Hydrogen hydroxy stretching frequencies

Table 6. Hydroxy stretching frequencies in hydrogen forms of zeolites and their proposed assignments ...

Flett [32] has found similar effects with amino-anthraquinones and he has shown that in these structures hydrogen bonding can play only a small part, even with unsubstituted amines. Thus the NH stretching frequency of 1-amino-anthraquinone is not very different from that of 2-naphthylamine, and the NH frequency of 1-methyl-amino-anthraquinone is only 100 cm" lower than is usual for secondary amines. This contrasts sharply with the behaviour of the corresponding hydroxy-compounds, in which no OH stretching frequencies are shown in the normal frequency range. Furthermore, Flett finds that 2-amino-anthraquinones show nearly as much movement of the carbonyl absorption as the 1-amino-materials, and... 

In considering monomeric OH frequencies one must always consider the possibility of internal hydrogen bonding leading to lower frequencies. a-Hydroxy acids for example give four OH stretching bands in dilute solution, corresponding to free alcohol, free acid, alcohol bonded to acid, and acid bonded to alcohol. The frequency of this last is 3440 cm". ... 

Unsymmetrical para-substituted benzils have two bands at 1690-1660 cm (5.92-6.02 im). Or/Zio-hydroxy or ort/zo-amino-aryl ketones exhibit a strong band in the region 1655-1610cm (6.04-6.21 im) due to the carbonyl stretching vibration. The presence of intramolecular hydrogen bonding causes this frequency to be lower than might otherwise be expected. 

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