck. 

While in the liquid nitrogen bath, the sample (held by the magnetic wand) is manoeuvred into a cryovial, which is held submerged in the liquid with a vial clamp. 

Cold gaseous nitrogen stream (f = -180°) aimed at the rotation centre of the goniometer Curved forceps Gloves or finger cots Vial clamp... 

Ctyotongs vial clamp immersion in liquid nitrogen. 

The viscosity of the reaction mixture is now too high for the final polymerization to be carried out in the same apparatus . For laboratory purposes simple metal forms are sufficient.They consist of two metal plates covered with a Teflon film. A temperature-and chemicals-resistant hose (e.g., VITON A) serves as sealing and distance control.The whole set-up is pressed together with clamps until a distance of about 5 mm is reached. When filled with the hot prepolymerization mixture they are heated in a vacuum oven under nitrogen ( ) according to the following program ... 

An alternative, and more expensive, technique involves the application of commercial glass inserts, which are offered by Wilmad for all commercial MAS NMR rotor types. Approximately 60 or 200 mg of catalyst powder can be filled into a 4-mm or 7-mm glass insert, respectively. After calcination of the catalyst and adsorption of reactant molecules introduced from a vacuum line, the glass insert is sealed at the waist (Fig. 7). To prevent heating of the sample, the glass ampoule is clamped in one of the chucks and cooled by liquid nitrogen. 

Fill dropping funnel 8 with a solution of 75 g of sodium acetate in 100 ml of water. Fill the apparatus with dry nitrogen from gas meter 2, opening clamps 9 and 10 and closing the clamp on the rubber tube connecting flask 15 to a water-jet pump. Make sure that the nitrogen passes through wash bottles 27 and 18 filled with vaseline oil. 

---