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.     

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.     

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.     

Simultaneous spectrophotometric determination of traces of cobalt,nickel and copper with n,n'-bis(3-dimethylaminopropyl)dithio-oxamide

The cobalt, nickel and copper complexes of N,N'-bis(3-dimethylaminopropyl)dithio-oxamide have been characterized in terms of color, effect of pH, rate of color formation, structure in solution, order of addition of reagents, adherence to Beer's law, and sensitivity. The reactivity of the reagent to other ions has been reported. A method for the simultaneous spectrophotometric determination of cobalt, nickel and copper has been developed. The results of the application of this procedure to synthetic samples and to several National Bureau of Standards samples are given.     

New substituted 2,2'-dipyridines and their chelation as fe(ii) and cu(i) complex cations

A study has been made of three new substituted 2,2'-dipyridines, the 4,4'-diphcnyl- and diaminodipyridincs and 4,4',6,6'-tetramethyldipyridine. Comparison is made between their chelation properties as Fe(Il) and Cu(I) colored complexes with similarly substituted di- and tripyridines previously described.4,4'-Diphcnyl-2,2'-dipyridinc forms a ferrous complex of exceptionally large molar absorbtivity (21300), and which has two widely separated absorption maxima (386 and 552 mμ) and equal sensitivity at both absorption peaks. The Cu(I) complex is very sensitive to oxidation in contact with air.4,4'-Diamino-2,2'-dipyridinc is noteworthy because of its ability to reduce Fe(IIl) to Fe(II).     

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.     

Spectrophotometric study of n,n'-bis(m-sulphobenzyl)dithio-oxamide as a reagent for nickel(II)

N,N'-Bis(m-sulphobenzyl) dithiooxamide forms a water-soluble intensely red chelate with nickel-(II) in buffered solutions at pH 10, A 1 Ni : 1R complex is obtained. The absorption maximum of the complex lies at 500 mμ, where the absorbance of (SB)₂DTO is negligible. The molar extinction coefficient is ca, 6962. Beer's law is obeyed over the range from 0.5 μg to 50 μg per ml.     

Studies on tetrachlorodithizone isomers and their applications to the extraction of metal ions

Six isomeric tetrachlorodithizones were synthesized and their electronic and i.r. spectra were measured. Their acid dissociation constants and partition coefficients between 0.5 M NaClO₄ solution and carbon tetrachloride are reported. Their extraction equilibria with Cd(II). Co(II), Cu(II), Hg(II), Ni(II), Pb(II), Tl(I), Zn(II) and Bi(III) and the spectrophotometric characteristics of the complexes formed are described. The 3,3',4,4'-tetrachloro isomer is spectrophotometrically more sensitive than dithizone for Zn, Pb, Hg(II) and Bi(III) whereas the 2,2',3,3'- and 2,2',5,5'-isomers are more sensitive for copper ions. For most of the metals tested, the tetrachlorodithizones allowed quantitative extraction at lower pH than is possible with dithizone.     

Synthesis and electrochemical and spectroscopic studies of a N,N,N',N'-tetraphenylbenzidine-bridged bis(2,2'-bipyridine) ligand and diruthenium complex

A N,N,N',N'-tetraphenylbenzidine-bridged bis(2,2'-bipyridine) ligand and corresponding diruthenium complexes were synthesized and characterized. They show rich multistep redox processes due to the stepwise oxidations of the amine units and ruthenium components. Their absorption and emission spectral changes in response to electrochemical stimulus were examined by spectroelectrochemical measurements. DFT and TDDFT calculations were performed to complement the experimental results.     

Spectrophotometric study of n,n'-bis (2-sulphoethyl)dithio-oxamide as a reagent for palladium

N,N'-bis(2-Sulphoethyl)dithio-oxamide forms two water-soluble yellow chelates with palladium(II), in strong hydrochloric acid solution or in buffered weak acid solution; with excess of reagent, a 1Pd:2R complex is always obtained. The absorption maximum occurs at 425 mμ in 6 M hydrochloric acid and at 382 mμ in buffered weak acid solution (pH 6.6). The colour is formed more slowly in strong acid solution, but there are fewer interferences. Relatively high concentrations of Co²⁺, Ni²⁺ and Hg²⁺can be tolerated, as well as smaller concentrations of Ir³⁺, Rh³⁺ and Cr³⁺. The molar absorption coefficients are 12,860 and 10,840 respectively in 6 M hydrochloric acid and buffered weak acid solution. The standard deviation in both cases is 0.004 absorbance units, i.e. respectively 0.033 and 0.039 μg of Pd.     

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.     

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.     

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.     

Spectrophophotometric determination of manganese with n,n,n',n'-tetrakis(2-hydraxypropyl)ethylenediamine

A new spectrophotometric method for the determination of manganese with N,N,N,N'-tetrakis-(2-hydroxypropyl) ethylenediamine has been developed. The sensitivity is 0.12 μm of Mn per cm² for log I₀/I= 0.001 and Beer's law is obeyed between 2 and 100 p.p.m. of manganese. An ionexchange separation of interfering ions was satisfactory for thc analysis of a variety of National Bureau of Standards samples with good accuracy. The standard deviation with a Mn-bronze was 1.25%.     

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.     

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.     

Reaction of synthetic equivalents of arylideneimines, <Emphasis Type="Italic">viz.</Emphasis>, 1-aryl- <Emphasis Type="Italic">N,N’</Emphasis>-bis(arylidene)methanediamines,with 2,3-diphenylcyclopropenone

N,N’-Bis(arylidene)methanediamines regiospecifically react with 2,3-diphenylcyclo- propenone to form stable adducts of both the mono- and the diaddition. Ammonium acetate serves as the catalyst of the process. During hydrolysis of these adducts, an oxidative coupling of 1,2-dihydro-3H-pyrrol-3-ones occurs with the formation of 2,2’,4,4’,5,5’-hexaaryl-l,1’,2,2’- tetrahydro-H,3’-2,2’-bipyrrole-3,3’-diones.     

Spectrophotometric constants in glacial acetic acid of 2,2'-dipyridine and its 4,4'-disubstituted derivatives as fe(ii) complex cations

A continuing study of of previous work involving; the same organic reagents – 2,2'-dipyridine and lts 4.4'-disubstituted derivatives as Fe(II)complex caution – in glacial acetic acid and in buffered aqueous solutions. Determination of the spectrophotometric Constants (wave length of maximum absorbtion and molar absorptivity) in glacial acetic acid for the visual and near ultraviolet region. of the spectrun has been supplied     

N,N&#x27;-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.     

Alkyl substituted 2,2'-diquinolines and alteration of their spectrophotometric constants following copper (I) chelation

A study has been made of 10 substituted 2,2'-diquinolines together with their physical constants involving maximum and minimum wavelengths of absorption and associated molecular extinction coefficients. An attempt has been made to interpret the results in relation to the π-electron distribution brought about by substitution of methyl or phenyl groups for hydrogen. The known proficiency of the phenyl groups as an electron donor as compared with the lesser tendency provided by the methyl alkyl group, previously clearly shown in the case of similar substitutions in 1,10-phenanthroline, has been found to apply in the case of 2,2'-diquinoline. The study of mono- and di-substitutions in the 3,4- and 4,4'-positions in 2.2'-diquinoline have been included. It is thought that a better understanding has been attained of the factors influencing structural modifications in the parent molecule which would be worthy of consideration in the case of future attempted developments. The most efficient diquinoline yet described, namely, 4,4'-diphenyl-2,2'-diquinoline (molecular extinction coefficient 9020, wavelength of maximum absorption 559 mμ), was obtained following the disclosed principles of structure.