Solubility of fluorinated metal diethyldithiocarbamates in Supercritical carbon dioxide

Laintz, Kenneth E.; Wai, Chien M.; Yonker, Clement R.; Smith, Richard

doi:10.1016/0896-8446(91)90008-t

Cited by 194 publications

(157 citation statements)

References 14 publications

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“…When metal ions are chelated with suitable organic ligands, their solubility can be significantly increased. Some highly CO 2 -philic fluorinated or siloxane-based ligands are in removing various metals from solid and liquid matrices [176][177][178][179]. Zhang et al [123] have developed an extraction method using RAFT polymerization in order to functionalize a bipyridine group with VAc oligomers.…”

Section: Co 2 -Philic Polymers and Surfactantsmentioning

confidence: 99%

RAFT Polymerization of Vinyl Esters: Synthesis and Applications

et al. 2014

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This article is the first comprehensive review on the study and use of vinyl ester monomers in reversible addition fragmentation chain transfer (RAFT) polymerization. It covers all the synthetic aspects associated with the definition of precision polymers comprising poly(vinyl ester) building blocks, such as the choice of RAFT agent and reaction conditions in order to progress from simple to complex macromolecular architectures. Although vinyl acetate was by far the most studied monomer of the range, many vinyl esters have been considered in order to tune various polymer properties, in particular, solubility in supercritical carbon dioxide (scCO 2 ). A special emphasis is given to novel poly(vinyl alkylate)s with enhanced solubilities in scCO 2 , with applications as reactive stabilizers for dispersion polymerization and macromolecular surfactants for CO 2 media. Other miscellaneous uses of poly(vinyl ester)s synthesized by RAFT, for instance as a means to produce poly(vinyl alcohol) with controlled characteristics for use in the biomedical area, are also covered.

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Section: Co 2 -Philic Polymers and Surfactantsmentioning

confidence: 99%

RAFT Polymerization of Vinyl Esters: Synthesis and Applications

et al. 2014

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“…3 It is known that fluorinated metal chelates are CO 2 -philic. 4 Thus, fluorination of ligands is one method of increasing solubility of metal complexes in CO 2 . This approach requires the design and synthesis of specific fluorinated macrocyclic compounds.…”

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confidence: 99%

Selective extraction of strontium with supercritical fluid carbon dioxide

Wai¹,

Yak²,

Chen³

et al. 1999

Chem. Commun.

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Strontium (Sr 2+ ) can be selectively extracted from aqueous solutions into supercritical fluid CO 2 at 60 °C and 100 atm with dicyclohexano-18-crown-6 (DC18C6) using CF 3 (CF 2 ) 6 CO 2 − (PFOA − ) or CF 3 (CF 2 ) 6 CF 2 SO 3 − (PFOSA − ) as a counter anion; at a mole ratio of Sr 2+ : DC18C6 : PFOA − = 1:10:50, the extraction of Sr (5.6 × 10 −5 M) from water at pH 3 is near quantitative whereas Ca 2+ and Mg 2+ at equal concentration are only extracted to a level of 7 and 1%, respectively; PFOSA − is an effective counter anion for selective extraction of Sr 2+ from 1.3 M HNO 3 with DC18C6 in supercritical CO 2 .Research in selective transport of metal ions in supercritical (sc)-CO 2 is of considerable current interest because of its potential applications in a variety of chemical processes which may be carried out in this environmentally friendly solvent. 1,2 Selective extraction of alkali metal and alkaline earth metal ions from aqueous solutions to organic solvents with crown ethers is well established in the literature. Extraction of these hard metal ions with crown ethers in scCO 2 is expected to be difficult because of limited solubilities of the resulting metal complexes in CO 2 . 3 It is known that fluorinated metal chelates are CO 2 -philic. 4 Thus, fluorination of ligands is one method of increasing solubility of metal complexes in CO 2 . This approach requires the design and synthesis of specific fluorinated macrocyclic compounds. Another method is to extract crown ether-metal complexes as ion-pairs into scCO 2 utilizing fluorinated counteranions. We report for the first time the successful extraction of Sr 2+ from aqueous media into scCO 2 utilizing a macrocyclic compound and a fluorinated counter anion.It is known that 18-membered crown ethers with cavity diameters in the range 2.6-2.8 Å are the most suitable hosts for Sr 2+ (2.2 Å). 5 For example, 90 Sr can be selectively extracted from nitric acid solutions with dicyclohexano-18-crown-6 (DC18C6) dissolved in a paraffinic or halogenated solvent, where nitrate serves as the counter anion. 6 This macrocyclic system is currently being evaluated for removing 90 Sr (t ½ = 30 years), a major uranium fission product, from the high level acidic nuclear wastes stored at the Idaho DOE site. However, disposal of organic liquid wastes generated from any solvent extraction process is a problem of environmental concern today because of changing government regulations. Supercritical fluid extraction provides several advantages over conventional solvent extraction including minimization of waste generation, allowing rapid separation of

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“…However, the solubilities of catalysts usually used in organic solvents are very low in supercritical carbon dioxide. The solubility enhancements by fluorination have been reported by several papers [1][2][3][4][5]. The interactions between carbon dioxide and fluorinated compounds have been investigated and the reason of the solubility enhancement due to specific interactions remains controversial [6,7].…”

Section: Introductionmentioning

confidence: 99%