Carboxylate anion ammonium salts

Chem. Descrip. Carboxylated polyelectrolyte ammonium salt Uses Pigment dispersanL thixotrope for gk s and semigloss latex paints Features Hydrophilic exc. gloss tential low foam good water resist. Properties Colorless liq. dens. 9.6 Ib/gal vise. 260 cps f.p. 32 F anionic 35% act. 

Chem. Descrip. Polymeric carboxylic acid ammonium salt Ionic Nature Anionic... 

Flotation reagents are used in the froth flotation process to (/) enhance hydrophobicity, (2) control selectivity, (J) enhance recovery and grade, and (4) affect the velocity (kinetics) of the separation process. These chemicals are classified based on utili2ation collector, frother, auxiUary reagent, or based on reagent chemistry polar, nonpolar, and anionic, cationic, nonionic, and amphoteric. The active groups of the reagent molecules are typically carboxylates, xanthates, sulfates or sulfonates, and ammonium salts. 

It is thought that these trialkonolamine borates may enhance the reactivity of the rhodium carbonyl anions by minimizing their tendency to form contact ion pairs in solution under the reaction conditions employed. The same patent discloses that ammonium salts and salts of Groups I and II, especially cesium and ammonium carboxylate salts, function as promoters (63). 

Methyl esters undergo trans-esterification with the quaternary ammonium salts at high temperature and the reaction has been used with some effect for the preparation of, for example, n-butyl esters by heating the methyl ester with tetra-n-butylammo-nium chloride at 140°C [31]. Optimum yields (>75%) are obtained in HMPA or in the absence of a solvent. A two-step (one-pot) trans-esterification under phase-transfer catalysed conditions in which the carboxylate anion generated by initially hydrolysis of the ester is alkylated has been reported for Schiff s bases of a-amino acids [32] and for A-alkoxycarbonylmethyl [1-lactams [33]. Direct trans-esterification of methyl and ethyl esters with alcohols under basic catalytic conditions occurs in good yield in the presence of Aliquat [34, 35]. 

Guanidine forms salts with such relatively weak acids as nitromethane, phthalimide, phenol and carbonic acid [20], Interactions between carboxylate anions of proteins and added guanidinium ion are thought [19, 56] to be weaker than the interactions with ammonium ions the role of guanidinium-carboxylate interactions in stabilizing natural protein conformations has been discussed [36c]. A few reports of metal complex formation by guanidines [57-60], and aminoguanidines [61] have appeared. 

The same authors did not observe intramolecular cyclization by the coupling reaction of the ammonium cation and the carboxylate anion, at least in their work [81]. The presence of elimination reactions of the ammonium salt should not be ruled out, at least at high temperatures. 

Typical synthetic procedures include the reaction of alkyl halides with the silver salts of carboxylic acids, the reaction of carboxylate anions in alkali with an excess of a dialkyl sulphate, (especially dimethyl sulphate), and heating tertiary184 or quaternary ammonium salts of carboxylic acids. These routes are particularly valuable for the preparation of esters of seriously sterically hindered acids. For example, Fuson et al.iK made the methyl ester of 2,4,6-triethylbenzoic acid by heating the tetramethyl ammonium salt to 200-250°C, viz. 

Therefore the extent of extraction or back-extraction is governed by the concentration of X- in the aqueous phase, the distribution coefficients, and selectivities depending on the anion. In nitrate solutions, the distribution coefficient decreases as the atomic number of the REE increases, whereas in thiocyanate solutions, the distribution coefficient roughly increases as the atomic number of the REE increases. The position of yttrium in the lanthanide series is not the same in nitrate and thiocyanate solutions, and this phenomenon has been used for high purity yttrium manufacture in the past. A combination of extraction by carboxylic acids then by ammonium salts is also utilized for production of high purity yttrium. 

Initiation takes place by rapid reaction of an ammonium salt with the anhydride (Eq. (46)) whereby ammonium carboxylate is formed. In the propagation step, the carboxylate anion opens an epoxy ring and forms an ammonium alcoholate (Eq. (47)). The latter reacts with the anhydride to yield another ester bond, and ammonium carboxylate is recovered (Eq. (48)). Termination occurs through decomposition of the ammonium counter ion, the alkoxide anion abstracting a proton from the quaternary nitrogen with the formation of a deactivated tertiary amine. 

Initiation involves the reaction of the tertiary amine (the most widely used Lewis base) with an epoxy group, giving rise to a zwitterion that contains a quaternary nitrogen atom and an alkoxide anion. The alkoxide reacts at a very fast rate with an anhydride group, leading to a species containing a carboxylate anion as the active center. This ammonium salt can be considered as the initiator of the chainwise copolymerization. 

Biocidal applications. The use of quaternary ammonium salts in disinfecting systems for household and industrial cleaners has been known for many years [95, 96]. Alkyl-benzyldimethyl quaternaries, alkyltrimethyl quaternaries, and dialkyldimethyl quaternaries are the more commonly used biocidal quaternary ammonium salts [16]. Recently, dialkyldimethyl quaternary ammonium salts have received renewed attention as potential wood preservatives to replace the heavy metal types [97]. Metal-free wood preservative formulations containing dialkyldimethyl ammonium salts with non-halide anions, such as carboxylates, borates, and carbonates, have been developed [98, 99]. 

Now we can carry out an Sn2 reaction on the sulfonate with a carboxylate anion. A terra-alkyl ammonium salt is often used in the polar solvent DMF to get a clean reaction. This is the key step and we don t want any doubt about the outcome. 

It is important to note that even certain phase-transfer catalysts can be carbonylated to carboxylic acids, not by cobalt tetracarbonyl anion catalysis, but by acetylcobalt tetracarbonyl. This is a slow but high-yield reaction that occurs for quaternary ammonium salts that are capable of forming reasonably stable free radicals. For example, phenylacetic acid is formed in 95% yield from benzyltriethylammonium chloride (benzyl radi-... 

Another feature of the results presented in Table 4 is that all but two of them feature salts in which the photoreactive component is a carboxylate anion and the chiral auxiliary is an ammonium ion. There is, of course, no reason why salts composed of reactive ammonium ions and optically pure carboxylate (or sulfonate) anions should not give equally good results, and entries 10 and 13 illustrate this point. 

Depending on their chemical structure, surfactants capable of forming micelles are usually classified into cationic e.g. ammonium salts), anionic e.g. sulfates, carboxylates), ampholytic e.g. zwitterionic salts), and non-ionic surfactants (usually containing polyoxyethene chains) cf. Table 2-10 in Section 2.5. 

Heating at high temperature (>100 °C) dehydrates the resulting ammonium salt of the carboxylate anion to form an amide, though the yield can be low. 

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