Tetraalkylammonium sulfonates

Poole SK, Shetty PH, Poole CF (1989) Chromatographic and spectroscopic studies of the solvent properties of a new series of room-temperature liquid tetraalkylammonium sulfonates. Anal Chim Acta 218 241-264... 

The catalytic conditions (aqueous concentrated sodium hydroxide and tetraalkylammonium catalyst) are very useful in generating dihalo-carbenes from the corresponding haloforms. Dichlorocarbene thus generated reacts with alkenes to give high yields of dichlorocyclopropane derivatives,16 even in cases where other methods have failed,17 and with some hydrocarbons to yield dicholromethyl derivatives.18 Similar conditions are suited for the formation and reactions of dibromocar-benc,19 bromofluoro- and chlorofluorocarbene,20 and chlorothiophenoxy carbene,21 as well as the Michael addition of trichloromethyl carbanion to unsaturated nitriles, esters, and sulfones.22... 

Other tetraalkylammonium salts are also used in electrochemical measurements they are tetraalkylammonium nitrates, picrates, carboxylates, sulfonates, etc. They can be prepared in the laboratory, by neutralizing the corresponding acid in water with ftjNOH just to the equivalence point, removing water, and then drying. If necessary, the products are recrystallized. Some tetraalkylammonium salts form hydrates and are difficult completely to dehydrate. For practical information, see, for example, Ref. [19]. 

Cesium fluoride has been used to displace halogens, sulfonate groups and nitro groups among others, with fluorine. 1-Bromooctane (1), ethyl bromoacetate (2), benzyl bromide (3) and octyl tosylate (4) have been converted to the respective fluorides 5-7 by treatment with cesium fluoride in the presence of 10% tetraalkylammonium salt (Bu4NBr or Aliquat 336) in the absence of solvent.166... 

The aromatic sulfonates have been employed mostly for reductions, but they would be expected to be reasonably stable toward oxidation. To obtain a reasonable hydrotropic effect, rather high concentrations are used in the original hydrodimerization reaction of acrylonitrile, the medium may be regarded as either a solution of tetraalkylammonium p-toluenesulfonate in water or the salt containing some water. 

The reactions of alkyl sulfonates with sodium, potassium or tetraalkylammonium carboxylates generally proceed with inversion of configuration. In the case of f-alkyl sulfonates, however, a varied amount of elimination products is invariably formed. Of all metal carboxylates, cesium salts (Scheme 43) have proved vastly superior with respect to reactivity and the suppression of undesirable side reactions. ... 

The extraction and chromatography of polar aromatic sulfonates are usually based on ion-pair formation, traditionally with tetraalkylammonium cations,because of their acidity. However, tetraalkylammonium cations are not suited for LC-MS coupling as they are virtually nonvolatile and tend to form adducts that complicate MS detection. ... 

IP-RPLC with TrBA is suitable for the LC-MS analysis of the degradation products of dyes. " However, the alkylamines used for ion-pairing need to be volatile, which limits the number of carbons they can bear. Contrary to the tetraalkylammonium counter-ions, di- and tri-alkylamines do not tend to form adducts in modern API interfaces. Instead, they can act as H donors in their ammonium form and may then influence the ionization process of sulfonates in by decreasing the sensitivity of detection. " " In the same way, these amines diminish the risk of sodium adduct formation and of multiple charging. Due to their suppression effect, the concentration of alkylamines should be reduced to the lowest level acceptable for chromatographic retention. 

NOTE Other phase transfer catalysts were evaluated and all were approximately equally as effective (PT-catalysts ranged from tetraalkylammonium halides to polyethylene glycols). In the same manner the bispropargyl ether of 4,4 -dihydroxydiphenyl sulfone (same as from preparation 6.2) gave a 96.2% yield, m.p. 184-186°C of light tan colored crystals. The NMR was consistent with its structure. 

One interesting design of macromolecular soluble metal complexes is binding of a rhodium complex with sulfonated triphenylphosphine to a soluble polyelectrolyte, polydiallyldimethylammonium tetrakis(3,5-bis(trifluorome-thyl)phenyl borate. In this ease, the content of phosphine groups enables us to control the catalyst solubility in methanol at high content of the phosphine counter ion, the polymer is insoluble and if the ratio of tetraalkylammonium groups to phosphine groups is 4 1 and 10 1, the polymer is soluble in methanol and is an active catalyst of 1-hexene hydroformylation. The catalyst was separated by ultrafiltration [177]. 

Thus, beyond the seminal contributions on deaminations, side reactions were found to most frequently occur in attempted sulfonate displacements when poor nucleophiles, especially fluoride, or the conditions of solvolysis were applied. In this way, impetus for the development of better LGs, represented by trifiuoro-methanesulfonates (triflates) and imidazolesulfonates (imidazylates), as well as more powerful nucleophiles, e.g., tetraalkylammonium salts, was added. In the case of intended fluorinations, the classical sulfonate/fluoride tandem [usually triflate/tetrabutylammonium fluoride (TBAF) or triflate/tris(dimethylamino)... 

Phase transfer-catalyzed fluorination of alkyl halides and sulfonates is efficiently achieved via treatment with solid potassium fluoride in the presence of triphenyltin fluoride cocatalyst. Similarly, the tetraalkylammonium salts of tin, germanium, and silicon have also been studied for their ability to promote phase transfer-catalyzed fluorination. Notably, TBAT was shown to be not nearly as efficient a cocatalyst under conditions analogous to those used for the tin compounds. ... 

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