Ketones absorption spectra

Unfortunately, addition of copper(II)nitrate to a solution of 4.42 in water did not result in the formation of a significant amount of complex, judging from the unchanged UV-vis absorption spectrum. Also after addition of Yb(OTf)3 or Eu(N03)3 no indications for coordination were observed. Apparently, formation of a six-membered chelate ring containing an amine and a ketone functionality is not feasible for these metal ions. Note that 4.13 features a similar arrangement and in aqueous solutions, likewise, does not coordinate significantly to all the Lewis acids that have been... 

Different molecules absorb radiation of different wavelengths. An absorption spectrum will show a number of absorption bands corresponding to structural groups within the molecule. For example, the absorption that is observed in the UV region for the carbonyl group in acetone is of the same wavelength as the absorption from the carbonyl group in diethyl ketone. 

Figure 14.5. Infrared spectra of a ketone, upper spectrum, and aldehyde. Both have strong =0 absorption bands. Hexanal has a chain of -CH2 groups and -CH3 group, and thus the strong absorption just less than 3000 cm"1. 

The method was first applied by Rothman, Case, and Kearns to the determination of the Ti- -So absorption spectrum of 1-bromonaphthalene. Sixteen photochemically active aromatic ketones cind aldehydes have been investigated by Kearns and Case Transitions from So to two triplet states were located and assigned as n,n ) and... 

Assignment of the transient absorption spectrum typically is done by reference to the low-temperature spectra described above. It is also important to analyze the chemical reactions of the intermediates. For example, triplet carbenes are known to react with O2 very efficiently to give ketones. So, if the detected intermediate can be observed to react with O2, there is additional evidence for assignment as a triplet carbene (see Section 6.5). 

The frequency of the ester carbonyl responds to environmental changes in the vicinity of the carbonyl group in much the same manner as ketones. The spectrum of phenyl acetate, Figure 3.25, illustrates most of the important absorption characteristics for esters. 

There are now several indications that the photolysis of hexafluoro-acetone is not as simple as it was originally supposed. Herzberg et al.,59 showed that the absorption spectrum of CF2 appeared under flash photolysis conditions and Kutschke60 has identified higher perfluoroalkanes in the normal photolysis, formed, it is supposed, by mechanisms analogous to those proposed for the 1,3-dichlorotetrafluoroacetone. The C F2 involved in all these reactions may arise from disproportionation reactions, possibly on the walls of the vessel, or may be produced in a molecular process from the ketone itself. 

Such a process would have an intensity exponent of unity as observed. A further fact in support of the disproportionation mechanism is that the yield of CF2CI2 is largely independent of the ketone pressure at room temperature an abstraction mechanism would require a first-order dependence upon ketone pressure. While the dimer of CF2, tetrafluoro-ethylene, has never been observed in the reaction mixture, a white solid collected in the cell which was probably a polymer of CF2. While the experimental conditions are not strictly comparable, it is significant that the absorption spectrum of CF2 has been observed in the flash photolysis of 1,3-dichlorotetrafluoroacetone.39 When the temperature is raised, however, the yield of CF2C12 in normal photolysis, increases rapidly suggesting an energy of activation and this process can only be chlorine abstraction. The rate function ... 

Once again the absorption spectrum of CF2 appears when the ketone is flash photolyzed in the gas phase but the intensity of the lines is much weaker than in the case of 1,3-dichlorotetrafluoroacetone. The yields of the two halogenated methanes rise with increase in temperature showing that they may also arise by an abstraction process which becomes more important at elevated temperatures. When the rate function... 

It may be of interest to compare the photochemistry of the unsubstituted cyclic ketones. The effect of ring size on the ultraviolet absorption spectrum has been discussed (4,22) although its pertinence to the photochemistry is not obvious. 

Oxonine 1, a derivative of the diterpene alkaloid aconitine, undergoes smooth oxidation when treated with exactly one equivalent of periodic acid. The product thus obtained, which shows no aldehyde or ketone absorption in the ir spectrum, is converted into 2 when heated in dilute aqueous base with air passing through the solution. 

A spectrophotometric investigation of the ground-state absorption of benzophenone in pure SC CO2 and in the presence of 2-propanol was performed in order to determine both benzophenone solubility and the potential for solute/solute or co-solvent/solute aggregations. Linear Beer s law plots of absorbance versus concentration of benzophenone over a concentration range of 1-15 mM in SC OO2 insured that the ketone was fully disolved and in a non-associated form under the conditions of the laser experiments (- 10 mM). Analysis of the absorption spectrum of benzophenone in SC CO2 ranging from high to low pressure, resulted in absorption bands nearly... 

In the case of D-psicose14 and D-sorbose80 the fceto-pentaacetates, as well as some of their derivatives, have been prepared by the diazomethane synthesis. The only crystalline product which was isolated from the low temperature acetylation of D-psicose137 was the fceto-pentaacetate. /ceabsorption spectrum indicated the presence of the ketonic group and its structure was further verified by catalytic hydrogenation,102 followed by acetylation, in which case both L-iditol and... 

Identification The infrared absorption spectrum of the sample exhibits relative maxima at the same wavelengths as those of a typical spectrum as shown in the section on Infrared Spectra, using the same test conditions as specified therein. Assay Not less than 50.0%, by volume, of ketones as carvone. 

The IR of Compound B shows a ketone absorption. The splitting pattern of the H NMR spectrum indicates an isopropyl group and indicates that the compound is a methyl ketone. 

Electronic Spectrum. Acetone is the simplest ketone and thus has been one of the most thoroughly studied molecules. The it n absorption spectrum extends from 350 nm and reaches a maximum near 270 nm (125,175). There is some structure observable below 295 nm, but no vibrational and rotational analysis has been possible. The fluorescence emission spectrum starts at about 380 nm and continues to longer wavelengths (149). The overlap between the absorption and the fluorescence spectra is very poor, and the 0-0 band has been estimated to be at - 330 nm (87 kcal/mol). The absorption spectra, emission spectra, and quantum yields of fluorescence of acetone and its symmetrically methylated derivatives in the gas phase havbe been summarized recently (101). The total fluorescence quantum yield from vibrationally relaxed acetone has been measured to be 2.1 x 10 j (105,106), and the measurements for other ketones and aldehydes are based on this fluorescence standard. The phosphorescence quantum yield is -0.019 at 313 nm (105). 

Electronic Spectrum. The absorption spectrum of 2-pentanone is typical of the it - n band of the alkyl ketones. A structureless band extends from 330 to 220 nm and there is a maximum at 280 nm. 

The products and quantum yields for the photolysis of 1,3-dichlorotetrafluoro-acetone , of l,l,3-trichlorotrilluoroacetone S and of 1,1,3,3-tetra-chlorodifluoroacetone indicate major primary steps of Type 2 with the possibility of some complication from steps of Type 3. The absorption spectrum of CF2 has been observed in the flash photolysis of the first two of these ketones. 

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