Air sensitivity is a term used, particularly in

chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the elements that make up matter to the compounds made of atoms, molecules and ions: their composition, structure, proper ...

, to denote the reactivity of

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

s with some constituent of

air The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing f ...

. Most often, reactions occur with atmospheric

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements ...

(O₂) or

water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as ...

vapor (H₂O), although reactions with the other constituents of air such as

carbon monoxide Carbon monoxide ( chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simpl ...

(CO),

carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is t ...

(CO₂), and

nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...

(N₂) are also possible.

Method

A variety of

air-free technique Air-free techniques refer to a range of manipulations in the chemistry laboratory for the handling of compounds that are air-sensitive. These techniques prevent the compounds from reacting with components of air, usually water and oxygen; less ...

s have been developed to handle air-sensitive compounds. Two main types of equipment are

glovebox A glovebox (or glove box) is a sealed container that is designed to allow one to manipulate objects where a separate atmosphere is desired. Built into the sides of the glovebox are gloves arranged in such a way that the user can place their hand ...

es and

Schlenk line The Schlenk line (also vacuum gas manifold) is a commonly used chemistry apparatus developed by Wilhelm Schlenk. It consists of a dual manifold with several ports. One manifold is connected to a source of purified inert gas, while the other is co ...

s. Glove boxes are sealed cabinets filled with an

inert gas An inert gas is a gas that does not readily undergo chemical reactions with other chemical substances and therefore does not readily form chemical compounds. The noble gases often do not react with many substances and were historically referred to ...

such as

argon Argon is a chemical element with the symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas. Argon is the third-most abundant gas in Earth's atmosphere, at 0.934% (9340 ppmv). It is more than twice a ...

. Normal laboratory equipment can be set up in the glovebox, and manipulated by the use of gloves that penetrate its walls. 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. Chemicals and equipment can be transferred in and out via an

airlock An airlock, air-lock or air lock, often abbreviated to just lock, is a compartment with doors which can be sealed against pressure which permits the passage of people and objects between environments of differing pressure or atmospheric compo ...

. 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. The technique is modified from the double-tipped needle technique. These methods allow working in totally controlled and isolated environment.

Air sensitivity compound

Substances that would react, explode or oxidise with air, such as

organometallic compound Organometallic chemistry is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkali, alkaline earth, and transition metals, and s ...

s (chemical compounds containing at least one chemical bond between a metal and carbon atom, including alkaline earth, alkaline and

transition metals In chemistry, a transition metal (or transition element) is a chemical element in the d-block of the periodic table (groups 3 to 12), though the elements of group 12 (and less often group 3) are sometimes excluded. They are the elements that ca ...

). They may include

metalloids A metalloid is a type of chemical element which has a preponderance of properties in between, or that are a mixture of, those of metals and nonmetals. There is no standard definition of a metalloid and no complete agreement on which elements are ...

like tin, boron and sometimes silicon encountered in chemistry, which are sensitive to oxygen and moisture.

Alkali metal The alkali metals consist of the chemical elements lithium (Li), sodium (Na), potassium (K),The symbols Na and K for sodium and potassium are derived from their Latin names, ''natrium'' and ''kalium''; these are still the origins of the names ...

s and other

pyrophoric A substance is pyrophoric (from grc-gre, πυροφόρος, , 'fire-bearing') if it ignites spontaneously in air at or below (for gases) or within 5 minutes after coming into contact with air (for liquids and solids). Examples are organolith ...

compounds which react violently with water can be handled safely using air free techniques. Some semiconductors are air-sensitive.

References

{{DEFAULTSORT:Air Sensitive Air-free techniques

Method

Air sensitivity compound

See also

References