Betaines amine, free

Unlike betaines, amine oxides are never anionic. However, they do show cationic or nonionic behavior depending on the pH, and therefore behave quite similarly [40]. Amine oxides are produced by the oxidation of tertiary alkylamines for example, dimethyl or ethoxylated amines with hydrogen peroxide. They are colorless liquids and free from salt (NaCl). As such, they are excellent foamers. The various types of amine oxides are shown in Figure 12.14. 

Most studies of micellar systems have been carried out on synthetic surfactants where the polar or ionic head group may be cationic, e.g. an ammonium or pyridinium ion, anionic, e.g. a carboxylate, sulfate or sulfonate ion, non-ionic, e.g. hydroxy-compound, or zwitterionic, e.g. an amine oxide or a carboxylate or sulfonate betaine. Surfactants are often given trivial or trade names, and abbreviations based on either trivial or systematic names are freely used (Fendler and Fendler, 1975). Many commercial surfactants are mixtures so that purity can be a major problem. In addition, some surfactants, e.g. monoalkyl sulfates, decompose slowly in aqueous solution. Some examples of surfactants are given in Table 1, together with values of the critical micelle concentration, cmc. This is the surfactant concentration at the onset of micellization (Mukerjee and Mysels, 1970) and can therefore be taken to be the maximum concentration of monomeric surfactant in a solution (Menger and Portnoy, 1967). Its value is related to the change of free energy on micellization (Fendler and Fendler, 1975 Lindman and Wennerstrom, 1980). 

The presence of an internal salt, a zwitterion or betaine, in cephalosporins enhances their solubity in water, making such agents particularly suitable for parenteral administration. The preparation of one such dmg first involves the replacement of allyl oxygen in the tert-butylcarbonyloxy protected 7-ACA derivative (23-1) by nitrogen in azaindan (23-2) to afford the betaine (23-3). The protecting group is then removed so as to free the amine on the azetidone (23-4) by treatment with trifluoroacetic acid. Reaction with the thiazole free acid (23-5) in the presence of DCC then affords cefpirone (23-6) [26]. 

Reaction of the salts 349 (Section III,D,4) with a number of primary amines and hydrazines gives the 11-amino bromides (350). Treatment of two of these salts [350 R = R = H, R = Me.NiCiU)., and NH CSNH] with base gives the free betaines [346 R = R2 = H, R = Me2N(CH2)3 and NH2CSNH] as stable solids. 

Over the past decade, studies by DeGroot [6] and others have indicated that free amines present in cocamidopropyl betaine appear to be sensitizers. It has not been clear as to whether the problem was due to free DMAPA or cocamidopropyl dimethylamine but recent evidence suggests it maybe due to both. The producers of these products reacted to the problem and the typical alkylamidopropyl betaine produced today contains less than 10 ppm of free DMAPA and less than 0.5% of cocamidopropyl dimethylamine (Table 6.9). 

As the tertiary amines are consumed during carboxymethylation, the pH value falls considerably. This slows the reaction rate proportionally because free amines are also removed from the reaction medium by protonation as well as carboxymethylation. By maintaining an alkaline pH throughout the reaction, carboxymethylation can be carried out faster and more completely, with less amidoamine in the final product [26], This technique can give amidoamine contents of <0.3% in the betaine. Some types of CAPB have higher amidoamine contents, up to 3%, for special applications. 

Column 2 strongly basic anion exchanger hydroxide. Retains carboxy-lates and WW and SW amphoterics. Elute with hydrochloric acid. Car boxy lates and amphoterics are eluted rapidly. Response of phosphate esters is uncertain, but if they were not retained by column 1 they would be retained by column 2 and also eluted rapidly. Quaternary salts are converted to the hydroxide, weakly basic cationics (amines, amine oxides) to the free base and betaines to the zwitterionic form. All of these pass through. 

The first end-point measures the excess hydrochloric acid. The additional titrant to the second end-point measures the betaine. A third point of inflection, corresponding with the titration of glycolic acid, monochloro-acetic acid and free amine, is found if the titration is continued further. These extraneous substances, being titrated over a different part of the curve, do not interfere, and the authors [19] confirmed by experiment that this was so. 

Chem. Descrip. Lauryl dimethyl betaine Ionic Nature Amphoteric Chem. Analysis 1% max. free amine CAS 683-10-3 EINECS/ELINCS 211-669-5... 

The precise characterization of commercial betaines is difficult because of the variety of similar compounds which may be present in the product (1,11). Free amine concentration is a critical parameter because of the odor it gives to the product. 

Alkyldimethylbetaine and free amine can be determined by potentiometric acid-base titration (12). For titration of the betaine, the sample is dissolved in a mixture of 10 1 methyl isobutyl ketone/isopropanol to which a little HCl has been added. Three breaks are observed on titration with ethanolic KOH, corresponding respectively to excess HCl, the betaine, and combined impurities amine, glycolic acid, and monochloracetic acid (see Fig. 1). Carbon dioxide must be excluded during the titration. Sodium chloride is insoluble in the solvent system and precipitates. The titration is very sensitive to water concentration (16)... 

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