Conjugated Schiff bases. VII—Decarbonylation of some 1,3-hetrodienes under electron impact

The mass spectra of some 1,3- heterodienes containing the 1-oxa-4-aza-butadiene system have been determined and the characteristic fragmentation pathways are discussed. The pathways suggested are supported by the appropriate metastables, the spectra of model compounds and by deuterium labelling. The 1, 3-heterodienes substituted by the thioarylamide group from ions involving participation of the sulphur atom.     

An example of the base induced isomerisation of the epoxide ring in enolizable epoxyketones: isomerisation of 8,9-epoxy-6,7,8,9-tetrahydro-5H-benzocyclohepten-5-one and some of its derivatives

The title compounds in the basic medium (RO^?/ROH) afford an unique example of competition between isomerisation via the enolate anion and epoxide-ketone isomerisation.     

Statistics of polymer chains in orienting fields

The theory of a freely jointed polymer chain is modified by introduction of interactions between dipole chain segments and an orienting field. Such a field results either from external forces (e.g. external electric or magnetic fields) or represents interactions between dipole segments of chains (molecular mean-field). The distribution of orientations of chain segments and the free energy of a chain in such orienting fields are calculated and discussed.     

Thermal decomposition of basic aluminium potassium sulfate. Part II. Kinetics of the reaction

The kinetics of individual stages of thermal dissociation of basic aluminium potassium sulfate (BAPS) were studied thermogravimetrically under isobaric and isothermal conditions at a reduced pressure of the order of 10^?3 hPa and in the atmosphere of gaseous products of the reaction (H₂O, SO₂).The kinetic parameters of all the reaction stages have been identified and the nature of the stages and the effect of changes of the reaction of conditions on the course of the processes have been determined.     

Synthesen und Stereochemie des 3,6,10,13-Tetrathia[6.6.1]propellans

3,6,10,13-Tetrathia[6.6.1]propellane (1) has been prepared by two independent syntheses.1 exists as an equilibrium of two conformers with C₂ and C_s symmetry, respectively. The heterocyclic rings adopt a twist-tub conformation. The multistage synthesis of1 makes also 1,5-cyclooctadiene (5) accessible, as the result of [4_s+4_s]-cycloaddition. The formation of [6.6.1]propellanes of the isomeric [6.0.6.1]dispiranes depends on the nature of the hetero atom.

     

Diastereomeric non-equivalence of (−)-ω-camphanic esters of chiral secondary alcohols in 13C NMR spectroscopy

The diastereomeric differences (Δδ) were measured by ¹³C NMR spectroscopy for a series of 11 (?)-ω-camphanic esters of secondary alcohols of known absolute configuration. This method cannot be used for the determination of the absolute configuration, but it can be applied to the estimation of the enantiomeric purity of chiral alcohols.     

Dilation equations and Markov operators

Using the theory of Markov operators, we give a new proof of the known fact saying that for every positive integers N and k>1, and for every nonnegative reals c₀,…,cN satisfying the first sum rule the dilation equation

     

Synthesis and structure of a 1:1 complex of a chiral methyl 4,6-0-benzylidene-2 , 3-0 (1 ,2-bis (ethoxyethoxy) -benzenediyl) - α,d-glucopyranoside and potassium iodide

The chiral crown ether was prepared according to the method described in the literature and its complex with potassium iodide was obtained. The crystal data are as follows: a = 10.315(4), b = 9.265(4), c = 15.88(2) Å, β = 100.70(7)°. V = 1494 Å,³ Z = 2, D₀ = 1.55 Mg m^?3 space group symmetry P2₁.The structure was determined by the heavy atom method using 2214 independent observed reflections. The conformation of the macrocyclic ring is discussed.