Mechanisms of 5'-O-Benzoyl-2,3'-anhydrothymidine Reactions with Nucleophiles: II. Kinetics of the Reaction with Triethylammonium Tetrazolide in DMF

The reaction of 5'-O-benzoyl-2,3'-anhydrothymidine with triethylammonium tetrazolide in DMF at 100-120°C is described by a second-order kinetic equation, following the first-order kinetics in each of the reactants. On the basis of the experimental activatin parameters, H298 = 80 kJ/mol, S = -116 J× mol^{- 1} K^{- 1}, a mechanism was proposed, according to which in the rate-determining stage of S_N2 reaction triethylammonium tetrazolide attacks the C^{3 '} atom of 5'-O-benzoyl-2,3'-anhydrothymidine with simultaneous loosening of the C^{3 '}ÄO² anhydro bond.     

Synthesis and In vitro Study of Cytotoxic Activity of New Tetrazole-Containing 2,4-Diamino-1,3,5-triazine Derivatives

Russian Journal of General Chemistry - New tetrazole-containing derivatives of 2,4-diamino-1,3,5-triazine were synthesized. The cytotoxic activity of the obtained compounds against Huh-7 and HeLa...     

Smectic membranes in motion: approaching the fast limits of x-ray photon correlation spectroscopy

The dynamics of the layer-displacement fluctuations in smectic membranes have been studied by x-ray photon correlation spectroscopy (XPCS). We report transitions from an oscillatory damping regime to simple exponential decay of the fluctuations, both as a function of membrane thickness and upon changing from specular to off-specular scattering. This behavior is in agreement with recent theories. Employing avalanche photodiode detectors and the uniform filling mode of the synchrotron storage ring, the fast limits of XPCS have been explored down to 50 ns.     

Complex dynamic behavior of fluctuating smectic- A films as studied by scattering with coherent X-rays

Coherent dynamic x-ray scattering has been used to study the thermally excited layer fluctuations in freely suspended smectic films of the compound 4O.8. Using 8-keV x rays and films with a thickness around 0.3 &mgr;m we resolve relaxation times down to a few &mgr;s. A combination of damped and oscillatory behavior is observed for the layer undulations, which can be attributed to inertial effects. These are due to the surface contribution to the free energy which cannot be disregarded for thin films.