Preparation of Polycinnamamide Catalyzed by Palladium-Graphite through the Heck Reaction

Abstract

Palladium-graphite (Pd-Gr) was successfully used as a heterogeneous catalyst for the preparation of polycinnamamide through the Heck reaction. The condensation reaction of ethyl acrylate and iodobenzene catalyzed by Pd-Gr proceeded efficiently in the presence of tributylamine in an aprotic polar solvent such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), and dimethyl sulfoxide (DMSO). The polymerization of N,N'-(3,4'-oxydiphenylene)bis-(acrylamide) and bis(4-iodophenyl) ether catalyzed by Pd-Gr was carried out in the presence of tributylamine in DMF a t 100 "C. The polymerization proceeded efficiently to form polycinnamamide, but required a longer reaction time compared to the polycondensation catalyzed by palladium acetate. The structure of the resulting polymer was confirmed as trans-polycinnamamide by two-dimensional NMR measurements. The resulting polymer was almost white, which means that it was less contaminated by palladium metal. The removal and recycling of Pd-Gr were much easier than in the case of homogeneous catalysts.

Synthesis and Properties of Hyperbranched Poly(triphenylamine)s Prepared by Palladium Catalyzed C–N Coupling Reaction

“…We have previously reported the palladium catalyzed polycondensations to form linear polyamides, 14 polycinnamamides, 15,16 and hyperbranched polyesters. 17 Recently, Buchard and Hartwig have been independently reported palladium catalyzed C-N coupling reactions.…”

Visible Light Catalyzed Step‐Growth Polymerization through Mizoroki–Heck Coupling Reaction

“…Poly(penylenevinylene) (PPV) and its derivatives with side chains, as well as block copolymers containing PPV segments, were synthesized through Mizoroki–Heck coupling reaction between divinyl and dihalide monomers 27. Other conjugated polymers containing functional moieties, for instance, polycinnamate28 and polycinnamamide,29 were also reported. In these studies, MHCR was generally performed at high temperature, thus unpredictable and complicated side reactions may occur 30.…”

Pd/C as a Clean and Effective Heterogeneous Catalyst for C–C Couplings toward Highly Pure Semiconducting Polymers

“…In pharmaceutical or other small molecules synthesis, it has been proven that replacing the homogeneous Pd catalysts with heterogeneous Pd/C could reduce the level of Pd impurity in products from thousands ppm to several ppm. ,,, For example, researchers at Merck demonstrated that using Pd/C as a catalyst for Suzuki coupling can minimize the Pd level in a drug intermediate below 10 ppm, but the soluble catalyst PdCl 2 (dppf) led to a level of residual Pd as high as 3500 ppm . As for polymers, Kakimoto et al reported that the amount of palladium in the polyamide via Heck coupling reaction catalyzed by heterogeneous Pd/graphite was 10 times less than that in the polymer prepared by homogeneous Pd(OAc) 2 /P(Tol) 3 . Like pharmaceuticals, high purity is also much needed for the semiconducting polymers .…”

“…However, the Pd/C or other heterogeneous Pd-catalyzed C–C couplings are mostly developed for the synthesis of small molecules. − There are only a few reports about the heterogeneous Pd-catalyzed C–C coupling polymerization. For example, Pd on graphite was used as heterogeneous catalyst for the Heck reaction between ethyl acrylate and iodobenzene toward the preparation of polycinnamamide . The polyketone synthesized by copolymerization between the carbon monoxide and styrene using Pd/C–bipyridine ligand as catalyst was reported recently .…”

“…For example, Pd on graphite was used as heterogeneous catalyst for the Heck reaction between ethyl acrylate and iodobenzene toward the preparation of polycinnamamide. 16 The polyketone synthesized by copolymerization between the carbon monoxide and styrene using Pd/C−bipyridine ligand as catalyst was reported recently. 17 As far as the synthesis of π-conjugated polymers is concerned, the heterogeneous Pd-catalyzed C−C couplings has not been investigated.…”