Tetrakis(hydroxymethyl)phosphonium chloride

Tetrakis(hydroxymethyl)­phosphonium chloride

Names
Preferred IUPAC name Tetrakis(hydroxymethyl)phosphonium chloride
Other names Tetrahydroxymethylphosphonium chloride, THPC
Identifiers
CAS Number	124-64-1^Y
ChEMBL	ChEMBL2131547
ChemSpider	29038^Y
ECHA InfoCard	100.004.280
EC Number	204-707-7
PubChem CID	31298
RTECS number	TA2450000
UNII	58WB2XCF8I^Y
UN number	2810
CompTox Dashboard (EPA)	DTXSID5021330
Properties
Chemical formula	C4H12ClO4P
Molar mass	190.56 g·mol^−1
Appearance	white solid
Density	1.341 g/cm^3
Melting point	150 °C (302 °F; 423 K)
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H301, H302, H311, H312, H314, H315, H330, H334, H411
Precautionary statements	P260, P261, P264, P270, P271, P273, P280, P284, P285, P301+P310, P301+P312, P301+P330+P331, P302+P352, P303+P361+P353, P304+P340, P304+P341, P305+P351+P338, P310, P312, P320, P321, P322, P330, P332+P313, P342+P311, P361, P362, P363, P391, P403+P233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is ^YN ?) Infobox references

Tetrakis(hydroxymethyl)phosphonium chloride (THPC) is an organophosphorus compound with the chemical formula [P(CH₂OH)₄]Cl. It is a white water-soluble salt with applications as a precursor to fire-retardant materials[1] and as a microbiocide in commercial and industrial water systems.

Synthesis, structure and reactions

THPC can be synthesized with high yield by treating phosphine with formaldehyde in the presence of hydrochloric acid.[1]

PH₃ + 4 H₂C=O + HCl → [P(CH₂OH)₄]Cl

The cation P(CH₂OH)₄^+ features four-coordinate phosphorus, as is typical for phosphonium salts.

THPC converts to tris(hydroxymethyl)phosphine upon treatment with aqueous sodium hydroxide:[2]

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

Application in textiles

THPC has industrial importance in the production of crease-resistant and flame-retardant finishes on cotton textiles and other cellulosic fabrics.[3] [4] A flame-retardant finish can be prepared from THPC by the Proban Process,[5] 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.[6]

[P(CH₂OH)₄]Cl + NH₂CONH₂ → (HOCH₂)₂P(O)CH₂NHC(O)NH₂ + 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.

Tris(hydroxymethyl)phosphine and its uses

Tris(hydroxymethyl)phosphine, which is derived from tetrakis(hydroxymethyl)phosphonium chloride, is an intermediate in the preparation of the water-soluble ligand 1,3,5-triaza-7-phosphaadamantane (PTA). This conversion is achieved by treating hexamethylenetetramine with formaldehyde and tris(hydroxymethyl)phosphine.[7]

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 ethene gas, resulting in N-boc-3-pyrroline.[8] 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.[9]

References

1. Svara, Jürgen; Weferling, Norbert; Hofmann, Thomas (2006). "Phosphorus Compounds, Organic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a19_545.pub2. ISBN 3527306730.
2. M. Caporali, L. Gonsalvi, F. Zanobini, M. Peruzzini "Synthesis of the Water-Soluble Bidentate (P,N) Ligand PTN(Me)" Inorg. Syntheses, 2011, Vol. 35, p. 92–108. doi:10.1002/9780470651568.ch5
3. Fischer, Klaus; Marquardt, Kurt; Schlüter, Kaspar; Gebert, Karlheinz; Borschel, Eva-Marie; Heimann, Sigismund; Kromm, Erich; Giesen, Volker; Schneider, Reinhard; Lee Wayland, Rosser (2000). "Textile Auxiliaries". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a26_227. ISBN 3-527-30673-0.
4. Weil, Edward D.; Levchik, Sergei V. (2008). "Flame Retardants in Commercial Use or Development for Textiles". J. Fire Sci. 26 (3): 243–281. doi:10.1177/0734904108089485. S2CID 98355305.
5. "Frequently asked questions: What is the PROBAN® process?". Rhodia Proban. Archived from the original on December 7, 2012. Retrieved February 25, 2013.
6. Reeves, Wilson A.; Guthrie, John D. (1956). "Intermediate for Flame-Resistant Polymers-Reactions of Tetrakis(hydroxymethyl)phosphonium Chloride". Industrial and Engineering Chemistry. 48 (1): 64–67. doi:10.1021/ie50553a021.
7. Daigel, Donald J.; Decuir, Tara J.; Robertson, Jeffrey B.; Darensbourg, Donald J. (2007). "1,3,5-Triaz-7-Phosphatricyclo[3.3.1.1 ^3,7 ]Decane and Derivatives". Inorganic Syntheses. Vol. 32. pp. 40–42. doi:10.1002/9780470132630.ch6. ISBN 978-0-470-13263-0. {{cite book}}: |journal= ignored (help)
8. Ferguson, Marcelle L.; O’Leary, Daniel J.; Grubbs, Robert H. (2003). "Ring-Closing Metathesis Synthesis Of N-Boc-3-Pyrroline". Organic Syntheses. 80: 85. doi:10.15227/orgsyn.080.0085.
9. Vullo, W. J. (1966). "Hydroxymethyl Replacement Reactions of Tetrakis(hydroxymethyl)phosphonium Chloride". Ind. Eng. Chem. Prod. Res. Dev. 58 (4): 346–349. doi:10.1021/i360020a011.