Spectrophotometric or absorptiometric determination of copper with 2,2'-diaminodiethylether-n,n.n', n'-tetraacetic acid

A spectrophotometric determination of copper with 2,2'-diaminodiethylether-N,N,N',N'-tetraacetic acid is proposed. Maximum absorbance is obtained at 720 mμ at pH 2 (1–3) and 25–650 μg Cu/ml can be determined. The reaction is unaffected by temperature or time of standing, and very few ions interfere. A 1 : 1 copper-EEDTA complex is formed.     

The reactions of some bromo-derivatives of compounds having reactive methylene groups with thioureas,and of some resultant thiouronium salts with base

Whereas α-bromocarbonyl compounds react with thiourea to give thiazole derivatives, bromomalononitrile and bromobis(phenylsulphonyl)methane underwent protodebromination. With N,N,N',N'-tetramethylthiourea many of the bromo-compounds gave thiouronium salts but protodebromination sometimes supervened. N,N'-Disubstituted thioureas provided examples of salt formation, protodebromination and cyclisation reactions. The only thiouronium salt to provide an ylide on treatment with base was the S- [bis(phenylsulphonyl)methyl]-N,N,N',N'-tetramethythiouronium bromide. N,N'-Disubstituted salts gave isothioureas rather than ylides. Thiouronium dicyanomethylide underwent cyclisation rather than a Wittig reaction when heated with p-nitrobenzaldehyde, and the aldehyde condensed with the resultant 2-aminothiazole.     

Some metallofluorescent derivatives of 2,2'-diamino-diphenyl-n,n,n',n'-tetraacetic acid

The N,N,N',N'-tetraacetic acid derivatives of five 4,4'-disubstituted 2,2'-diaminodiphenyls have been prepared and their fluorescent properties examined. 2,2'-Diaminodiphenyl-4,4'-dicarboxylic acid-N,N,N',N'-tetraacetic acid exhibits intense fluorescence in aqueous solution above pH 4, and forms stable non-fluorescent l:1 complexes with copper(II) and nickel(II) ions at pH 7.5. The quenching of the fluorescence of the compound by nickel(II) may be used in the fluorimetric determination of nickel.     

Synthesis of 2,2'-biindolyls by coupling reactions

Coupling reactions of indoles forming 2,2'-biindolyls have been investigated. 2-Iodo-N-methyl-indole and unactivated copper gave N,N'-dimethyl-2,2'-biindolyl whereas activated copper yielded N-methyl-indole and the symmetrical trisindolobenzene 5. A mechanism involving the elimination of copper hydride to form a hetaryne intermediate is suggested.Coupling of N-benzenesulfonyl-2-lithioindole with CuCl₂ yielded 2,2'-biindolyl after hydrolysis. N-methyl-2-lithioindole likewise gave N,N'-dimethyl-2,2'-biindolyl.     

Interaction of P(III) compounds with silyl halides : The mechanism of the reaction of phosphorous triamides with trialkylsilyl halides

The reaction of phosphorous hexamethyltriamide with trimethylsilyl iodide or bromide provides a convenient synthesis of the corresponding N,N,N',N'-tetramethylphosphorodiamidous halide. Low temperature ³¹P NMR studies gave evidence of the formation of a phosphonium salt-type complex with direct P-Si bonding in the first step of the reaction. Analogous phosphonium salt intermediates involving P-P bonds were found to be involved in some ligand exchange process between two tricoordinated phosphorus species.     

Reactions of n,n'-thiocarbonyl diimidazole with 1,3-dipolar agents : The synthesis of 5-substituted-2-(1-imidazolyl)-1,3,4-thiadiazoles and 5-( 1-imidazolyl)-1,2,3,4-thiatriazole

By the reaction of N,N'-thiocarbonyl diimidazole with diazomethane, diazoacetic ethylester, phenyl diazoketone and 4-nitrophenyl diazomethyl ketone catalysed by tertiary amines, 5-substituted 2-(1-imidazolyl)-1,3,4-thiadiazoles were prepared, by the action of N,N'-thiocarbonyl diimidazole with azoimide, trimethylsilyl azide and thiophosgene 5-(1-imidazolyl)-1,2,3,4-thiatriazole was synthesised. The structure of compounds prepared was proved by ¹H NMR and mass spectrometry.     

3,3'-Dihydroxybenzidine-n,n,n',n'-tetraacetic acid as a metallofluorescent indicator in edta titrations

3,3'-Dihydroxybenzidine-N,N,N',N'-tetraacetic acid has been prepared and examined as a metallofluorescent indicator in compleximetric titrations. Copper(II) and lead(II) are determined by titration with EDTA in the presence of the indicator, the blue fluorescence of which is restored at the end-point. Manganese, zinc, cobalt and cadmium can also be determined if a dyestuff such as Rhodamine B is present along with the indicator.     

Amidinoethylation—a new reaction—IV : The amidinoethylation of alcohols: a facile synthesis of 3-alkoxy-N,N'-substituted-propanamidines

The amidinoethylation of alcohols takes place by the addition of sodium alkoxides 2 (R¹ = Me, Et) to the CC double bond of a variety of N,N'-substituted-propenamidines 1 (Method A). This illustrates the activation of the CC double bond by the conjugated amidine function and provides a new class of Michael acceptors for alcohols. However, this activation is poorer than with other nucleophiles or Michael acceptors. The amidinoethylation makes available 3-alkoxy-N,N'-substituted-amidines not easily accessible by other classical methods. However, it is demonstrated that the general N,N'-substituted-amidine synthesis via the nitrilium salts can also apply to nitrile compounds having an alkoxygroup present on the molecule (method B). Since the cyanoethylation of alcohols (4) is a very fast and facile reaction the method B is the preferred strategy for the synthesis of 3-alkoxy-N,N'-substituted-propanamidines 3.     

N-Haloamidines-V: Reaction of N-chloro-N'-aroyl-acetamidines and -benzamidines with enamines

The reaction between N-chloro-N'-aroyl-amidines and β,β-disubstituted enamines affords 1 - aroyl - 4 -amino - 4,5 - dihydro - imidazoles in low yields, the main reaction product being N - (2 - morpholino - 2,2 -disubstituted) - ethylidene - N' - aroyl - amidines. A similar reaction course was not observed with enamines bearing a hydrogen atom in the β-position. In this case only products derived from electrophilic chlorination on enamines were isolated.     

Spectrophotometric determination of the dissociation constants of n.n'-bis(2-hydroxyethyl)dithio-oxamide

The dissociation constants of N, N'-bis(2-hydroxyethyl)dithio-oxamide were determined by a spectrophotometric method. The dissociation constants were calculated by means of a weighted least squares technique. N, N'-Bis(2-hydroxyethyl)dithio-oxamide was found to be a dibasic acid with a thermodynamic dissociation constant pK1-11/04. At ionic strength μ - 0.5, pK1 - 10.71 and pK2 13.92.     

Spectkophotometric determination of the dissociation constants of n,n'-bis(3-hydroxypropyl)dithiooxamide and n,n'-bis(2-hydroxypropyl)dithiooxamide

The dissociation constants of N,N'-bis(3-hydroxypropyl)dithiooxamide and N,N'-bis(2-hydroxypropyl)dithiooxamide were determined by a spectrophotometric method using a weighted least squares technique for the calculations. For N,N'-bis(3-hydroxypropyl) dithiooxamide a thermodynamic constant pK₁^T of 11.37 was found. At ionic strength μ = 1, pK₁ = 11.27 and pK₂ = 14.29. For N,N'-bis-(2-hydroxypropyl) dithiooxamide, these values were respectively: pK₁^T = 11.11; pK₁ = 10.99 and pK₂ = 13.75.     

N,N'-diarylformamidinato complexes of the platinum group metals

Some platinum group metal hydrides react with N,N'-diarylcarbodiimides in boiling toluene to yield products containing novel bidentate N,N'-diarylformamidinate (ArNCHNAr) ligands.     

A convenient synthesis of 2-acyl benzothiazoles/thiazoles from benzothiazole/thiazole and N,N'-carbonyldiimidazole activated carboxylic acids

A convenient and efficient strategy for the synthesis of 2-acyl benzothiazoles/thiazoles has been developed. The treatment of benzothiazole/thiazole with allylic Grignard reagents readily generates the corresponding 2-Grignard reagents, which is followed by a reaction with N,N'-carbonyldiimidazole activated carboxylic acids to afford various 2-acyl benzothiazoles/thiazoles products. The synthetic method is applicable to a wide array of carboxylic acids and allows easy access to 2-acyl benzothiazoles/thiazoles with considerable yields under mild reaction conditions.     

Chemical analysis of mixtures of some heavy metals by means of differential reaction rates of ligand substitution reactions

The simultaneous determination of some heavy metals in their mixtures is described. The method is based on the differential reaction rate of ligand substitution reactions involving ethyleneglycol bis(2-aminoethylether)N,N,N',N'-tetraacetic acid (EGTA) and 4-(2-pyridylazo)-resorcinol (PAR). Various combinations at the 10^-6M level of heavy metal ions such as manganese(II), iron(III), cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II), mercury(II) and lead(II) can be determined photometrically.     

Synthese de la cyclo-5'-8 desoxy-5' adenosine: stereochimie et mecanisme de la cyclisation d'un derive de l'iodo-5' adenosine par le zinc

N,N'-Dibenzoyl 2', 3'-O-isopropylidene 5'-deoxy 5'-iodo adenosine can efficiently transformed into the corresponding 5',8-cyclo-7,8-dihydronucleoside by zinc in pyridine. Only one diastereoisomer is obtained. By spin decoupling and NOE techniques at 250 MHz, the R-configuration at C-8 was established. This compound showed typical dihedral angles of about 90° for the vicinal protons H-1', H-2' and H-3', H-4'. Using adenosine derivatives stereospecifically labelled at C-5', it was demonstrated that the cyclisation occurs with racemisation at that position.     

Analysis of the dipole moments of some possible thiouronium and guanidinium fluorenylides

The dipole moments of “thiouronium fluorenylide”, “N,N'-diphenylthiouronium fluorenylide”, and “N.N'-diphenylguanidinium fluorenylide” are analysed, confirming that the thiourea derivatives exist largely, and the guanidine derivative entirely, as prototropic fluorenyl-isothioureas or diphenylguanidine respectively.     

The preparation of novel 4,4'- and N,N'-linked pipecolic acid derivatives

Routes used for the preparation of the novel 4,4'- and N,N'-linked pipecolic acids (1a,band 2b,c) are described and discussed together with the characterisation of the products and intermediates.     

Monophotonic ionization through a long-lived ion-pair: N,N,N',N'-tetramethylbenzidine in acetonitrile solution

The photoionization of N,N,N',N'-tetramethylbenzidine (TMB) has been studied by measurements of transient absorption and transient photoconductivity in several organic solvent. It has been concluded that the solvent-solute exciplex interactions are responsible for the photoionization of TMB in solutions of acetonitrile, benzonitrile, and pyridine.     

Characterization of a potentially axially symmetric europium(III) complex of a tetraacetate,tetraaza, macrocyclic ligand by luminescence excitation,emission and lifetime spectroscopy

The Eu(III) complex of the octadentate macrocyclic ligand, 1,4,7,10-tetraazacyclododecane-N,N',N'',N''' -tetraacetate, DOTA, has been examined by luminescence excitation, emission, and lifetime spectroscopy using pulsed dye laser techniques. The results confirm the expected axially symmetric nature of the major component in solution and reveal that 1.2 ± 0.4 water molecules arc coordinatcd to the Eu(III) ion in the complex.     

AcylCo(III) Salen : A new unsymmetrical ketone synthesis

New acyl complexes of N,N'-ethylenebis(salicylideneiminato)cobalt(III) 2 were prepared and their acyl transfer reactions with several nucleophiles were examined. The reaction with MeMgI at room temp gave unsymmetrical ketones of the type MeCOR in reasonably good yields.