Facile O-deallylation of allyl ethers via S(N)2' reaction with tert-butyllithium

[reaction: see text] Allylic ethers are converted to the corresponding alcohol or phenol in virtually quantitative yield at temperatures below ambient simply by stirring a hydrocarbon solution of the ether with 1 molar equiv of tert-butyllithium. The reaction, which produces 4,4-dimethyl-1-pentene as a coproduct, most likely involves an S(N)2' attack of the organolithium on the allyl ether.     

Magnetic ordering below 10K in the high-Tc superconductor YBa2(Cu0.985Fe0.015)3O7−σ

The high-temperature superconductor with the nominal composition YBa₂Cu₃O_7?σ has been doped with iron 93% enriched in⁵⁷Fe. When 1.5 at % Fe substitutes for Cu, the transition temperature is reduced by about 30° K with full ac shielding (X′=?1/4π) achieved by ≈40 K. At room temperature the Mössbauer spectrum consists of three overlapping doublets. Below 10 K, hyperfine-field splitting is observed; relaxation still takes place at T=1.8 K.     

One-Center coulomb,two-center hybrid,and two-center coulomb integrals over STP functions

Diatomic integral formulas involving Slater-transform-Preuss functions are obtained for the Coulomb and hybrid types. One-center Coulomb integrals are also considered. All results have finite sums containing a one-dimensional numerical integration.     

A computer interface for digitizing ultrasonic information

An interface is described which links an ultrasonic B-scanner to a small digital computer. The interface digitizes the image signals from the scanner to 10 levels. The 10 levels are then converted to a four-bit binary word, four of which are packed into a 16-bit word. The 16-bit words are then transferred to the digital computer.     

Complex refractive indexes for polymers over the infrared spectral region: Specular reflection IR spectra of polymers

A dispersion analysis is used to determine the complex refractive indexes over the infrared for the following polymeric systems: isotactic poly(methyl methacrylate), syndiotactic poly(methyl methacrylate), poly(2-methyl-1-pentene)sulfone, poly(perfluoropropylene oxide), poly(pyromellitimide), poly(styrene), and poly(vinyl alcohol). These were combined with solutions of Maxwell's equations for electromagnetic radiation at interfaces in a FORTRAN computer code to model specular relection infrared spectra. Calculations and experimental data are compared to demonstrate the complicated nature of specular reflection and the ability of the modelling to simulate the observed spectra.     

Diffraction of waves by inhomogeneous obstacles

Summary The two dimensional problem of diffraction of scalar waves by a bounded inhomogeneity in an otherwise unbounded medium is studied both theoretically and numerically. Using singular operator properties, existence and uniqueness of the solution, and the convergence of the numerical method used are proved.     

Theoretical studies of atmospheric triatomic molecules: Ab initio characterization of Rydberg series in CO2

The ab initio Koopmans' Theorem is used to determine energy levels and orbital characteristics for the lowest members of s, p, d, f, g, h Rydberg series in CO₂. The energy levels are in good agreement with results of SCF calculations and experimental energy levels. It appears that unambiguous spectral assignments can be based upon the comparison of ab initio and observed energy levels in the case of penetrating Rydberg orbits. The energy levels associated with the higher angular momentum orbits exhibit degeneracies and separations which more closely approximate those of the hydrogen atom.     

Optical isotope shifts of146Sm and151Sm

We have measured the optical isotope shifts of¹⁴⁶Sm and¹⁵¹Sm by laser resonance fluorescence. From these measurements the changes in the mean square nuclear radii are: Δ〈r²〉 (A=144 to 146)=0.266(10) fm², and Δ〈r²〉 (A=151 to 152)=0.262(10) fm². These results, together with those of the stable isotopes, show that the average nuclear expansion of samarium can be accounted for by the liquid drop model with deformations.     

Continuous degeneracy and energy-localization of molecular orbitals

The energy-localization method is examined for continuous degeneracy using a grouptheoretic approach. Conditions for the degenerate orbitals are obtained and an enumeration of symmetry groups where continuous degeneracy may occur is given. It is found that the orbitals may be equivalent under operations not contained in the total symmetry group. An alternative explanation for the free rotation of the lone pairs in F₂ is offered.