Trimethylammonium salts

Molecular weights of polymers that function as bridging agents between particles are ca 10 —10. Ionic copolymers of acrylamide are the most significant commercially (see Acrylamide POLYMERS). Cationic comonomers include (2-methacryloyloxyethyl)trimethylammonium salts, diethyl aminoethyl methacrylate [105-16-8], and dimethyldiallylammonium chloride [7398-69-8], anionic comonomers include acryUc acid [79-10-7] and its salts. Both types of polyacrylamides, but especially the anionic, can be more effective in the presence of alum (10,11). Polyetbylenimine and vinylpyridine polymers, eg, po1y(1,2-dimethy1-5-viny1pyridiniiim methyl sulfa te) [27056-62-8] are effective but are used less frequentiy. 

The leaving group also affects the amount of internal versus terminal alkene that is formed. The poorer the leaving group, the more El cb-like is the transition state. This trend is illustrated for the case of the 2-butyl system by the data in Table 6.6. Positively charged leaving groups, such as in dimethylsulfonium and trimethylammonium salts, may favor a more El cb-like transition state because their inductive and field effects increase the acidity of the p protons. 

The selective basic degradation of 1,2-dicarbaclovodode-carborane(12) and its C-methyl and C-phenyl derivatives has been recently reported.3 The ethanolic potassium hydroxide degradation of C, C"-dimethyl-l, 2-dicarbaclovododecaborane (12) and the isolation of the trimethylammonium salt of the resulting B9C2Hio(CH3)2 anion are described here as an illustration of this general reaction. The properties of the trimethylam-... 

The KB9C2H10(CH3)2 recovered from the ethanol solution is dissolved in 150 ml. of water, and a solution of 22 g. of trimethylammonium chloride in 100 ml. of water is added slowly with vigorous stirring. The precipitated salt is isolated by filtration, washed once with 50 ml. of cold water, and dried in vacuum over phosphorus(Y) oxide. The yield of (CH3)3NHB9C2Hio-(CH3)2 is 37.8 g. (98%). To purify the salt by crystallization, a boiling solution of 38 g. of the salt in 2 1. of water is allowed to cool slowly to 0°. Eighty per cent of the material is recovered in the first crop. Successive crops of the trimethylammonium salt may be obtained, or the anion may be recovered as the less soluble tetramethylammonium salt by addition of an aqueous solution of tetramethylammonium chloride to the mother liquor. The tetramethylammonium salt may be recrystallized from an ethanol-water solution. 

Method B using a polymer-supported trimethylammonium salt The oxirane (10 mmol) and RCOSPh (10 mmol) in diglyme (5 ml) are added to the resin (= 0.5 mmol -NMef salt) and the mixture is stirred at 110°C for 24 h. The resin is removed and Et20 (30 ml) is added to the filtrate. The ethereal solution is washed well with water, dried (MgS04), and evaporated to yield the p-acyloxyethyl thioether. 

To a greater or lesser degree the spectra of all C-6 ionic salts, whether they are substituted with a covalent group at C-2 or not, are comprised of a mixture of the spectra of C-6 ionic and C-6 covalent forms. Differences among the spectra of the compounds result from secondary effects on the structure of the bare anions such as hydrogen bonding and dimerization due to hydrophobic dye/dye molecular interactions. This is particularly obvious when the fluorescence spectra of the ammonium salts at room temperature of the C-2, C-6 bis trimethylammonium salt shows a triad of broad peaks centered at 583 nm. At reduced temperature the same compound shows three sharper peaks at 538, 583, and 605 nm. The shortest wavelength of these... 

A highly pure compound can be obtained by transformation into the benzyl-trimethylammonium salt (see below), which can be crystallized from THF-isopropyl alcohol. 

The amino group can be A-alkylated with iodomethane (Scheme 8.6) to give initially A-methylaniline and then A,A-dimethylaniline. The final product is the trimethylammonium salt, which is formed by quaternization of the nitrogen. 

Reaction monitoring is highly facilitated as routine experiments such as II NMR, 13C NMR, mass spectrometry, IR spectroscopy, elemental analysis can be performed. This is mainly due to the simplicity of the structure. Unlike polymeric supports where signals from the support often prevent accurate measurement of conversion or side product concentration, trimethylammonium salts have only a limited effect on NMR spectra with a singlet and a multiplet in the 3.0-3.2 ppm region. Additionally onium salt supported products can eventually be analyzed using HPLC and mass spectrometry. 

Treatment of 2,3-bis(teT/-butylsulfanyl)cyclopropenethione with hydrogen sulfide/trimeth-ylamine in methanol gave the trimethylammonium salt of 2-to-f-butylsulfanyl-3-thioxocyclo-prop-l-enethiolate (2), which was further transformed by treatment with cyanogen bromide and then aniline or diisopropylamine to give amino-substituted products 3 and 4, respective-... 

The reaction of polychloropyridazines with trimethylamine at room temperature gives trimethylammonium salts, which when heated in dimethylfor-mamide, were transformed into dimethylaminopyridazines. For example,... 

In the presence of 15% pentanol, large amounts of water can be solubilized into heptane or toluene solutions of Ci2-Ci6 alkylpyridinium or alkyltrimethylammo-nium bromides (Venable, 1985). In heptane/pentanol, the longer-chain surfactants appear to be more effective than the shorter ones, while in toluene/pentanol the shorter ones appear to be more effective. In both solvent mixtures, the pyridinium salts are more effective solubilizers than the corresponding trimethylammonium salts. All the quaternaries investigated were more effective than sodium dodecyl sulfate. 

Schikowsky [71]. Accordingly, three pathways exist for the direct photolysis heterolysis of the C-I bond, homolysis of the C-I bond, and formation of a charge-transfer complex with the counterion (Scheme 3). A similar competition between homolytic and heterolytic photocleavage pathways has also been observed in (l-naphthylmethyl)-trimethylammonium salts [72],... 

Other Reactions.—Hofmann degradation of 5a-cholestan-4)8-yltrimethylammon-ium salts gives the Saytzeff (A ) product the large 4 -10)5-interaction gives the elimination El character, as found previously in the 6)S-derivative. The 4a-yl-trimethylammonium salt, like some other equatorial derivatives, suffers N-demethylation, with some elimination to give the ( Hofmann ) product. ... 

Hofmann degradation of 5of-cholestan-4a- and -4/3-yI trimethylammonium salts closely resembled that of the C-6 quaternary ammonium salts the 4j -compound producing solely the 4-ene by Saytzeff elimination whilst the 4a-epimer gives largely demethylated 4a-dimethylamino-steroid, with some 3-ene. ... 

Borax has frequently been used in conjunction with such reagents as (3-chloro-2-hydroxypropyl)trimethylammonium salts,1853 epichlorohydrin or formaldehyde,1401185318541855 melamine-formaldehyde resins,1856 (carboxymethyl) starch, oxidized (carboxymethyl)starch, (carboxymethyl)starch-acrylamide copolymer,1857 and oxidized starch.1858 Boric acid was also used jointly with formaldehyde,1859 and starch dialdehyde has been crosslinked with boric acid.526... 

With a primary amine such as n-octylamine, we observe at low conversion (8 %) high selectivity for the N-monoalkylated product whereas 90 % N,N-dimethylated amine are formed at high conversion (94 %). In reductive alkylation, it is even more difficult to obtain the monomethylated product selectively. For example, in the Eschweiler Clarke procedure [17], only the dimethylated amine is formed, even with an amine-to-formaldehyde ratio of 1. In the Hofmann-type reaction, a mixture of mono- and dimethylamine with the corresponding trimethylammonium salt is generally produced. 

For polysalt amphoteric membranes, a cationic polyelectrolyte solution such as poly(benzyl trimethylammonium salt) and an anionic polyelectrolyte solution such as poly(styrene sulfonate) are mixed and a polymer salt precipitated. The polymer salt is then dissolved in a suitable solvent and is formed into a membrane by a casting method.103... 

For the preparation of codeine from morphine a number of methylation procedures are available among which the use of trimethylammonium salts is customary and has been referred to in Chap. 4. 

One example of side chain co-function modification in 1-boraadamantane is known (Equation (12)). It should be noted that the trimethylammonium salt (86) is readily soluble in water <91JOM(412)311>. 

A typical synthetic transformation using the Hofmann elimination also illustrates an alternative synthetic approach to this reaction. Reaction of iodomethane with the dimethylamino moiety in 215 leads to the trimethylammonium salt. This ammonium leaving group allows the usual Hofmann elimination sequence, with thermal syn-elimination giving the vinyl derivative, 216.203 204 j is variation is important since using an amine as a Hofmann precursor is often more convenient than relying on an Sn2 reaction of an amine and a halide to produce the requisite ammonium salt (sec. 2.1.A). 

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