Polymerizations in liquid sulfur dioxide

Soares, Bluma G.

doi:10.1016/s0079-6700(96)00025-1

Cited by 11 publications

(9 citation statements)

References 65 publications

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“…The latter approach is used on industrial scale, where processes dealing with a recirculation of SO 2 in a closed contour are well known. Since the first report by Walden at the beginning of the 20th century [40], a variety of Lewis acid-mediated chemical transformations [41][42][43][44][45], especially those with carbenium ion intermediates [46][47][48][49][50][51][52][53][54][55][56], have benefited from the use of liquid SO 2 as the reaction medium. To the best of our knowledge, there has been only one example where liquid SO 2 has been applied as the glycosylation medium to stabilize the oxocarbenium ion formed from glycosyl perchlorate that is generated in situ from glycosyl chloride and AgClO 4 [56].…”

Section: Introductionmentioning

confidence: 99%

Metal-free glycosylation with glycosyl fluorides in liquid SO₂

Gulbe¹,

Lugiņina²,

Jansons³

et al. 2021

Beilstein J. Org. Chem.

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Liquid SO2 is a polar solvent that dissolves both covalent and ionic compounds. Sulfur dioxide possesses also Lewis acid properties, including the ability to covalently bind Lewis basic fluoride ions in a relatively stable fluorosulfite anion (FSO2 −). Herein we report the application of liquid SO2 as a promoting solvent for glycosylation with glycosyl fluorides without any external additive. By using various temperature regimes, the method is applied for both armed and disarmed glucose and mannose-derived glycosyl fluorides in moderate to excellent yields. A series of pivaloyl-protected O- and S-mannosides, as well as one example of a C-mannoside, are synthesized to demonstrate the scope of the glycosyl acceptors. The formation of the fluorosulfite species during the glycosylation with glycosyl fluorides in liquid SO2 is proved by 19F NMR spectroscopy. A sulfur dioxide-assisted glycosylation mechanism that proceeds via solvent separated ion pairs is proposed, whereas the observed α,β-selectivity is substrate-controlled and depends on the thermodynamic equilibrium.

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Section: Introductionmentioning

confidence: 99%

Metal-free glycosylation with glycosyl fluorides in liquid SO₂

Gulbe¹,

Lugiņina²,

Jansons³

et al. 2021

Beilstein J. Org. Chem.

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“…Aromatic polyether sulfones are some of the important engineering plastics, which are prepared by condensation polymerization and used in a wide range of application fields. Poly(vinyl sulfone)s, that is, poly(alkylene sulfone)s, are obtained by the free-radical copolymerization of olefins or cycloolefins with sulfur dioxide (SO 2 ). − Many kinds of vinyl monomers, such as styrene, vinyl chloride, and acrylic monomers, have been used for the synthesis of poly(vinyl sulfone)s. − The resulting poly(vinyl sulfone)s contain weak sulfur−carbon bonds, which are readily cleaved and induce a fast depolymerization (Scheme ). The copolymerization is usually performed at a low temperature below a ceiling temperature using a redox initiator to obtain a high-molecular-weight polymer.…”

Section: Introductionmentioning

confidence: 99%

Soluble and Thermally Stable Polysulfones Prepared by the Regiospecific and Alternating Radical Copolymerization of 2,4-Hexadiene with Sulfur Dioxide

et al. 2010

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We synthesized the alternating copolymers of 1,3-diene monomers with sulfur dioxide (SO 2 ) as a new class of thermally stable polymers by the radical copolymerization process and the subsequent hydrogenation. The copolymerizations of 2,4-hexadiene (HD), 1,3-butadiene (BD), and isoprene (IP) with SO 2 were carried out at -78 to 0 °C in toluene in the presence of tert-butyl hydroperoxide, which acts as one component in the redox initiating system in combination with SO 2 . The resulting poly(diene-alt-SO 2 )s were found to consist of highly controlled repeating units, that is, an alternating and 1,4-regiospecific repeating structure. Poly(HD-alt-SO 2 ) was soluble in several organic solvents, such as chloroform, nitromethane, tetrahydrofuran, acetone, and dimethyl sulfoxide. In contrast, poly(IP-alt-SO 2 ) was soluble only in dimethyl sulfoxide, whereas poly(BD-alt-SO 2 ) was insoluble in all of the solvents. The poly(diene-alt-SO 2 )s readily degraded upon heating because of the expected fast depolymerization. We have demonstrated that the thermal stability of the poly(diene-alt-SO 2 )s is modified by the hydrogenation of the double bond in the polymer main chain. The hydrogenation of poly(HD-alt-SO 2 ) resulted in a drastic increase in the 5% weightloss temperature from 135 to 317 °C.

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“…Poly(olefin sulfone)s (POS)s are copolymers formed from the free-radical copolymerization of sulfur dioxide and an olefin monomer . These polymers are known to depolymerize when exposed to heat, ionizing radiation and base − and these characteristics have been targeted in the development of photoresists and other degradable materials. − Base depolymerization traditionally proceeds through a mechanism involving the deprotonation of the polymer backbone, chain unzipping, and ultimately the regeneration of the monomer units .…”

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confidence: 99%

Base-Triggered Degradation of Poly(vinyl ester sulfone)s with Tunable Sensitivity

Casey

Moore

2016

ACS Macro Lett.

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A series of poly(vinyl ester sulfone)s are synthesized and are found to rapidly degrade in the presence of base. Solution phase NMR indicates that the sensitivity of these polymers to base depends on the identity of the ester functional group of the polymers. From most to least sensitive these are poly(vinyl chloroacetate sulfone) > poly(vinyl acetate sulfone) > poly(vinyl benzoate sulfone) > poly(vinyl pivalate sulfone). Significantly, these polymers were more reactive to base than the aliphatic poly(1-hexene sulfone). Additionally, degradation of these polymers in bulk occurs rapidly with exposure to aqueous solutions of base. The polymers are stable in water and possess good barrier properties; films of 30 μm thickness allow on average <1% crossover of dye over 7 days. Based on the data collected, poly(vinyl ester sulfone) polymers are promising for use in microcapsules, in particular, for applications where sustained or staged release would benefit from a series of different microcapsule compositions.

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Polymerizations in liquid sulfur dioxide

Cited by 11 publications

References 65 publications

Metal-free glycosylation with glycosyl fluorides in liquid SO₂

Metal-free glycosylation with glycosyl fluorides in liquid SO₂

Soluble and Thermally Stable Polysulfones Prepared by the Regiospecific and Alternating Radical Copolymerization of 2,4-Hexadiene with Sulfur Dioxide

Base-Triggered Degradation of Poly(vinyl ester sulfone)s with Tunable Sensitivity

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Polymerizations in liquid sulfur dioxide

Cited by 11 publications

References 65 publications

Metal-free glycosylation with glycosyl fluorides in liquid SO2

Metal-free glycosylation with glycosyl fluorides in liquid SO2

Soluble and Thermally Stable Polysulfones Prepared by the Regiospecific and Alternating Radical Copolymerization of 2,4-Hexadiene with Sulfur Dioxide

Base-Triggered Degradation of Poly(vinyl ester sulfone)s with Tunable Sensitivity

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Metal-free glycosylation with glycosyl fluorides in liquid SO₂

Metal-free glycosylation with glycosyl fluorides in liquid SO₂