An experimental test of the Bernstein—Levine theory of branching ratios

The first test of the information-theoretic approach to branching ratios has been made for the reaction: F + HD å HF2 (V′, R′) + D å DF3(V′, R′) + H.The vibrational (V′) and rotational (R′) product energy-distributions for both branches of this reaction have been obtained by the infrared chemiluminescence technique, and have been used in the calculation of an information-theoretic branching ratio, Γ_HF/DF = 1.41 ± 0.18. This is in excellent agreement with the experimentally measured branching ratio of 1.45. However, results from classical trajectory calculations raise a question as to the significance of this agreement. Classical trajectory calculations (on various energy-surfaces) predict an increase in Γ with reagent J. The information-theoretic analysis applied to the product energy-distributions from these trajectory calculations leads to a qualitatively different result. As a possible alternative to the information-theoretic view, simple kinematic features are noted which could account for Γ > 1, as well as for the significant differences in product energy-distribution. On this alternative view, the two features are not indisolubly linked — the extent to which they appear in conjunction will depend on the nature of the energy surface.     

Benzodiazepine Analogues. Part 15.1 Synthesis of Benzoxathiepine Derivatives

Stepwise cyclisation sequences have provided access to a series of novel 4-phenyl-3, 4-dihydro-1,5-benzoxathiepine-2-ones and 2-and 3-phenyl-4, 1-benzoxathiepine analogues.     

General Synthetic Route to Monosubstituted Cycloheptadienes from Organometallic Compounds

An examination of the literature reveals that only a limited number of monosubstituted cycloheptadiene compounds have been reported. An obvious synthetic route to 5-substituted -1, 3-cycloheptadiene derivatives would be the reaction of nucleophiles with the cycloheptadienyl cation, but this pathway is generally unsuccessful due to the limited stability of the cation. On the other hand, the iron tricarbonyl complex of this cation shows remarkable stability¹ and an ability to react with nucleophiles². If the -Fe(CO)₃ group could be removed easily, a facile route to this family of organic compounds would be available. This work reports our investigation of the range of nucleophiles that can be utilized and the oxidizing agents that can remove efficiently the -Fe(CO)₃ group.     

The (S−1,S) inventory model and its counterparts in queueing theory

We explore the relationship between the ($S?1,S$) inventory model and three well-known queueing models: the Erlang loss system, the machine-repair model and a two-node Jackson network. Exploiting this relationship allows us to obtain key performance measures of the ($S?1,S$) model, like the so-called virtual outdating time, the number of items on the shelf in steady state, the long-run rate of unsatisfied demands and the distribution of the empty shelf period.     

Dabco-Catalysed Reactions of Salicylaldehydes with Acrylate Derivatives

Treatment of salicylaldehydes with acrylate derivatives in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO) has been shown to afford both coumarin and chromene derivatives, and factors influencing the product distributions have been investigated.     

Regioselective A-Ring Chlorination of Benzodiazepine Analogues Using tert-Butyl Hypochlorite

Treatment of 2-phenyl-2,3-dihydro-1,4-benzodiazepin-5(4H)-one and a series of 1,4-benzoxazepinone analogues with tert-butyl hypochlorite affords products shown, by NMR and MS spectroscopy, to be chlorinated exclusively in the A-ring at positions 7 and/or 9.     

Preparation of Nitriles by Dehydration of Primary Carboxawides with a Supported phosphorus pentoxide reagent

The use of a supported phosphorus pentoxide reagent in the synthesis of selected nitriles is discussed.