Tetramethylammonium

If tetramethylammonium chloride is dissolved in hydrochloric acid, the unstable salt [(CH3)4N] [HClj], can be crystallised out here chlorine is showing weak hydrogen bonding (cf. F H—F which is stable, and Cl - H—Cl which is unstable). 

Ammonium Compounds. Salts and hydroxides containing quadricovalent nitrogen are named as a substituted ammonium salt or hydroxide. The names of the substituting radicals precede the word ammonium, and then the name of the anion is added as a separate word. For example, (CH3)4N+I is tetramethylammonium iodide. 

Above about 50°C tetramethylammonium hydroxide is formed as a by-product it is the sole product above 100°C (214). 

Monobasic acids are determined by gas chromatographic analysis of the free acids dibasic acids usually are derivatized by one of several methods prior to chromatographing (176,177). Methyl esters are prepared by treatment of the sample with BF.—methanol, H2SO4—methanol, or tetramethylammonium hydroxide. Gas chromatographic analysis of silylation products also has been used extensively. Liquid chromatographic analysis of free acids or of derivatives also has been used (178). More sophisticated hplc methods have been developed recentiy to meet the needs for trace analyses ia the environment, ia biological fluids, and other sources (179,180). Mass spectral identification of both dibasic and monobasic acids usually is done on gas chromatographicaHy resolved derivatives. 

Sodium or tetramethylammonium triacetoxyborohydride has become the reagent of choice for diastereoselective reduction of P-hydroxyketones to antidiols. Trialkylborohydrides, eg, alkaH metal tri-j -butylborohydrides, show outstanding stereoselectivity in ketone reductions (39). 

The ozonides are characterized by the presence of the ozonide ion, O - They are generally produced by the reaction of the inorganic oxide and ozone (qv). Two reviews of ozonide chemistry are available (1,117). Sodium ozonide [12058-54-7] NaO potassium ozonide [12030-89-6] 35 rubidium ozonide [12060-04-7] RbO and cesium ozonide [12053-67-7] CsO, have all been reported (1). Ammonium ozonide [12161 -20-5] NH O, and tetramethylammonium ozonide [78657-29-1/, (CH ) NO, have been prepared at low temperatures (118). 

Tetramethylammonium chloride [75-57-0] is an example. Ditahowalkyldimethylammonium chloride [68783-78-8] is an example. 

Physical Properties. Most quaternary compounds are soHd materials that have indefinite melting poiats and decompose on heating. Physical properties are determined by the chemical stmcture of the quaternary ammonium compound as well as any additives such as solvents. The simplest quaternary ammonium compound, tetramethylammonium chloride [75-57-0] is very soluble ia water (163) and iasoluble ia nonpolar solvents. As the molecular weight of the quaternary compound iacreases, solubiUty ia polar solvents decreases and solubiUty ia nonpolar solvents iacreases (164—166). For example, trimethyloctadecylammonium chloride [112-03-8] is soluble ia water up to whereas dimethyldioctadecylammonium chloride [107-64-2] has... 

Cychc carbonates are produced ia high yield under very mild conditions by treating chlorohydrins with tetramethylammonium hydrogen carbonate ia acetonitrile [75-05-8] under a CO2 atmosphere (38). 

Modern analytical pyrolysis has conventionally been canied out only by thermal energy to break some covalent bonds in the sample molecules at elevated temperatures to produce smaller and/or volatile fragments (pyrolyzates). On the other hand, the reactive pyrolysis in the presence of organic alkaline, such as tetramethylammonium hydroxide [(CH / NOH] (TMAH) has recently received much attention especially in the field of chai acterizing condensation polymers. 

Tetramethylammonium bromide [64-20-0] M 154.1, sublimes with dec >230°. Crystd from EtOH, EtOH/diethyl ether, MeOH/acetone, water or from acetone/MeOH (4 1) by adding an equal volume of acetone. It was dried at 110° under reduced pressure or at 140° for 24h. 

Tetramethylammonium chloride [75-57-0] M 109.6, m >230°(dec). Crystd from EtOH, EtOH/CHCl3, EtOH/diethyl ether, acetone/EtOH (1 1), isopropanol or water. Traces of the free amine can be removed by washing with CHCI3. 

Tetramethylammonium hydroxide (5H2O) [10424-65-4 (5H2O), 75-59-2 (aq soln) ] M 181.2, m 63°, 65-68°. Freed from chloride ions by passage through an ion-exchange column (Amberlite IRA-400, prepared in its OH" form by passing 2M NaOH until the effluent was free from chloride ions, then washed with distilled H2O until neutral). A modification, to obtain carbonate-free hydroxide, uses the method of Davies and Nancollas [Nature 165 237 1950]. 

Tetramethylammonium perchlorate [2537-36-2] M 173.6, m >300 °(dec). Crystd from acetone and dried in vacuo at 60° for several days. 

Tetramethylammonium tetraphenylborate [15525-13-0] M 393.3. Recrystd from acetone, acetone/CCl4 and from acetone/1,2-dichloroethane. Dried over P2O5 in vacuum, or in a vacuum oven al 60° for several days. 

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... 

It is interesting to note that although the first examples of template effects were observed in nitrogen macrocycles (see chapter 2) no template effect appears to operate in the synthesis of 72. Richman and Atkins note this in their original report . The authors replaced the sodium cation with tetramethylammonium cations and still obtained greater than 50% yield of tetra-N-tosyl-72. Shaw considered this problem and suggested that because of the bulky N-tosyl groups, .. . the loss of internal entropy on cyclization is small He offered this as an explanation for the apparent lack of a template effect in the cyclization. 

Gramine forms flat needles or leaflets, m.p. 138-9°, [a]p 0°, and yields a pierate, m.p. 144-5°, perehlorate, m.p. 150-1° platiniehloride, red needles, m.p. 180-1° dec.) and a methiodide, m.p. 176-7°. Aeeording to Madinaveitia, gramine on treatment with methyl iodide in methyl aleohol yields trimethylamine, tetramethylammonium iodide and a substanee presumed to be 3-hydroxymethylindole. With ethyl iodide in acetone a normal ethiodide, CiaH gNjI, m.p. 176°, is formed. 

The preparation of 2,6-difluoropyridine in 97% yield from 2,6-dichloropyridine can be accomplished at lower temperatures (150 °C) by using a catalytic amount of tetramethylammonium chloride in dimethyl sulfoxide containing less than 1% water [66]... 

Cyclic sulfates rapidly react with the fluoride ion sources to give monofluoro derivatives Thus, the 2,3-cyclic sulfate of methyl-4 6 O benzylidene p D manno pyranoside cleanly reacts with tetramethylammonium fluoride to give methyl 4,6-0-benzylidene 2 deoxy 2 fluoro-p-D-glucopyranoside-3-sulfate Acid hydrolysis followed by acetylation gives 2 deoxy 2 fluoro-P-D-glucopyranoside triacetate in 84% isolated yield [5S] (equation 38)... 

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 . ... 

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