The mass spectra of 1,1,1-trichloro-2,4-pentanedione and its Al(III), Cr(III), Fe(III), Mn(II), Co(II) and Cu(II) complexes

The compounds 1,1,1-trichloro-2,4-pentanedione, Cu(II)tca₂, Co(II)tca₂, Mn(II)tca₂, Al(III)tca₃, Cr(III)tca₃ and Fe(III)tca₃ (tca?1,1,1-trichloro-2,4-pentanedionato, [CCl₃COCHCOCH₃]^?) have been prepared and their mass spectra have been obtained. The mass spectral results have been compared with findings for comparable fluorinated and nonhalogenated compounds. Comparisons are made in terms of internal redox reactions and hard and soft acid base theory. Rearrangement of chloride from ligand to metal accompanied by the elimination of CO or other neutral even electron fragments emerges as an important reaction for the ions of these compounds. While the internal redox reactions characteristic of all previous β-diketonate complex mass spectra still occur, their importance appears reduced to some degree by the facility of the chlorine rearrangement.     

Investigations of aromatic polyesters with polynaphthalene systems in the main chain—VI: NMR studies of the structure of the aromatic copolyesters

Nuclear magnetic resonance spectra of several kinds of terephthalic copolyesters of 4,4′dihydroxydinaphthyl 1,1′ and 2,2 bis(4-hydroxyphenyl) propane were recorded. Proton signals of the terephthalic acid unit corresponding to heterolinkages and homolinkages could be observed in the range from 8.23 to 8.53 ppm. The average sequence lengths and the degrees of randomness in the copolyesters were calculated from the intensities of these signals.     

Solid state spin densities in triplet-exciton TCNQ salts

The combination of molecular spin densities and of structural data is shown to provide a sensitive test for the fine structure splittings and principal axes of triplet spin excitons in organic ion-radical crystals, in support of weakly-perturbed molecular sites in these solids. The exchange pathway in Rb(TCNQ) and the occurrence of dimer radicals, with fractional charges, in several tetrameric (TCNQ)₄^2? stacks illustrate the comparisons afforded by computations of fine structure parameters for triplets states in the solid.     

Steric structure of phosphorus-contaiming heterocycles

Conclusions The steric structure of 3-halo-1-thia-3-phosphethanes with a tetracoordinated phosphorus atom was investigated by the methods of dipole moments and Kerr constants, enlisting data on quantum chemical calculations of the energies of the conformations.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2240–2244, October, 1973.The authors would like to thank I. M. Shermergorn for providing the samples for the investigations.     

Chemische Vitamin D<Subscript>3</Subscript>-Bestimmung in Lebertran

The different aspects of Vitamin D₃ determination and the data reported in the literature are discussed. The spectrophotometric determination of Vitamin D₃ in cod-liver oil is carried out after the alkaline saponification, extraction of unsaponified parts, precipitation of accompanying sterols and the column- and thin-layer chromatographic purification and separation of vitamin D₃ on 40 cm plates from other vitamins. The dyestuff α-naphtholbenzein is suited well as standard substance for the better location and identification of vitamin D₃ zone on the thin-layer plate. The results obtained from the chemical method were checked through the simultaneous biological determination.     

Austausch von Chlorisotopen am Phosphoratom, 1. Mitt.: Dialkylchlorthiophosphate

Zusammenfassung An den Modellverbindungen Dialkylchlorthiophosphat (RO)₂P(S)Cl (R=Me, Et, n-Pr) und Diphenylchlorthiophosphat (PhO)₂P(S)Cl wurde der Austausch Chlorid—Radiochlorid am Thiophosphorylzentrum untersucht. Die bimolekularen Geschwindigkeitskonstanten, die Aktivierungsenergien und Aktivierungsentropien wurden berechnet. Der Einfluß von Substituenten auf bimolekulare Substitutionsreaktionen am vierfach koordinierten Phosphoratom wurde diskutiert.

---

Chlorine isotopic exchange at phosphorus atoms, I.: Chloridothiophosphates

The chloride—radiochloride ion exchange at the thiophosphoryl centre has been studied using dialkylchloridothiophosphates (RO)₂P(S)Cl (R=Me, Et, n-Pr) and diphenylphosphorochloridothionate, (PhO)₂P(S)Cl, as model compounds. The bimolecular rate constants, energies and entropies of activation have been calculated. Effects of the substituents in the bimolecular displacement reaction on four-coordinated phosphorus atom have been discussed.

---

---

Mit 3 Abbildungen     

Zur Oxydation von Tiron mit Wasserstoffperoxid in Gegenwart von Kobalt

Zusammenfassung Die Kinetik und der Mechanismus der von Kobaltionen katalysierten Tiron-Wasserstoffperoxid-Reaktion werden untersucht. Bei der Oxydation des Tirons bildet sich ein farbloses Produkt unbekannter Struktur, dessen Konzentrationszunahme zur photometrischen Messung der Reaktionsgeschwindigkeit dient. Unter den gewählten Bedingungen (3,56 · 10^–4 M Tiron, 0,1 M Wasserstoffperoxid, pH 10,3) verläuft die Reaktion bezüglich der Tiron- und Katalysatorkonzentration nach der 1. Ordnung. Die katalytische Reaktion, deren Geschwindigkeitskonstante zu 4,7 · 10⁴ l Mol^–1 · s^–1 ermittelt wurde, kann zur Kobaltbestimmung im Bereich von 0,6–10 ng/ml verwendet werden.Die Ergebnisse der Untersuchungen über die Oxydationsgeschwindigkeit des Tirons und über die Zersetzungsgeschwindigkeit des Wasserstoffperoxids in Abhängigkeit vom pH-Wert deuten darauf hin, daß die Zersetzung des Wasserstoffperoxids Voraussetzung für die Oxydation des Tirons ist. Während Tiron selbst eine stabilisierende Wirkung auf das Oxydationsmittel ausübt, katalysiert ein in Gegenwart von Kobaltionen entstehender Komplex dessen Zersetzung.

---

Summary The kinetics and the mechanism of the tiron-hydrogen peroxide reaction catalysed by cobalt ions are investigated. The oxidation of tiron results in a product of unknown structure, whose increase of concentration is utilized for photometric reaction rate measurements. On the conditions used (3.56 · 10^–4 M tiron, 0.1 M hydrogen peroxide, pH 10.3) the reaction is of the first order with respect to tiron and catalyst concentration. The catalytic reaction, the rate constant of which was evaluated to be 4.7 · 10⁴ l · Mol^–1 · s^–1, can be used for the determination of cobalt in the range from 0.6 to 10 ng/ml.The results of the investigations on the oxidation rate of tiron and on the decomposition rate of hydrogen peroxide in dependence on pH indicate that the decomposition of hydrogen peroxide is a prerequisite for the oxidation of tiron. Whereas tiron itself shows a stabilizing effect on the oxidant, the complex formed in presence of cobalt ions catalyses the decomposition of hydrogen peroxide.

---

---

Frau M. Borrmann gilt unser Dank für experimentelle Mitarbeit.     

Photofragmentierung von Cyclohexa-1,3-dien-5,6-dicarbonsäure-anhydriden [1]

The photochemical elimination of the anhydride function («C₂O₃») from the dihydrobenzenoid anhydrides 6a-6c is described. Some applications and limitations of this double bond producing reaction are given. A formal correlation between ease of «C₂O₃» elimination upon irradiation and upon electron impact respectively is indicated.     

Crystalline calmagite and a study of sulphonation effects on azo dye metal-ion indicators

Calmagite was introduced in 1960 as a stable substitute for Eriochrome Black T in EDTA titrations of calcium plus magnesium. The colour changes were the same but somewhat sharper. Indicator stock solutions were stable indefinitely. The new indicator was designed as an indicator and not as a wool dye. Azo dye impurities which may be present in some commercial supplies tend to lengthen the end-points. A simple means of removing these impurities to yield crystalline indicator has been developed. The effects of sulphonation on the performance of azo dyes as indicators have been studied.     

Laurenanes: fenestranes with a twist

Four isomeric alcohols derived from the diterpene lauren-1-ene (1) have been examined by NMR methods (nuclear Overhauser enhancements, coupling constants, and variable-temperature studies) and by molecular mechanics using the MM3 force field to investigate a conformational twisting of the [5.5.5.7]fenestrane ring system. Results have been correlated with a concurrent study of remote functionalization reactions induced by iodobenzene diacetate/iodine under ultrasonic irradiation. Three of the laurenan-2-ols, 6, 7, and 8, lead to the same tetrahydrofuran derivative, 2beta,14beta-epoxylaurenane (9), and evidence for beta-cleavage of the alkoxy radical intermediate is obtained through the isolation of a ring-cleavage product 11 with a rearranged carbon skeleton. The products from the remaining alcohol 3 demonstrate solution dynamics involving the conformational twisting of the laurenane skeleton.