Quaternary amines specifications

Currently available BAS include cholestyramine, colestipol and colesevelam hydrochloride (colestimide). Cholestyramine comprises a long-chain polymer of styrene with divinylbenzene trimethylbenzylammonium groups, whereas colestipol is a long-chain polymer of l-chloro-2,3-epoxypropane with diethylenetriamine. Colesevelam HCl is poly(allylamine hydrochloride) cross-linked with epichlorohydrin and alkylated with 1-bromodecane and 6-bromo-hexyl-trimethylammonium bromide. Bile-acid binding is enhanced and stabilised in the latter compound by long hydrophobic sidechains, increased density of primary amines, and quaternary amine sidechains. For this reason, colesevelam HCl exhibits increased affinity, specificity and capacity to bind bile acids compared with the other BAS. Colesevelam HCl also binds dihydroxy and trihydroxy bile acids with equal affinity, contrasting with cholestyramine and colestipol that preferentially bind dihydroxy bile acids (CDCA and deoxycholic acid). The latter BAS can lead to an imbalance towards trihydroxy bile acids and a more hydrophilic bile-acid pool. 

Once DNA has been condensed by a polycation, it is important for these complexes to retain a certain level of stability in salt solutions to allow sufficient time for cellular uptake of the particles. Izumrudov et al. (1999) studied the stability of a variety of polymers including polyvinylpyridines, linear poly amines, branched polyamines, polymethacrylates, and polyamides in salt solutions at a variety of pHs. They observed that polymers with predominantly primary amines produced the most stable polymer/DNA complexes followed by tertiary then quaternary amines, while higher molecular weight polymers resulted in more stable complexes for all amine types. Thus, it may be possible to specifically control complex stability by adjusting the relative amount of each amine type in the polymer. 

Mixtures of more complex nitrogen-containing compounds such as amine oxides and ethoxylated quaternary amines are also amenable to the type of Investigation described above ( ). The CAD spectra of these substances are dominated by a few informative ions which result from specific fragmentations characteristic of the class of compounds. The Crfi2n+2 1099 series also occurs but at a less abundant level for the ethoxylated compounds, and the series is of low abundance for the amine oxides. 

Quaternary amines, such as tetraalkylammonium bromides and hydroxides (the alkyl group being Q to C4) are the typical zeolite templates. Quaternary amines fulfill the above-mentioned requirements of stability, specific interaction with the precursor (electrostatic interaction between quaternary amines and silicate), and easy removal (by calcination). 

Conventional ionization techniques like El or Cl are less well suited for the characterization of quaternary amines, which are the most common cationic surfactants. Because of their thermal instability and low volatility their corresponding mass spectra only show decomposition products and fragment ions which make it impossible to analyze environmental samples of unknown composition. By the use of EAB-MS and FD-MS, however, ionization of quaternary amines can be achieved without decomposition. FAB spectra are characterized by strong quasimolecular ions as well as structure specific ions. ° FAB in combination with collisionally activated decomposition (CAD) in a tandem mass spectrometer enables a clear differentiation between quasimolecular and fragment ions, which is often difficult using FAB alone. FD spectra of quaternary amines are dominated by quasimolecular ions as already described for other surfactant... 

Obviously, alkaloids are not the only group of substances containing tertiary and quaternary amine groups, so not much specificity can be claimed. Most of the literature dealing with the specificity of the Dragendorff,s reagent concentrates on the risk of false positive reactions by other secondary metabolites potentially present in plant material. Here cumarines, hydroxyflavones, some triterpenes, and cardenolides could be mentioned. Even proteins can sometimes give positive reactions. 

Hard-surface, usually metal, cleaning in which very specific kinds of dirt need to be removed, such as grease on engines, rust on metal parts or burned carbon on cooking surfaces. The detergents may also need to be biocidal, such as blended non-ionic and quaternary amine surfactants. 

A third group of ion-exchange supports are pellicular, consisting of a solid inert core made of PSDVB agglomerated with 350 nm functionalized latex. The quaternary amine groups are closely and uniformly bound on the microbeads, improving flow and reducing non-specific retention. These pellicular supports are primarily used for carbohydrate analysis. 

Quaternary amine salts may be titrated with acid by conventional nonaqueous procedures. To be precise, the anion associated with the quaternary is titrated. In the case of halides, mercuric acetate is added to replace free halide ion with easily titratable acetate ion [see Section III] (8,9). Such methods are suitable for analysis of pure samples, which do not contain other salts. A more specific assay of cationic surfactants is the two-phase titration with an anionic surfactant, described in Chapter 16. 

The procedure given here is ASTM D2076 (10). The AOCS procedure, Te 3a-64, is almost identical (11). Both are written specifically for analysis of quaternary amines. 

The action of redox metal promoters with MEKP appears to be highly specific. Cobalt salts appear to be a unique component of commercial redox systems, although vanadium appears to provide similar activity with MEKP. Cobalt activity can be supplemented by potassium and 2inc naphthenates in systems requiring low cured resin color lithium and lead naphthenates also act in a similar role. Quaternary ammonium salts (14) and tertiary amines accelerate the reaction rate of redox catalyst systems. The tertiary amines form beneficial complexes with the cobalt promoters, faciUtating the transition to the lower oxidation state. Copper naphthenate exerts a unique influence over cure rate in redox systems and is used widely to delay cure and reduce exotherm development during the cross-linking reaction. 

Analytical methods iaclude thin-layer chromatography (69), gas chromatography (70), and specific methods for determining amine oxides ia detergeats (71) and foods (72). Nuclear magnetic resonance (73—75) and mass spectrometry (76) have also been used. A frequentiy used procedure for iadustrial amine oxides (77) iavolves titratioa with hydrochloric acid before and after conversion of the amine to the quaternary ammonium salt by reaction with methyl iodide. A simple, rapid quaHty control procedure has been developed for the deterrniaation of amine oxide and unreacted tertiary amine (78). 

Since then, organic amines, quaternary-ammonium bases, metal complexes, and other compounds have been extensively used in zeolite synthesis, acting as space fillers with low specificity, structure-directing agent, or true templates ... 

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