Selective Hydrogenation of Cyclopentadiene to Cyclopentene Using Colloidal Palladium Supported on Chelate Resin

Abstract

Cyclopentadiene was hydrogenated to cyclopentene selectively by using colloidal palladium supported on chelate resin with iminodiacetic acid moieties as a catalyst. The catalyst, containing metal particles of 1–6 nm in diameter, was prepared by reduction of the palladium(II)–chelate resin complex with methanol. Cyclopentene was produced in 97.1% yield at 100% conversion of cyclopentadiene at 30 °C under 1 atm of hydrogen. This value in yield was also achieved on repeated uses of the catalyst. The hydrogenation rate was correlated to the polarity parameter, ET(30) values, of the solvents used in the reaction, except in the case of dimethyl sulfoxide. The hydrogenation rates of cyclopentadiene (RD) and cyclopentene (RE) were expressed as RD=kD[H2][catalyst] and RE=kE[H2][cyclopentene][catalyst], respectively, where kD and kE are the rate constants. The equilibrium constant for complex formation between cyclopentadiene and the catalyst, KD, was estimated to be over 400 times larger than that between cyclopentene and the catalyst, KE. A mechanism, including the coordination of olefins to the catalyst and the subsequent hydrogenation of the coordinated complexes, was proposed.

Reduced Transition Metal Colloids: A Novel Family of Reusable Catalysts?

“…Hirai studied extensively the use of colloidal catalysts for the selective hydrogenation of dienes to form monoenes. Hydrogenation of cyclopentadiene into cyclopentene was performed with a colloidal suspension of Pd particles stabilized by PVP. , Cyclooctene was also obtained by selective hydrogenation of cycloocta-1,5-diene with Pd colloids . Hydrogenation of the 1,3-isomer occurs faster than hydrogenation of 1,5- and 1,4-isomers.…”

One‐pot Synthesis of 1,3‐Butadiene and 1,6‐Hexanediol Derivatives from Cyclopentadiene (CPD) via Tandem Olefin Metathesis Reactions

“…Moreover, CPD is an exceptionally acidic hydrocarbon, which can be easily deprotonated giving an aromatic cyclopentadienyl anion . The main reactions of CPD includes cycloaddition, addition, substitution and oxidation reactions. Furthermore, its consecutive Diels‐Alder reaction leading to CPD polymers or oligomers are also reported …”

A Kinetic Probe of the Effect of a Stabilizing Polymer on a Colloidal Catalyst: Accelerated Enantioselective Hydrogenation of Ethyl Pyruvate Catalyzed by Poly(vinylpyrrolidone)-Stabilized Platinum Colloids

“…The catalytic properties of transition metal colloids have been known for many years. − Many of the reactions known to be catalyzed by supported metal catalysts, especially hydrogenations, have been investigated with colloidal analogue catalysts, and broad similarities have been recognized. − In using stabilized colloidal metals as support-free analogues to classical heterogeneous catalysts, it is important to bear in mind the influence that stabilizer molecules could have on the surface chemistry of the colloidal catalysts. Although little is known about the details of the surface chemistry involved in, for example, polymer stabilization of colloidal metals, it is commonly assumed that the stabilizer adsorbs at the particle surface and thus provides a steric barrier to interparticle collision.…”