You searched for: hetero aromatic molecules (Engelska - Polska)

they are used for the calculation of log pow for aromatic molecules or substructures.
są one stosowane dla obliczeń log pow cząsteczek aromatycznych lub podstruktur.

the addition of 5 % polyvinylpyrrolidone-40000 mwt (pvp-40) is recommended when performing the direct pcr test to reduce the incidence of amplification inhibition by aromatic molecules in the extract.
zaleca się dodatek 5 % poliwinylopirolidonu - o masie cząsteczkowej 40 000 (pvp-40), podczas wykonywania bezpośredniego badania pcr, w celu zmniejszenia inhibicji namnażania przez cząsteczki aromatyczne obecne w ekstrakcie.

thiophenes furans and pyridines are in general the most readily available of the various hetero-aromatic systems and therefore we have carried out a great deal of metallation and derivatization reactions with these compounds. furan and thiophene are cheap starting compounds and the stability of their easily obtainable 2-lithio derivatives permits reactions with a variety of "electrophilic" reagents. hetero-aromatics with two or more hetero atoms (e.g. thiazoles, pyrazoles, oxazoles) are less readily available, and some of their metal derivatives have a low thermo stability (cyclofragmentations). for these reasons their metallation and functionalization reactions have been studied less extensively [1]. the majority of the metallated hetero-aromatic compounds are obtained by direct metallation [1,2,5]. the "hetero-atom effect" (inductive, coordinative and polarizability influence) in most cases directs the metallation to the position 0(- to the hetero atom and gives rise to an easier deprotonation compared with that of benzene [1]. in some cases, bromine-lithium exchange offers the possibility of introducing the metal in a position that is not accessible by direct deprotonation. in incidental cases, grignard compounds have been prepared from halogenated hetero aromates and magnesium.
siłą napędową dla wymiany br/li jest prawdopodobnie znacznie słabszy, w przypadku phenyllithium, ponieważ różnica w wytrzymałości bazowej phli i 3-thienyllithium nie jest duża. z drugiej strony kwasowość 2-proton jest wystarczające do szybko deprotonowanie przez phli.