3,3′,3′′-Phosphanetriyltris(benzenesulfonic acid) trisodium salt (abbreviated TPPTS), is an organic compound that is also known as sodium triphenylphosphine trisulfonate. The compound has the formula P(C₆H₄SO₃Na)₃. This white solid is an unusual example of a water-soluble

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 ...

. Its complexes are also water-soluble. Its complex with

rhodium Rhodium is a chemical element with the 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 isoto ...

is used in the industrial production of

butyraldehyde Butyraldehyde, also known as butanal, is an organic compound with the formula CH3(CH2)2CHO. This compound is the aldehyde derivative of butane. It is a colorless flammable liquid with an unpleasant smell. It is miscible with most organic solvents. ...

Synthesis

TPPTS is synthesized by

sulfonation Aromatic sulfonation is an organic reaction in which a hydrogen atom on an arene is replaced by a sulfonic acid functional group in an electrophilic aromatic substitution. Aryl sulfonic acids are used as detergents, dye, and drugs. Stoichiometry an ...

triphenylphosphine Triphenylphosphine (IUPAC name: triphenylphosphane) is a common organophosphorus compound with the formula P(C6H5)3 and often abbreviated to P Ph3 or Ph3P. It is widely used in the synthesis of organic and organometallic compounds. PPh3 exists a ...

. The sulfonation occurs at one meta-position of each of the three phenyl rings. The sulfonation agent is

oleum Oleum (Latin ''oleum'', meaning oil), or fuming sulfuric acid, is a term referring to solutions of various compositions of sulfur trioxide in sulfuric acid, or sometimes more specifically to disulfuric acid (also known as pyrosulfuric acid). Ole ...

, a solution of sulfur trioxide in sulfuric acid. Immediately upon dissolving in the oleum, the phosphine is protonated. It is the phosphonium salt that undergoes the sulfonation which explains its meta selectivity: :HP(C₆H₅)₃⁺ + 3 SO₃ → P(C₆H₄SO₃H)₃sup>+ As a

Lewis base A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any sp ...

, tppts is stronger than triphenylphosphine.

TPPTS at the origin of two-phase homogeneous catalysis

TPPTS was first synthesized in 1975 by E.G Kuntz who was an engineer at Rhône-Poulenc with the aim of carrying out a two-phase homogeneous catalysis in which the aqueous phase catalyst could be easily separated from the reaction products and recycled. Using TPPTS, allowed him to prepare water-soluble complexes with Rh(I), Ni(0), Pd(0). E.G. Kuntz patented several two-phase homogeneous catalytic reactions: *hydroformylation of propylene with Rh(I) TPPTS, later leading to the Ruhrchemie / Rhône-Poulenc process. *hydrocyanation of olefins and dienes with Ni(0) TPPTS. *

telomerization Telomerization is a reaction that produces a particular kind of oligomer with two distinct end groups. The oligomer is called a telomer. Some telomerizations proceed by radical pathways, many do not. A generic equation is: : A-B + n M -> A-M_ ...

of butadiene to 2.7 octadiene -1-ol with Pd(0) TPPTS. *The Rh(I) TPPTS catalyst was later used by D.Morel to synthetize geranylacetone from myrcene and farnesylacetone from beta-farnesene which are intermediates in the synthesis of vitamin E. This process was industrialized by Rhône-Poulenc in 1988. The industrial use of TPPTS and homogeneous biphasic catalysis has been reviewed.

Uses in hydroformylation

Complexes of TPPTS are very soluble in water, which is the basis of its industrial application. Tppts-based rhodium catalysts were introduced in 1984 for a two-phase

hydroformylation 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 (CHO) and a hydrogen atom to a carbon-carbon d ...

propene Propylene, also known as propene, is an unsaturated organic compound with the chemical formula CH3CH=CH2. It has one double bond, and is the second simplest member of the alkene class of hydrocarbons. It is a colorless gas with a faint petrole ...

by the Ruhrchemie / Rhône-Poulenc process. Hydroformylation, also known as oxo synthesis, is the reaction of an

alkene In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond. Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.H. Stephen Stoker (2015): General, Organic, an ...

with

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 simple ...

and

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...

. Traditionally, hydroformylation is catalyzed by rhodium or cobalt complexes in nonaqueous solution The industrial use of Tppts and homogeneous biphasic catalysis were mostly ignored in academic research until E.G. Kuntz published a review of its previous work in 1987. É.G. Kuntz, « Homogeneous catalysis in water », Chemtech, 1987, p. 570-575 Then, from 1990, use of TPPTS was rapidly become popular with thousand of citations in 2004.

References

Tertiary phosphines Sulfonates