Thermal studies on lead(II) salts

The thermal decomposition of synthetic lead(II) hydroxide chloride has been studied between 490 and 520 K over a range of partial pressures of water vapour. The reaction rate is controlled by diffusion of water vapour and Arrhenius parameters have been calculated. The activation energy varies between 92 and 145 kJ mol^?1 and the frequency factor between 10⁹ and 10¹⁵ sec^?1. Water vapour pressure has a profound effect on the reaction rate and a double minimum in the rate is observed. Enthalpimetric data are also presented for the decomposition.     

The dehydroxylation of tricalcium aluminate 6-hydrate

The thermal decomposition of tricalcium aluminate 6-hydrate^* has been studied and kinetic parameters determined for each of the two stages in the reaction. The first stage was studied in the temperature range 505-610 K and the second between 950 and 1025 K at partial pressures of water vapour between 0.1 mN m^?2 and 3.2 kN m^?2. For the first stage below 555 K the rate-controlling process is one of nucleation and growth of product phase, which changes at higher temperatures to a diffusion-controlled process. The Arrhenius parameters for each of these processes vary with external water vapour pressure. The second stage of the reaction is controlled by a phase boundary reaction for which Arrhenius parameters are given.     

The thermal unimolecular decomposition of bromocyclobutane

The thermal unimolecular decomposition of bromocyclobutane has been investigated over the temperature range of 791–1224 K using the technique of very low-pressure pyrolysis (VLPP). HBr elimination is the sole mode of decomposition under the experimental conditions. No evidence could be found for the ring-cleavage pathway to ethylene and vinyl bromide. Assuming a four-center transition state and an Arrhenius A factor the same as that for HCl elimination from chlorocyclobutane, RRKM calculations show that the experimental unimolecular rate constants are consistent with the Arrhenius expression where θ = 2.303RT kcal/mol. The activation energy is higher than that for the open-chain analog, 2? bromobutane. This finding is consistent with the results for the corresponding chloro and iodo compounds.     

Electrophilic Substitution of 1,3-Dimethoxybenzene By Pentadienyltricarbonyliron Cations

Kinetics of reactions of several open-chain pentadienyltricarbonyliron cations with 1,3-dimethoxybenzene have been studied; the reactions are faster than those of the cyclohexadienyltricarbonyliron cation and a mechanism is proposed.     

Syn to anti isomerization and degradation of phosphines of the 7-phosphanorbornene system by action of methanol

$\text{Syn}$-Substituted phosphines of the 7-phosphanorbornene system form unstable phosphorane adducts with methanol that either fragment by retro-McCormack cycloaddition or undergo polytopal rearrangement and loss of methanol to give the first examples of $\text{anti}$ phosphines.     

An exact solution to reggeon calculus

By choosing a suitable but unconventional bare pomeron propagator and bare triple-pomeron coupling the Dyson equations of reggeon calculus are shown to reduce to algebraic equations for the various coupling constants. The resulting pomeron, which is identical to the input pomeron is the familiar black or gray disk.