High-sensitivity measurement of metastable ion abundances

Measurement of metastable ion abundances over a dynamic range of 10⁵ is possible with a specially designed mass spectrometer.     

The use of metastable ion characteristics for the determination of ion structures of some isomeric cannabinoids

The mechanism of formation of the prominent C₁₅H₁₉O₂ ion at m/e 231 in the mass spectra of Δ¹⁽⁶⁾-tetrahydrocannabinol and five isomeric cannabinoids has been investigated. Except via a well-documented two step process, involving an RDA mechanism, a sizeable percentage of these ions is formed by a novel one-step route from the molecular ion. This was deduced from the spectra of deuterium-labelled compounds and measurements of the kinetic energy release of metastable ions. The latter value for the one step process varies from 25–44 meV for the six compounds investigated, attributed to two interdependent effects, different transition state geometries and common transition states differing in the time elapsing before their formation.     

The simulation of the growth of colonies in the spinodal decomposition of metastable phases

The generalized continual hole gas model and Monte Carlo simulations were used to study the growth of colonies and lamellar segregations in the decomposition of metastable phases. The morphology of segregations qualitatively changed as the temperature decreased and depended substantially on the initial state (the presence of grain boundaries and critical equilibrium phase nuclei). The simulation results were compared with the kinetics of growth of eutectic colonies and morphologies of the decomposition of metastable austenite.     

Raman spectra of biphenyl negative ion in tetrahydrofuran solution

Raman spectra of the mono-negative ion of biphenyl in tetrahydrofuran solution were obtained by Ar⁺, He–Ne and Kr⁺ laser exciting lines. The observed frequency shift from the neutral molecule and intensity enhancement by resonance Raman effect is discussed on the basis of MO considerations.     

Oscillatory photochemical decomposition of tetrathionate ion

When subject to illumination, tetrathionate ion decomposes in an oscillatory fashion with a period of about 1 h to yield products identified as colloidal sulfur and trithionate ion. This system represents the first experimental example of a stirred, batch photochemical oscillator. A simple model consisting of four reaction steps and four adjustable rate parameters gives good agreement with the observed oscillatory behavior.     

Rhodium ion catalyzed decomposition of aryldiazoalkanes

Aryldiazomethanes are converted by rhodium(II) acetate and iodorhodium(III) tetraphenylporphyrin to $\text{cis}$- rather than $\text{trans}$-1,2-diarylethylenes. Secondary aryldiazoalkanes react with rhodirum(II) acetate to give azines.     

A novel mass marker for metastable ion scans in a double focusing mass spectrometer

Characterization and assignment of the products of metastable decompositions which are transmitted by a double focusing mass spectrometer, is often complicated by the inability to measure precisely the parent/daughter ion mass values directly from the spectra which appear on chart paper. This is often because there are considerably fewer peaks in these types of spectra compared with a normal mass spectrum obtained from high energy reactions in the ion source. Electronic circuits are described which permit accurate parent/daughter ion mass values to be obtained when the products of metastable decompositions are transmitted through the ZAB-2F double focusing mass spectrometer. Digital logic circuitry is also described which is used to mark mass values during a scan by driving either a solenoid pen drive unit for a chart recorder or a galvanometer on a multi-range ultraviolet oscillograph recorder.     

Four distinctively different decomposition pathways of metastable Supermesityltellurium(IV) trichloride

Chlorination of bis(supermesityl)ditelluride RTeTeR (R = 2,4,6-t-Bu3C6H2) with 3 equiv of sulfuryl chloride SO2Cl2 provided the intrinsically unstable supermesityltellurium(IV) trichloride RTeCl3 (1) as bright yellow crystals. Severe repulsion between the equatorial Cl atom and one tert-butyl group in an ortho position in the supermesityl ligand is the reason for the extreme reactivity of 1, which is in contrast to that of all previously known monoorganotellurium trihalides. In the solid state at room temperature, (the triclinic modification of) 1 reacts slowly under HCl elimination and intramolecular Te-C bond formation to give the bicyclic 5,7-di-tert-butyl-2-hydro-3,3-dimethylbenzo[b]tellurophene-1,1-dichloride (2), which was originally obtained as a colorless amorphous solid. On one occasion, when the solid-state reaction was allowed to occur under air conditions, compound 2 and a colorless crystalline byproduct, namely, trans-supermesityltellurium hydroxide dichloride (3), had formed, from which a few crystals were hand-selected. The formation of 3 has been tentatively rationalized by a solid-state hydrolysis of a second (monoclinic?) modification present in the bulk material of 1. In diethyl ether, THF, or carbon disulfide, a redox equilibrium exists between yellow supermesityltellurium(IV) trichloride RTeCl3 (1), deep blue supermesityltellurenyl(II) chloride RTeCl (4), and chlorine gas, which can be shifted to 4 when the reaction vessel is purged with argon to remove the chlorine gas. Compound 4 was also obtained by the reaction of RTeTeR (R = 2,4,6-t-Bu3C6H2) with 1 equiv of SO2Cl2. When a solution of 1 was stored with an excess of SO2Cl2 for a prolonged amount of time, Te-C bond cleavage occurred and [(Et2OH)2Te2Cl10].2Et2O (5) was formed. Compounds 1-5 have been characterized by X-ray crystallography.     

Ferrous ion induced decomposition of alkyl hypochlorites

The decomposition of primary, secondary and tertiary alkyl hypochlorites induced by ferrous and other one-electron oxidizable metal ions leads to δ-chloro alcohols in yields of 34–76%. In decomposition of tertiary alkyl hypochlorites, β-fragmentation competes with intramolecular δ-chlorination. Tertiary cycloalkyl hypochlorites containing five- or six-membered rings undergo β-cleavage giving the corresponding ω-chloro ketones, while 1-methylcycloheptyl and 1-methylcyclooctyl hypochlorites by decomposition with ferrous ion proceed by transannular functionalization of δ-carbon atom and β-cleavage as a competing reaction.     

The direct observation of a highly mobile positive ion in nanosecond pulse irradiated liquid cyclohexane

The electrical conductivity induced by pulse irradiation of liquid cyclohexane has been studied by means of microwave absorption. The conductivity in pure cyclohexane, due principally to the excess electron, is reduced to less than 10% of the initial value on addition of 5 × 10^?4 M of the electron scavenger SF₆. The conductivity remaining after addition of SF₆ is however more than an order of magnitude larger than expected for massive ions in cyclohexane and, since it is almost completely removed by the addition of 4 × 10^?3 M of the positive ion scavenger NH₃, is attributed mainly to the high mobility of the positive hole in this liquid. The ratio of the electron to hole mobility is determined to be 15. The mean lifetime of the hole under the present conditions is 86 ns. The rate constant for reaction of the hole with NH₃ is determined to be 1.8 × 10¹¹ M^?1 s^?1. From the conductivity remaining after removal of both the electron and the hole the sum of the mobilities of the resulting molecular ions is determined to be 8.4 × 10^?4 cm² V^?1 s^?1.     

Unimolecular decomposition of energy-selected anisole ions. Breakdown graph and metastable decay rates

The fragmentation behavior of the anisole ion (C₆H₅OCH^+·₃) was examined using threshold photoelectron-photoion coincident (TPEPICO) mass spectrometry. Four major fragments are observed in the ion time-of-flight spectra at photon energies less than 14 eV: C₆H₅O⁺ (m/z 93), C₆H⁺₇ (m/z 79), C₆H⁺₆ (m/z 78), and C₅H⁺₅ (m/z 65). Rate constants for the production of the ion m/z 78 near threshold were found to agree well with those calculated on the basis of RRKM theory. Most of the excess energy at threshold for this process is a result of the kinetic shift.     

The ferric ion catalyzed decomposition of hydrogen peroxide in perchloric acid solution

Predictions of the “redox” and “complex” schemes for the Fe³⁺ catalyzed decomposition of H₂O₂ have been compared with published and new experimental data by numerical integratior of the appropriate complete sets of differential equations. Apparent discrepancies for the redox scheme at high Fe³⁺/H₂O₂ ratios are shown to disappear in the complete treatment, and inconsistencies of the complex scheme with both kinetic data and spectroscopic measurements are pointed out.     

Pulse radiolysis of cyclohexane: The identity of the high-mobility positive ion

Previous experimental observations and new pulse radiolysis results concerning the high-mobility positive ion in cyclohexane are examined. Apparent disagreement among these observations concerning the existence of a high-mobility positive ion can be explained if there are two positive ions of major importance in cyclohexane radiolysis. The possibility is examined that the c-C₆H₁₂⁺ ion has a “normal” mobility and that hydride transfer or proton transfer, involving c-C₆H₁₁⁺ or c-C₆H₁₃⁺ respectively, is responsible for the observed high mobility.