Purity enhancement factor

Determine the solid phase yield (defined as the ratio of moles of solid deposited/mole of CO2 in feed) of each of the two species, as well as the purity enhancement factor of 1,10-decanediol in the deposited solid phase when the temperature is reduced from 318 K to 308 K at each one of the four pressures identified above. 

Purity enhancement factor = ratio of mole fraction of decanediol/benzoic acid in the deposited solid phase to that in the feed phase. 

Sections of wing samples from Cicadetta cells cicadas were coated in a layer of high purity (99.99%) silver 60 nm thick using a Kurt J Lesker CMS-18HV electron beam deposition system controlled by a quartz crystal microbalance. These cicada wing substrates were found to produce a SERS enhancement factor of 10 when self-assembled monolayers of thiophenol were formed on their metalized surfaces. More recent work by Kostovski et al. has focused on... 

In order to provide a better estimate of the enantioselectivity of the catalyst, we prepared an authentic sample of (+)-chorismate by kinetic resolution of the racemate with 1F7 (37). Circular dichroism spectroscopy confirmed the identity and high optical purity of the recovered, HPLC-purified compound. Initial rate measurements with the individual isomers show that (-)-chorismate is favored over (+)-chorismate by the antibody by a factor of at least 90 to 1 at low substrate concentrations. The slight rate enhancements above background observed for the (+)-isomer may be due to general medium effects rather than interaction with a specific locus on the antibody surface. To test this possibility we are currently examining the ability of the transition state analog 3 to inhibit rearrangement of this optical isomer. 

Chiral-specific photochemistry using CPL depends on the circular dichroism (A = r l) of the reactants, i.e., the differences in the absorption coefficients or right and left CPL. The rate of the reaction depends on the amount of light absorbed so if A > 0, there will be a bias towards one of the enantiomers leading either to its preferential enhancement or destruction and an ee The enantiomeric purity of the chiral product is determined by the anisotropy factor, g, where g - A / and = 0.5( r+ l). For optically active compounds g values are fairly small, 0.01. 

Description The CD column (1) combines reaction and fractionation in a single-unit operation. Alkylation takes place isothermally and at low temprature. CD also promotes the continuous removal of reaction products from reaction zones. These factors limit byproduct impurities and enhance product purity and yield. Low operating temperatures and pressures also decrease capital investment, improve operational safety and minimize fugitive emissions. 

The second reversed-phase LC purification of both factors used a Vydac C4 column eluted with a gradient of acetonitrile-0.1% aqueous heptafluorobutyric acid (HFBA). This gave a markedly different selectivity than the acetonitrile-0.1% TFA system for FI, with an extremely efficient removal of non-immunoreactive UV-absorbing materials. A somewhat different CH3CN/0.1% HFBA program provided a substantial enhancement of the purity of F2, although less dramatically than for FI. 

One additional factor to keep in mind in mind is the greater purity of most crystalline materials, which can contribute significantly to their enhanced stability, especially during the earliest stages of drug development. 

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