Preparation
Bis(2-chloroethyl)-2-chloroethyl phosphonate is acylated by phosgene or thionyl chloride in the presence of a catalyst to obtain a mixture of vinylphosphonochloride and 2-chloroethylphosphonochloride. The vinylphosphonochloride and 2-chloroethylphosphonochloride are separated by vacuum distillation. The vinylphosphonochloride and 2-chloroethylphosphonochloride are then hydrolyzed to obtain vinylphosphonic acid and ethephon.
Chemical Properties
Vinylphosphonic acid is a colorless, transparent to light yellow liquid containing an unsaturated bond in its structure, which allows for flexible conversion to other organophosphine compounds.
Uses
VPA based homopolymers and copolymers find usage in corrosion treatment, fuel cells, dental cement, drug delivery, and bio-mimicry.
Uses
Vinylphosphonic acid (VPA) can be used as a monomer unit for the synthesis of poly(vinylphosphonic acid) via free radical polymerization. It is also used to develop copolymers of VPA with acrylonitrile,
N-isopropylacrylamide, styrene, vinylpyrrolidone, and acrylic and methacrylic acid. These copolymers find potential application in hydrogels, drug delivery, biomimetic mineralization, and polymer electrolyte membranes in fuel cells.
It can also be used as an organic building block to prepare (
E)-styryl phosphonic acid derivatives by reacting with various aryl halides via Pd-catalyzed Heck coupling reaction.
General Description
Vinylphosphonic acid (VPA) is an organophosphorus compound that is used in the surface treatment of metal substrates. It can be used in the preparation of poly(VPA) by radical polymerization in the presence of initiator systems and chain transfer agents. PVPA tends to have an electrolytic nature, which is useful for a variety of energy based applications.
Flammability and Explosibility
Not classified
Purification Methods
This fireproofing agent, and ingredient for making polymers, is obtained as a syrup on hydrolyzing vinylphosphonyl dichloride with cold H2O and solidifies on prolonged drying over P2O5/KOH. When distilled at 235-240o/0.0006mm, it gives the anhydride (d 1.304, n 1.5874) [Kabachnik & Medvedi Izvest Akad Nauk SSSR, Ser Khim 868 1953, Chem Abstr 54 10834 1960]. It is best kept as the sodium salt (m 350o) which precipitates when a solution of EtOH containing NaOEt (from 2g of Na) is added to vinylphosphonic acid (3.2g), and is recrystallised from EtOH (5.1g, quantitative). The p-anisidinium salt forms mauve prisms m 250o (from EtOH/Et2O). The dimethyl ester, M 136.1, d4 1.1405, nD 1.4330, has b 72.5o/10mm and 197-202o/760mm. [Kabachnik et al. J Gen Chem USSR (Engl Trans) 33 375 1963, Beilstein 4 IV 3568.]
