The effect of high intensity ultrasound on the synthesis of some polyurethanes

High intensity ultrasound has been applied to the preparation of polyurethanes from a number of diisocyanates and diols. In all cases, the sonochemical reactions proceeded faster in the early stages and led to higher molecular weight polymers. The effect of changing the ultrasound intensity is discussed and some speculation as to the mechanism of the reaction enhancement is given.     

Crystallization of the Fe84-xVxB16 amorphous alloys

Resistometric and Mössbauer measurements of the isothermal crystallization of nearly eutectic Fe-V-B amorphous alloys containing up to 8 at.%V were performed. The concentration dependence of the hyperfine fields of the crystallization products was found. The α-Fe-V and tetragonal mixed boride were detected and their contents in the course of crystallization estimated. The crystallization kinetics corresponds to the growth of α-phase nuclei proved by CEMS at the contact surface.     

Enantioselective catalysis using phosphorus-donor ligands containing two or three P-N or P-O bonds

This review describes some recent developments in the area of asymmetric catalysis using organometallic complexes of ligands which contain two or three P-O or P-N bonds. This category of ligands has, until the last five years or so, been underrepresented in asymmetric catalysis, particularly in contrast to phosphine ligands. Recent breakthroughs in methodology for the synthesis and manipulation of such materials have resulted in the delivery of ligands which demonstrate remarkably high enantioinduction properties in a series of asymmetric transformations.     

A direct stereospecific synthesis of 9,11-etheno- and 9,11-ethano-PGH1 derivatives

The reaction of methyl 10-oxodec-S-ynoate with cyclopentadiene is reported as the key step in the synthesis of 9,11-etheno- and 9,11-ethano-PGH₁ derivatives.