Alcoholysis and aminolysis of Di-and trithioester chain-transfer agents of free-radical polymerization

Kabachii, Yu. A.; Kochev, S. Yu.

doi:10.1134/s0965545x0607008x

Cited by 13 publications

(9 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These kinetic parameters are again used in a microkinetic model, now to simulate the reaction at experimental conditions used in literature in good agreement with the reported findings (cf. Table S10 in the Supporting Information for details). ,,, In particular, comparison with kinetic experiments on xanthates and dithiobenzoates by Kabachii and Kochev show that simulated conversions deviate less than a factor of 2. Taking into account that the reaction parameters are solely obtained using theoretical methods, this is a very satisfactory result and exemplifies the predictive power of theoretical modeling.…”

Section: Resultsmentioning

confidence: 95%

Computational Investigation of the Aminolysis of RAFT Macromolecules

et al. 2016

View full text Add to dashboard Cite

This work presents a detailed computational study and kinetic analysis of the aminolysis of dithioates, dithiobenzoates, trithiocarbonates, xanthates, and thiocarbamates, which are frequently used as chain-transfer agents for reversible addition-fragmentation chain-transfer (RAFT) polymerization. Rate coefficients were obtained from ab initio calculations, taking into account a diffusional contribution according to the encounter pair model. A kinetic model was constructed and reveals a reaction mechanism of four elementary steps: (i) formation of a zwitterionic intermediate, (ii) formation of a complex intermediate in which an assisting amine molecule takes over the proton from the zwitterionic intermediate, (iii) breakdown of the complex into a neutral tetrahedral intermediate with release of the assisting amine molecule, and (iv) amine-assisted breakdown of the neutral intermediate to the products. Furthermore, a comparative analysis indicates that the alkanedithioates and dithiobenzoates react the fastest, followed, respectively, by xanthates and trithiocarbonates, which react almost equally fast, and dithiocarbamates, which are not reactive at typical experimentally used conditions.

show abstract

Section: Resultsmentioning

confidence: 95%

Computational Investigation of the Aminolysis of RAFT Macromolecules

et al. 2016

View full text Add to dashboard Cite

show abstract

“…NaHS has been briefly studied as a nucleophilic agent for the conversion of RAFT agents into thiols so this outcome was not unexpected. 60 However, due to reactivity of the thioamides to thiols, we decided to remove the RAFT end groups before carrying out the thionation reaction. Therefore, diblock copolymers 3 and 4, as well as copolymer 2a, were subjected to a radical-induced reduction using N-ethylpiperidine hypo- phosphite (EPHP) and a thermal initiator, to give a hydrogen end group.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…The latter was apparent by the immediate decolorisation of the polymer. NaHS has been briefly studied as a nucleophilic agent for the conversion of RAFT agents into thiols so this outcome was not unexpected . However, due to reactivity of the thioamides to thiols, we decided to remove the RAFT end groups before carrying out the thionation reaction.…”

Section: Resultsmentioning

confidence: 99%

Macromolecular Hydrogen Sulfide Donors Trigger Spatiotemporally Confined Changes in Cell Signaling

et al. 2015

View full text Add to dashboard Cite

Hydrogen sulfide (H2S) is involved in a myriad of cell signaling processes that trigger physiological events ranging from vasodilation to cell proliferation. Moreover, disturbances to H2S signaling have been associated with numerous pathologies. As such, the ability to release H2S in a cellular environment and stimulate signaling events is of considerable interest. Herein we report the synthesis of macromolecular H2S donors capable of stimulating cell signaling pathways in both the cytosol and at the cell membrane. Specifically, copolymers having pendent oligo(ethylene glycol) and benzonitrile groups were synthesized, and the benzonitrile groups were subsequently transformed into primary aryl thioamide groups via thionation using sodium hydrosulfide. These thioamide moieties could be incorporated into a hydrophilic copolymer or a block copolymer (i.e., into either the hydrophilic or hydrophobic domain). An electrochemical sensor was used to demonstrate release of H2S under simulated physiological conditions. Subsequent treatment of HEK293 cells with a macromolecular H2S donor elicited a slow and sustained increase in cytosolic ERK signaling, as monitored using a FRET-based biosensor. The macromolecular donor was also shown to induce a small, fast and sustained increase in plasma membrane-localized PKC activity immediately following addition to cells. Studies using an H2S-selective fluorescent probe in live cells confirmed release of H2S from the macromolecular donor over physiologically relevant time scales consistent with the signaling observations. Taken together, these results demonstrate that by using macromolecular H2S donors it is possible to trigger spatiotemporally confined cell signaling events. Moreover, the localized nature of the observed signaling suggests that macromolecular donor design may provide an approach for selectively stimulating certain cellular biochemical pathways.

show abstract

“…In order to asses the degree of control during concurrent ATRP and RAFT polymerization with 3 , the polymers were cleaved after the polymerization. The most widely used reagents to cleave thiocarbonylthio groups are nucleophiles, such as primary or secondary amines, ,– hydroxides, – or ionic reducing agents, such as borohydrides. ,– The polymers were cleaved either by aminolysis of the trithiocarbonate moiety or by methanolysis of both the trithiocarbonate and ester functions present in the backbone of the polymers. Aminolysis was achieved by stirring a mixture of 2.5 × 10 −3 mmol of polystyrene or poly( n -butyl acrylate), 2.5 mmol of ethylenediamine, and 0.01 mmol of triethylamine in 10 mL of tetrahydrofuran for 72 h at room temperature.…”

Section: Resultsmentioning

confidence: 99%

Dibromotrithiocarbonate Iniferter for Concurrent ATRP and RAFT Polymerization. Effect of Monomer, Catalyst, and Chain Transfer Agent Structure on the Polymerization Mechanism

Nicolaÿ

Matyjaszewski

2008

Macromolecules

View full text Add to dashboard Cite

An iniferter comprising a trithiocarbonate (TTC) moiety and two bromine chain ends was prepared and used to successfully conduct, independently or concurrently, atom transfer radical polymerization (ATRP) and reversible addition−fragmentation chain transfer (RAFT) polymerization. RAFT polymerization was carried out by self-initiation (styrene, (St)) or in the presence of a thermal initiator (acrylates) and yielded polymers with narrow molecular weight distribution (M w/M n ≤ 1.16 (St) and M w/M n ≤ 1.15 (acrylates)). Methyl methacrylate (MMA) polymerization under these conditions was poorly controlled. However, ATRP of MMA with the dibromotrithiocarbonate (DiBrTTC) iniferter was successful in the presence of copper catalysts formed with various nitrogen-based ligands. Polymers with narrow molecular weight distribution (M w/M n < 1.27) were obtained in every case. Depending on the ligand, polymerization proceeded only through the bromine chain ends or through both the bromine chain ends and the TTC moiety, providing the first example of an ATRP with a trithiocarbonate. ATRP and RAFT polymerization of St and n-butyl acrylate (nBA) were conducted concurrently using CuBr/PMDETA as catalytic system. Polymers with broad molecular weight distribution (M w/M n ≈ 1.6) and polymodal size exclusion chromatography traces were obtained due to chain reshuffling through the TTC moiety. SEC analysis of the polymers after aminolysis or methanolysis showed that ATRP and RAFT occurred simultaneously, with good control, for each nBA and St (M w/M n < 1.3). Triblock, pentablock, or multiblock copolymers were prepared in two steps by appropriate selection of monomers and catalytic systems.

show abstract

Alcoholysis and aminolysis of Di-and trithioester chain-transfer agents of free-radical polymerization

Cited by 13 publications

References 6 publications

Computational Investigation of the Aminolysis of RAFT Macromolecules

Computational Investigation of the Aminolysis of RAFT Macromolecules

Macromolecular Hydrogen Sulfide Donors Trigger Spatiotemporally Confined Changes in Cell Signaling

Dibromotrithiocarbonate Iniferter for Concurrent ATRP and RAFT Polymerization. Effect of Monomer, Catalyst, and Chain Transfer Agent Structure on the Polymerization Mechanism

Contact Info

Product

Resources

About