Spectrophotometric determination of scandium with anthrarufin-2,6-disulfonic acid (disodium salt)

A new spectrophotometric method for the determination of scandium, is described using anthraru-fin-2, 6-disulfonic acid (disodium salt) as a reagent. The color reaction has a sensitivity of 0.004 μg Sc per cm² for log $\text{I}{}_0\text{1}$ = 0.001 and obeys Beer's law up to 2 p.p.m. The effects of ph, time, order of addition of the reagents, temperature, and diverse ions were investigated. A separation procedure was developed and applied to six salt solutions containing scandium plus a variety of foreign ions.     

Synthesis of 4a-, 4e-phenyladamantanones and 2,4-o-benzenoadamantane by π-route

The acid catalysed reaction of 4-oxa-homoadamantan-5-one ($\text{1}$) with benzene yielded a mixture of 4^a-phenyladamantan-2-one ($\text{7}$), the equatorial isomer' ($\text{8}$) and 2-phenyl-2,4-o- benzenoadamantane ($\text{9}$) A plausible reaction pathway for the occurrence of $\text{9}$. is put forward. The structure of $\text{9}$, was deduced from spectroscopic data and reaction of the proposed intermediate 2,4^a-diphenyladamantan-2-ol ($\text{11}$) with acid. 2,4-o-Ben-zenoadamantane ($\text{16}$) is prepared likewise.     

Electronic control of stereoselectivity-21 : Stereochemical parallelism between dienophilic capture and singlet oxygenation of isodicyclopentadiene derivatives

The stereochemistry and product distribution resulting from reaction of 4',5',6',7'- tetrahydrospirol[cyclopropane-1,2']-[4,7]methano[2$\text{H}$]indene(5), endo-2-methyl(6a) and 2,2-dunethyl-4,7-dihydro-4,7-methano-2$\text{H}$-indene (6b), as well as 4',5',6',7'-tetrahydrospiro[cyclopentane-1,2']-[4,7]methano-[2$\text{H}$]indene (7) with singlet oxygen have been determined. Stereochemical assignments to the diepoxide products were readily deduced by ¹³C-NMR comparison with the spectra of the parent isomcrs of established structure (X-ray). To unravel the stereochemistry of the epoxy aldehydes, recourse was made to 2D NOE experiments The observed stereosclectivity and reaction profile of each substrate are analyzed and placed in proper mechanistic and energetic perspective.     

A kinetic study of the permanganate—oxalate reaction and kinetic determination of manganese(II) and oxalic acid by the stopped-flow technique

The reduction of permanganate by oxalate in the presence of manganese(II) ion in acidic media is described. All reactions were run at 525 nm and constant ionic strength 1.0 M. The reaction was found to obey the rate expression —$\text{d[MnO}{}_4{}^{\mathrm{-}}\text{]}\text{d}\text{t}$ = k [Mn²⁺] [C₂O₄^2-]² [MnO₄^-] [H⁺]^-2 = k' [MnC₂O₄] [MnO₄^-]. The values of k and k' were shown to be 5.4 × 10⁴ M^-1 s^-1 and 8.2 × 10⁴ M^-1 s^-1, respectively. Reaction rate methods for the determination of manganese(II) and oxalic acid are reported. The rate of disappearance of permanganate was monitored automatically and related directly to manganese-(II) and oxalic acid concentrations. Manganese(II) in the ranges 1–10 × 10^-4 M and 1–10 × 10^-3 M and oxalic acid in the range 0–20 μg ml^-1 can be determined very rapidly with a precision of 1–2%.     

Relationship between the general laws of vapor-liquid equilibria and the analytical curve of emission spectrometry

The relationship between the vapor-liquid equilibrium and the analytical curve of emission spectrometry is discussed on the basis of Hirata's equation, i.e., $\text{y}{}_1\text{y}{}_2$ = α($\text{x}{}_1\text{x}{}_2$)^β, where y is the mole fraction in the vapor phase, x in the liquid phase, α and β are constants for binary systems in a certain concentration range, and the indices $\text{1}$ and $\text{2}$ refer to the two components. Evaporation produced by different atomization-excitation systems can be characterized by apparent evaporation constants, α' and β', the values of which fall between the true values, α and β, of the normal distillation, and unity. Two powder techniques were selected representing the limiting cases: injection spark excitation (α' ≈ α, β' ≈ β) and controlled arc excitation (α' ≈ 1, β' ≈ 1). Using these excitation methods, the analytical curves of the impurities in industrial alumina and electrocorundum were studied using cup-electrode techniques with arc excitation. As a result, one of Hirata's rules could be selected for a given pair of elements. An unambiguous correlation between the properties of the analytical curves and Hirata's rules could be established.     

A novel synthesis of 3-cyanoindoles and a new route to indole-3-carboxylic acid derivatives

2-Alkyl-3-cyanoindoles are obtained when 1-alkylmethyl-2-chloro-(or 2-phenylsulfonyl)-3-phenylsulfonylindoles are reacted with excess azide ion (90°/DMF). The reaction is considered to occur by a fragmentation recombination process in which the Schiff's base $\text{12}$ is of central importance. This proposal is supported by the formation of 2-substituted indole-3-carboxylates $\text{17}$ from aldehydes and the α-phenylsulfonyl-$\text{o}$-aminophenylacetic acid ester derivative $\text{16}$.     

Examples of transvesicular reactions

The oxidation of vesicle-entrapped Ellman's anion ($\text{1}$) by exovesicular $\text{o}$-iodosobenzoate ion ($\text{2}$) is a permeation-limited, transvesicular reaction; transvesicular esterolyses reactions are also illustrated.     

Alkali salts of (ω-sulphoxyalkyl)-acrylates and -methacrylates: Radical polymerization and copolymerization

A new preparation of alkali salts of (ω-sulphoxyalkyl)-acrylates and -methacrylates, by reaction of alkali salts of acrylic and methacrylic acids with cyclic sulphates, is described; spectral characterization of the products is described. The kinetics of the radical polymerization of sodium (2-sulphoxyethyl)methacrylate (SSEM) were studied; monomer reactivity ratios for copolymerization with methacrylic acid were: r₁ = 1.1 ± 0.15 and r₂ = 0.73 ± 0.05. Dark electrical surface conductivity of some homopolymers and copolymers with methacrylic acid was found to be 10⁴–10¹¹$\text{Ω}{}^{\mathrm{?1}}$, depending on relative humidity.     

The trapping of excitons by impurities and its dependence on the impurity concentration

When excitons migrate through molecular crystals containing impurities the relative probabilities of their decay at a site of the host lattice or at an impurity can often be deduced experimentally from the material's luminescence spectrum. Theoretically, the mean probability $\text{K}$ that an exciton will be captured by an impurity can be calculated by solving a diffusion equation with a term that takes account of the exciton-impurity interaction. The results of such calculations are reported, with particular emphasis on the dependence of $\text{K}$ on the impurity concentration c for small values of c. It is found that if the impurities behave as absorbing spheres $\text{K}$ is proportional to c, but if the interaction potential is of the multipole-multipole form then d(log$\text{K}$)/d(logc) depends on the exciton's mean free path and on c, and can be much less than unity. The physical reasons for these results are discussed.     

Spectro photometric determination of bromate with o-arsanilic acid

o-Arsanilic acid reacts with bromate ions in dilute acid solution and forms a reddish-brown color which is suitable for the spectrophotometric determination of bromate. The reaction has a sensitivity of 0.05 μg BrO₃^- per cm2 for log $\text{I}{}_{\mathrm{o}}\text{l}$ = 0.001 and obeys Beer's law up to 50 p.p.m.The standard deviation for the color development (387 p.p.m. brornate) is 0.95%, and 0.52% in the determination of bromate in salt solutions.Optimum analytical conditions for the reaction have been established and a procedure for the spectrophotometric determination of bromate is given.     

Chemoselective protection of heteroaromatic aldehydes as imidazolidine derivatives : Preparation of 5-substituted furan- and thiophene-2-carboxaldehydes via metallo-imidazolidine intermediates

Furan-, thiophene- and $\text{N}$-methylpyrrole-2-carboxaldehydes may be transformed into the corresponding $\text{N}$,$\text{N}$'-dimethylimidazolidines in a reaction not requiring acid catalysis. The resulting furan and thiophene (but not $\text{N}$-methylpyrrole) derivatives may be metallated in high yields [predominantly at the 5 (α-) positions of the heteroaromatic rings] and the carboxaldehyde functionality regenerated under very mild conditions. Treatment of the aldehydoketone 2-acetyl-5-formylthiophene with $\text{N}$,$\text{N}$'-dimethylethylenediamine gives $\text{only}$ the product of reaction at the aldehyde function thus establishing this methodology as a potentially valuable method for the protection of an aldehyde in the presence of a ketone.     

Direct current and differential pulse polarographic behaviour of benzylpenicilloic acid

The differential pulse and direct current polarographic behaviour of benzylpenicilloic acid (BPA) is discussed. In pH 9.2 borate buffer, the single anodic wave (E_{$\text{1}\text{2}$} = -0.25 V) obtained is diffusion-controlled at concentrations less than 2 × 10^-5 M but adsorptioncontrolled in 10^-4 M solution. Cyclic voltammetry at a hanging mercury drop electrode shows that the electrode reaction is reversible at pH 9.2. The differential pulse peak current is linearly related to concentration in the range 10^-6—2 × 10^-5 M. Penicillamine yields an anodic peak well separated from the BPA peak. Both substances may be determined in each other's presence. Intact penicillin decreases the BPA peak but the linearity between i_p and BPA concentration is maintained.     

The spectrophotometric determination of nitrate in natural waters,with particular reference to sea-water

Nitrate can be reduced to nitrite in good yield by means of hydrazine in alkaline solution; the reaction is promoted by catalytic quantities of copper. The authors have established the optimum conditions for tlie reduction and applied the method to the determination of nitrate in fresh waters and in sea-waters. The nitrite formed is determined by Mellon and Rider's modification of the Griess-Ilosvay procedure. The reduction with hydrazine is carried out in the presence of 0.25 p.p.m. of copper at pH 9.6 in a solution buffered with sodium phenate. It is complete within 24 hours at room temperature. The method will detect ca. 0.3 μg NO₃$\text{N}\text{l}$ and gives a standard deviation of ca. 2% in the range 20-600 μg NO₃-$\text{N}\text{l}$. Up to 60 determinations can be made per 6 hour working period. The interference of nitrite has been investigated. Ammonium salts, urea, and amino acids do not interfere, at the concentrations at which they occur in sea-water.It is preferable to analyse samples immediately after collection, but if this is not possible, they should be filtered, sterilized with 2 p.p.m. of mercuric chloride and stored in glass containers.     

Mass spectrometry of 1 phenyl-1, 2-dibromopropylphosphonic acid and its methyl ester

$\text{erythro}$-1-Phenyl-1,2-dibromopropylphosphonic acid is known to decompose rapidly into the monomeric metaphospbate-anion (PO₃), 1-phenyl-1-bromopropene, and bromide ion in protic or aprotic solvents in the presence of a hindered tertiary amine. The present study compares the behavior of this phosphonic acid in solution and in the gas phase. The gas-phase thermolysis of the acid involves mainly the loss of bromine and of the phosphoryl group, -P(O)(OR) (OR') (R = R' = H). The same type of pathway is followed in the ionization/excitation processes (“cationic reactions”) that follow from electron impact in mass spectrometry. The thermal and cationic reactions of the monomethyl and dimethyl esters of the phosphoric acids (R=H,R'= CH₃ and R = R' = CH₃, respectively, in -P(O)(OR)(OR')) are entirely analogous to those of the free dibasic acid.     

v-Triazolines. part XXI. Spiro[bicyclo[2.2.1]hept-2-ene[54']1',2'.s'-triazole]derivatives from cyclopentadiene and 5-amino-4-methylene-v-triazolines

1R^*, 4R^*, 5S^*, 5'S^*-5'-Amino-1'-(4-nitrophenyl)-4',5'-dihydrospiro[bicyclo [2.2. 1]hept-2-ene[5.4]-1',2',3'-triazoles]$\text{2}$ have been obtained both by ?4 +2]-cycloaddition of cyclopentadiene to amino-methylene-1-(4-nitrophenyl)-4,5-dihydro-v-triazoles $\text{1}$ and by [3+2]-cycloaddition of 4-nitrophenylazide to 5-aminomethylene-2-norborenes $\text{4}$. The configuration has been fully established by X-ray crystallographic analysis. The course of the cycloaddition and the thermal behaviour of $\text{2}$ are discussed.     

Preferential energy transfer from N2(A) to specific energy levels of Cu atoms

Emission spectra resulting from reaction of “clean” N₂(A³ Σ_u⁺) with copper atoms were studied using a flowing afterglow apparatus. The population distribution of the Cu states was calculated from the spectrum; it indicates that Cu atoms are excited by nearly resonant energy transfer processes. N₂(A,v') + Cu(²S_{$\text{1}\text{2}$}) → N₂(X, v) + Cu^* , and that the transfer is most efficient for N₂(A,v') → N₂(X,v) transitions with large Franck-Condon factors. The preferential energy transfer results in population inversion between some of the Cu states.     

Magnetic susceptibility of Co4+(d5) in octahedral and tetrahedral environments

Measurements of magnetic susceptibility on compounds containing stoichiometric Co⁴⁺ are reported. The compound Ba₂CoO₄ has the Co⁴⁺(d⁵) ion at a tetrahedral site and displays a susceptibility of the expected magnitude for $\text{S =}\text{5}\text{2}$. The compounds Ba₃Co₂CO₉ and BaCoO₃ have the Co⁴⁺ at an octahedral site and show a susceptibility expected for low spin, $\text{S =}\text{1}\text{2}$. For the low spin case significant deviations from Kotani's calculated susceptibility were observed. Improvement of the theory was made through incorporation of the effects of distortion from perfect octahedral symmetry and the inclusion of higher electronic configurations above t⁵₂ in the ²T₂ ground state. A case of low spin Ni in octahedral environment is also reported.     

Synthesis of the natural enantiomers of ascochlorin,ascofuranone and ascofuranol

Three fungal metabolites with a common structural feature as prenylated phenols were synthesized in their naturally occurring and optically active forms: ascochlorin [(2'$\text{E}$,4'$\text{E}$,1'$\text{R}$,2'$\text{R}$,6'$\text{R}$)-(-)-5-chloro-2,4-dihydroxy-6-methyl-3-[5'-(1',2',6'-trimethyl-3'-oxo-cyclohexyl)-3'-methyl-2', 4'-pentadienyl] benzaldehyde], ascofuranone [(2'$\text{E}$,6'$\text{E}$,1'$\text{S}$)-(-)-5-chloro-2, 4-dihydroxy-6-methyl-3-[7'-(3',3'-dimethyl-4'-oxo-2'-oxacyclopentyl)-3',7'-dimethyl -2', 6'-heptadienyl] benzaldehyde] and ascofuranol [(2'$\text{E}$,6'$\text{E}$,1'$\text{S}$,4'$\text{S}$)-(-)-5-chloro-2,4-dihydroxy-6-methyl-3-[7'-(3', 3'-dimethyl-4'-hydroxy-2'-oxacyclopentyl)-3', 7'-dimethyl-2',6'-hepta-dienyl]benzaldehyde ]. (+)-Ascofuranone and (+)-ascofuranol were also synthesized. By the present synthesis the absolute configuration of the natural (-)-ascofuranol was established as (1'$\text{S}$,4'$\text{S}$).     

Fast neutron activation analysis of bulk coal samples for alumina,silica and ash

The fast neutron activation technique was applied to bulk samples (≈11 kg) of Australian black coal. The determination of alumina is based on the reaction ²⁷Al(n,p)-²⁷Mg by counting the 0.844-MeV peak (t_{$\text{1}\text{2}$} = 9.4 min). Silica is determined by means of the reaction ²⁸Si(n,p)²⁸Al; the 1.78-MeV peak (t_{$\text{1}\text{2}$} = 2.3 min) is counted and a correction for the interference from alumina is applied. The ash content is based on the correlation between ash and the sum of alumina and silica. The accuracies (1 SD) for the determination of alumina, silica and ash were 0.52% Al₂O₃, 0.79% SiO₂ and 1.02% ash, respectively. The ash, alumina and silica contents of the samples were in the ranges 8.8–37.5%, 1.3–10.3% and 6.4–22%, respectively.     

Anodic reactions of the halides in dimethyl sulfoxide at the pyrolytic graphite electrode

The anodic reactions of the halide ions in dimethyl sulfoxide at the pyrolytic graphite electrode have been studied. The iodide ion demonstrates a 3-step oxidation; the bromide, a 2-step oxidation and chloride, a 1-step oxidation. The electrode reaction (X^-→$\text{1}\text{2}$ X₂ + e^-) is complicated by a catalytic reaction occurring after the electrode reaction. The catalytic reaction is important for only bromide and chloride causing a considerable diffusion current enhancement. The αn_a value for all 3 primary reactions is of the order of 0.5.