Detachment reagent

Since it became obvious that liquid HF is not at all the detachment reagent of choice (see in contrast [35, p. 380]), the search for a similarly efficient reagent resulted recently in the utilization of boron tris (trifluoroacetate) [172], which in trifluoroacetic acid is reported to smoothly liberate peptides bound to the polymer support by benzyl ester type linkages. All above-mentioned protecting groups stable against trifluoroacetic acid are simultaneously cleavable. Trifluoromethanesulfonic acid [173] and pyridinium polyhydro-genfluoride are proposed for the same purpose [174] (Fig. 52). 

It is important that the method used to detach cells from their growing surface is compatible with end use. For final use as cell control material, it is important to use a methodology that preserves structural integrity and membrane protein localization. Enzymatic-based reagents may affect proteins on the surface of cells. 

The reaction of these aldehydes, derived from periodate oxidation, with carbonyl reagents has also been investigated. Studies 147 148 were made on oxidized laminarin, a (1 —> 3)-linked polysaccharide, in which only the terminal residues had been oxidized. The addition of phenylhydrazine acetate detached the remainder of the terminal residue as glyoxal phenyl-osazone. When the aldehydic compounds derived from the periodate oxidation of raffinose and trehalose818a were reacted with p-nitrophenylhydrazine, the authors were surprised to find that one molecule of oxidized raffinose, containing six aldehydic functions, reacts with only three molecules of the reagent, and that the four aldehydic functions of the oxidized trehalose molecule react with only two. The reactions of periodate-oxidized carbo-... 

FIGURE 5.22 (A) Reaction of an Fmoc-amino acid with 2-chlorotrityl chloride resin.56 The ester bond formed is cleavable by the mild acid, which does not affect tert-butyl-based protectors. (B) Generation of a protected peptide containing cystine by detachment of a chain, deprotection of cysteine residues, and oxidation of the sulfhydryls by the reagent containing iodine. The cations produced are trapped by CF3CH2OH. 

Table II. Damage from sulfhydryl-binding reagents to the detached leaves of two tobacco varieties...

The complexes are air stable indeed, a limitation is the need for powerful oxidizing agents, such as Jones reagent CrVI, to detach the arene ligand.38 They are highly reactive toward nucleophiles. This limits the number of compatible synthesis manipulations that can be carried on in the presence of the [(arene)Mn(CO)3] unit but broadens the scope of effective nucleophiles. 

Transfer the solvent to the extractor. Repeat the sample bottle rinse with an additional 50 to 100 mL portion of methylene chloride and add the rinse to the extractor. Add 200 to 500 mL methylene chloride to the distilling flask and sufficient reagent water to ensure proper operation. Extract for 16 hours. Allow to cool, then detach the flask and dry the sample by running it through a rinsed funnel packed with a glass wool plug ant 5 g of anhydrous sodium sulfate into a 500 mL KD flask. Proceed to Section 9.6. 

Here, pathway 1 (reaction 1) is the coordinated addition of ozone (1) to ethylene (2), which proceeds through the formation of a weakly-boimd complex that transforms into primary ethylene ozonide (PO) or 1.2.3-trioxolene upon passing through the symmetrical transient state (TSl). Pathway 2 (reaction 2, the DeMore mechanism [15]) involves the collision during spontaneous orientation of the reagents (3) and the rotational transition to the biradical transient state (TS2) (4) followed by the formation of the same PO. Proceeding from the above-said, we supplement this pathway with the reaction of detachment of molecular oxygen and the formation of intermediate biradical (5) the latter may either decompose with the formation of formaldehyde (6) and carbene (7) or transform into acetaldehyde (8) or epoxide (9). Finally, pathway 3 involves the transition of ozone into the triplet state (10). This pathway is similar to reaction 2. Here, the same biradical (5) is formed it transforms into the... 

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