198404-98-7Relevant articles and documents
Biomass- And calcium carbide-based recyclable polymers
Metlyaeva, Svetlana A.,Rodygin, Konstantin S.,Lotsman, Kristina A.,Samoylenko, Dmitriy E.,Ananikov, Valentine P.
, p. 2487 - 2495 (2021/04/07)
Biomass is a renewable source of valuable feedstock for the chemical industry of the future. A promising approach to the utilization of valuable components of biomass is the synthesis of monomers and polymers, if the overall technology is designed for a clean cycle without pollution of the environment with newly created polymers. In this work, we have developed a methodology for the recycling of polymers based on biomass and calcium carbide. First, we modified a series of biomass-derived terpene alcohols with calcium carbide followed by polymerization of the isolated vinyl ethers. Then, to study the recycling potential, the obtained polymers were subjected to pyrolysis at moderate temperatures (200-450 °C). The pyrolysis products were analyzed using TGA-MS, GC-MS, and NMR, and it was found that the polymers can be transformed quite easily. The products of the pyrolysis consisted of the starting terpenols, as well as the corresponding non-toxic ketones or aldehydes: up to 87% of the starting alcohol or up to 100% of the total sum of alcohol + aldehyde or alcohol + ketone (GC-yields). Then, the reaction mixture was hydrogenated and resulted in the formation of starting alcohol only. According to the studied pathway of polymers re-building, a terpene fragment attached to the main polyethylene chain through an oxygen atom promotes the transformation of the obtained polymers. Thus, the products of pyrolysis are environmentally friendly and can be reused in the further synthesis of monomers. The developed system has shown a unique assembling/disassembling ability and advances the concept of reusable bio-derived high value-added materials.
CYCLOPROPANATION OF SUBSTITUTED ALKENES
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Paragraph 0068, (2019/06/20)
Disclosed is a cyclopropanation process comprising the step of reacting an alkene compound having at least one carbon-carbon double bond with at least one dihaloalkane. The reaction is carried out in the presence of (i) particulate metal Zn, (ii) catalytically effective amount of particulate metal Cu or a salt thereof, (iii) at least one haloalkylsilane, and (iv) at least one solvent.
Transition-metal-catalyzed cyclopropanation of nonactivated alkenes in dibromomethane with triisobutylaluminum
Brunner, Gerhard,Elmer, Susanne,Schroeder, Fridtjof
, p. 4623 - 4633 (2011/10/09)
The cyclopropanation of nonactivated alkenes with inexpensive triisobutylaluminum (TIBA), in dibromomethane as solvent and reagent, is efficiently catalyzed by FeCl3 at ambient temperature. Catalytic amounts of CuI salts, CpTiCl3, and [CpFe(CO) 2]2 are similarly effective. 2-Methylpropane, generated after quench of excess TIBA can be trapped, and excess dibromomethane can be recycled, which makes the method industrially applicable. Solvent-free DIBAH or TIBA reduction of unsaturated carbonyl compounds, followed by in situ TIBA cyclopropanation of the unsaturated aluminum alcoholates in dibromomethane give cyclopropyl alkanols. Dienols such as geraniol, linalool or nor-radjanol are selectively cyclopropanated in their distal position, which allows the synthesis of flavor and fragrance compounds such as δ-citral, cis-javanol, and 7-methyl-georgywood. Uncontrollable exothermic events are avoided due to relatively low reaction temperatures made possible by the catalysts and by the addition mode of the reagents.[1]
