Tributylphosphine is the organophosphorus compound with the

chemical formula A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as pare ...

, often abbreviated as . It is a tertiary phosphine. It is an oily liquid at room temperature, with a nauseating odor. It reacts slowly with atmospheric

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

, and rapidly with other

oxidizing agent An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or " accepts"/"receives" an electron from a (called the , , or ''electron donor''). In ot ...

s, to give tributylphosphine oxide. It is usually handled using air-free techniques.

Preparation

Tributylphosphine is prepared industrially by the hydrophosphination of

phosphine Phosphine (IUPAC name: phosphane) is a colorless, flammable, highly toxic compound with the chemical formula , classed as a pnictogen hydride. Pure phosphine is odorless, but technical grade samples have a highly unpleasant odor like rotting ...

with

1-butene 1-Butene (IUPAC name: But-1-ene, also known as 1-butylene) is the organic compound with the formula CH3CH2CH=CH2. It is a colorless gas, but easily condensed to give a colorless liquid. It is classified as a linear alpha-olefin (terminal alkene). ...

: the addition proceeds by a

free radical A daughter category of ''Ageing'', this category deals only with the biological aspects of ageing. Ageing Biogerontology Biological processes Causes of death Cellular processes Gerontology Life extension Metabolic disorders Metabolism ...

mechanism, and so the Markovnikov rule is not followed. : Tributylphosphine can be prepared in the laboratory by reaction of the appropriate

Grignard reagent Grignard reagents or Grignard compounds are chemical compounds with the general formula , where X is a halogen and R is an organic group, normally an alkyl or aryl. Two typical examples are methylmagnesium chloride and phenylmagnesium bromi ...

with phosphorus trichloride although, as it is commercially available at reasonable prices, it is rare to have to perform the small-scale preparation. :

Reactions

Tributylphosphine reacts with

to give the corresponding phosphine oxide (here tributylphosphine oxide): : Because this reaction is so fast, the compound is usually handled under an inert atmosphere. The phosphine is also easily alkylated. For example, benzyl chloride gives a phosphonium salt (here tributyl(phenylmethyl)phosphonium chloride):Jürgen Svara, Norbert Weferling and Thomas Hofmann "Phosphorus Compounds, Organic" in Ullmann's Encyclopedia of Industrial Chemistry, 2006, Wiley-VCH, Weinheim. : Tributylphosphine is a common

ligand In coordination chemistry, a ligand is an ion or molecule with a functional group that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's el ...

for the preparation of complexes of

transition metal 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. The lanthanide and actinid ...

s in low

oxidation state In chemistry, the oxidation state, or oxidation number, is the hypothetical Electrical charge, charge of an atom if all of its Chemical bond, bonds to other atoms are fully Ionic bond, ionic. It describes the degree of oxidation (loss of electrons ...

s. It is cheaper and less air-sensitive than trimethylphosphine and other trialkylphosphines. Although its complexes are generally highly

soluble In chemistry, solubility is the ability of a substance, the solute, to form a solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form such a solution. The extent of the solubi ...

, they are often more difficult to crystallize compared to complexes of more rigid phosphines. Furthermore, the 1H NMR properties are less easily interpreted and can mask signals for other ligands. Compared to other tertiary phosphines, it is compact ( cone angle: 136°) and basic ( χ-parameter: 5.25 cm⁻¹)

Use

Tributylphosphine finds some industrial use as a catalyst modifier in the

cobalt Cobalt is a chemical element; it has Symbol (chemistry), symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. ...

-catalyzed

hydroformylation In organic chemistry, hydroformylation, also known as oxo synthesis or oxo process, is an industrial process for the production of aldehydes () from alkenes (). This chemical reaction entails the net addition of a formyl group () and a hydrogen ...

alkene In organic chemistry, an alkene, or olefin, is a hydrocarbon containing a carbon–carbon double bond. The double bond may be internal or at the terminal position. Terminal alkenes are also known as Alpha-olefin, α-olefins. The Internationa ...

s, where it greatly increases the ratio of straight-chain

aldehyde In organic chemistry, an aldehyde () (lat. ''al''cohol ''dehyd''rogenatum, dehydrogenated alcohol) is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred ...

s to branched-chain aldehydes in the product mixture. However,

tricyclohexylphosphine Tricyclohexylphosphine is the tertiary phosphine with the formula P( C6H11)3. Commonly used as a ligand in organometallic chemistry, it is often abbreviated to PCy3, where Cy stands for cyclohexyl. It is characterized by both high basicity (p''K ...

is even more effective for this purpose (although more expensive) and, in any case,

rhodium Rhodium is a chemical element; it has symbol Rh and atomic number 45. It is a very rare, silvery-white, hard, corrosion-resistant transition metal. It is a noble metal and a member of the platinum group. It has only one naturally occurring isot ...

catalyst Catalysis () is the increase in rate of a chemical reaction due to an added substance known as a catalyst (). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quick ...

s are usually preferred to

catalysts for the hydroformylation of alkenes. It is the precursor to the

pesticide Pesticides are substances that are used to control pests. They include herbicides, insecticides, nematicides, fungicides, and many others (see table). The most common of these are herbicides, which account for approximately 50% of all p ...

(2,4-dichlorobenzyl)tributylphosphonium chloride (" Phosfleur"). Although tributylphosphine is generally regarded as toxic, its biological effects can be manipulated by

drug delivery Drug delivery involves various methods and technologies designed to transport pharmaceutical compounds to their target sites helping therapeutic effect. It involves principles related to drug preparation, route of administration, site-specif ...

strategies. For example, a photoactivatable version of tributylphosphine has been used to induce disulfide bond cleavage and reductive stress in living cells.

Odor

The main laboratory inconvenience of tributylphosphine is its unpleasant smell.

Hazards

Tributylphosphine is moderately toxic, with an LD50 of 750 mg/kg (oral, rats).

References

{{Reflist

External links

NMR data for tributylphosphineMaterial Safety Data SheetUse of tributyl phosphine for the reduction of disulfide bonds in proteins
Butyl compounds Organophosphorus compounds Tertiary phosphines