Question

In a discussion of quantitative analysis using the mid-IR region, it was suggested that either the OH stretching band or the C-O stretching band could be used to measure hexanol in a mixture of hexanol and hexane. Which band would you choose to give more accurate results? Why?

Answer 1

O-H stretching is more accurate provided that there is no water either from atmosphere or from contamination.

As O-H stretching band (hexanol) appear as a strong & sharp signal in the region 3500-3700 cm^-1, whereas C-O stretching (hexanol) is 970-1250 cm^-1 at the same time alkane C-H bending vibrations (From hexane) also appears in the region 1350-1470 cm^-1 it is nearer to C-O stretching frequency. To avoid ambiguities it is better to go for O-H signal band more accurate results.

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