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An ordinary glovebox, showing the two gloves for manipulation, with airlock on the right. The most straightforward type of air-free technique is the use of a glovebox.A "glove bag" uses the same idea, but is usually a poorer substitute because it is more difficult to purge, and less well sealed.
The Birkeland–Eyde process was one of the competing industrial processes in the beginning of nitrogen-based fertilizer production. It is a multi-step nitrogen fixation reaction that uses electrical arcs to react atmospheric nitrogen (N 2) with oxygen (O 2), ultimately producing nitric acid (HNO 3) with water. [1]
In the reaction, thermal or photochemical decomposition of N-halogenated amine 1 in the presence of a strong acid (concentrated sulfuric acid or concentrated CF 3 CO 2 H) generates a nitrogen radical intermediate. The radical then abstracts an intramolecular hydrogen atom to give a cyclic amine 2 (pyrrolidine or, in some cases, piperidine).
The hot gases are cooled under high pressure, allowing the ammonia to condense and be removed as a liquid. Unreacted hydrogen and nitrogen gases are returned to the reaction vessel for another round. [3] While most ammonia is removed (typically down to 2–5 mol.%), some ammonia remains in the recycle stream.
Gas bubblers are used to exclude air from a reaction or a system. In the former case, the gas bubbler is fitted on the condenser of the reaction set-up. In the latter case, an oil bubbler is usually installed at the end of the inert gas manifold on a Schlenk line to prevent contamination by atmospheric oxygen and water .
The equation loses accuracy for gaps under about 10 μm in air at one atmosphere [9] and incorrectly predicts an infinite arc voltage at a gap of about 2.7 μm. Breakdown voltage can also differ from the Paschen curve prediction for very small electrode gaps, when field emission from the cathode surface becomes important.
Forming gas is a mixture of hydrogen (mole fraction varies) [1] and nitrogen. It is sometimes called a "dissociated ammonia atmosphere" due to the reaction which generates it: 2 NH 3 → 3 H 2 + N 2. It can also be manufactured by thermal cracking of ammonia, in an ammonia cracker or forming gas generator. [2]
The inert-gas line is vented through an oil bubbler, while solvent vapors and gaseous reaction products are prevented from contaminating the vacuum pump by a liquid-nitrogen or dry-ice/acetone cold trap. Special stopcocks or Teflon taps allow vacuum or inert gas to be selected without the need for placing the sample on a separate line. [3]