Crystal structure of ethyl pyruvate-2-methyl-4-chloro-phenyl hydrazone

Ethyl pyruvate-2-methyl-4-chloro-phenylhydrazone, C₁₂H₁₅N₂O₂Cl, is an important intermediate for the synthesis of ethyl-5-chloro-7-methyl indole-2-carboxy-late. Crystals are orthorhombic witha=6.99(4),b=23.75(6),c=17.05(6) Å and eight molecules per cell in the space group Cmca. The structure was solved by direct methods using film data and refined by block diagonal least squares method to anR-index of 0.052. The molecule occupies the space group mirror(m) special position. The stacking of the molecules is stabilized by van der Waal’s contacts.     

On cardioactive steroids. XII. The synthesis of (natural) bufalin and α′-isobufalin

An efficient and simple synthesis of bufalin (1) via furan-containing intermediates is described. The same method was also used for the synthesis of α-isobufalin (2) which was prepared with equal simplicity, but in lower yield.     

Enzymatic synthesis of optically active amino acids. Effect of solvent on the enantioselectivity of lipase-catalysed ring-opening of oxazolin-5-ones.

Reaction medium plays an important role in governing the enantioselectivity of the lipase-catalysed ring opening of 4-substituted-2-phenyl-oxazolin-5-ones.     

D1AD2 theorems for multidimensional matrices

A new technique for proving D₁AD₂ theorems is given. Also a generalization of D₁AD₂ theorems to multidimensional matrices is indicated.     

Heat transfer in laminar flow of Bingham material through a circular pipe

Summary The fully developed heat transfer in laminar flow of Bingham material through a straight circular pipe has been analysed when the effect of dissipation is taken into consideration. The temperature distribution, the mixed-mean temperature and the Nusselt number are calculated and found to depend on the Modified Reynolds number, the Brinkman number and the rate of heat transfer at the wall. The effect of dissipation is to increase the temperature and the mixed-mean temperature of the material while the Nusselt number is found to decrease with increasing dissipation.Nomenclature r, , z space coordinates - u, v, w velocity components - density of the fluid - modulus of rigidity (constant) - bulk modulus - e _kk, the dilation - ₁ coefficient of viscosity (constant) - e _ik strain tensor - d _ik rate of strain tensor - p _ik stress tensor primes denote deviatoric components of tensors, e.g. - p _ik p _ik p _ik, p=–1/3p _kk - yield value (constant) - D/Dt material derivative with regard to time following the particle - R radius of the pipe - r ₀ radius of the yield surface (cylindrical) - r=r ₀/R non-dimensional radius of the yield surface - T ₀ temperature of the pipe - K conductivity - Modified Reynolds number - Br Brinkman number     

Purpurinimide-fullerene dyads: introduction of fullerene moiety at various peripheral positions of the purpurinimide system

[reaction: see text] Fullerene was regioselectively introduced at various peripheral positions of N-hexyl-purpurinimide for photoinduced electron transfer studies. Remarkably different effects of the position of the fullerene moiety in the formation of atropisomers were observed.     

Dephasing-induced vibronic resonances in difference frequency generation spectroscopy

The difference frequency generation (DFG) signal from a two electronic level system with vibrational modes coupled to a Brownian oscillator bath is computed. Interference effects between two Liouville space pathways result in pure-dephasing-induced, excited-state resonances provided the two excitation pulses overlap and time ordering is not enforced. Numerical simulations of two-dimensional DFG signals illustrate how the ground and excited electronic state resonances may be distinguished.     

Reaction route graphs. III. Non-minimal kinetic mechanisms

The concept of reaction route (RR) graphs introduced recently by us for kinetic mechanisms that produce minimal graphs is extended to the problem of non-minimal kinetic mechanisms for the case of a single overall reaction (OR). A RR graph is said to be minimal if all of the stoichiometric numbers in all direct RRs of the mechanism are equal to +/-1 and non-minimal if at least one stoichiometric number in a direct RR is non-unity, e.g., equal to +/-2. For a given mechanism, four unique topological characteristics of RR graphs are defined and enumerated, namely, direct full routes (FRs), empty routes (ERs), intermediate nodes (INs), and terminal nodes (TNs). These are further utilized to construct the RR graphs. One algorithm involves viewing each IN as a central node in a RR sub-graph. As a result, the construction and enumeration of RR graphs are reduced to the problem of balancing the peripheral nodes in the RR sub-graphs according to the list of FRs, ERs, INs, and TNs. An alternate method involves using an independent set of RRs to draw the RR graph while satisfying the INs and TNs. Three examples are presented to illustrate the application of non-minimal RR graph theory.