Salicylaldoxime
Encyclopedia
Salicylaldoxime is a chemical compound
described by the formula C6H4CH=NOH-2-OH. It is the oxime
of salicylaldehyde
. This crystalline solid is a chelator
and sometimes used in the analysis of samples containing transition metal
ion
s, with which it often forms brightly-coloured coordination complexes.
In the era when metals were analysed by spectrophotometry
, many chelating ligand
s were developed that selectively formed brightly coloured complexes with particular metal ions. This methodology has been eclipsed with the introduction of inductively coupled plasma
methodology. Salicylaldoxime can be used to selectively precipitate
metal ions for gravimetric determination
. It forms a greenish-yellow precipitate with copper at a pH
of 2.6 in the presence of acetic acid
. Under these conditions, this is the only metal that precipitates; at pH 3.3, nickel
also precipitates. Iron (III) will interfere.
Adsorbed or chemically bonded to a solid support such as silica gel
, it can be used to preconcentrate or extract
metals from a dilute solution such as seawater. It has been used as an ionophore in ion selective electrode
s, with good response to Pb2+ and Ni2+.
Salicylaldoxime has also been used to probe ion channels in muscle tissue and as a probe in photosystem I
.
Chemical compound
A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...
described by the formula C6H4CH=NOH-2-OH. It is the oxime
Oxime
An oxime is a chemical compound belonging to the imines, with the general formula R1R2C=NOH, where R1 is an organic side chain and R2 may be hydrogen, forming an aldoxime, or another organic group, forming a ketoxime. O-substituted oximes form a closely related family of compounds...
of salicylaldehyde
Salicylaldehyde
Salicylaldehyde is the chemical compound with the formula C6H4CHO-2-OH. Along with 3-hydroxybenzaldehyde and 4-hydroxybenzaldehyde, it is one of the three isomers of hydroxybenzaldehyde. This colorless oily liquid has a bitter almond odor at higher concentration and a characteristic buckwheat...
. This crystalline solid is a chelator
Chelation
Chelation is the formation or presence of two or more separate coordinate bonds between apolydentate ligand and a single central atom....
and sometimes used in the analysis of samples containing transition metal
Transition metal
The term transition metal has two possible meanings:*The IUPAC definition states that a transition metal is "an element whose atom has an incomplete d sub-shell, or which can give rise to cations with an incomplete d sub-shell." Group 12 elements are not transition metals in this definition.*Some...
ion
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...
s, with which it often forms brightly-coloured coordination complexes.
In the era when metals were analysed by spectrophotometry
Spectrophotometry
In chemistry, spectrophotometry is the quantitative measurement of the reflection or transmission properties of a material as a function of wavelength...
, many chelating ligand
Ligand
In coordination chemistry, a ligand is an ion or molecule that binds to a central metal atom to form a coordination complex. The bonding between metal and ligand generally involves formal donation of one or more of the ligand's electron pairs. The nature of metal-ligand bonding can range from...
s were developed that selectively formed brightly coloured complexes with particular metal ions. This methodology has been eclipsed with the introduction of inductively coupled plasma
Inductively coupled plasma
An inductively coupled plasma is a type of plasma source in which the energy is supplied by electric currents which are produced by electromagnetic induction, that is, by time-varying magnetic fields.-Operation:...
methodology. Salicylaldoxime can be used to selectively precipitate
Precipitation (chemistry)
Precipitation is the formation of a solid in a solution or inside anothersolid during a chemical reaction or by diffusion in a solid. When the reaction occurs in a liquid, the solid formed is called the precipitate, or when compacted by a centrifuge, a pellet. The liquid remaining above the solid...
metal ions for gravimetric determination
Gravimetry
Gravimetry is the measurement of the strength of a gravitational field. Gravimetry may be used when either the magnitude of gravitational field or the properties of matter responsible for its creation are of interest...
. It forms a greenish-yellow precipitate with copper at a pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
of 2.6 in the presence of acetic acid
Acetic acid
Acetic acid is an organic compound with the chemical formula CH3CO2H . It is a colourless liquid that when undiluted is also called glacial acetic acid. Acetic acid is the main component of vinegar , and has a distinctive sour taste and pungent smell...
. Under these conditions, this is the only metal that precipitates; at pH 3.3, nickel
Nickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...
also precipitates. Iron (III) will interfere.
Adsorbed or chemically bonded to a solid support such as silica gel
Silica gel
Silica gel is a granular, vitreous, porous form of silica made synthetically from sodium silicate. Despite its name, silica gel is a solid. It is a naturally occurring mineral that is purified and processed into either granular or beaded form...
, it can be used to preconcentrate or extract
Extract
An extract is a substance made by extracting a part of a raw material, often by using a solvent such as ethanol or water. Extracts may be sold as tinctures or in powder form....
metals from a dilute solution such as seawater. It has been used as an ionophore in ion selective electrode
Ion selective electrode
An ion-selective electrode , also known as a specific ion electrode , is a transducer that converts the activity of a specific ion dissolved in a solution into an electrical potential, which can be measured by a voltmeter or pH meter. The voltage is theoretically dependent on the logarithm of the...
s, with good response to Pb2+ and Ni2+.
Salicylaldoxime has also been used to probe ion channels in muscle tissue and as a probe in photosystem I
Photosystem I
Photosystem I is the second photosystem in the photosynthetic light reactions of algae, plants, and some bacteria. Photosystem I is so named because it was discovered before photosystem II. Aspects of PS I were discovered in the 1950s, but the significances of these discoveries was not yet known...
.