Double-layer effects on simple electrode reactions III. The reduction of Eu3+ and Cr3+ in the presence of thiocyanate anions. Evidence for ligand bridging

The rates of reduction of Eu³⁺ and Cr³⁺ have been measured in mixed perchlorate + thiocyanate electrolytes at constant ionic strength, using low concentrations of thiocyanate to minimize its association with the cationic reactants. The effect of adsorbed thiocyanate anions on the reduction kinetics of Cr³⁺ resembled those produced by iodide and bromide on both Cr³⁺ and Eu³⁺. However, thiocyanate exhibited an unusual catalytic effect on the reduction of Eu³⁺ which was identified as arising from a reaction pathway involving thiocyanate-bridging between the mercury surface and the Eu³⁺. The diagnostic criteria used to support the proposed mechanism included analysis of the rate—potential behavior and of the effects of competitively adsorbed iodide ions upon the reduction rates.     

Preparation and chain extension of C100dicarboxylic acid

The selective degradation of polyethylene crystals with fuming nitric acid has been used to prepare a C₁₀₀ chain with terminal functional groups. After treating this product with concentrated sulphuric acid, it is shown by average molecular weight, titration and infra-red spectroscopy measurements that each molecule contains two carboxylic acid groups. This C₁₀₀ dicarboxylic acid is chain extended with several low molecular weight difunctional coupling agents. Block copolymers of this acid and poly(propylene glycol) have been prepared.     

Extraction properties of octaethyltetraamidopyrophosphate (OETAPP)

The extraction of uranium was studied in the system of 0.1 M OETAPP in CHCl₃/HCl or HNO₃. The distribution coefficients of HCl and HNO₃ were calculated as a function of OETAPP concentration. The amount of OETAPP in the aqueous phase containing HCl and HNO₃ was found from the measurements of surface tension of this phase. The distribution of HCl and HNO₃ between an organic and aqueous phase was studied as a function of the concentration in the aqueous phase of the acid in question. The solvation energy of the extracted complexes was calculated on the basis of the measured potential differences. The cohesion and adhesion energies of the studied systems are given as well.     

Comparison of the structural and chemical composition of giant T-even phage heads.

A study has been made of the structure of the capsids of T4D giant phage produced from mutants in gene 23 and temperature-sensitive mutants in gene 24, and T4D and T2L giant phage formed by the addition of L-canavanine followed by an Larginine chase in the growth medium. All the giant phage capsids have been shown to be built according to the same geometrical architecture. This consists of a near-hexagonal surface net, lattice constant 129.5 A, folded into a left-handed T = 13 prolate icosahedron elongated along one of its fivefold symmetry axes. Their only apparent difference from wild-type T-even phage capsids is their abnormally elongated tubular part. A comparison of the capsomere morphologies and protein compositions of the giant phage capsids showed that all T4D giants are identical but differ from T2L: The T4D capsomere has a complex (6 + 6 + 1)-type morphology, whereas the T2L has a simple 6-type. T2L phage, however, lack two capsid proteins, "soc" and "hoc", present in T4D. The difference in capsomere morphology can therefore be related to the difference in the protein compositions of these two phage. Possible differences between the initiation and means of length regulation of giant phage heads and the aberrant polyheads are discussed.     

Some difficulties in the application of the concept of density of states

The problem of defining N(E), the density of states, for molecular systems is discussed. It is shown that a numeric evaluation of N(E) is often only approximate, even for continuous data, and is not well defined for quantized systems. The application of the concept of density of states is discussed, particularly with regard to the RRKM theory of unimolecular reactions. The sum of states, W(E), and density of states curves are evaluated for several harmonic and anharmonic model systems and the results discussed in order to illustrate the foregoing considerations.     

Analyse de la fraction monophénolique des condensats de fumée de cigarettes par association de méthodes chromatographiques

Résumé Les monophénols sont isolés des condensats de fumées de cigarette par chromatographie sur couche mince de Kieselgel G avec un mélange (31) de cyclohexane et d'acétate d'éthyle extraits du support, puis séparé et dosés par chromatographie en phase gazeuse sur colonne capillaire. Le rendement de l;opération est de 80±2% pour le triméthyl 3,4,5 phénol, de 65% pour le triméthyl 2,3,5 phénol. Les teneurs obtenues sont de 8g de phénol, 3g de (para + méta) crésol et 0,5 g de diméthyl 2,6 phénol par mg de condensat. De nombreux autres alkylphénols ont été identifiés.

---

Analysis of the monophenolic fraction of tobacco smoke condensates by a combination of chromatographic methods

Summary Monophenols are separated from tobacco smoke condensates by thin-layer chromatography on Kieselgel G using a 31 mixture of cyclohexane and ethylacetate. The monophenolic fraction is recovered from the support and analyzed by GC on a capillary column. The yield is 80±2% for 3,4,5 trimethylphenol and 65% for 2,3,5 trimethylphenol. The concentration determined for phenol, (para+meta) cresol and 2,6 dimethylphenol are 8,3 and 0.5 g per mg of condensate respectively. Numerous other alkyl phenols have been identified.

     

Total synthesis of indole and dihydroindole alkaloids. VII. The total synthesis of isovelbanamine, velbanamine, cleavamine, 18beta-carbomethoxycleavamine and catharanthine.

A synthesis of a variety of nine-membered ring intermediates in the cleavaminevelbanamine series is described. The formation of the penultimate intermediate involves a fragmentation reaction in which the cleavamine system is generated from an appropriate rigid pentacyclic Iboga alkaloid derivative. Thus dihydrocatharanthinol tosylate (VIII) on reaction with triethylamine in refluxing benzene undergoes fragmentation to the 5, 18-seco-diene X. This latter substance is then elaborated in various ways to the desired compounds.     

Etude de la chloration du polychlorure de vinyle en fonction de sa tacticite

Polyvinyl chloride samples of various tacticity have been prepared and photochlorinated in CCl₄ for 4 hr. The chlorination degree correlates directly with the degree of syndiotacticity. Initial PVC with syndiotacticity about 56 per cent, which can be regarded as alternate sequences of syndiotactic and isotactic diads, is quickly chlorinated. The mechanism of chlorine attack on the macromolecula is directly connected with the stereoregularity.     

New method for the synthesis of macrocyclic compounds

A mixture of isomers corresponding to closing of the ring at the 3 and 4 positions of the thiophene ring is formed during intramolecular acylation of 12-(5-methyl-2-thienyl)-lauryl chloride in a homogeneous medium; the reaction proceeds primarily to favor the formation of the isomer with the larger ring (80%). A method for the synthesis of macrocyclic -alkylcycloalkanones by reductive desulfurization of the corresponding bicyclic ketones, which contain thiophene rings, was developed.See Izv. Akad. Nauk SSSR, Ser. Khim., 2228 (1970) for Communication XI.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1467–1472, November, 1970.     

Coulometric titration of acids in non-aqueous solvents

Coulometric titrations of mineral acids, sulphonic acids, carboxylic acids, enols, imides and phenols have been carried out in t-butanol or in acetone with electrically generated tetrabutylammonium hydroxide. Either a potentiometric titration or a visual indicator end-point may be used. The amount of acid titrated ranges from 10 to 60 muequiv, and the precision and accuracy of the method are excellent.