The Sulfurization of Unsaturated Compounds.

Westlake, Harry E.

doi:10.1021/cr60123a002

Cited by 15 publications

(9 citation statements)

References 33 publications

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“…The starting temperature of homolytic fission for S 8 has not been agreed, with reports ranging from 140 to 181 o C 49,53–56 . That catalysts allow temperatures below this range to be used may therefore make a crucial difference to the nature of the reaction.…”

Section: Resultsmentioning

confidence: 86%

Catalytic inverse vulcanization

et al. 2019

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The discovery of inverse vulcanization has allowed stable polymers to be made from elemental sulfur, an unwanted by-product of the petrochemicals industry. However, further development of both the chemistry and applications is handicapped by the restricted choice of cross-linkers and the elevated temperatures required for polymerisation. Here we report the catalysis of inverse vulcanization reactions. This catalytic method is effective for a wide range of crosslinkers reduces the required reaction temperature and reaction time, prevents harmful H2S production, increases yield, improves properties, and allows crosslinkers that would be otherwise unreactive to be used. Thus, inverse vulcanization becomes more widely applicable, efficient, eco-friendly and productive than the previous routes, not only broadening the fundamental chemistry itself, but also opening the door for the industrialization and broad application of these fascinating materials.

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Section: Resultsmentioning

confidence: 86%

Catalytic inverse vulcanization

et al. 2019

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“…Sulfurized olefins (polysulfides), obtained by the treatment of alkenes with elemental sulfur at elevated temperatures (Scheme 1A), are among the most common organosulfur additives to petroleum-derived products 6,7. Polysulfides also figure prominently in the chemistry and biology of Allium species, which include garlic and petiveria (Scheme 1B).…”

Section: Introductionmentioning

confidence: 99%

The antioxidant activity of polysulfides: it's radical!

2019

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“…One of the complicated factors is the complex nature of sulfur itself, which exists in at least two allotropes and a large number of reported liquid forms. 21 And not until 1944 the S 8 ring structure was confirmed by the electron diffraction experiments, 22 which, however, followed by a more controversial question of whether the dominant reaction is ionic or radical nature or both because the S 8 ring has the potential of either homolytic fission or heterolytic fission shown in Figure 1. The other complicated factor is the diversity and complexity of the resultant products, and not only that, the three-dimensional cross-linking networks formed by sulfurized rubber cannot melt or dissolve, so it is very difficult to obtain the accurate structure of the varieties of specific cross-linking structures by conventional analytical techniques.…”

Section: Introductionmentioning

confidence: 99%

“…Nevertheless, we have to admit that the vulcanization mechanism of a sulfur-only system is not easier to be clarified as expected. One of the complicated factors is the complex nature of sulfur itself, which exists in at least two allotropes and a large number of reported liquid forms . And not until 1944 the S 8 ring structure was confirmed by the electron diffraction experiments, which, however, followed by a more controversial question of whether the dominant reaction is ionic or radical nature or both because the S 8 ring has the potential of either homolytic fission or heterolytic fission shown in Figure .…”

Section: Introductionmentioning

confidence: 99%

Insights into the Vulcanization Mechanism through a Simple and Facile Approach to the Sulfur Cleavage Behavior

Lian

et al. 2017

Macromolecules

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The vulcanization mechanism remains unclear due to the difficulty of characterization and the complexity of the vulcanization systems. In this work, a series of epoxy model systems were used to study the sulfur cleavage behavior, from which the study process of the vulcanization mechanism was significantly simplified and a brand new sulfur-only vulcanization mechanism was revealed by the FTIR and DSC analysis. Our studies suggest that thiyl radicals derived from the homolytic cleavage of sulfur play the dominant role in the vulcanization, while the heterolytic fission of sulfur cannot occur as expected because this reaction needs 200 °C. Nevertheless, sulfur anions, which are easy to be understood derived from the heterolytic cleavage of sulfur, are actually transformed from the thiol groups that are produced through the reaction of thiyl radicals abstracting α-H atoms of allyl groups in rubber, and this maybe the reason that vulcanization mechanism remains controversial for centuries.

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The Sulfurization of Unsaturated Compounds.

Cited by 15 publications

References 33 publications

Catalytic inverse vulcanization

Catalytic inverse vulcanization

The antioxidant activity of polysulfides: it's radical!

Insights into the Vulcanization Mechanism through a Simple and Facile Approach to the Sulfur Cleavage Behavior

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