Nitrogen trifluoride

• Nitrogen (III ) fluoride
• Nitrogen fluoride
• Trifluoramin
• Trifluorammoniak

Colorless gas with a musty odor

Gaseous

1.54 g · cm -3 ( -129 ° C)

-206.6 ° C

-128.8 ° C

Very poor in water ( 61 mg · l -1 at 20 ° C)

0.235 (4 ) D ( 7.8 x 10-31 C · m)

Risk

17200 (in terms of 100 years)

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Nitrogen trifluoride is a chemical compound belonging to the group of Stickstoffhalogenide.

• 4.1 production

History

Nitrogen trifluoride was presented in 1928 by Otto Ruff ( 1871-1939 ) for the first time by electrolysis of anhydrous ammonium bifluoride ( NH4HF2 ). In 1957 succeeded Peter Sartori, to make the procedure much safer by eliminating the formed as by- products unstable and explosive substances fluoroamine NH2F and difluoroamine NHF2 through which is introduced in the reaction of manganese dioxide.

Production and representation

It can be produced by catalytic reaction of ammonia with fluorine or by the electrolysis of molten ammonium hydrogen fluoride:

The representation of the elements, however, is possible only under unusual conditions (ie electrical discharges at high pressure and high temperatures).

Properties

Physical Properties

Nitrogen trifluoride is built pyramidal, where the nitrogen atom is located at the top of the pyramid. The bond lengths and angles are shown in Fig.

Chemical Properties

Nitrogen trifluoride not react at room temperature with water and has almost no ammonia, in contrast to the basic characteristics. It is a powerful oxidizing agent. With aluminum chloride it reacts to form aluminum fluoride:

Environmental characteristics and occurrence

Nitrogen trifluoride acts as a greenhouse gas 17,200 times more powerful than carbon dioxide and has an atmospheric half-life of 740 years. It is detected by an amendment since 2012 by the Kyoto Protocol. The Earth's atmosphere is to contain 5400 tons of nitrogen trifluoride according to the latest research now (2008). In a study of air samples from 30 years in 2008 researchers at the Scripps Institution of Oceanography, University of California, San Diego, found that nitrogen trifluoride common than previously thought in almost four fold higher concentration in the atmosphere. The concentration is on the northern hemisphere was significantly higher than in the southern. This result matches the localization of the main Emittenden in the northern industrial states. Primary Issuer was formerly the microelectronics industry, today it is the flat screen and thin-film solar cell industry. During the observation period, the researchers were able to demonstrate a mean concentration increase of about 11% per year. Given the high greenhouse gas potential advised the researchers to put nitrogen trifluoride on the list of threatening greenhouse gases whose emissions are controlled under the Kyoto Protocol. At the UN climate conference in Doha 2012, the chemical was finally added to the list of greenhouse gases on 8 December 2012 in an addition to the Kyoto Protocol. This supplement applies from the beginning of the second commitment period - Kyoto II - until 2020.

Use

Nitrogen trifluoride is used in the semiconductor and in very large quantities in the liquid crystal display and solar industries to clean the PECVD chambers of silicon dioxide, silicon oxynitride and silicon nitride residues. The sharp rise in Stickstofftrifluoridkonzentration in the atmosphere is due to these applications. The replacement by toxic but more environmentally friendly fluorine is tested on an industrial scale. Furthermore, there was a time in the military high-energy hydrogen fluoride lasers ( eg MIRACL ) used, was used as the oxidizer in rocket fuels, tested as an additive to incandescent gas fillings and for the production of extremely toxic tetrafluorohydrazine ( N2F4 ) - another rocket fuel component and unwanted by-product of Stickstofftrifluoridherstellung - used.

Production

A total of 2008, approximately 4,000 tons of nitrogen trifluoride were produced. By far the world 's largest producer of nitrogen trifluoride is the American chemical company Air Products & Chemicals Inc.. Would the entire Stickstofftrifluoridjahresproduktion released into the atmosphere, the greenhouse effect thereby produced would correspond to that which would be produced by the release of approximately 67 million tonnes of CO2.

Safety

Nitrogen trifluoride is classified according to EC Directives as oxidising and harmful. It decomposes on heating and reacts violently with some organic compounds (eg combustible material ).