Radical chemistry in polymer science: an overview and recent advances

• Zixiao Wang,
• Feichen Cui,
• Yang Sui and
• Jiajun Yan

Beilstein J. Org. Chem. 2023, 19, 1580–1603, doi:10.3762/bjoc.19.116

• upcycling of polymeric wastes, i.e., chemical conversion of polymeric wastes into high-value raw materials [200]. Upcycling of polyesters has been extensively studied in recent years [201]. Nevertheless, upcycling of vinyl polymers, which comprise a major portion of commercial polymers, remains a great

Valorisation of plastic waste via metal-catalysed depolymerisation

• Francesca Liguori,
• Carmen Moreno-Marrodán and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2021, 17, 589–621, doi:10.3762/bjoc.17.53

• selective depolymerisation methods of plastics. Achievements are broken down according to the plastic material, namely polyolefins, polyesters, polycarbonates and polyamides. The focus is on recent advancements targeting sustainable and environmentally friendly processes. Biocatalytic or unselective

• ]. This justifies for the easier depolymerisation of polyesters and polycarbonates compared to polyolefins [79][80]. By contrast, poor selectivity and slow kinetics of depolymerisation can be circumvented using a catalyst. 2.1 Chemolysis Several catalytic depolymerisation processes of plastics have been

• conditions. For instance, for polyesters, alcoholysis may provide mixed monomers formally derived from transesterification reactions [89][90], while aminolysis provides amides and alcohols [91][92]. In the search of “greener” technologies for plastic recycling, catalytic hydrogenolysis processes have been

Synthesis of functionalized diazocines for application as building blocks in photo- and mechanoresponsive materials

• Widukind Moormann,
• Daniel Langbehn and
• Rainer Herges

Beilstein J. Org. Chem. 2019, 15, 727–732, doi:10.3762/bjoc.15.68

• mechanoresponsive polymers such as polyurethanes, polyesters, polyamides, polyureas and polyolefines. (a) Isomerization of parent diazocine 1. Distances of carbon atoms para to the ethylene bridge were determined at the B3LYP/6-31g* level of DFT [23]. (b) UV–vis spectra of parent diazocine 1 (left), 3,3

Application of olefin metathesis in the synthesis of functionalized polyhedral oligomeric silsesquioxanes (POSS) and POSS-containing polymeric materials

• Patrycja Żak and
• Cezary Pietraszuk

Beilstein J. Org. Chem. 2019, 15, 310–332, doi:10.3762/bjoc.15.28

• metathesis with 4-bromostyrene and Heck coupling with 4-acetoxystyrene. The resulting acetoxy compounds were then hydrolyzed to produce hydroxy-functionalized derivatives. These compounds, after purification, were reacted with adipic acid chloride to form POSS-moiety containing highly crosslinked polyesters

Olefin metathesis in multiblock copolymer synthesis

• Maria L. Gringolts,
• Yulia I. Denisova,
• Eugene Sh. Finkelshtein and
• Yaroslav V. Kudryavtsev

Beilstein J. Org. Chem. 2019, 15, 218–235, doi:10.3762/bjoc.15.21

• the parent homopolymers are exhausted. 1H NMR spectroscopy was implemented to track the evolution of the chain structure in the course of MCM between polybutadiene (PBD) or polyisoprene (PI) and olefin-containing polyesters or polyurethane, as well as changes in the chain stereospecificity during the

• multiblock copolymers with long blocks demonstrated two glass temperatures, which get closer to each other upon block shortening and then a single-phase copolymer with one Tg was formed [84][86][87][88]. Besides, the semitransparent, hard, and brittle copolymers obtained by MCM of PBD and polyesters became

• bioimaging and in vivo tumor targeting [60]. The multiblock copolymer capable of post-functionalization [76]. Multiblock copolymers synthesized by macromolecular cross metathesis. Changes in the DSC thermograms during MCM of PBD and polyesters (left) [84] and PNB–PCOE (right) mediated by Gr1 catalyst [89

Copolymerization of epoxides with cyclic anhydrides catalyzed by dinuclear cobalt complexes

• Yo Hiranoi and
• Koji Nakano

Beilstein J. Org. Chem. 2018, 14, 2779–2788, doi:10.3762/bjoc.14.255

• synthetic method for polyesters as the polymers’ architectures and properties can be easily controlled depending on the combination of two monomers. Thus, a variety of catalyst designs has been reported to prepare the desired copolymers efficiently. We herein report dinuclear cobalt–salen complexes with a

• turnover frequencies ever reported. A variety of epoxides and CAs were also found to be copolymerized successfully by the dinuclear cobalt complex with a high catalytic activity. Keywords: cobalt; copolymerization; cyclic anhydrides; epoxides; polyesters; Introduction Aliphatic polyesters have received

• significant attention owing to their good biocompatibility and biodegradability [1][2][3][4]. These attractive features allow them to be applied in medical and ecological materials as well as in commodity materials. The conventional way of synthesizing polyesters is the step-growth polymerization of diacids

Cobalt–metalloid alloys for electrochemical oxidation of 5-hydroxymethylfurfural as an alternative anode reaction in lieu of oxygen evolution during water splitting

• Jonas Weidner,
• Stefan Barwe,
• Kirill Sliozberg,
• Stefan Piontek,
• Justus Masa,
• Ulf-Peter Apfel and
• Wolfgang Schuhmann

Beilstein J. Org. Chem. 2018, 14, 1436–1445, doi:10.3762/bjoc.14.121

• -refinery based chemicals for a “green” chemical industry [6][7][8]. FDCA was suggested to replace, e.g., terephthalic acid as building block for the formation of polyamides, polyesters, and polyurethanes [6]. Especially, the polymer polyethylene terephthalate (PET), a perpetually used polymer, could be

Spectroelectrochemical studies on the effect of cations in the alkaline glycerol oxidation reaction over carbon nanotube-supported Pd nanoparticles

• Dennis Hiltrop,
• Steffen Cychy,
• Karina Elumeeva,
• Wolfgang Schuhmann and
• Martin Muhler

Beilstein J. Org. Chem. 2018, 14, 1428–1435, doi:10.3762/bjoc.14.120

• biopolymers like polyesters and polyurethanes [4]. The route to higher functionalized products starting from glycerol via electrosynthesis offers several advantages compared with thermal gas-phase oxidation processes. In the aqueous environment low temperatures and pressures are applied allowing a higher

Theoretical simulation of the infrared signature of mechanically stressed polymer solids

• Matthew S. Sammon,
• Milan Ončák and
• Martin K. Beyer

Beilstein J. Org. Chem. 2017, 13, 1710–1716, doi:10.3762/bjoc.13.165

• interpret. For polymers with strong IR active modes, like polyamides or polyesters, we have shown here that the peak positions of real samples do not shift strongly. This is due to the exponential force distribution used for the modeling, which means that most functional polymer strands are exposed to very

• for 0 nN using numerical calculations as implemented in TURBOMOLE. See Supporting Information File 1 for details. N-Propylpropanamide and propyl propanoate were used as model molecules for polyamides and polyesters, respectively. Since polymers consist of multiple repetition units, any vibrational

Detection of therapeutic radiation in three-dimensions

• John A. Adamovics

Beilstein J. Org. Chem. 2017, 13, 1325–1331, doi:10.3762/bjoc.13.129

• their effective atomic number is not tissue equivalent. Acrylates, polyesters, polystyrenes and polycarbonates were also eliminated due to the relatively high exotherms created (>100 °C) during polymerization which prematurely oxidize the leuco dyes and rendered the dosimeter product unusable due to

Isosorbide and dimethyl carbonate: a green match

• Fabio Aricò and
• Pietro Tundo

Beilstein J. Org. Chem. 2016, 12, 2256–2266, doi:10.3762/bjoc.12.218

• the synthesis of bio-based polymers (Figure 1). In fact, isosorbide has been extensively employed for the preparation of polyesters, polyurethanes and polycarbonates [72][73][74][75][76][77][78][79][80][81]. Isosorbide is also considered as a possible candidate to replace petroleum-derived and toxic

Cross-metathesis of polynorbornene with polyoctenamer: a kinetic study

• Yulia I. Denisova,
• Maria L. Gringolts,
• Alexander S. Peregudov,
• Liya B. Krentsel,
• Ekaterina A. Litmanovich,
• Arkadiy D. Litmanovich,
• Eugene Sh. Finkelshtein and
• Yaroslav V. Kudryavtsev

Beilstein J. Org. Chem. 2015, 11, 1796–1808, doi:10.3762/bjoc.11.195

• course of polymerization but also through chemical modification of macromolecules [1]. In particular, main-chain polyesters and polyamides are capable of cross-reactions (also known as interchange reactions) characterized by the rearrangement of macromolecular backbones via break up and the formation of

• ’ Ru catalysts to make polybutadiene networks malleable [11] and self-healing [12] and to marry chain-growth 1,4-polybutadiene with step-growth unsaturated polyesters [13][14]. Hydrogenation of the reaction product led to saturated ethylene/ester copolymers with a multiblock chain structure predefined

Dicarboxylic esters: Useful tools for the biocatalyzed synthesis of hybrid compounds and polymers

• Ivan Bassanini,
• Karl Hult and
• Sergio Riva

Beilstein J. Org. Chem. 2015, 11, 1583–1595, doi:10.3762/bjoc.11.174

• acids and their derivatives (esters and anhydrides) have been used as acylating agents in lipase-catalyzed reactions in organic solvents. The synthetic outcomes have been dimeric or hybrid derivatives of bioactive natural compounds as well as functionalized polyesters. Keywords: biocatalysis

• ; dicarboxylic acids; lipase; polyesters; regioselectivity; Introduction The finding that enzymes can work in organic solvents has significantly expanded the scope of preparative scale biocatalyzed transformations [1][2][3][4]. An uncountable number of reports have been published on this topic since the

• , these molecules have allowed the synthesis of dimeric or hybrid derivatives of bioactive natural compounds as well as the biocatalyzed production of functionalized polyesters. Review 1. Synthetic exploitation of dicarboxylic esters a) Synthesis of activated esters In most of the biocatalyzed

An economical and safe procedure to synthesize 2-hydroxy-4-pentynoic acid: A precursor towards ‘clickable’ biodegradable polylactide

• Quanxuan Zhang,
• Hong Ren and
• Gregory L. Baker

Beilstein J. Org. Chem. 2014, 10, 1365–1371, doi:10.3762/bjoc.10.139

• Aliphatic polyesters, in particular polylactide (PLA), are now widely used for biomedical applications, such as surgery sutures [1], implants for bone fixation [2], drug delivery vehicles [3][4] and tissue engineering scaffolds [5] because of their excellent biocompatibility, biodegradability and mechanical

N-Alkylated dinitrones from isosorbide as cross-linkers for unsaturated bio-based polyesters

• Oliver Goerz and
• Helmut Ritter

Beilstein J. Org. Chem. 2014, 10, 902–909, doi:10.3762/bjoc.10.88

• ) were used as model systems and reacted with dimethyl itaconate to further characterize the 1,3-dipolaric cycloaddition. Keywords: bio-based polyesters; cross-linkers; dinitrones; 1,3-dipolar cycloaddition; isosorbide; Introduction Nitrones represent a class of compounds with a versatile use as

• synthesis of polymers bearing nitrones as photosensitive material [7][8] was also described. We focused on the preparation of polynitrones as efficient cross-linkers for unsaturated polyesters based on fumaric und maleic acid [9]. In the light of the growing interest in polymers from renewable resources the

• synthesis of bio-based nitrones as novel cross-linkers for unsaturated bio-polyesters [10] offers an interesting access to biocompatible materials. This paper presents the synthesis of bio-based N-alkylated dinitrones based on isosorbide and the subsequent use of these dinitrones as cross-linkers in a 1,3

Damage of polyesters by the atmospheric free radical oxidant NO₃^•: a product study involving model systems

• Catrin Goeschen and
• Uta Wille

Beilstein J. Org. Chem. 2013, 9, 1907–1916, doi:10.3762/bjoc.9.225

• polymers, the mechanism of their degradation upon exposure to environmental oxidants is barely understood. In this work, model systems of important structural motifs in commercial high-performing polyesters were used to study the reaction with the night-time free radical oxidant NO3• in the absence and

• presence of other radical and non-radical oxidants. Identification of the products revealed ‘hot spots’ in polyesters that are particularly vulnerable to attack by NO3• and insight into the mechanism of oxidative damage by this environmentally important radical. It is suggested that both intermediates as

• well as products of these reactions are potentially capable of promoting further degradation processes in polyesters under environmental conditions. Keywords: environmental oxidants; free radicals; nitrate radicals; polyester degradation; product studies; reaction mechanisms; Introduction Polymers

Spectroscopic characterization of photoaccumulated radical anions: a litmus test to evaluate the efficiency of photoinduced electron transfer (PET) processes

• Maurizio Fagnoni,
• Stefano Protti,
• Davide Ravelli and
• Angelo Albini

Beilstein J. Org. Chem. 2013, 9, 800–808, doi:10.3762/bjoc.9.91

• further evolution that precluded back electron transfer and any chemical reaction with the radical anion. In fact, no accumulation occurred with 1,4-diazabicyclo[2.2.2]octane (DABCO), for which this condition is not possible. The radical anions were produced from benzene polyesters too, but decomposition

1-n-Butyl-3-methylimidazolium-2-carboxylate: a versatile precatalyst for the ring-opening polymerization of ε-caprolactone and rac-lactide under solvent-free conditions

• Astrid Hoppe,
• Faten Sadaka,
• Claire-Hélène Brachais,
• Gilles Boni,
• Jean-Pierre Couvercelle and
• Laurent Plasseraud

Beilstein J. Org. Chem. 2013, 9, 647–654, doi:10.3762/bjoc.9.73

• of ε-caprolactone (ε-CL) and rac-lactide (rac-LA) under solvent-free conditions and using 1-n-butyl-3-methylimidazolium-2-carboxylate (BMIM-2-CO2) as precatalyst is described. Linear and star-branched polyesters were synthesized by successive use of benzyl alcohol, ethylene glycol, glycerol and

• under vacuo (method A) or by addition of NaBPh4 (method B). Possible catalytic and deactivation mechanisms are proposed. Keywords: aliphatic polyesters; green polymerization reaction; imidazolium-2-carboxylates; N-heterocarbene precursor; organocatalysis; Introduction Poly(ε-caprolactone) (PCL) and

• polylactic acid (PLA) are biologically relevant aliphatic polyesters. Their applications vary, due to their compatibility with other polymers and their biodegradability, from packaging to pharmaceutics and medicine [1][2][3][4][5][6]. PCL serves for instance as a scaffold for tissue engineering [7][8] and as

The cross-metathesis of methyl oleate with cis-2-butene-1,4-diyl diacetate and the influence of protecting groups

• Arno Behr and
• Jessica Pérez Gomes

Beilstein J. Org. Chem. 2011, 7, 1–8, doi:10.3762/bjoc.7.1

• derivatives that yield diverse types of α,ω-difunctional monomers, which can be processed into polymers (polyamides, polyesters, polyolefins, etc.), partial or even complete substitution of the steadily decreasing petrochemicals by materials from renewable resources is warranted [12][13][14]. So far, cross

About the activity and selectivity of less well-known metathesis catalysts during ADMET polymerizations

• Hatice Mutlu,
• Lucas Montero de Espinosa,
• Oĝuz Türünç and
• Michael A. R. Meier

Beilstein J. Org. Chem. 2010, 6, 1149–1158, doi:10.3762/bjoc.6.131

• catalysts was observed for the synthesis of the desired renewable polyesters with molecular weights of up to 17000 Da, which is considerably higher than molecular weights obtained using the same monomer with previously studied catalysts. Moreover, olefin isomerization side reactions that occur during the

• ADMET polymerizations were studied in detail. The isomerization reactions were investigated by degradation of the prepared polyesters via transesterification with methanol, yielding diesters. These diesters, representing the repeat units of the polyesters, were then quantified by GC-MS. Keywords: ADMET

• temperature, C2 showed a considerably lower degree of isomerization of 9.91%; however only oligomers (Mn 1700 Da) were obtained. Another goal of this research was to suppress the isomerization side reaction and thus to synthesize well-defined polyesters. Benzoquinones are very effective additives for the

Miniemulsion polymerization as a versatile tool for the synthesis of functionalized polymers

• Daniel Crespy and
• Katharina Landfester

Beilstein J. Org. Chem. 2010, 6, 1132–1148, doi:10.3762/bjoc.6.130

• in direct miniemulsion with significant advantages compared to the traditional bulk process. In fact, the bulk process yields only low molecular weight polymers and conversions are limited to 80% after 5 days (see Figure 5). Polyesters were polymerized by enzymatic polymerization of pentadecanolide

Conjugated polymers containing diketopyrrolopyrrole units in the main chain

• Bernd Tieke,
• A. Raman Rabindranath,
• Kai Zhang and
• Yu Zhu

Beilstein J. Org. Chem. 2010, 6, 830–845, doi:10.3762/bjoc.6.92

• -substituted DPP derivatives [14][15]. Polymer networks containing non-conjugated, copolymerized DPP units were prepared, whilst linear DPP-containing polyesters and polyurethanes were first described by Lange and Tieke in 1999 [23]. The polymers were soluble and could be cast into orange films that exhibited

Poly(glycolide) multi-arm star polymers: Improved solubility via limited arm length

• Florian K. Wolf,
• Anna M. Fischer and
• Holger Frey

Beilstein J. Org. Chem. 2010, 6, No. 67, doi:10.3762/bjoc.6.67

• polyesters such as polylactic acid (PLA) and poly(ε-caprolactone) [1] are of great interest due to their biodegradability, biocompatibility and permeability for many drugs. In contrast, poly(glycolic acid) (PGA) is scarcely used because of its high degree of crystallinity and its insolubility in all common

Functionalized polymers: synthesis and properties

• Helmut Ritter

Beilstein J. Org. Chem. 2010, 6, No. 55, doi:10.3762/bjoc.6.55

• instance, are preferentially made of standard polymeric materials such as polyolefins, polyesters or polyamides. It is therefore obvious that the future of polymer chemistry will be influenced by the elaboration of new functional polymers. At the beginning of the application of synthetic materials