Analog enrichment

Brunner, W., Sutherland, F. H. Focht, D. D. (1985). Enhanced biodegradation of polychlorinated biphenyls in soil by analog enrichment and bacterial inoculation. Journal of Environmental Quality, 14, 324-8. 

A distinct advantage of the mass spectrometer is that it can simultaneously differentiate and quantify a compound with a normal abundance of isotope from an analog enriched with a stable isotope (e.g., relative to H> relative to relative to " N, or relative to O). A com-... 

Focht, D. D. 1987. Analog enrichment decontamination process. European Patent 211,546, Feb. 25 cited in Chem. Abstr. CA 107(2) 12352g. 

An adsorbent can be visualized as a porous soHd having certain characteristics. When the soHd is immersed in a Hquid mixture, the pores fill with Hquid, which at equilibrium differs in composition from that of the Hquid surrounding the particles. These compositions can then be related to each other by enrichment factors that are analogous to relative volatiHty in distillation. The adsorbent is selective for the component that is more concentrated in the pores than in the surrounding Hquid. 

Lipophilic dyes in aqueous alcoholic solutions can be employed in an analogous manner [92, 93]. They are enriched at the zones of lipophilic substances, so that these appear deeply colored on a pale background. This does not apply to fatty acids with less than 12 C atoms [94]. 

Homomodal LC-LC. In this type of development, the chromatographic improvement occurs by switching columns of analogous selectivity. Mainly the goal is to optimize an already satisfactory separation, that is, to concentrate a dilute sample (sample enrichment) or to shorten an analysis time. 

Two types of sulfoximinocarboxylates (analogous to sulfinylcarboxylates 16), namely 5 -aryl-5 -methoxycarbonylmethyl-A(-methyl sulfoximine 36 and -methyl-5 -phenyl-A(-ethoxycarbonyl sulfoximine 37, were subjected to hydrolysis in the presence of PLE in a phosphate buffer. As a result of a kinetic resolution, both the enantiomerically enriched recovered substrates and the products of hydrolysis and subsequent decarboxylation 38 and 39, respectively, were obtained with moderate to good ees (Equations 20 and 21). Interestingly, in each case the enantiomers of the substrates, having opposite spatial arrangement of the analogous substituents, were preferentially hydrolysed. This was explained in terms of the Jones PLE active site model. ... 

The last example is mediated by a monooxygenase that can be induced by benzene, toluene, and ethylbenzene, and also by xylenes and styrene. A plausibly analogous situation exists for strains of Pseudomonas sp. and Rhodococcus erythropolis that were obtained by enrichment with isopropylbenzene, and that could be shown to oxidize trichloroethene (Dabrock et al. 1992). In addition, one of the pseudomonads could oxidize 1,1-dichloroeth-ene, vinyl chloride, trichloroethane, and 1,2-dichloroethane. 

Anaerobic degradation of cycloalkanes has seldom been reported. The pathway used for the degradation of ethylcyclopentane by a sulfate-reducing enrichment is analogous to the fumarate pathway used for -alkanes (Part 1 of this chapter) with the formation of 3-ethylcyclopentanecar-boxylate followed by ring fission to 3-ethylpentan-l,5-dioate (Rios-Hamandez et al. 2003). 

A sulfate enrichment culture prepared from a contaminated site gave enrichment factors (e) of-1.1 for naphthalene and -0.9 for 2-methylnaphthalene (Griebler et al. 2004). These values combined with literature values from analogous laboratory experiments were used to quantify degradation of toluene, xylenes, and naphthalene at the site. Additional evidence for degradation of BTEX was derived from analyses of established metabolites produced by anaerobic degradation. 

Hanessian reported the synthesis of enantiomerically pure or highly enriched allylglycine and its chain-substituted analogs from the reaction of the sultam derivatives of O-benzyl glyoxylic acid oxime with ally he bromides in the presence of zinc powder in aqueous ammonium chloride (Eq. 11.41).72 Brown noticed the critical importance of water in the asymmetric allylboration of /V-trimethylsilyIbcnzaldimines with B-allyldiisopinocampheylborane.73 The reaction required one equivalent of water to proceed (Eq. 11.42). 

Chiral Bronsted acid co-catalysts do not promote formation of optically enriched products in analogous couplings to pyruvates, although increased rate and conversion in response to the Bronsted acid co-catalyst is unmistakably apparent. For pyruvates, protonation likely occurs subsequent to the C-C... 

Glenn Theodore Seaborg (1912-1999), together with Stanley Gerald Thompson (1912-1967) and Albert Ghiorso ( 1915). The bombardment of americium-241 with alpha particles led to element 97 with atomic mass number 243. The enrichment involved chemical methods, as the properties of the element were assumed to be analogous to those of the lanthanides. 

The spectrum of silicon based polymers is enriched by high tech ceramics like silicon nitride and carbide, respectively. These materials are produced by pyrolysis of appropriate polymeric precursors such as polysilanes, polycarbosilanes and polysilazanes (preceramics). These synthetic ceramics display a certain analogy to silicates, having SiC, SiN, or Si(C,N) as structural subunits instead ofSiO. 

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