3- Methyl-2-butanone infrared spectrum

The conformational profile for 2-butanone has been developed from analysis of its infrared spectrum. The dominant conformation is anti with a C(1)H and the C(4) methyl group eclipsed with the carbonyl. 

An infrared spectrometer determines the positions and relative sizes of all the absorptions, or peaks, in the infrared region and plots them on a piece of paper. This plot of absorption intensity versus wavenumber (or sometimes wavelength) is referred to as the infrared spectrum of the compound. Figure 2.4 shows a typical infrared spectrum, that of 3-methyl-2-butanone. The spectrum exhibits at least two strongly absorbing peaks at about 3000 and 1715 cm for the C—H and C=0 stretching frequencies, respectively. 

FIGURE 2.4 The infrared spectrum of 3-methyl-2-butanone (neat liquid, KBr plates). 

Figure 12.2 is an infrared spectrum of 3-methyl-2-butanone. The horizontal axis at the bottom of the chart paper is calibrated in frequency (wavenumbers, cm ) that at the top is calibrated in wavelength (micrometers, ju,m). The frequency scale is often... 

Figure 2.4 shows a typical infrared spectrum, that of 3-methyl-2-butanone. The spectrum exhibits at least two strongly absorbing peaks at about 3000 and 1715 cm for the C—H and C=0 stretching frequencies, respectively. 

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