Hypophosphite
Encyclopedia
The hypophosphite ion
is H2PO2−, hypophosphorous acid
minus one hydrogen ion
.
Hypophosphites are the compounds containing this ion, with phosphorus
in oxidation state
+1, or similar covalent ones.
Two hydrogens are attached directly to the phosphorus atom.
The IUPAC (mostly organic)
name for the same ion is phosphinate. This is virtually not used for hypophosphite ion itself, with both hydrogens remaining, but for substituted
ions. For example, "dimethylphosphinate" ion would be (CH3)2PO2−.
Hypophosphites can be made by heating white phosphorus in warm aqueous alkali:
Hypophosphites are reducing agents:
Hypophosphites are used in electroless nickel plating
as the reducing agent to deposit for example Ni metal from Ni salts.
The hypophosphite ion is thermodynamically unstable, and disproportionate
s on heating to phosphine
gas
and phosphite
salt
s:
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...
is H2PO2−, hypophosphorous acid
Hypophosphorous acid
Hypophosphorous acid is a phosphorus oxoacid and a powerful reducing agent with molecular formula H3PO2. Inorganic chemists refer to the free acid by this name , or the acceptable name of phosphinic acid. It is a colorless low-melting compound, which is soluble in water, dioxane, and alcohols...
minus one hydrogen ion
Hydrogen ion
Hydrogen ion is recommended by IUPAC as a general term for all ions of hydrogen and its isotopes.Depending on the charge of the ion, two different classes can be distinguished: positively charged ions and negatively charged ions....
.
Hypophosphites are the compounds containing this ion, with phosphorus
Phosphorus
Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...
in oxidation state
Oxidation number
In coordination chemistry, the oxidation number of a central atom in a coordination compound is the charge that it would have if all the ligands were removed along with the electron pairs that were shared with the central atom. Oxidation numbers are often confused with oxidation states.The...
+1, or similar covalent ones.
Two hydrogens are attached directly to the phosphorus atom.
The IUPAC (mostly organic)
IUPAC nomenclature of organic chemistry
The IUPAC nomenclature of organic chemistry is a systematic method of naming organic chemical compounds as recommended by the International Union of Pure and Applied Chemistry . Ideally, every possible organic compound should have a name from which an unambiguous structural formula can be drawn. ...
name for the same ion is phosphinate. This is virtually not used for hypophosphite ion itself, with both hydrogens remaining, but for substituted
Substituent
In organic chemistry and biochemistry, a substituent is an atom or group of atoms substituted in place of a hydrogen atom on the parent chain of a hydrocarbon...
ions. For example, "dimethylphosphinate" ion would be (CH3)2PO2−.
Hypophosphites can be made by heating white phosphorus in warm aqueous alkali:
- P4 + 3 OH− + 3 H2O → 3 H2PO2− + PH3
Hypophosphites are reducing agents:
- H2PO2− +3OH− → HPO32− + 2H2O + 2e-
Hypophosphites are used in electroless nickel plating
Electroless nickel plating
Electroless nickel plating is an auto-catalytic chemical technique used to deposit a layer of nickel-phosphorus or nickel-boron alloy on a solid workpiece, such as metal or plastic. The process relies on the presence of a reducing agent, for example hydrated sodium hypophosphite which reacts with...
as the reducing agent to deposit for example Ni metal from Ni salts.
The hypophosphite ion is thermodynamically unstable, and disproportionate
Disproportionation
Disproportionation, also known as dismutation is used to describe a specific type of redox reaction in which a species is simultaneously reduced and oxidized so as to form two different products....
s on heating to phosphine
Phosphine
Phosphine is the compound with the chemical formula PH3. It is a colorless, flammable, toxic gas. Pure phosphine is odourless, but technical grade samples have a highly unpleasant odor like garlic or rotting fish, due to the presence of substituted phosphine and diphosphine...
gas
Gas
Gas is one of the three classical states of matter . Near absolute zero, a substance exists as a solid. As heat is added to this substance it melts into a liquid at its melting point , boils into a gas at its boiling point, and if heated high enough would enter a plasma state in which the electrons...
and phosphite
Phosphite
A phosphite is a salt of phosphorous acid. The phosphite ion is a polyatomic ion with a phosphorus central atom where phosphorus has an oxidation state of +3...
salt
Salt
In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...
s:
- 2 H2PO2− → PH3PhosphinePhosphine is the compound with the chemical formula PH3. It is a colorless, flammable, toxic gas. Pure phosphine is odourless, but technical grade samples have a highly unpleasant odor like garlic or rotting fish, due to the presence of substituted phosphine and diphosphine...
+ HPO42−PhosphateA phosphate, an inorganic chemical, is a salt of phosphoric acid. In organic chemistry, a phosphate, or organophosphate, is an ester of phosphoric acid. Organic phosphates are important in biochemistry and biogeochemistry or ecology. Inorganic phosphates are mined to obtain phosphorus for use in...