Synthesis and Characterization of 2-Carboxyethyltriphenyl Phosphonium Tribromide and Its Application as Catalyst in Silylation of Alcohols and Thiols Under Solvent-Free Condition

Abstract

A phosphonium-based catalyst, 2-carboxyethyltriphenyl phosphonium tribromide (CTPTB), has been synthesized by reacting triphenyl phosphine with acrylic acid and potassium bromide under solvent-free condition followed by oxidation of Br⁻ to with KMnO₄. This hitherto unknown tribromide reagent is characterized by ultraviolet–visible, Fourier transform–infrared, ¹H NMR, and ³¹P NMR spectroscopy. Its efficacy as catalyst is established by investigating its catalytic activity in silylation of alcohols and thiols by hexamethyl disilazane (HMDS). It is found to be a very good catalyst and selectively and efficiently catalyzes the silylation reactions.

GRAPHICAL ABSTRACT

Keywords:

• Acrylic acid
• alcohols
• hexamethyl disilazane (HMDS)
• oxidation
• potassium bromide
• silylation
• tribromide reagent

ACKNOWLEDGMENT

The authors are thankful to the Sophisticated Analytical Instrument Facility, Indian Istitute of Technology, Bombay, for providing the spectral analyses of the compounds.

Notes

^a Alcohol/thiols (20 mmol), HMDS (10 mmol), CTPTB (0.1 mmol).

^b Products were identified by their IR and NMR spectral data and comparing them with published data.

^c Isolated yield.

^d Reactions were monitored by TLC and products were extracted by ethyl acetate.

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