Octadecylphosphonic acid

General description and preparation:

Octadecylphosphonic acid (ODPA) [4724-47-4] is a white crystalline solid with the melting point of 93-95 °C.^[1] It is a long chain phosphonic acid compound, irritating to eyes, respiratory system and skin. It is an amphiphilic molecule, possessing both hydrophilic and lipophilic properties. Octadecylphosphonic acid can be prepared by Arbuzov reaction via nucleophilic attack of a trialkyl phosphite to octadecyl bromide (stearyl bromide). Phosphonic acid is obtained after hydrolysis of appropriate phosphonate. Recently was reported the use of tris(trimethylsilyl) phosphite [P(OTMS)₃]. Treatment of H₃PO₃ with 1 equiv of stearyl bromide and excess BSTFA followed by hydrolysis with methanol and water gives stearylphosphonic acid in nearly quantitative yield.^[2]

Application of Octadecylphosphonic acid:

ODPA is used in thermal paper for receipts, adding machines and tickets. The acid serves as a matrix. When heat liquefies the acid, a reaction between the dye and the acid occurs. This reaction causes the colour of the thermal paper to change.^[3] It acts as surfactant, emulsifier, dispersant and chelating agent.  It is utilized for proteomics research. In addition to this, it is used to prepare modified mesoporous magnetic nano particles through Lewis acid/base interaction.^[4] ODPA is mostly known for its ability to form self-assembled monolayers (SAMs) on a large variety of substrates.^[5] It has demonstrated potential for deterring bacterial attachment to titanium.^[6]

Product categorization (Chemical groups):

Main category:

• Phosphorus reagents

Second level:

• Aliphatic compounds

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