Uses
Octadecylphosphonic acid is used as detergents, dispersants, emulsifiers, and chelating agents. Alkyl phosphonic acids are typically sparingly soluble in both organic solvents and water, but become more soluble in water when neutralized to phosphonates at neutral to high pH.
Chemical Properties
crystalline solid
Uses
n-Octadecylphosphonic acid is used in thermal paper for receipts, adding machines and tickets. It acts as surfactant, emulsifier, dispersants and chelating agents. Further, it is a long chain phosphonic acid compound utilized for proteomics research. In addition to this, it is used to prepare modified mesoporous magnetic nano particles through Lewis acid/base interaction.
General Description
Octadecylphosphonic acid (OPA) is used as a self-assembled monolayer that forms a surfactant which strongly bonds with the surface atoms of different metal oxides. It provides hydrophobic properties and covers a higher surface area than the predominantly used silanes.
Synthesis
Under argon protection, octadecyl diethyl phosphite (1.2 g) was added to a Schlenk flask with 10 mL of dichloromethane. TMSBr (2.0 g, 4 mmol) was added slowly via syringe and the reaction mixture was stirred overnight at room temperature. The following day, dichloromethane and unreacted TMSBr were removed by distillation under reduced pressure. 15 mL of methanol was added to the residue and stirring was continued for 3 hr. Subsequently, methanol was evaporated under reduced pressure to give an off-white crystalline solid. The crude product was dissolved in boiling hexane with vigorous stirring and left to partition, cooled to room temperature and filtered. This purification process was repeated three times for complete removal of oily impurities, resulting in a white solid product. The product was characterized as follows: 1H NMR (CDCl3, ppm, J Hz): δ 8.73 (br, 2H, OH), 1.90 (m, 2H, PCH2, J = 26.75), 1.616 (br, 2H, CH2), 1.39 (br, 2H, CH2), 1.19 (s, 30H, CH2-alkyl), 0.877 (t, 3H, CH3, J = 13.0). Mass spectrum: [M+] = 334.26. Elemental analysis: C18H39O3P, calculated values: C, 64.64; H, 11.75; measured values: C, 64.62; H, 11.72.
References
[1] Bulletin of the Chemical Society of Ethiopia, 2014, vol. 28, # 1, p. 143 - 148
[2] Phosphorus, Sulfur and Silicon and Related Elements, 2002, vol. 177, # 4, p. 877 - 891
[3] Chemistry of Materials, 2018, vol. 30, # 21, p. 8034 - 8039
