A novel synthesis of 7-acetyl-4,5,5a,6,6a,7,8,9-octahydroindeno[7,1-fg]quinolin-9-one

Treatment of the acetylenic acid 3 with magnesium carbonate in water at 60° yielded the tetracyclic ketone 5.     

The application of resonance monochromators to the determination of lithium in blood serum by atomic absorption spectrophotometry

Lithium in blood serum can be determined rapidly and with sufficient accuracy by atomic absorption measurement of solutions of blood serum diluted with water, using either a conventional atomic absorption spectrophotometer or one with a resonance monochromator. Calibrating solutions contain sodium and potassium at approximately the concentrations present in the serum solutions as these metals cause a slight enhancement of lithium absorption in the air/coal gas flame. Results are reproducible to within ±0.2 μg Li/ml in the serum and the limits of sensitivity attainable for samples diluted 1:10 are 0.3μg Li/ml in the serum with the conventional instrument and 0.6 μg Li/ml in the serum with the resonance monochromator.     

Structure and vibrational dynamics of isotopically labeled lithium borohydride using neutron diffraction and spectroscopy

The crystalline structure of a ⁷Li and ¹¹B labeled lithium borohydride has been investigated using neutron powder diffraction at 3.5, 360, and 400 K. The B-H bond lengths and H-B-H angles for the [BH₄]⁻ tetrahedra indicated that the tetrahedra maintained a nearly ideal configuration throughout the temperature range investigated. The atomic displacement parameters at 360 K suggest that the [BH₄]⁻ tetrahedra become increasingly disordered as a result of large amplitude librational and reorientational motions as the orthorhombic to hexagonal phase transition (T=384 K) is approached. In the high-temperature hexagonal phase, the [BH₄]⁻ tetrahedra displayed extreme disorder about the trigonal axis along which they are aligned. Neutron vibrational spectroscopy data were collected at 5 K over an energy range of 10-170 meV, and were found to be in good agreement with prior Raman and low-resolution neutron spectroscopy studies.     

Rotational cooling of rigid rotors desorbed from flat surfaces

A simple model is presented for predicting the final rotational state distribution of an initially physisorbed rigid rotor. Based on the assumptions that the adsorbed rotor is freely rotating and that desorption occurs by a weak coupling between the rotational and desorbing degrees of freedom, a significant rotational “cooling” is predicted.     

A statistical-based approach to assessing the fidelity of combinatorial libraries encoded with electrophoric molecular tags. Development and application of tag decode-assisted single bead LC/MS analysis

A statistical sampling protocol is described to assess the fidelity of libraries encoded with molecular tags. The methodology, termed library QA, is based on the combined application of tag decode analysis and single bead LC/MS. The physical existence of library compounds eluted from beads is established by comparing the molecular weight predicted by tag decode with empirical measurement. The goal of sampling is to provide information on overall library fidelity and an indication of the performance of individual library synthons. The minimal sampling size n for library QA is l0 x the largest synthon set. Data are reported as proportion (p) +/- lower and upper boundary (lb-ub) computed at the 95% confidence level (alpha = 0.05). As a practical demonstration, library QA was performed on a 25,200-member library of statine amides (size = 40 x 63 x 10). Sampling was conducted three times at n approximately 630 beads per run for a total of 1902 beads. The overall proportions found for the three runs were consistent with one another: p = 84.4%, lb-ub = 81.5-87.2%; p = 83.1%, lb-ub = 80.2-85.95; and p = 84.5%, lb-ub = 81.8-87.3%, suggesting the true value of p is close to 84% compound confirmation. The performance pi of individual synthons was also computed. Corroboration of QA data with biological screening results obtained from assaying the library against cathepsin D and plasmepsin II is discussed.     

Deactivation pathways in collisions of Kr with CO2(001)

We present the results of a quantal close coupling calculation of the deactivation of CO₂(001) by Kr in a collinear model. It is found that for relative translational energies less than 0.4 eV linearly constrained CO₂(001) can be described as existing in quasi-equilibrium with CO₂(200) since all other VV and VT processes have negligible probability compared to the process Kr + CO₂(001) → Kr + CO₂(200). This transition has an energy defect of only 313.1 cm^?1 and probably accounts for its relative efficiency. This study represents the first accurate quantal calculation of inelastic scattering of an atom with a triatomic described by a realistic potential.     

High-temperature rate constant determination for the reaction of OH with iso-butanol

This work presents the first direct experimental study of the rate constant for the reaction of OH with iso-butanol (2-methyl-1-propanol) at temperatures from 907 to 1147 K at near-atmospheric pressures. OH time-histories were measured behind reflected shock waves using a narrow-linewidth laser absorption method during reactions of dilute mixtures of tert-butylhydroperoxide (as a fast source of OH) with iso-butanol in excess. The title reaction's overall rate constant (OH + iso-butanol →(k(overall)) all products) minus the rate constant for the β-radical-producing channel (OH + iso-butanol →(k(β)) 1-hydroxy-2-methyl-prop-2-yl radical + H(2)O) was determined from the pseudo-first-order rate of OH decay. A two-parameter Arrhenius fit of the experimentally determined rate constant in the current temperature range yields the expression (k(overall) - k(β)) = 1.84 × 10(-10) exp(-2350/T[K]) cm(3) molecule(-1) s(-1). A recommendation for the overall rate constant, including k(β), is made, and comparisons of the results to rate constant recommendations from the literature are discussed.     

Rotational rainbows in inelastic atom—molecule differential cross sections

The existence of rotational raibows in atom-rigid rotor inelastic differential cross sections is shown by considering the classical limit of the centrifugal sudden-rotational sudden expression for the scattering amplitude.     

Isotopic oxygen exchange rates between [V18O42]12− and water

Summary From kinetic studies of¹⁸O-exchange between aqueous solutions of K₁₂V₁₈O₄₂ · 16H₂O and water it is concluded that [V₁₈O₄₂]^12– exists as a discrete ion in this medium. The rate of exchange is relatively slow (t_1/2 ca. 6×10⁴s at 0°C) and obeys the McKay equation within the precision obtainable. The sensitivity of the ion to its environment in the solid state, leading to induced exchange, prevented a decision as to whether all oxygens are kinetically equivalent. It is clear, however, that the ions remains intact for long periods in solution in the absence of air.