Hello, Ameer Alwash . The aldehydic proton (H b ) in aromatic schiff base derivatives is highly deshielded due to the anisotropy created by the pi electrons of the C=O bond, and induction caused by the highly electronegative oxygen atom. It usually appears as a singlet at 9-10 ppm in the proton NMR spectrum.

The integration of this peak should correspond to one proton, but it might be affected by factors such as calibration errors, impurities, solvent peaks, or overlapping signals. If the peak is tall and broad, it might also indicate exchangeable protons that are involved in hydrogen bonding.

You can try to compare your spectrum with some reference spectra of similar compounds, such as acetaldehyde, to see if there are any differences or similarities. You can also try to use other spectroscopic methods, such as IR or mass spectrometry, to confirm the structure of your synthesized compounds.