Tetramethylammonium halides

The extraction mechanism accommodates a large number of anionic reactions and provides a rationale for general absence of catalytic activity by hydrophilic ammonium salts, e.g. tetramethylammonium halides [24, 25], which have negligible solubility in organic solvents. Similarly, owing to the highly hydrophilic nature of the hydroxide anion, the mechanism is also untenable as a rationalization for the majority of base-catalysed reactions. 

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.)...

Wood and co-workers have reported an extensive series of careful measurements from 0.1 to 0.8 mol kg on alkali halides, nitrates and carboxylates, and on tetramethylammonium halides. An equilibrium technique was used. The results were fitted to extended Debye-Huckel equations. The solvent has a high dielectric constant (178 at 30.5°C) and osmotic and activity coefficients are higher at corresponding concentrations than in water. The sequences of specific differences are, however, the same as in water. This implies that the... 

It is not difficult to incorporate this result into the general mechanism for hydrogen halide additions. These products are formed as the result of solvent competing with halide ion as the nucleophilic component in the addition. Solvent addition can occur via a concerted mechanism or by capture of a carbocation intermediate. Addition of a halide salt increases the likelihood of capture of a carbocation intermediate by halide ion. The effect of added halide salt can be detected kinetically. For example, the presence of tetramethylammonium... 

The alkyl halide (ethyl bromide in the above equation) can react further with the primary amine produced to give a secondary amine and with that to form a tertiary amine and finally a quaternary ammonium salt. Quaternary ammonium hydroxides are very strong bases like sodium hydroxide. Tetramethylammonium hydroxide is a very important chemical used in the manufacture of semiconductors and other electronic industry products. 

Benzylic halides produce isonitriles (80-90%) with tetramethylammonium cyanoargentate, prepared from tetramethylammonium chloride and silver cyanide [20]. The reaction fails with simple haloalkanes. 

What makes the TTF-TCNQ family distinct from the other salts of TCNQ with cations, such as alkali metals and tetramethylammonium, is that the charge transfer,/ in the TTF-TCNQ family is incomplete (f < 1). TTF-TCNQ members are also different from the TTF-halides in the TTF-halides, where the charge on each halide atom is unity, partial charge transfer (mixed valency) is realized by the formation of nonstoichiometric materials, while in the TTF-TCNQ family, the composition is stoichiometric (1 1), but mixed valence arises because of partial electron-transfer. 

The effect of the anion on the copolymerization rate is controversial. Hilt et al.41 established for different sodium halides the following order of efficiency F < Cl < Br < J . This order was interpreted on the basis of the increase in nucleophilicity or polarizability of the anions. Sfluparek and Mleziva 43) observed that the reaction rate of the benzoate anion was about twice as high as that of the bromide anion in the copolymerization of epichlorohydrine with phthalic anhydride. On the other hand, Luston and Manasek56) did not detect any effect of the anion size on the copolymerization rate initiated by tetramethylammonium and tetrabutylammonium halides. 

Introduction, Amines are organic derivatives of ammonia, with one, two, or three hydrogen atoms replaced by an organic radical. The three types of amines, primary (RNHj), secondary (RjNH), and tertiary (R3N), may be prepared by the reaction of mono-halides with ammonia. In the case of reactive halides, like methyl iodide, the reaction proceeds to the formation of the quaternary salt— tetramethylammonium iodide ... 

It is often difficult to make a comparison between the various results obtained for the same polyenes as different reaction conditions (ratio of reactants, temperature, time) were used in each case. The addition of dichlorocarbene (chloroform/base/phase-transfer catalysis) to straight chain and cyclic unconjugated di- and trienes, carried out under identical conditions but varying the catalysts, showed the peculiar properties of tetramethylammonium chloride. Under precisely tailored conditions, either highly selective mono- or polyaddition of dichlorocarbene to the polyenes is possible tetramethylammonium chloride was the most efficient catalyst for monocyclopropanation. (For the unusual properties of tetramethylammonium salts on the phase-transfer catalyzed reaction of chloroform with electrophilic alkenes see Section 1.2.1.4.2.1.8.2. and likewise for the reaction of bromoform with allylic halides, see Section 1.2.1.4.3.1.5.1.). For example, cyclopropanation of 2 with various phase-transfer catalysts to give mixtures of 3, 4, and 5, ° of 6 to give 7 and 8, ° and of 9 to give 10 and 11. °... 

The thermal decomposition of a variety of tetramethylammonium salts of weak bases has been studied and the major product is generally the methylated anion 92>. The temperature required to decompose the bromide and chloride salts to trimethylamine and the methyl halide is near 360 °C and the products recombine on cooling. The fluoride salt decomposes at a much lower temperature (180 °C) and the products do not recombine 92>. Decomposition of the borohydride salt at 225 °C gives trimethylamine borane and methane 11h... 

At the end of this time, the volatile chloride is separated from the tetramethylammonium chloride by distillation, by again using high-vacuum gas-transfer techniques. Quantitative recovery of the volatile halide can be effected in all cases. The final specific activity of the labeled chloride depends upon the initial specific activity of the labeled tetramethylammonium salt and the quantity of volatile halide labeled. On the assumption of complete randomization of chlorine activity, the specific activity of the volatile halide is given by ... 

Neckers and coworkers have prepared diaryliodonium butyltriphenylborate salts 15-18 (Figure 7.2) by anion exchange of the respective diaryliodonium halides with tetramethylammonium butyltriphenylborate... 

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