Stereoselectivity Supercritical phase

Phenol-ketone novolacs 1487, 1488 Phenol-nitrile complexes 377 Phenol radical cations 1101 fragmentation of 289-291 Phenols—see also Biphenols, Bis-phenols, Hydroxybenzenes, Polyphenols acidities of, gas-phase 310-312 acylation of 629-632, 933, 934 Lewis acid catalyzed 631 montmoriUonite-catalyzed 632 pyridine-catalyzed 631 adsorption of 944 alkylation of 606-629, 941 Brdnsted acid catalyzed 612 Lewis acid catalyzed 607-611 solid acid catalyzed 612-621 stereoselective 621-626 under supercritical conditions 621 as antioxidants 139-143, 840-901 ort/io-substituted 845 thermochemistry of 139, 140, 179 autoxidation of 1118, 1119 bromination of 649-651 jr-cation interaction of 322 chlorination of 649 comparison with isoelectronic methyl, amino and fluoro aromatic derivatives 226... 

As seen from Figure 93.2, the diastereoselectivity in the DBH photolysis in supercritical fluids (SC-CO2 and SC-C2H5) depends on pressure. The increase of pressure up to 200 bar leads to a ca. 2.3-fold decrease of the stereoselectivity kj /k mtio) in SC-CO2 and sc-C2H. Analysis of the observed pressure dependence in terms of coUisional (self-diffiision coefficient) and frictional (viscosity) effects discloses that frictional impositions by the fluid media account best for the experimental observations. This is consistent with the experimental observations on solvent effects for liquid-phase DBH photol) is. ... 

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