Removal s. Elimination

N-heterocyclics by - 24, 846 Removal s. Elimination, Protective groups, removal Replacement (s. a. Substitution)... 

Fluoride-induced /S-elimination reactions of silanes having leaving groups in the position are important processes in synthetic chemistry, as, for, example in the removal of / -trimethylsilylethoxy groups. 

Removal by / -elimination. 9-Fluorenylmethoxycarbonylglycine allowed to stand 10-12 hrs. in liq. NHg glycine. Y ca. 100%. - The above protective group can be cleaved by basic reagents under mild conditions. It may be modified for greater or lesser sensitivity toward basic reagents. Also cleavage in morpholine or ethanolamine s. L. A. Carpino and G. Y. Han, Am. Soc. 92, 5748 (1970). 

The composition of several FSM s may introduce combinational loops. Various methods to detect them are reviewed in [18,26]. When the existence of combinational stability without memory effect can be established, the composition of FSM s is equivalent to a product FSM, after component boundary removal and elimination of the interconnecting local variables[19]. 

The human body has developed over the thousands of years of its evolution a myriad of defense systems that can, in most people, metabolize the many chemicals that enter our bodies through our food and drink, our skin, and our lungs in small, inconsequential amounts and concentrations. As a result of this, it is possible for us to be exposed to low levels, or even occasional moderate levels, of toxic chemicals without exhibiting any adverse effects. The body s defenses take care of these through removal by elimination from the body or storage in body tissues. These metabolic processes will be described more in Section 4.3.2. 

The capsular polysaccharide of Klebsiella type 47 contains side-chains attached to the main chain by way of D-glucuronic acid residues.The side-chains were removed to give a linear polysaccharide by the following sequence of reactions (i) substitution of hydroxy- and carboxy-groups with methyl vinyl ether, (ii) /S-elimination by treatment with base, and (iii) removal of modified uronic acid residues and protecting groups by mild hydrolysis with acid. 

Fingernail poUsh remover contains either acetone or ethyl acetate, which are both nonpolar. Acetone is a Uttle harder on the skin, so some people prefer ethyl acetate. Fingernail poUsh remover has other uses around the house. Whenever 1 try to remove the price tag from a book, for example, and it leaves a gummy residue, 1 use fingernail poUsh remover to eliminate the remaining residue. (Ethyl acetate seems to work just a Uttle bit better than acetone does for this purpose.) Of course, 1 apply only a small amount first, just to make sure the ethyl acetate is not going to discolor the book s cover. 1 do not recaU that it ever has, but it does not hurt to check first. Fingernail poUsh remover can also be used to remove ink or other stains from smooth surfaces if other cleaners do not work. 

Acid-soluble sugars, phosphates, nucleotides, and phospholipids are usually removed by taking advantage of the acid and alcohol insolubility of nucleic acids and nucleoproteins. Protein removal or elimination may be accomplished in three ways (1) acid hydrolyms of the nucleic acids to acid-soluble components without protein hydrolysis (S) hydrolysis of protein phosphorus to inorganic phosphorus and of RNA to acid-soluble mononucleotides by alki and (S) dissociation of nucleic acid from protein by salt extraction followed by protein denaturation. The separation of the two types of nucleic acids from each other, which is required in any case depending on ultraviolet spectrophotometry or phosphate analysis, is... 

It is clear that iodination of a public water supply precludes selective iodine supplementation among different individuals, which may be considered to be a disadvantage. On the other hand, it may be an advantage in view of the fact that the principal success of iodized salt has occurred in those areas where iodization is mandated by law and the element of individual choice is removed s. As with other broadly applied public health measures, authorization by the appropriate governmental agencies is required, but this does not differ from the situation that applies in the case of chlorination or fluoridation of water, or the mandatory vaccination that has eliminated smallpox. 

In 1875 Alexander M Zaitsev of the University of Kazan (Russia) set forth a gen erahzation describing the regioselectivity of p eliminations Zaitsev s rule summarizes the results of numerous experiments m which alkene mixtures were produced by p elim matron In its original form Zaitsev s rule stated that the alkene formed in greatest amount is the one that corresponds to removal of the hydrogen from the f3 carbon hav mg the fewest hydrogens... 

Similar to IFP s Dimersol process, the Alphabutol process uses a Ziegler-Natta type soluble catalyst based on a titanium complex, with triethyl aluminum as a co-catalyst. This soluble catalyst system avoids the isomerization of 1-butene to 2-butene and thus eliminates the need for removing the isomers from the 1-butene. The process is composed of four sections reaction, co-catalyst injection, catalyst removal, and distillation. Reaction takes place at 50—55°C and 2.4—2.8 MPa (350—400 psig) for 5—6 h. The catalyst is continuously fed to the reactor ethylene conversion is about 80—85% per pass with a selectivity to 1-butene of 93%. The catalyst is removed by vaporizing Hquid withdrawn from the reactor in two steps classical exchanger and thin-film evaporator. The purity of the butene produced with this technology is 99.90%. IFP has Hcensed this technology in areas where there is no local supply of 1-butene from other sources, such as Saudi Arabia and the Far East. 

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