W-shape

A useful alternative W-shaped pofenfial function to fhaf in Equation (6.93) is... 

The BQ term alone, wifh B positive, would give a pofenfial resembling fhe harmonic oscillator pofenfial in Figure 6.4 (dashed curve) buf wifh steeper sides. The inclusion of fhe AQ term, wifh A negative, adds an upside-down parabola af 0 = 0 and fhe resulf is a W-shaped pofenfial. The barrier heighf b is given by... 

Since, in fhe excifed sfafe, fhe fluorine atoms may be above or below fhe plane of fhe benzene ring fhe potential function for Vu is W-shaped, like fhaf in Figure 6.4f(b). Fitting the observed vibrational energy levels to the potential function in Equation (6.93) gives fhe heighf of fhe barrier to planarify as 78 cm. ... 

The disrotatory mode, in which the methyl groups move away from each other, would be more favorable for steric reasons. If the ring opening occurs through a discrete cyclopropyl cation, the W-shaped allylic cation should be formed in preference to the sterically less favorable U-shaped cation. This point was investigated by comparing the rates of solvolysis of the cyclopropyl tosylates 6-8 ... 

The horizontal mixers normally used consist of a w shaped mixing bowl with two Z blades (Figure 2). These mixers do not have a removable bowl so the dough has to be tipped out. The mixers can deliver large amounts of energy at low speeds. 

Elimination.1 The dehydroiodination of y-iodo ketones or y-iodo esters with DBU at 25° to form cyclopropanes occurs readily only when the proton and the iodo group can adopt a W-shaped geometry. Thus the cyclopropane 1 is formed... 

The shape of the microfiber influences the end properties. For instance, Tomen has developed Technofine , a polyester microfiber with a W-shaped cross section. The increased surface allows a more rapid transport of water away from the skin and also increases the evaporation rate, making garments sowed from it quicker-drying and more adsorbent. 

In addition to rapid exchange of thiolate ligands with R SH and for R S , the mononuclear complexes [Fe(NO)2(SR)2] also undergo (23) rapid exchange of the nitrosyl ligands in the presence of isotopically labeled nitrite a W-shaped N203 intermediate was proposed (23) [Eq. (22)]. 

The kinetic results for the lipase-catalysed enantioselective hydrolysis of the esters (236)-(240) can be interpreted in terms of frontier orbital localization.213 The porcine pancreatic lipase (PPL)-mediated optical resolution of 18 racemic esters can be explained by a mechanistic model involving a W-shaped active conformation of the substrate lying in a diastereo-discriminating plane.214... 

M.-E. Saint-Victor and D. Patterson, The W-Shape Concentration Dependence on C and Solution Non-randomness Ketones + Normal and Branched Alkanes , Fluid Phase Equilib., 35, 237-252 (1987). 

See for example R. G. Rubio, M. Caceres, R. M. Masegosa, L. Andreolli-Ball, M. Costas, and D. Patterson, Mixtures with W-Shape Curves. A Light Scattering Study , Ber. Bunsenges. Phys. Chem., 93, 48-56 (1989) and A. Lainez, M. R. Lopez, M. Caceres, J. Nunez, and R. G. Rubio, Heat Capacities and Concentration Fluctuations in Mixtures of... 

Miyake I, Takanishi Y, Rao NVS, Kr M, Ishikawa K, Takezoe H (2005) Novel chiral filament in an achiral W-shaped liquid crystalline compound. J Mater Chem 15 4688 1694... 

In the event that two substituents at different carbon atoms in the aziridine cycle are hydrogen atoms (for example, A and C in Scheme 1.33), the ylides being formed are called S-shaped, W-shaped, or U-shaped [115] (Scheme 1.34). The reaction of dipolar cycloaddition of S-shaped ylides forms adducts with trans orientation of the protons, while W- and U-shaped ylides lead to cis adducts (for suprafacial reactions). 

---