Synthesis of tetraethylammonium dithionite and its dissociation to the sulfur dioxide radical anion in organic solvents

Lough, Samuel M.; McDonald, John W.

doi:10.1021/ic00260a004

Cited by 37 publications

(29 citation statements)

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“…45 Due to its poor solubility in organic solvents, 61 the concentrations of S 2 O 4 2- anion and consequently the concentrations SO 2 •- resulting from dithionite anion dissociation are very small. In these solvents, an excess of Na 2 S 2 O 4 , was employed, 45,46 and the concentration of SO 2 •- species was maintained low and constant during the course of the polymerization.…”

Section: Resultsmentioning

confidence: 99%

Aqueous SARA ATRP using inorganic sulfites

Abreu

Carmali

et al. 2017

Polym. Chem.

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Aqueous supplemental activator and reducing agent atom transfer radical polymerization (SARA ATRP) using inorganic sulfites was successfully carried out for the first time. Under optimized conditions, a well-controlled poly[oligo(ethylene oxide) methyl ether acrylate] (POEOA) was obtained with <30 ppm of soluble copper catalyst using tris(2-pyridylmethyl)amine (TPMA) ligand in the presence of an excess of halide salts (e.g. NaCl). Inorganic sulfites (e.g. Na2S2O4) were continuously fed into the reaction mixture. The mechanistic studies proved that these salts can activate alkyl halides directly and regenerate the activator complex. The effects of the feeding rate of the SARA agent (inorganic sulfites), ligand and its concentration, halide salt and its concentration, sulfite used, and copper concentration, were systematically studied to afford fast polymerizations rates while maintaining the control over polymerization. The kinetic data showed linear first-order kinetics, linear evolution of molecular weights with conversion, and polymers with narrow molecular weight distributions (Đ ~1.2) during polymerization even at relatively high monomer conversions (~80%). “One-pot” chain extension and “one-pot” block copolymerization experiments proved the high chain-end functionality. The polymerization could be directly regulated by starting or stopping the continuous feeding of the SARA agent. Under biologically relevant conditions, the aqueous SARA ATRP using inorganic sulfites was used to synthesize a well-defined protein-polymer hybrid by grafting of P(OEOA480) from BSA-O-[iBBr]30.

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Section: Resultsmentioning

confidence: 99%

Aqueous SARA ATRP using inorganic sulfites

Abreu

Carmali

et al. 2017

Polym. Chem.

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“…40 While the exact SO 2 •− concentration in the polymerization mixture was unknown, this information was not strictly necessary for an accurate kinetic analysis of the system. In fact, rate coefficients of all reactions involving SO 2 •− were measured as apparent rate coefficients k app = k × [SO 2 •− ], considering constant [SO 2 •− ] during polymerization.…”

Section: Resultsmentioning

confidence: 99%

Mechanism of supplemental activator and reducing agent atom transfer radical polymerization mediated by inorganic sulfites: experimental measurements and kinetic simulations

et al. 2017

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The mechanism of atom transfer radical polymerization (ATRP) mediated by sodium dithionite (Na2S2O4), with CuIIBr2/Me6TREN as catalyst (Me6TREN: tris[2-(dimethylamino)ethyl]amine) in ethanol/water mixtures, was investigated experimentally and by kinetic simulations. A kinetic model was proposed and the rate coefficients of the relevant reactions were measured. The kinetic model was validated by the agreement between experimental and simulated results. The results indicated that the polymerization followed the SARA ATRP mechanism, with a SO2•− radical anion derived from Na2S2O4, acting as both supplemental activator (SA) of alkyl halides and reducing agent (RA) for CuII/L to regenerate the main activator CuI/L. This is similar to the reversible-deactivation radical polymerization (RDRP) procedure conducted in the presence of Cu0. The electron transfer from SO2•−, to either CuIIBr2/Me6TREN or R–Br initiator, appears to follow an outer sphere electron transfer (OSET) process. The developed kinetic model was used to study the influence of targeted degree of polymerization, concentration of CuIIBr2/Me6TREN and solubility of Na2S2O4 on the level of polymerization control. The presence of small amounts of water in the polymerization mixtures slightly increased the reactivity of the CuI/L complex, but markedly increased the reactivity of sulfites.

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“…The mechanism of dithionite‐mediated reactions seems to be well established 6, 7, 12–15. It has been demonstrated that the active species in this reaction is the radical anion SO

_{2}^{−·}

, which is formed by the dissociation of the S 2 O

_{4}^{2−}

dianion.…”

Section: Resultsmentioning

confidence: 98%

“…It has been demonstrated that the active species in this reaction is the radical anion SO

_{2}^{−·}

, which is formed by the dissociation of the S 2 O

_{4}^{2−}

dianion. This dissociation constant increases when the polarity of the solvent decreases 12, 13. The mechanisms of the basic hydrolysis of (NH 2 ) 2 CSO

_{2}^{8}

and its reaction with MV 2+ 16 have been investigated only recently.…”

Section: Resultsmentioning

confidence: 98%

Single‐electron‐transfer/degenerative‐chain‐transfer mediated living radical polymerization of vinyl chloride catalyzed by thiourea dioxide/octyl viologen in water/tetrahydrofuran at 25 °C

Percéc¹,

Popov²,

Ramirez‐Castillo³

2004

J. Polym. Sci. A Polym. Chem.

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The single‐electron‐transfer/degenerative‐chain‐transfer mediated living radical polymerization (SET–DTLRP) of vinyl chloride (VC) in H2O/tetrahydrofuran at 25 °C catalyzed by thiourea dioxide [(NH2)2CSO2] is reported. This polymerization occurs only in the presence of a basic sodium bicarbonate (NaHCO3) buffer and the electron‐transfer cocatalyst octyl viologen. The resulting poly(vinyl chloride) (PVC) has a number‐average molecular weight of 1500–7000 and a weight‐average molecular weight/number‐average molecular weight ratio of 1.5. This PVC does not contain detectable amounts of structural defects and has both active chloroiodomethyl and inactive chloromethyl chain ends. Because of possible side reactions caused by the primary sulfoxylate anion (SO 22−), the catalytic activity of (NH2)2CSO2 in the SET–DTLRP of VC is lower than that of the single‐electron‐transfer agent sodium dithionite. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 287–295, 2005

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Synthesis of tetraethylammonium dithionite and its dissociation to the sulfur dioxide radical anion in organic solvents

Cited by 37 publications

References 0 publications

Aqueous SARA ATRP using inorganic sulfites

Aqueous SARA ATRP using inorganic sulfites

Mechanism of supplemental activator and reducing agent atom transfer radical polymerization mediated by inorganic sulfites: experimental measurements and kinetic simulations

Single‐electron‐transfer/degenerative‐chain‐transfer mediated living radical polymerization of vinyl chloride catalyzed by thiourea dioxide/octyl viologen in water/tetrahydrofuran at 25 °C

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