Kinetic study of carbene polymerization of ethyl diazoacetate by palladium and rhodium catalysts

Abstract

Kinetic studies of the carbene polymerization of ethyl diazoacetate (EDA) by palladium (Pd) or rhodium (Rh) catalysts were investigated by real-time Fourier transform infrared (FTIR) spectroscopy. Both (L-prolinate) Rh I (1,5-cyclooctadiene) and (L-prolinate)Rh I (2,5-norbornadiene) mediated EDA polymerization were proved to be first order reactions, suggesting that the formation of "Rh-carbenoid" is the rate determining step. The activation energy (11.24 kJ mol À1 ) of the polymerization of "carbenes" generated from EDA with (L-prolinate)Rh I (1,5-cyclooctadiene) as the catalyst was calculated from kinetic data via the Arrhenius equation. On the other hand, the polymerizations of EDA catalyzed by three kinds of Pdcatalysts were revealed as zero order reactions, suggesting that the rate determining step involves the formation of an EDA-Pd transition state complex through a coordinated step. Refilling more EDA to the (bis(acetonitrile)dichloropalladium)-mediated carbene polymerization system did not change the reaction order. The rate constant increases gradually with the increase of the dosage of the catalyst and decreases with the cycle-index, which proves the formation of "EDA-Pd transition state complex" and the propagating species with Pd-C bonds at the end of the polymer chain.

One-pot catalyst-free synthesis of down- and upconversion fluorescent oligopyrazolines from diazoacetates and maleic anhydride

“…1A is 2-D model of the kinetic process showing the dependence of the transmittance on the reaction time from 0 to 500 min. The decrease of the band intensity at 2115 cm −1 assigned to the stretching vibration of -CHvN 2 38 is expressed visually, which is also indicated in the 3-D spectrum of Fig. 1B.…”

Synthesis and Enhanced Photofluorescence of Pyrazoline‐Ester Copolymers from Bisdiazoacetates and Diacrylates

“…The broad band at about 3356 cm −1 is assigned to NH stretching vibration, and the bands near 2938–2855 cm −1 are assigned to CH 3 , CH 2 , and CH stretching vibrations. The band at 2110 cm −1 is assigned to CHN 2 stretching vibration, and the bands at 1738–1697 cm −1 are assigned to ester groups. Obviously, the IR spectra of P1, P2, P5, and P8 are very much alike, suggesting the expected pyrazoline ring structure in the polymer backbone.…”

Fabrication of Large Single Crystals for Platinum‐Based Linear Polymers with Controlled‐Release and Photoactuator Performance

“…Therefore,w ew ere able to obtain the reaction kinetics (e.g.Arrhenius parameters) of the depolymerization process via in situ FT-IR. [16] When treating poly(Pt-BA2DA) at 60 8 8C, the reaction rate was calculated to be 0.1850 min À1 for poly(Pt-BA2DA)!Pt-BA2DA-i phase transformation, which is more than two magnitudes higher than that of the Pt-BA2DA-i!Pt-BA2DA transformation (0.0017 min À1 ) ( Figure 4d and S8). Thel arge difference between the two reaction rates indicates that much higher energy was required for the transformation process of Pt-BA2DA-i!Pt-BA2DA compared to poly(Pt-BA2DA)!Pt-BA2DA-i process.…”