High‐pressure Nucleation of Low‐Density Polymorphs

The crystallized above 0.3 GPa polymorphs β and γ of bis-3-nitrophenyl disulphide, are less dense than the ambient-pressure polymorph α. This high-entropy nucleation illustrates the molecular-scale mechanism of empirical Ostwald’s rule of stages. This method, in contrast to mechanochemical techniques, is ideally suited the kinetic nucleation of new low-density conformational polymorphs.<br /

Squeezing out the Catalysts: The Disulphide Bond Exchange in Aryl Disulphides at High Hydrostatic Pressure

Exchange of the disulphide bond is a prominent example of equilibrium reactions. Therefore, the wide library of disulphide exchange reactions requires the application of catalysts, such as reducing agents, strong bases, ultraviolet light, or ultrasounds to stimulate higher conversion yields. We employed the pressure between 100 and 400 MPa, for promoting the exchange reactions between various homodimeric aryl disulphides and for optimized conditions obtained 100 % yields and pure single-crystal form of the heterodimer. The reactions were performed in a diamond-anvil cell, as well as in a hydraulic piston-and-cylinder press, and the products were characterized by X-ray diffraction, mass and NMR spectroscopy. <br /