Phosphonium sulfonates

A drawback is that phosphonium sulfonate is not very hygroscopic, but it severely lowers the mechanically properties. On the other hand, alkali metal sulfonates exhibit excellent antistatic performance, but they are hygroscopic. 

However, an excellent antistatic performance is obtained by adding phosphonium sulfonates and phosphate ester that have ether moieties in the organic chain, e.g., a phosphate with polyoxyethylene nonylphenyl ether (30). 

Acid-catalysed esterification reactions in ILs have been extensively studied, and will be the main focus of this section. In 2001, Deng et al. first reported the synthesis of allq l acetate esters in an IL with concentrated sulfuric acid as the acid catalyst (Scheme 3.7). The majority of subsequent studies, however, have switched away from an IL with an added acid catalyst and towards Bronsted acid ionic liquids (BAILs) - a type of task-specific ionic liquid. BAILS incorporate an acidic moiety (typically either a sulfonic acid or a protonated nitrogen) on the cation allowing the BAILS to have dual functionality as both a solvent and a catalyst. There are several different classes of BAILs that have been applied to esterifications such as imidazo-lium 1, imidazolium sulfonic 2, phosphonium sulfonic 3, pyridinium sulfonic 4, quaternary ammonium 5, quaternary ammonium sulfonic 6 and lactam 7 based-BAILs (Scheme 3.8). 

The level of water content in the ILs also influences the yields of the esterification/ For the phosphonium sulfonic BAIL (Table 3.1 Entiy 8) it was demonstrated that 30% (w/w) water resulted in highest yields and percentages of water above or below this value diminished the yield of ester. The reasons for the necessity of water are unclear, however, it may be due to creation of a proton transfer network within the IL. 

Sulfonates s. Acyl sulfonates. Metal —, Phosphonium —, Sulfonic acid esters Suifonation s. a. Replacement of hydrogen by sulfonic acid groups N-Sulfonation 17, 355 Sulfones Cs. a. Replacement of sulfonyl groups, C- and a-Sulfonyl. . . )... 

Elimination of the sulfone linker has also been used in the formation of aryl sulfonamides, dehydroalanine, and heterocyclic 2-substituted-4-piperidones." Pendant phosphonium sulfone intermediate 169 was subjected to Wittig reagent to form sulfone-bound vinyl ketones 170 (Scheme 12.35). Benzylamine as nucleophile and base was then... 

In 2007, Nozaki et al. reported that the mixture of Pd(dba)2 and phosphonium sulfonate (la, lb) catalyzed the alternating copolymerization of vinyl acetate with CO (Scheme 12, top). The alternating structure of the obtained copolymers was unambiguously confirmed by NMR analyses and MALDI-TOF mass analysis. However, head-to-tail selectivity was found to be less controlled, which suggests that VAc insertion into the acyl-palladium bond may occur in both the 2,1-and 1,2-mode. The productivity was up to 3.0gmmor h" and the molecular weight (AfJ was up to 38 000. 

A one-pot synthesis of alkyl perfluoroalkyl ketones has been developed. Phosphoranes, generated in situ, are acylated with a perfluoroacyl anhydnde, and the resultmg phosphonium salts are hydrolyzed with alkali [4S (equation 48) Hydrolysis of a carbon-sulfur bond in 2-chloro-2,4,4-trifluoro-1,3-dithietane-S-trioxide, which can be obtained from 2,2,4,4-tetrachloro-l,3-dithietane by fluor-mation with antimony trifluoride followed by selective oxidations, opens the nng to produce 2-chloro-1,1,2-trifluorodimethyl sulfone [49] (equation 49)... 

Aldol addition and related reactions of enolates and enolate equivalents are the subject of the first part of Chapter 2. These reactions provide powerful methods for controlling the stereochemistry in reactions that form hydroxyl- and methyl-substituted structures, such as those found in many antibiotics. We will see how the choice of the nucleophile, the other reagents (such as Lewis acids), and adjustment of reaction conditions can be used to control stereochemistry. We discuss the role of open, cyclic, and chelated transition structures in determining stereochemistry, and will also see how chiral auxiliaries and chiral catalysts can control the enantiose-lectivity of these reactions. Intramolecular aldol reactions, including the Robinson annulation are discussed. Other reactions included in Chapter 2 include Mannich, carbon acylation, and olefination reactions. The reactivity of other carbon nucleophiles including phosphonium ylides, phosphonate carbanions, sulfone anions, sulfonium ylides, and sulfoxonium ylides are also considered. 

Among the olefination reactions, those of phosphonium ylides, phosphonate anions, silylmethyl anions, and sulfone anions are discussed. This chapter also includes a section on conjugate addition of carbon nucleophiles to a, (J-unsaturated carbonyl compounds. The reactions in this chapter are among the most important and general of the carbon-carbon bond-forming reactions. 

Nowadays we look with other eyes at organometallic compounds the family of which has expanded enormously. Some members of this family are soluble in water due to their ionic nature the legions of anionic carbonylmetallates (e.g. [Ni(CN)(CO)3] ) and cationic bisphosphine Rh-chelate complexes (e.g. [Rh(BDPP)(COD)] ) just come to mind. Others obtain their solubility in water from the well soluble ligands they contain these can be ionic (sulfonate, carboxylate, phosphonate, ammonium, phosphonium etc. derivatives) or neutral, such as the ligands with polyoxyethylene chains or with a modified urotropin structure. 

In a different approach [11] to access pure products, the use of strong oleum (65% SO3) for sulfonation of PPh3 resulted in quantitative formation of TPPTS oxide. This was converted to the ethyl suhbester through the reaction of an intermediate silver sulfonate salt (isolated) with iodoethane. Reduction with SiHCls in toluene/THF afforded tris(3-ethylsulfonatophenyl)phosphine which was finally converted to pure 3 with NaBr in wet acetone. In four steps the overall yield was 40% (for PPhs) which compares fairly with other procedures to obtain pure TPPTS. Since phosphine oxides are readily available from easily formed quaternary phosphonium salts this method potentially allows preparation of a variety of sulfonated phosphines (e.g. (CH3)P(C6H4-3-S03Na)2). 

The Heck reaction is a C-C coupling reaction where an unsaturated hydrocarbon or arene halide/triflate/sulfonate reacts with an alkene in presence of a base and Pd(0) catalyst so as to form a substituted alkene. Kaufmann et al. showed that the Heck reaction carried out in presence of ILs such as tetra-alkyl ammonium and phosphonium salts without the phosphine ligands, resulted in high yields of product. They attributed the activity to the stabilizing effect of ammonium and phosphonium salts on Pd(0) species. Carmichael et al. used ionic liquids containing either A,A -dialkylimidazolium and A-alkylpyridinium cations with anions such as halide, hexafluorophosphate or tetrafiuoroborate to carry out reactions of aryl halide and benzoic anhydride with ethyl and butyl acrylates in presence of Pd catalyst. An example of iodobenzene reacting with ethyl acrylate to give trans-et vy cinnamate is shown in Scheme 14. 

By allowing the phosphonium trifluoromethane sulfonates to react with LiAlH they obtained new compounds which were characterized by NMR(531p = -35 ppm) and assigned structure 1J. Further evidence was gained by protonation, which afforded phosphoranes F2 the latter reaction could be reversed under the action of LiAlH ... 

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