Tetramethylammonium chloride cations

The tetramethylammonium salt [Me4N][NSO] is obtained by cation exchange between M[NSO] (M = Rb, Cs) and tetramethylammonium chloride in liquid ammonia. An X-ray structural determination reveals approximately equal bond lengths of 1.43 and 1.44 A for the S-N and S-O bonds, respectively, and a bond angle characteristic bands in the IR spectrum at ca. 1270-1280, 985-1000 and 505-530 cm , corresponding to o(S-N), o(S-O) and (5(NSO), respectively. Ab initio molecular orbital calculations, including a correlation energy correction, indicate that the [NSO] anion is more stable than the isomer [SNO] by at least 9.1 kcal mol . ... 

In an attempt to demonstrate the existence of pentavalent nitrogen, Schlenk and Holtz studied the reaction of triphenylmethyl sodium with tetramethylammonium chloride (52). The highly colored material was strongly conducting in polar solvents and could be identified as a salt, the stability of which is due to the resonance stabilization of the triphenyl-methide anion. In the absence of such stabilizing substituent effects (53), as with n-butyl or another alkyllithium reagent, a metalation of the tetramethylammonium cation occurs, which leads to type I products (18) ... 

The addition of HC1 to 3-hexyne shows an unexpectedly different picture. The rate law is rather complicated and the reaction is accelerated by addition of chloride ion (as tetramethylammonium chloride). The product distribution ranges from that shown under 5 of Table 2 to the almost exclusive formation of ammonium chloride. The postulated mechanism excludes the formation of vinyl cations intermediates and indicates a concerted transition state for the reaction of type 16. 

Unimolecular capsules have also been prepared around a single resorcin[4] arene core, such as 80, held together by hydrogen bonds [ 179]. These capsules form in the presence of tetramethylammonium chloride, whereby the cation exists within the cavity and the chloride anion exists outside. Evidence for this arrangement was obtained from both solution studies ( H-NiMR) and X-ray crystal structures (Fig. 64). Studies with either larger or smaller cationic partners to the chloride formed weaker, less stable complexes, indicating that the size of the cation may template the capsule formation. 

Fig. 64 Side view of the crystal structure of 80 binding tetramethylammonium chloride with the cation in the cavity and the anion located outside...

Formic acid melts at 8.40°C and has a cryoscopic constant Ac = 1.932 K kg mol". These results of J. Lange were obtained by a Beckmann cooling-curve technique in which a differential apparatus gave values of freezing point depression for which a precision of 0.0001 K was reported. Formic acid has a dielectric constant of 58.5 at 16°C and results for potassium chloride, potassium picrate and tetramethylam-monium chloride were fitted to an extended Debye-Hiickel equation for completely dissociated electrolytes. Tetramethylammonium chloride showed the smallest deviation from the limiting law and this was ascribed to the affinity of the organic cation for the solvent. 

Ballester and co-workers reported the solid-state self-assembly of resorcinecalix [4]pyrrole 60 with tetramethylammonium chloride (Fig. 5.46) [120]. The solid packing was controlled by their ratio in the crystallization solutio n. A 1 1 ratio yielded a crystal structure with a columnar packing of the endo cavity complex, in which calix[4]pyrrole units were bridged together by tetramethylammonium cations. 

Solid lithium aluminium hydride can be solublized in non-polar organic solvents with benzyltriethylammonium chloride. Initially, the catalytic effect of the lithium cation in the reduction of carbonyl compounds was emphasized [l-3], but this has since been refuted. A more recent evaluation of the use of quaternary ammonium aluminium hydrides shows that the purity of the lithium aluminium hydride and the dryness of the solvent are critical, but it has also been noted that trace amounts of water in the solid liquid system are beneficial to the reaction [4]. The quaternary ammonium aluminium hydrides have greater hydrolytic stability than the lithium salt the tetramethylammonium aluminium hydride is hydrolysed slowly in dilute aqueous acid and more lipophilic ammonium salts are more stable [4, 5]. 

Fig. 5.32. Alkylation and GC of aqueous inorganic halides. A, authentic salts B, solution prepared on a cation-exchange column. Peaks 1 = methylfluoride 2 = water 3 = methyl chloride 4 = methyl bromide 5 = trimethylamine 6 = methyl iodide. Conditions stainless-steel column, 10 ft. x 1/4 in. O.D., Chromosorb 101 (80-100 mesh) helium flow-rate, 75 ml/min column temperature, 125°C injection port temperature, 360°C 6 til of an aqueous solution of tetramethylammonium halides (0.25 M each) injected. (Reproduced from Anal. Chem., 42 (1970) 1672, by courtesy of J. MacGee and the American Chemical Society.)...

When strongly hydrophobic cationic surfactants are present in the mobile phase the hydrophobic surface of the stationary phase becomes dynamically conditioned with respect to the adsorption of the surfactant. This confers an ion-exchange capability on the stationary phase. Cassidy and Elchuk (32, 33) reported use of cetylpyridinium chloride to coat the stationary phase "permanently", but used tetrabutyl and tetramethylammonium salts in the mobile phase. Their equilibration procedure also employed the use of acetonitrile in the initial conditioning step, thus increasing the overall cost of the analysis. Knox and Hartwick (36)... 

The simultaneous detection of small cations (ammonium, sodium, potassium, calcium, magnesium, and strontium) and anions (bromide, chloride, nitrite, nitrate, sulfate, perchlorate, thiocyanate, and chlorate) from low explosives in postblast residue using an elaborate electrolyte composed of a cationic chromophore and modifiers (imidazole/HIB A/18-crown-6 ether/ACN), an anionic chromophore (1,3,6-naphthalenesulfonic acid) and flow reversal agent (tetramethylammonium hydroxide) has been presented. " ... 

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