Aromatic bands, infrared frequencies

Table 7.24 Absorption Frequencies of Other Double Bonds Table 7.25 Absorption Frequencies of Aromatic Bands Table 7.26 Absorption Frequencies of Miscellaneous Bands Table 7.27 Absorption Frequencies in the Near Infrared Table 7.28 Infrared Transmitting Materials...

Nitro groups of nitroalkanes can be identified by strong infrared bands at about 1550 cm-1 and 1375 cm-1, whereas the corresponding bands in the spectra of aromatic nitro compounds occur at slightly lower frequencies. A weak n —> n transition occurs in the electronic spectra of nitroalkanes at around 270 nm aromatic nitro compounds, such as nitrobenzene, have extended conjugation and absorb at longer wavelengths ( 330 nm). 

It has also been reported that an aromatic carbon-hydrogen out of plane deformation band at 759 cm"1 was sensitive to sequence distribution in styrene-maleic anhydride copolymers (2). A shoulder was noted at this frequency in the infrared spectra of the block copolymer, but it was not possible to demonstrate differences in the spectra of the alternating and block copolymers with the instrumentation available. 

On the basis of mass spectrometric and NMR-spectroscopic data, the structure of the alkaloids caseamine (alkaloid F-33) (VII, Scheme 7) and caseadine (alkaloid F-35) (VIII) isolated from Corydalis caseana A. Gray, could be determined 107). It is interesting to note the position of the oxygen substituents on the two aromatic rings. The absolute configuration of these two alkaloids was derived from infrared spectroscopy (Bohlmann s frequency— trans-band ) and optical rotation. The recently isolated alkaloids orientalidine (IX) and mecambridine (X) on... 

Infrared spectra of aromatic amine N-oxides and their metal complexes have been reviewed by Garvey et al. The N=0 stretching band of pyridine N-oxide (1265cm ) is shifted by 70-30 cm to a lower frequency upon complexation. The following references are given for three complexes Fe(Il) (123), Hg(II) (124), and Fe(III) (125). 

Table 8.2 (Alpert et al., 1970) gives a summary of the important group frequencies of amines. These have also been discussed in Rao (1963) and Bellamy (1958). Table 8.3 (Alpert et al, 1970) presents vibrations associated with the CN structure for the series methyl, dimethyl, and trimethyl amines. The bands for the corresponding hydrochlorides are also given. The infrared spectra of water solutions of the hydrochlorides of several biologically important amines have been recorded in the range 1550-909 cm (Kirschenbaum and Parker, 1961). Bentley et al. (1968) have discussed alkyl and aromatic amine spectra recorded in the range 700 300cm V...

Infrared bands (frequency) cm Group assignments CHg symmetric stretch CHg asymmetric stretch Aromatic CH stretches 2,875 2,970 3,000-3,200 (1. 2)... 

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