Polyenic groups

Values of electrical effect substituent constants for a few dienyl and polyenal groups have been reported25. They are set forth in Table 1 together with values of diynyl and phenyl groups for comparison. Also reported in Table 1 are values for some other types of substituents22,25 for purposes of comparison. 

Examples of the application of correlation analysis to diene and polyene data sets are considered below. Both data sets in which the diene or polyene is directly substituted and those in which a phenylene lies between the substituent and diene or polyene group have been considered. In that best of all possible worlds known only to Voltaire s Dr. Pangloss, all data sets have a sufficient number of substituents and cover a wide enough range of substituent electronic demand, steric effect and intermolecular forces to provide a clear, reliable description of structural effects on the property of interest. In the real world this is not often the case. We will therefore try to demonstrate how the maximum amount of information can be extracted from small data sets. 

On heating, migration of a hydrogen atom, alpha to a polyene group, to an alkyl free radical site would also convert a polyene to a polyenyl free radical, a transformation similar to transformation of the allyl free radical described above ... 

Menzol norethisterone. mepacrine [ban, inn] (quinacrine hydrochloride [usan]) can be used as an antimalarial and ANTHELMINTIC. It also acts as a POTASSIUM-CHANNEL BLOCKER (IsKICal)-mepartricin [ban, inn, usan] (Mepartricin A) is a (polyene group) ANTIBIOTIC mixture with ANTIFUNGAL and ANTIPROTOZOAL activity. Clinically, it can be used topically, principally for candidiasis. 

AY 22989) is a (polyene group) ANTIBIOTIC produced by Streptomyces hygroscopicus. It has activity as an ANTIFUNGAL,... 

M(CO)x lacks an odd number of electrons. The observant reader will note that all cases so far considered involve metal-containing components in which the metal requires only an even number of electrons to complete its coordination. There are, of course, about an equal number of instances in which an odd number of electrons are required. In those cases the metal will combine with some sort of polyenyl (as opposed to polyene) group. The important cases are those in which 3 or 5 electrons are required. In these the organic moieties are... 

UV spectroscopy also allows identification of subdivisions within the five polyene groups. Methylation adjacent to the polyene chromophore results in a bathochromic shift of the absorption maxima of about 6 nm. The presence of a ketone group adjacent to the chromophore radically alters the absorption spectrum, e.g. the carbonyl pentaene flavomycoin possesses only two absorption peaks, while the carbonyl hexaene dermostatin possesses a single peak [24—26]. 

In certain clear, transparent polymer materials new optical absorption bands - absorbing mainly in the ultraviolet or in the infrared region - form upon irradiation. These radiation-induced changes in the UV region involve (1) main-chain unsaturations of polyene groups (e.g., -C=C- in polyolefins) or (2) side-chain unsaturations (e.g., =C=0 groups in polymethylmethacrylate) as described by Charlesby (1960) and Dole (1972). The increase of absorbance of these absorption bands can be used for dosimetry measurements. 

A group of antibiotics that are produced by Streptomyces spp. contain polyene groupings. These antibiotics inhibit the growth of certain fungi and some of them have proved effective against fungal infections in man. 

Oxygen promotes HCI cleavage. Therefore, air increases dehydrochlorination on the other hand, air also retards discoloration and even brightens up slightly discolored PVC, because oxygen also reacts with the polyene groups and thus breaks up conjugated double bond systems [599]. 

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