Betaine compounds

Each of the aromatic monocatlonic systems (14)-(27) can be converted into a neutral system by substitution of an anionic O, S or NR group on to a ring carbon atom. However, (14) and (15) each give three such systems, (16)-(21) two each, and (22)-(27) one each. The resulting 24 systems can be divided into two groups 12 systems for the azolinones and related compounds (Scheme 4) and 12 systems for the mesoionlc (betaine) compounds (Scheme 5). 

To recognise ion suppression reactions, the AE blend was mixed together either (Fig. 2.5.13(a) and (b)) with the cationic quaternary ammonium surfactant, (c, d) the alkylamido betaine compound, or (e, f) the non-ionic FADA, respectively. Then the homologues of the pure blends and the constituents of the mixtures were quantified as presented in Fig. 2.5.13. Ionisation of their methanolic solutions was performed by APCI(+) in FIA-MS mode. The concentrations of the surfactants in the mixtures were identical with the surfactant concentrations of the blends in the methanolic solutions. Repeated injections of the pure AE blend (A 0-4.0 min), the selected compounds in the form of pure blends (B 4.0—8.8 min) and their mixtures (C 8.8— 14.0 min) were ionised and compounds were recorded in MID mode. For recognition and documentation of interferences, the results obtained were plotted as selected mass traces of AE blend (A b, d, f) and as selected mass traces of surfactant blends (B a, c, e). The comparison of signal heights (B vs. C and A vs. C) provides the information if a suppression or promotion has taken place and the areas under the signals allow semi-quantitative estimations of these effects. In this way the ionisation efficiencies for the pure blends and for the mixture of blends that had been determined by selected ion mass trace analysis as reproduced in Fig. 2.5.13, could be compared and estimated quite easily. 

It is of interest that arsenobetaine is accumulated so much more readily than other similar arsenic species. The cationic nature of the compounds may be significant those compounds not bioaccumulated by the mussel are all anionic or neutral at seawater pH, whereas those accumulated all contain a positive charge. The zwitterionic nature of arsenobetaine may also be a factor, and recent experiments with C-3 and C-4 arsenic containing betaines (compounds 42 and 43) support this view. Preliminary results (164 ) show that mussels bioaccumulate these compounds readily the relative bioaccumulation efficiency was C-2 betaine (arsenobetaine) 100, C-3 betaine 65, and C-4 betaine 6 (Table VII). These results also suggest that the distance between the charges in the molecules may be an additional factor. Expansion of studies on arsenic uptake from water may elucidate the actual processes of absorption of arsenobetaine, which may involve a specific ion channel. 

The synthesis of betaines of several aromatic azines and their benzologs by Katritzky et al. stimulated also investigations of the corresponding pyrida-zines. They were prepared by methylation of the corresponding pyridazinones with methyl toluene-p-sulfonate to 317 and subsequent conversion into betains (319). Contrary to other related betaines, compounds of the type 319 are unreactive toward a variety of dipolarophiles. The hydroxy form of the cation (317) was shown to (ncdominate over the oxo form (318). UV, IR, and NMR data have been used for structure examination of betaines (95) and some pyridazinones. NMR spectra established... 

H) Betaines (compounds reported = 3) In addition to the new betaine norzooanemonin (248), Weinheimer et reported the isolation of known trigonelline (249) and homarine (250) from specimens of P. americana collected in the Florida Keys. Each of these betaines is widely distributed in marine invertebrates. The structure of norzooanemonin was proposed on the basis of its spectroscopic data and was confirmed by total synthesis (Scheme 5). 

Aimed at investigating the taste enhancing activity of the individual enantiomers of alapyridaine, enantiopure 1 was prepared upon reductive animation of 5-(hydroxymethyl)-2-furanaldehyde and L-alanine with Raney nickel/hydrogen. This reaction resulted in the corresponding ( S)-A -(1-carboxyethyl)-2-hydroxymethyl-5-(methylamino)furan (Figure 7). The latter was converted into the target pyridinium betain compound by mild oxidation with bromine in water/methanol to yield (+)-(iS)-l. Similarly, the reaction with D-alanine resulted in (-)-(R)-l. After purification, the presence of (5)-l and (R)-1 was proven by polarimetry, revealing optical rotations of +40.2° and -38.6°, respectively (72). 

Excited states of ketones (compound I) and positive solvatochromic dyes, e.g. diethylamino p-nitrobenzene (compound II of table VII) or related compounds are more strongly solvated by polar solvents when comparki with apolar ones. The shift of the K a transition of substituted p-nitro enoles as well as the n a transition of ketones are used as empirical polarity scales, a and % of a solvent. The energy shifts of the a a transition of substituted pyridinium-N-phenoIate betaines (compound III) and the charge-transfer absorption... 

The names choline and betaine are retained for unsubstituted compounds. 

A wide variety of quaternaries can be prepared. Alkylation with benzyl chloride may produce quaternaries that are biologically active, namely, bactericides, germicides, or algaecides. Reaction of a tertiary amine with chloroacetic acid produces an amphoteric compound, a betaine. 

The threat of accidental misuse of quaternary ammonium compounds coupled with potential harmful effects to sensitive species of fish and invertebrates has prompted some concern. Industry has responded with an effort to replace the questionable compounds with those of a more environmentally friendly nature. Newer classes of quaternaries, eg, esters (206) and betaine esters (207), have been developed. These materials are more readily biodegraded. The mechanisms of antimicrobial activity and hydrolysis of these compounds have been studied (207). AppHcations as surface disinfectants, antimicrobials, and in vitro microbiocidals have also been reported. Examples of ester-type quaternaries are shown in Figure 1. 

The solubihty characteristics of sodium acyl isethionates allow them to be used in synthetic detergent (syndet) bars. Complex blends of an isethionate and various soaps, free fatty acids, and small amounts of other surfactants reportedly are essentially nonirritant skin cleansers (66). As a rule, the more detersive surfactants, for example alkyl sulfates, a-olefin sulfonates, and alkylaryl sulfonates, are used in limited amounts in skin cleansers. Most skin cleansers are compounded to leave an emollient residue on the skin after rinsing with water. Free fatty acids, alkyl betaines, and some compatible cationic or quaternary compounds have been found to be especially useful. A mildly acidic environment on the skin helps control the growth of resident microbial species. Detergent-based skin cleansers can be formulated with abrasives to remove scaly or hard-to-remove materials from the skin. 

These compounds are usually written in the unionized form as in (8 Z = NH, NR, O, S). Canonical forms of types (9) or (10) are important, i.e. these compounds can also be considered as betaines formally derived from azolium ions. Many compounds of this type are tautomeric and such tautomerism is discussed in Section 4.01.5.2. 

Azole iV-oxides, iV-imides and iV-ylides are formally betaines derived from iV-hydroxy-, iV-amino- and iV-alkyl-azolium compounds. Whereas iV-oxides (Section 4.02.3.12.6) are usually stable as such, in most cases theiV-imides (Section 4.02.3.12.5) andiV-ylides (Section 4.02.3.12.3) are found as salts which deprotonate readily only if the exocyclic nitrogen or carbon atom carries strongly electron-withdrawing groups. 

Diazoalkanes add to the carbon-carbon double bonds of 2,3-diphenylthiirene 1-oxide and 1,1-dioxide. The adducts lose SO or SO2 to give pyrazoles and related compounds (Scheme 103) (80CB1632). Mesoionic oxazolones (75CLH53), 4-methyl-5-phenyl-l,2-dithiolene-3-thione (80JOU395) and pyrylium betaines (72JOC3838) react similarly via intermediate adducts (Scheme 104). Enamines (Scheme 96) and ynamines add to the double bond of 2,3-diarylthiirene 1,1-dioxides to give acyclic and cyclic sulfones by a thermal. 

There are some reports on reactions involving complete N—N cleavage in diazirine reactions such as formation of amidine (205) from chlorophenyldiazirine, or on formation of products containing only one nitrogen atom. Betaine (206) was described as a product from difluorodiazirine and triphenylphosphine. Compound (207) is formed from decomposing (204) and cyclohexane (79AHC(24)63). 

Photoisomerization of azomethinimines to diaziridines was observed in several classes of compound. Diazepine (271) was converted, even by sunlight, to its diaziridine isomer (68JA4738). Further photoisomerizations were observed with azomethinimines (272) obtained from pyrazolidones (70JPR161), and with some pyridazinium betaines (273). 

Polyfluoroalkyl- andperfluoroalkyl-substituted CO and CN multiple bonds as dipolarophiles. Dmzo alkanes are well known to react with carbonyl compounds, usually under very mild conditions, to give oxiranes and ketones The reaction has been interpreted as a nucleophilic attack of the diazo alkane on the carbonyl group to yield diazonium betaines or 1,2,3 oxadiazol 2 ines as reaction intermediates, which generally are too unstable to be isolated Aromatic diazo compounds react readily with partially fluorinated and perfluorinated ketones to give l,3,4-oxadiazol-3-ines m high yield At 25 °C and above, the aryloxa-diazolines lose nitrogen to give epoxides [111]... 

Another solvatochromic polarity measure, (30), is the transition energy for compound 8, which is 2,6-diphenyl-4-(2,4,6-triphenylpyridinio)phenolate, also referred to as Dimroth-Reichardt s betaine. 

The structure of malonyl-a-aminopyridine (cf. 121) has been discussed by Snyder and Robinson/ who interpreted the infrared and ultraviolet spectra and the fact that it could be converted into a monochloro derivative (122, R = Cl) to indicate that the intra-molecularly hydrogen-bonded hydroxy form 122 (R = OH) was predominant. However, comparison of the basicities of the methoxy compound 122 (R = OMe), the mesomeric betaine 123 (R = Me), and the parent compound indicates that in aqueous solution the last exists mainly in the zwitterion form 123 (R = H), ... 

Tliis chapter covers nitrogen-containing fulvalenes that can be obtained by replacement of CH=CH and/or CH, for example, types 1-3 starting from compounds 1-6. Compounds in which nitrogen atoms are arranged on the periphery of the cross-conjugated system as in 15 or 16, as well as derivatives in which the central double bond contains heteroatoms as in 17, are not included. For azoniafulvalenes of type 17 and related heterocyclic betaines see (94AFIC197). 

Tire and NMR parameters of some 1-alkyl-4-benzimidazolyl-2-idene- (type 72) and l-alkyl-4-(5-methylpyrazolyl-3-idene)-l,4-dihydro pyridines (type 73) were discussed in 89CC1086 and 91JOC4223. Comparison of the shifts for DMSO-dg and CDCI3 solutions with data reported for quaternary pyridinium compounds as well as anionic species in the azole series and data obtained for mesoionic betaines of the azinium azolate class left no doubt that these heterofulvalenes have a betaine character and, therefore, the NMR signals correspond to their dipolar resonance form. 

There are specific associations of various types of dipoles with the four major classes of heterocyclic mesomeric betaines, which have implications in providing a rational foundation for correlating the chemical reactions of these compounds (85T2239). Eight dipole types, systematically generated by union of the heterocations H2C = with carbanions and... 

In general, the A -methyl derivative of a given compound absorbs at longer wavelengths than the O-methyl derivative. The intensity of a band which appears in aqueous solutions beyond the maximum absorption in alcohol and which is due to the absorption of the betainic species alone, is a measure of the tautomeric equilibrium. The pA"a value of the 2-methyl-hydroxyisoquinolinium chlorides increase in the order 4-hydroxy (4.93), 8-hydroxy (5.81), 6-hydroxy (6.02), 5-hydroxy (6.90), and 7-hydroxy (7.09 in water at 25 °C, respectively) (57JCS5010). Thus, 2-methyl-4-hydroxyisoqui-nolinium chloride is the strongest acid. The UV spectra of 2-methyl-isoquinolinium-5-olate (34) and 2-methyl-isoquinolinium-8-olate (39) were also presented (61BCJ533) and the formation of a quinoid structure of 2-methyl-isoquinolinium-6-olate (38) can also be detected by means of UV-spectroscopy. 

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