Protonic salts

It s often possible to lake advantage of their basicity to purify amines. For example, if a mixture of a basic amine and a neutral compound such as a ketone or alcohol is dissolved in an organic solvent and aqueous acid is added, the basic amine dissolves in the water layer as its protonated salt, while the neutral compound remains in the organic solvent layer. Separation of the water layer and neutralization of the ammonium ion by addition of NaOH then provides the pure amine (Figure 24.2). 

Photoinduced oxidation of 1,4-dimethoxybenzene (DMB) and tetrahydrofuran (THF) by [Au(C N N-dpp)Cl]+ in acetonitrile upon UV/Vis irradiation have been observed. The time-resolved absorption spectrum recorded 12 (xs after excitation of [Au(C N N-dpp)Cl] with a laser pulse at 35 5 nm showed the absorption band of the DMB radical cation at 460nm, whereas upon excitation at 406 nm in the presence of THF, a broad emission characteristic of the protonated salt of 2,9-diphenyl-l,10-phenanthroline (Hdpp ) developed at 500 nm. 

N-AryInitrones (XIII) formed by oxidation of N-hydroxy-N-methyl arylamines, show high reactivity toward carbon-carbon and carbon-nitrogen double bonds in non-aqueous media (21,203) (Figure 10). Under physiological conditions, however, it appears that N-arylnitrones exist as protonated salts that readily hydrolyze to formaldehyde and a primary N-hydroxy arylamine and efforts to detect N-arylnitrone addition products in cellular lipid, protein or nucleic acids have not been successful (204). Nitroxide radicals derived from N-hydroxy-MAB have also been suggested as reactive intermediates (150), but their direct covalent reaction with nucleic acids has been excluded (21). 

Condensation of the carbonyl function with an amine from a second 1,2-diaminoethane molecule coupled with a repeat of the initial reaction sequence will lead to the cyclic product. It is of interest that this is one case in which the synthesis will also proceed in the absence of a metal ion. Starting from a mono-protonated salt of 1,2-diaminoethane in acetone, the metal-free condensation may proceed via a reaction such as [2.7], Once again, a hydrogen-bonding network may act as a template for the reaction and also serve to stabilize the product once it is formed. A revised synthesis of the metal-free ligand (61) has been published (Hay,... 

Intense bands appear between 1620 and 1630 cm in vibrational spectra of 5,6-dihydro-47/-l,3-oxazinium salts 1. The fragment O —C—N may be responsible for this vibration. N-Protonated salts 1 have IR spectra with a wide band at 3305-3380 cm (NH") (89ZOR2416 92ZOR2569). 

Water-soluble derivatives of polythiophene have been made allowing counterions bound to the polymer backbone to self-dope with the protons (e.g., lithium and sodium ions) injecting electrons into the pi-system. Thus, combinations of sodium salts and proton salts (e.g., prepared from poly-3-(2-ethanesulfonate)thiophene) have been prepared that are both water-soluble and conducting. 

The physical and chemical properties of the X -phosphorins 118 and 120 are comparable to those of phosphonium ylids which are resonance-stabilized by such electron-pulling groups as carbonyl or nitrile substituents Thus they can be viewed as cyclic resonance-stabilized phosphonium ylids 118 b, c, d). As expected, they do not react with carbonyl compounds giving the Wittig olefin products. However, they do react with dilute aqueous acids to form the protonated salts. Similarly, they are attacked at the C-2 or C-4 positions by alkyl-, acyl- or diazo-nium-ions Heating with water results in hydrolytic P—C cleavage, phosphine oxide and the hydrocarbon being formed. 

It has been shown, by NMR studies, that the protonation of indolizines takes place exclusively at the 3-position when this position is unsubstituted. Depending on the nature and positions of the substituents, 3-substituted indolizines give mixtures of 1- and 3-protonated salts (Table 8). In 3,5-disubstituted indolizines, intramolecular overcrowding is reduced by protonation at the 3-position. 

This increase in water solubility on conversion of an amine to its protonated salt has enormous practical consequences in drug delivery. Many important amine-containing drugs, such as morphine (a painkiller) and tetracycline (an antibiotic), are insoluble in aqueous body fluids and are thus difficult to deliver to the appropriate site within the body. Converting these drugs to their ammonium salts, however, increases their solubility to the point where delivery through the bloodstream becomes possible. 

N-[2-(diethylamino)ethyl] phosphorothiolate (78-53-5) and corresponding alkylated or protonated salts (Rj alkyl or H X anion)... 

AEIV-Dialkyl (Rij2 Me, Et, n-Pr or /-Pr) aminoethyl-2-chlorides and corresponding protonated salts (X anion)... 

AEAi-Dimethylaminoethanol (108-01-0) and corresponding protonated salts iV,iV-Diethylaminoethanol (100-37-8) and corresponding protonated salts... 

Vast majority of the scheduled chemicals are directly analyzable by NMR the spectra can be recorded in aqueous or in organic liquids from acidic, neutral, or basic chemicals, and from alkylated and protonated salts. 

An X-ray analysis of salts of lupanine, (8) HC1 2H20 and (8) HC104 H20, showed that ring c was in a boat conformation (cf. Vol. 10, p. 68) infrared studies of the salts and of the anhydrous hydrochloride indicate that this conformation is retained in solution, but that ring c is changed to a chair confirmation in anhydrous lupanine perchlorate. Conformations of mono- and di-protonated salts of 17/5-methyl-lupanine, cr-isolupanine, and 17/ -methyl-cr-isolupanine were also discussed on the basis of i.r. data.11... 

FIGURE 8.2 Structure factors S(QZ) obtained from neutron-scattering patterns of butylam-monium vermiculite gels (upper panels) and from a 0.1 M protonated butylammonium salt solution with no clay (lowest panel). The upper panels show S(QZ) for gels prepared in a 0.1 M deuterated salt solution and in 0.1 and 0.01 M protonated salt solutions. The momentum transfer Q was perpendicular to the clay plates, and the structure factor S(QZ) has been normalized after correction for background scattering and absorption. 

PAni has a very complex structure and doping behaviour, see Fig. 9.6, and the spectra are sensitive to the polymer morphology, the level of oxidation and degree of protonation. This accounts for the considerable variation in tire spectra that have appeared in the literature. The effects are illustrated in Fig. 9.33 for various forms of the protonated salt. These spectra refer to dried films, electrochemically prepared at different electrode potentials, and subject to oxidation by exposure to air. This variation in preparation conditions means that the degrees of oxidation and protonation are not well defined, as evidenced by the pronounced differences in the spectra of the emeraldine prepared at the... 

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