Ultraviolet absorption maxima

Tabus XIII. Ultraviolet Absorption Maxima oi cis and trass... 

The prediction of the values of such shifts has been considered in closely related iV-heteroaromatio systems. Ultraviolet absorption maxima have been determined for pyrido[2,3-d]pyrimidines, i i . ti-44, 56,110-112 pyrido[3,2-d]pyrimidines/ pyrido[3,4-d]... 

The following ultraviolet absorption maxima have been measured ... 

Tablb XIII. Ultraviolet Absorption Maxima of cis and trans... 

Details of the ultraviolet absorption maxima for simple silenes, silaaro-matics, and for some relatively stable silenes are known and have been summarized.6 The simplest silenes absorb in the region 245-260 nm, with unknown extinction coefficients but as the substituents become increasingly complex, the Xmax values of the silenes increase until, with the silene (Me3Si)2Si=C(OSiMe3)Ad, the absorption occurs at 340 nm5 with an extinction coefficient of about 7400, consistent with a tt-it transition. A few further studies of interest are summarized below. 

Table 14. Ultraviolet Absorption Maxima and Extinction Coefficients of Model...

The Near Ultraviolet Absorption Maxima (in mu) of Some HalomethaneB (in the Vapor Phase Unless Otherwise Specified)... 

The longest-wavelength ultraviolet absorption maxima of methanol and methoxymethane (dimethyl ether) are noted in Table 9-3. In each case the absorption maximum, which probably involves an n ——> cr transition, occurs about 184 nm, well below the cut-off of the commonly available spectrometers. 

The wavelengths of the ultraviolet absorption maxima of the arenols shown in Table 26-1 indicate a considerable effect of substituents on these absorptions, which correspond to the 200-nm and 255-nm absorptions of benzene (Section 22-3 B). 

After the reaction product at the Rf value of 0.40 was eluted with water from the chromatogram, its spectrum in neutral solvent and its ionization Ac curve were recorded. The neutral spectrum and the ionization Ac curve of bis-4-hydroxy-3,5-dimethoxyphenylmethane in 47.5% ethanol were also recorded the wavelengths of the ultraviolet absorption maxima of the two compounds—eluted product and reference compound—are given in Table II. The spectra of the compounds possess maxima at nearly identical wavelengths. Thus, paper chromatography and ultraviolet spectroscopy indicate positively that bis-4-hydroxy-3,5-dimethoxyphenylmethane is a product of the reaction of syringyl alcohol with alkali in aqueous solution. 

Table II. Wavelength Locations of Ultraviolet Absorption Maxima of Bis-4-hydroxy-3,5-dimethoxyphenylmethane...

Table 21. Ultraviolet absorption maxima of styrylpyridine and complexes at 25 °C1)... 

Ultraviolet Absorption Maxima of Some Representative Molecules... 

For data on other compounds see the index of Ultraviolet Absorption Maxima in Part 3. 

Ultraviolet absorption, generalnotice, xv Ultraviolet absorption maxima indexes, acid solution, 1128-1134 alkaline solution, 1134-1138 neutral solution, 1138-1140... 

The wavelengths of main peaks are listed for acid, alkaline, and neutral solution in the index of Ultraviolet Absorption Maxima (p. 1128). Infra-Red Absorption. The wavenumbers of the six major peaks in the range 2000 to 650 an (5 to 15 Lim), in descending order of ampHtude, are recorded in the monographs in Pm 2. In many cases ftie infi-a-red spectrum is also reproduced. When selecting the six principal peaks, those which are in ftie region where Nujol absorbs (1490 to 1320 cmr, 6.7 to 7.6 um) have been omitted. Corrections for cahbration errors have been applied where these are known. The six principal peaks, in ascending order of ftie main peak, are listed in the index of Infra-red Peaks (p.1141). 

The ultraviolet absorption maxima of various 1,2,5-thiadiazoles are given in Table X. In general these spectra conform in shape,... 

Bis(4-imino-2-pentanonato)nickel(II) crystallizes from a benzene-petroleum ether mixture as dark red needles or as fine red-orange needles. The two forms have identical melting points. The compound is very soluble in chloroform, but less soluble in benzene, pyridine, and carbon tetrachloride, and very insoluble in water. The compound crystallizes from pyridine without adduct formation. The compound is diamagnetic and apparently has the trans configuration. Partial resolution in optically active fractions has been achieved by means of a chromatographic technique. Molecular weight determinations indicate that the compound is monomeric in chloroform and benzene solution. The visible absorption spectrum of this compound in chloroform is characterized by a band centered at 552 m/i (e = 43). The ultraviolet absorption maxima for solutions in 1 1 benzene-petroleum ether occur at 298, 348, and 364 m x (e = 4150, 4760, and 4460, respectively). ... 

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