Oligo solubility

The first series of soluble oligo(/ ara-phenylene)s OPVs 24 were generated by Kern and Wirth [48] and shortly after by Heitz and Ulrich [49]. They introduced alkyl substituents (methyls) in each repeat unit and synthesized oligomers 24 up to the hexamer. Various synthetic methods, like the copper-catalyzed Ullmann coupling, the copper-catalyzed condensation of lithium aryls, and the twofold addition of organomelallic species to cyclohexane-1,4-dione, have been thereby investigated. 

Kemkes256 assumes that the overall order relative to the esterification of terephthalic acid by 1,2-ethanediol in oligo(l,2-ethanediyl terephthalate) is two no mechanism has however been suggested. Mares257 considers that during the esterification of terephthalic acid with 1,2-ethanediol, two parallel kinetic paths take place, one corresponding to a reaction catalyzed by non-dissociated add and the other to a non-catalyzed process. In fact, Mares257 is reserved about the existence of protonic catalysis. Some other orders were found for the system terephthalic atid/l,2-ethanediol 0 (overall)318 2 (add) andO (alcohol)203 1 (add) and 1 (alcohol)181 1 (add)194 . These contradictory results could be partly due to the low solubility of terephthalic acid in 1,2-ethanediol. 

Observations of the ratio of oxidized plutonium to reduced plutonium may provide some insight to the observations of erratic formation and lack of equilibration in laboratory solutions at ORNL versus fairly consistent and predictable behavior in oligo-trophic lakes and marine systems. In coastal water and the relatively shallow Lake Michigan, Pu(V) is about 90 percent of the soluble plutonium, but in the upper waters of the open ocean, where it does not interact with the seafloor due to the depths,... 

The second synthetic route consists of the coupling of hexa(4-iodophenyl)ben-zene (34) with an alkylated oligophenylboronic acid to produce a hexa(oligo-phenyl)benzene by extending the aromatic chain [52]. This route is illustrated by the reaction of hexa(4-iodophenyl)benzene (34) with an alkylated terphenyl boronic acid with formation of the hexa(quaterphenyl)benzene derivative 33. Once again, the aliphatic substituents serve to guarantee sufficient solubility. 

C. Oligo- and Poly-nucleotides.—The stepwise enzymatic synthesis of internucleotide bonds has been reviewed. A number of polynucleotides containing modified bases have been synthesised " in the past year from nucleoside triphosphates with the aid of a polymerase enzyme, and the enzymatic synthesis of oligodeoxyribonucleotides using terminal deoxynucleotidyl transferase has been studied. Primer-independent polynucleotide phosphorylase from Micrococcus luteus has been attached to cellulose after the latter has been activated with cyanogen bromide. The preparation of insolubilized enzyme has enabled large quantities of synthetic polynucleotides to be made. The soluble enzyme has been used to prepare various modified polycytidylic acids. ... 

Lithium mesitylhydroborate was prepared by reaction of mesitylmagnesium bromide with trimethoxyborane and subsequent reduction with LiAlH4. The polymerization was performed by adding a THF solution containing a slight excess of lithium mesitylhydroborate to oligo(ethylene oxide) in THF. After treatment with alcohol, the lithium borate polymers were obtained as transparent soft solids soluble in methanol, THF, and chloroform. 

A synthesis of comblike organoboron polymer/boron stabilized imidoanion hybrids was examined via reactions of poly(organoboron halides) with 1-hexylamine and oligo(ethylene oxide) monomethyl ether and subsequent neutralization with lithium hydride (scheme 8). The obtained polymers (10) were amorphous soft solids soluble in common organic solvents such as methanol, THF, and chloroform. In the nB-NMR spectra (Fig. 11), neutralization of the iminoborane unit with lithium hydride... 

Add 50 pi of the SPDP (or LC-SPDP) solution to the oligo solution. Add 100 pi of the sulfo-LC-SPDP solution, if the water-soluble crosslinker is used. Mix. 

Another method is based on the same principle,112 in which the [14C]labelled methyl ester of D-galacturonan is prepared by esterification of pectic acid with [,4C]diazomethane. In the course of the enzymic de-esterification, aliquots are removed, and the unreacted substrate is precipitated with acidified ethanol or 1-propanol. After centrifugation, the labelled methanol in the supernatant liquor is determined in a liquid scintillation counter. An advantage of this method lies in the possibility of using, as substrates, short-chain oligo-D-galactosiduronates partially esterified with [14C]methanol. These substrates, beginning with the trisaccharide, are not soluble in 1 4 80% phenol-diethyl ether, which is used for the extraction of enzymically released, labelled methanol. 

Well-known important ligands (e.g. DIOP) can be made water soluble by functionalization with oligo- or polyoxyalkylenic groups. 

Figure 7.5 Water-soluble MSPs, based on a 2,6-pyridine dicarboxylate end-capped oligo(ethylene oxide) ditopic monomer (2a and 2b) and Zn ions prepared by Vermonden and coworkers (2003).

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