Tetrakis(hydroxymethyl)phosphonium chloride

Chembox new
Name = Tetrakis(hydroxymethyl)phosphonium chloride
ImageFile = Tetrakis(hydroxymethyl)phosphonium chloride.png OtherNames = Tetrahydroxymethylphosphonium chloride, THPC
Section1 = Chembox Identifiers
CASNo = 124-64-1

Section2 = Chembox Properties
Formula = (HOCH₂)₄PCl
MolarMass = 190.56 g/mol
Appearance = cyrstalline
Density = 1.341 g/cm³
Solubility = N/A
MeltingPt = 150 °C (423 K)
BoilingPt = N/A
Section7 = Chembox Hazards
ExternalMSDS =
RPhrases = R21 R25 R38 R41 R42/43 R51/53
SPhrases = S22 S26 S36/37/39 S45 S60 S61

Tetrakis(hydroxymethyl)phosphonium chloride (THPC) is a phosphonium salt with the chemical formula [(CH₂OH)₄P] Cl. The cation (CH2OH)4P⁺ is a four-coordinate phosphorus compound with the phosphorus atom carrying a positive charge. THPC has industrial applications as precursors to fire-retardant materials and synthetic applications as precursor to the useful ligand, tris(hydroxymethyl)phosphine.

ynthesis

THPC can be synthesized with high yield by treating phosphine with formaldehyde in the presence of hydrochloric acid.Fact|date=July 2008

:PH₃ + 4 H₂C=O + HCl → [P(CH₂OH)₄] Cl

Reactions

THPC is commonly used to prepare tris(hydroxymethyl)phosphine by treating it with aqueous sodium hydroxide. [Svara, Jürgen; Weferling, Norbert ; Hofmann, Thomas. Phosphorus Compounds, Organic. Ullmann's Encyclopedia of Industrial Chemistry. John Wiley & Sons, Inc, 2008 DOI: 10.1002/14356007.a19_545.pub2]

: [P(CH₂OH)₄] Cl + NaOH → P(CH₂OH)₃ + H₂O + H₂C=O + NaCl

Tris(hydroxymethyl)phosphine and its uses

Tris(hydroxymethyl)phosphine is an intermediate in the preparation of the water-soluble ligand 1,3,5-triaza-7-phosphaadamantane (PTA). This is done by treating hexamethylenetetramine with formaldehyde and tris(hydroxymethyl)phosphine. [cite journal | author = Daigel, Donald J. | title = 1,3,5-triaza-7phosphatricyclo [3.3.1.13.7] decane and derivatives | journal = Inorg. Synth. | volume = 32 | pages = 40–42 | year = 1998 | doi = 10.1002/9780470132630.ch6] Tris(hydroxymethyl)phosphine can also be used to synthesize the heterocycle, N-boc-3-pyrroline by ring-closing metathesis using Grubbs' catalyst (bis(tricyclohexylphosphine)benzylidineruthenium dichloride ). N-Boc-diallylamine is treated with Grubbs' catalyst, followed by tris(hydroxymethyl)phosphine. The carbon-carbon double bonds undergo ring closure, releasing ethylene gas, resulting in N-boc-3-pyrroline. [OrgSynth | author = Ferguson, Marcelle L.; O’Leary, Daniel J.; Grubbs, Robert H. | title = Ring-Closing Metathesis Synthesis Of N-Boc-3-Pyrroline | volume = 80 | pages = 85 | year = 2003 | prep = v80p0085] The hydroxymethyl groups on THPC undergo replacement reactions when THPC is treated with α,β-unsaturated nitrile, acid, amide, and epoxides. For example, base induces condensation between THPC and acrylamide with displacement of the hydroxymethyl groups. (Z = CONH₂)

: [P(CH₂OH)₄] Cl + NaOH + 3CH₂=CHZ → P(CH₂CH₂Z)₃ + 4CH₂O + H₂O + NaCl

Similar reactions occur when THPC is treated with acrylic acid; only one hydroxymethyl group is displaced, however. [cite journal | author = Vullo, W. J. | title = Hydroxymethyl Replacement Reactions of Tetrakis(hydroxymethyl)phosphonium Chloride | journal = Ind. Eng. Chem. Prod. Res. Dev. | year = 1966 | volume = 58 | issue = 4 | pages = 346–349 | doi = 10.1021/i360020a011]

Application in Textiles

THPC has industrial importance in the production of crease-resistant and flame-retardant finishes on cotton textiles and other cellulosic fabrics. A flame-retardant finish can be prepared from THPC by the ”Proban Process,” in which THPC is treated with urea. The urea condenses with the hydroxymethyl groups on THPC. The phosphonium structure is converted to phosphine oxide as the result of this reaction. [cite journal | author = Reeves, Wilson A.; Guthrie, John D. | title = Intermediate for Flame-Resistant Polymers-Reactions of Tetrakis(hydroxymethyl)phosphonium Chloride | journal = Industrial Engineering Chemistry | year = 1956 | volume = 48 | issue = 1 | pages = 64–67 | doi = 10.1021/ie50553a021]

: [P(CH₂OH)₄] Cl + NH₂CONH₂ → (CH₂OH)₂POCH₂NHCONH₂ + HCl + HCHO + H₂ + H₂O

This reaction proceeds rapidly, forming insoluble high molecular weight polymers. The resulting product is applied to the fabrics in a “pad-dry process.” This treated material is then treated with ammonia and ammonia hydroxide to produce fibers that are flame-retardant. THPC can condense with many other types of monomers in addition to urea. These monomers include amines, phenols, and polybasic acids and anhydrides.

References