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 Template:Chem2. 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
<templatestyles src="Reflist/styles.css" />
- ↑ Handling and Storage of Air-Sensitive Reagents, Technical Bulletin AL-134, Sigma-Aldrich
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Glove Boxes, The Glassware Gallery
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".Script error: No such module "Unsubst".
Script error: No such module "Check for unknown parameters".