Cellulose-SO3H as a recyclable catalyst for the synthesis of tetrahydropyranols via Prins cyclization

Tetrahydropyranols are prepared in good yields and with high cis-selectivity by means of the Prins cyclization using cellulose-sulfonic acid under mild reaction conditions. This is the first report on the preparation of tetrahydropyranols using epoxides and homoallylic alcohols via Prins cyclization.     

Mean amplitudes of vibration: Planar X2Y4 molecules

The theory of mean-square amplitude matrices is applied to the ethylene type of molecules. The mean amplitudes of thermal vibrations of atomic distances in these molecules are evaluated at 300K from their vibrational frequencies.One of the authors (S.M.) is grateful to the Council of Scientific and Industrial Research, Government of India, for the award of a Senior Research Fellowship.     

The nuclear magnetic resonance spectra of four spin systems

The spectra of a number ofp-disubstituted benzenes were analyzed earlier by Richards and Schaeffer by assuming that the twometa H-H coupling constants are equal and thepara H-H coupling constant is zero. In the present work a method for analysing this type of spectra, without making any simplifying assumptions, is proposed. The proton resonance spectra ofp-bromochlorobenzene,p-chlorotoluene andp-chloroiodobenzene were obtained and analyzed as examples, and all the parameters were determined in each case. The general form of this type of spectra for different values of chemical shift is discussed.     

Extraction-photometric determination of indium in zinc-base alloys with bromopyrogallol red

The extraction-photometric determination of indium at the 5 p.p.m. level in highpurity zinc and zinc-base alloys is described. After a preliminary separation of indium by isopropyl ether extraction from hydrobromic acid medium, indium is determined by extraction into benzyl alcohol of its complex with bromopyrogallol red at pH 9.0. It is shown that 2:1, 1:1 and 1:2 complexes can be formed in aqueous and water-ethanol media; the 1:3 complex reported earlier was not found. The composition of the complexes extracted into benzyl alcohol from aqueous solutions at pH 6.5 and 9.0, was found to be 1:2.     

Preparation and thermal stability of the U(IV)(SO4)2-DMF complex

A new DMF complex of U(SO₄)₂, i.e., U(SO₄)₂·2.2 DMF, was prepared and characterized using chemical analysis, X-ray powder diffraction studies, IR and measurement of magnetic susceptibility variation with temperature in the temperature range 77–300 K. Pyrolysis of the solvate was studied by means of TG under two different experimental conditions, and the actual thermal degradation path was deduced using a microthermobalance.     

Reactions of co-ordinated ligands: Kinetics and mechanisms in the charge transfer interaction between dichloro or diaquo triethylene tetramine Co(III) and ferrocyanide

The cherry red-coloured solid state product obtained by the reaction ofcis-σ diaquo Co (III) triethylene tetramine with ferrocyanide was examined by thermogravimetric, infrared and M?ssbauer techniques. Its electronic spectrum in aqueous medium was interpreted to consist of charge transfer IT transition at 440 nm and a ligand field transition around 330 nm. The kinetics of formation of this 1:1 product in solution was also studied.     

Streponigrin and related compounds. II. Synthesis of the c-ring precursors

Synthesis of the tricyclic analogue 1b of the antitumor antibiotic streptonigrin 1a by the application of Friedlander condensation required a substituted 2-acetylpyridine ( 2 ) as the precursor for the C-ring. A practical, 8-step sequence was devised for its synthesis starting from 2,5-lutidine.     

Possible splitting of energy levels of atoms or ions in octahedral crystals due to sets of equivalent neighbouring defects

Divalent ions when doped in alkali halide single crystals will go in alkali sites and form associate pairs with neighbouring cation vacancies or other impurity defects. As there will be sets of equivalent positions for such associated pairs, their energy levels will be degenerate. The reducible representations of these associated pairs involving first to sixth nearest neighbours have been reduced to the corresponding irreducible representations of the point group O _h , for cases having rock-salt structure as well as for cases having cesium chloride structure. It is pointed out that if there is a rapid hopping of the vacancies or the defects in the crystal one may expect because of the possible interactions in the system, a splitting of the energy levels of the pairs as indicated by the different irreducible representations. It is stated that this kind of splitting may be expected also in systems in which associated magnetic pairs are formed by two neighbouring spins.