Chemistry:Air sensitivity
Air sensitivity is a term used, particularly in chemistry, to denote the reactivity of chemical compounds with some constituent of air. Most often, reactions occur with atmospheric oxygen (O2) or water vapor (H2O),[1] although reactions with the other constituents of air such as carbon monoxide (CO), carbon dioxide (CO2), and nitrogen (N2) are also possible.[2]
Method
A variety of air-free techniques have been developed to handle air-sensitive compounds. Two main types of equipment are gloveboxes and Schlenk lines.[3] Glove boxes are sealed cabinets filled with an inert gas such as argon or nitrogen.[4] Normal laboratory equipment can be set up in the glovebox, and manipulated by the use of gloves that penetrate its walls.[5] The atmosphere can be regulated to approximately atmospheric pressure and set to be pure nitrogen or other gas with which the chemicals will not react.[6] Chemicals and equipment can be transferred in and out via an airlock.[7]
A Schlenk line is a vacuum and inert-gas dual-manifold that allows glassware to be evacuated and refilled with inert gas specially developed to work with air sensitive compounds. It is connected with a cold trap to prevent vapors from contaminating a rotary vane pump.[8] The technique is modified from the double-tipped needle technique.[9] These methods allow working in totally controlled and isolated environment.[10]
Air-sensitive compounds
Air-sensitive compounds are substances that would react with components in air. Almost all metals react with air to form a thin passivating layer of oxide, which is often imperceptible.
Many bulk compounds react readily with air as well. The reactive components of air are O
2, H
2O, CO
2, and sometimes N
2. Very many compounds react with some or all of these species.[11] Examples:
- O2: organolithium compounds and Grignard reagents
- H2O: anhydrous metal halides and acyl chlorides as well as organolithium compounds and Grignard reagents
- CO2: strong bases such as sodium hydroxide, as well as organolithium compounds and Grignard reagents
- N2: lithium metal (but not organolithium compounds)
Some semiconductors are air-sensitive.[12]
See also
References
- ↑ Handling and Storage of Air-Sensitive Reagents, Technical Bulletin AL-134, Sigma-Aldrich
- ↑ Dr. P. Wipf. "Techniques for handling air and moisture sensitivity". http://ccc.chem.pitt.edu/wipf/Web/Air_sensitive_techniques.pdf.
- ↑ W. Bouwkamp, Marco (2008). working with air and moisture sensitive compounds. Stratingh Institute for Chemistry, University of Groningen. pp. 4, 6.
- ↑ Glove Boxes, The Glassware Gallery
- ↑ Wipf, Dr. P (30 August 2015). techniques of handling air sensitivity compound. http://ccc.chem.pitt.edu/wipf/Web/Air_sensitive_techniques.pdf.
- ↑ "Air Sensitive Sample Analysis | Reduced Oxygen Moisture-Free Handling" (in en-US). Analysis of Carbon, Hydrogen, Nitrogen, Oxygen, and halogens including Fluorine. http://midwestlab.com/air-sensitive/.
- ↑ "Handling air‐sensitive compounds". http://web.uvic.ca/~berryde/chem222/McIndoe%20air-sensitive.pdf.
- ↑ "The Glassware Gallery: Schlenk Lines and Vacuum Lines". http://www.ilpi.com/inorganic/glassware/vacline.html.
- ↑ Smith Vosejpka, Laura J. (August 1993). "A simple and cost-effective technique for the transfer of air-sensitive solutions". Journal of Chemical Education 70 (8): 665. doi:10.1021/ed070p665.
- ↑ "Air-Sensitive Chemistry - Labware | Sigma-Aldrich" (in en). https://www.sigmaaldrich.com/labware/labware-products.html?TablePage=9571140.
- ↑ "Pyrophoric Control - FQE Chemicals". https://fqechemicals.com/contaminants/pyrophoric-control/.
- ↑ "Application of Air-sensitive Semiconductors in Nanoelectronics" (in en). http://www.sciencenewsline.com/news/2017092115240054.html.
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