Hydroxyl group, frequency shift

In the study of 13C-NMR spectra of 8 and 6, the presence of the hydroxyl group at C-14 is also evident since a downfield shift of 43 ppm from 6 (<521.2) to 8 (<563.87) is observed. The previously ambiguous assignments of C-15, C-16, C-5, and C-20 are also clarified through irradiation of H-16, H-5, and H-20 with low-power single-frequency off-resonance decoupling (SFORD) experiments. 

Table 6. Frequency of OH stretching in the H-bond between PS(OH)-9,7 and the counter polymers, and the frequency shifts related to free hydroxyl groups. Blend compositions PS(OH)/counter polymer 50 50 (w/w) [91]...

The conclusion of the existence of —0-—H 0—N— bonds is also based on the observation that the bands at 1567 cirr1 and 1361-1340 cm 1, which are characteristic of the nitro group in nitroparaffins, are shifted to lower frequencies, i.e. to 1555-1543 cm 1 and 1319-1310 cm 1 respectively and are weakened and widened in the presence of two or three hydroxyl groups. 

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