Syntheses and UV/Vis-Spectroscopic Properties of Hydrophilic 2-, 3-, and 4-Pyridyl-Substituted Solvatochromic and Halochromic PyridiniumN-Phenolate Betaine Dyes as New Empirical Solvent Polarity Indicators

Abstract

Syntheses and negative solvatochromism of nine new hydrophilic 2-, 3-, and 4-pyridyl-substituted pyridinium Nphenolate betaine dyes 3−11 are described. These were produced in order to obtain zwitterionic dyes better soluble in water and other aqueous media (such as binary water/solvent mixtures, aqueous ionophore solutions) than the rather

Syntheses and UV–visible spectroscopic properties of two new hydrophilic 2,6‐di(carbamoyl)‐substituted solvatochromic pyridinium N‐phenolate betaine dyes

“…In particular, betaine dye 4 should be useful for the indirect determination of E T (30) values for all kinds of aqueous media because of its water solubility, in addition to the hydrophilic, also water-soluble pyridylsubstituted betaine dyes described recently. 17 The advantage of betaine dye 4 over these pyridyl-substituted betaine dyes 17 is their simpler and less expensive synthesis. Disappointingly, in spite of the introduction of two hydrophilic N-methylaminocarbonyl groups, betaine dye 3 is not sufficiently soluble in water, presumably because of the preferred formation of intramolecular hydrogen bonds with the phenolate oxygen atom of 3 instead of intermolecular hydrogen bonds with the solvent.…”

“…water, N-methylformamide and the alcohols; the very weak C-H hydrogen-bond donors CHCl 3 , CH 2 Cl 2 and CH 3 CN are considered as non-HBD solvents) follow a regression line with a slope smaller than the regression line given by Eqn (3), which can be described by the equation Analogous HBD/non-HBD solvent dispersions of linear E T /E T correlations have also been found for some other pyridinium N-phenolate betaine dyes. 17 Surprisingly, the specific solvation of betaine dye 4 in HBD solvents leads to an altogether smaller susceptibility (slope only 0.789) of 4 against a solvent change. Nevertheless, Eqn (3) can be used for the calculation of E T (30) values for aqueous media, with the aid of E T (4) values of the more hydrophilic betaine dye 4, with sufficient precision.…”

“…15,16 However, replacement of at least two of the five peripheral phenyl groups by 2-, 3-or 4-pyridyl rings leads to comparatively good water-soluble pyridinium N-phenolate betaine dyes, as has been shown recently. 17 This increased solubility in water is obviously due to the possibility of forming intermolecular hydrogen bonds between water and the pyridyl-nitrogen atoms, thus pulling the whole dye into the aqueous solution. Other hydrophilic groups which should lead to better water solubility of 1 are carbamoyl groups of the type -CO-NH-CH 3 and -CO-N(CH 3 ) 2 .…”

A convenient access to 1-substituted-2-azinyl-1-ethanones via acylation of alkylated azines with N-acylbenzotriazoles

“…15 Previous protocols for syntheses of 1-substituted-2-azinyl-1-ethanones (Scheme 1) include: (i) from 1-substituted-2-azinylethynes by hydration in 2N H 2 SO 4 in the presence of HgCl 2 ; 16 (ii) reactions of organometallic reagents with aldehyde followed by Swern oxidation; 17 (iii) radical nucleophilic substitution reactions (S RN 1) of haloazines with ketone enolates; 18 (iv) reactions of α-haloazinium salts (pseudo-Vilsmeier reagents) with N,N-disubstituted enamines followed by acidic hydrolysis and dequaternization; 19 and (v) acylation of methylated azines. Approaches of type (v) are the most commonly used and include treatment of methlyazines with carbonitriles 20 or with activated derivatives of carboxylic acids, especially acid chlorides, 21 esters, 13,22 and amides. 23 Claisen-type condensation methods in refs 22a−c require either a 2:1 molar ratio of metallated alkylazine:acylating ester or 2 molar equivalents of base that might cause ester selfcondensation prior to the lateral acylation.…”

Coordination phenomena of alkali metal, alkaline earth metal, and indium ions with the 1,3,6-naphthalenetrisulfonate ion in protic and aprotic solvents

“…The properties of residual (or small amount of) water in organic solvents have been discussed previously [7,16]. Now that the "residual" water molecules in an organic solvent are isolated each other and cannot form the huge network through hydrogen bonding, its role in the non-aqueous solvent must be similar to diethyl ether [37,38]. The complete precipitation occurs also between Ca 2+ or Ba 2+ and L 3- (Fig.…”