Protection of carbonyl compounds is an important at the multistep total synthesis of the enantiomerically pure natural and non-natural compounds. Acetals and thioacetals were well known as the protecting intermediates [1, 2]. The nano magnetic Fe3O4@SiO2@(CH2)3NHSO3H catalyst was used for the protection process of aldehydes with diols and dithiols [3]. To determine the most stable structure of the products were applied DFT-B3LYP/6-31G* method. The obtained theoretical results on the synthesized products have shown that the structure of the products of diols in compare with dithiols demonstrated different electronic properties. The diols and dithiols both have two conformers. There are interesting result, due to the hyperconjugation effect between C-H and aromatic ring in diols and also hyperconjugation between π-electrons of aromatic ring and 3d orbital space of S-atoms in dithiol derivatives. The different interesting aspects of this experimental and theoretical investigation will be present and discuss
