Trimethylammonium

When ammonium chloride is heated to a higher temperature (160°) with a large excess of anhydrous formaldehyde (as paraformaldehyde), trimethyl-amine hydrochloride (trimethylammonium chloride) may be obtained ... 

Kinetic data are available for the nitration of a series of p-alkylphenyl trimethylammonium ions over a range of acidities in sulphuric acid. - The following table shows how p-methyl and p-tert-h xty augment the reactivity of the position ortho to them. Comparison with table 9.1 shows how very much more powerfully both the methyl and the tert-butyl group assist substitution into these strongly deactivated cations than they do at the o-positions in toluene and ferf-butylbenzene. Analysis of these results, and comparison with those for chlorination and bromination, shows that even in these highly deactivated cations, as in the nitration of alkylbenzenes ( 9.1.1), the alkyl groups still release electrons in the inductive order. In view of the comparisons just... 

CH3O—CO—CH2CH2N(CH3)3]CE [(2-Methoxycarbonyl)ethyl]trimethylammonium chloride... 

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. 

Choline salicylate ((2-hydroxyethyl)trimethylammonium salicylate) is contained in a list of safe and effective compounds (30). Choline salicylate [2016-36-6] (5) is the only liquid salicylate preparation available and is often useful for arthritic patients who have difficulty swallowing tablets. 

Cationic poly(vinyl alcohol) has been prepared by the reaction of A/-(3-chloro-2-hydroxypropyl)-Ai,Ai,A/-trimethylammonium chloride, PVA, and sodium hydroxide (143). Reactions between alkyUdene epoxide and PVA in particulate, free-flowing form in an alkaline environment have been reported (144). 

Purine, 8-trifluoromethyl-pX, 5, 524 (58JA3932, 58JA5744, 59JA2515) Purine, 6-trimethylammonium chloride H NMR, 5, 511 (78JOC2587)... 

Organic salts (e.g. trimethylammonium benzoate) are usually purified by recrystallisation from polar solvents (e.g. water, ethanol or dimethyl formamide). If the salt is too soluble in a polar solvent, its concentrated solution should be treated dropwise with a miscible nonpolar, or less polar, solvent (see Table 8, Chapter 1) until crystallisation begins. 

Aminoethyl)trimethylammonium chloride hydrochloride (chloramine chloride hydrochloride) [3399-67-5] M 175.1, m 260 (dec). Crystd from EtOH. (Material is very soluble in H2O). 

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 striking nucleofugacity of the trimethylammonium leaving group compared with the nitro group in the reaction with fluonde ion is illustrated by the relative reactivities of p-nitrophenyltnmethylammonium perchlorate and p dmi-trobenzene [7J] (Table 4)... 

FIGURE 22.4 New-man projections showing the conformations leading to (a) 1-butene, and (b) frans-2-butene by Hofmann elimination of sec-butyl-trimethylammonium hydroxide. The major product is 1-butene. 

Nucleophiles can also act as acids and bases, and this behavior substantially alters their nucleophilicity. At pH 5, trimethylamine exists mainly as its conjugate acid, trimethylammonium cation. First draw a Lewis structure, and then examine the electrostatic potential for trimethylammonium ion. On the basis of the map, which is the better nucleophile, the cation or the corresponding neutral amine At pH 12, phenol exists mainly as its conjugate base, phenoxide anion. First draw a Lewis structure (or series of Lewis structures), and then examine the electrostatic potential map for phenoxide anion. Which is the better nucleophile, phenoxide or phenol ... 

Electrostatic potential map for trimethylammonium ion shows most positively-charged regions (in blue). 

Examine atomic charges and display electrostatic potential maps for ammonium and trimethylammonium ions (protonated ammonia and trimethylamine, respectively). How many acidic hydrogens are there in each Assuming that solvent coordinates to acidic hydrogens, how many solvation sites are there in each ... 

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