Hydrazine And The Reaction Of Carbonyl Compounds And Its Mechanism

The reaction of the hydrazine with the aldehyde (or ketone) always leads to the formation of a hydrazone, which is an important compound because of its activation in biology and pharmacology. It is reported that Schiff base and their metal complexes have been widely applied. For example,some Schiff base and their metal complexes have been associated with unusual activation in biology such as resistance to virus , resistance to cancer, restraint to the growth of bacillus and elimination of superoxide anion radical(O₂^-).Some Schiff base complexes containing O or S or N exhibited the character of the peroxidase-like activity. The novel Schiff base compound synthesized by salicylaldehyde with hydrazine hydrate has the property that light can change its colcor. Some Schiff base linked to polymer can enhance fluorescence. 1,2,4-Triazines have been associated with diverse pharmacological activities such as antihypertension and inhibition of platelets, antileukemic, antiinflammatory, and are potent neuro-protective agents. So this reaction has attracted wide interest.Althought there are many reports with regarding to the synthesis of hydrazone, to the best of our knowledge theoretical studies of the mechanism of this reaction has never been reported yet. In this thesis, the synthesis has been used to the reaction of the hydrazine with the aldehyde, and the mechanism of this reaction has been studied by using the ab initio and the density function methods. The thesis consists of four parts.1. synthesize some new Schiff base ligandsSchiff base and their complexes are an important compound because of their activation in biology and pharmacology, but their activation lies on the structure of Schiff base and the metal ion. Different complexes have different functions. How to synthesize a new Schiff base ligand has attracted wide interest. So we synthesized salicylaldehyde azine, the novel furfural azine,and o-vanillin azine.2. The influence of the group in phenyl to the reactionThe experimental result shows that o-vanillin azine can be easily synthesized than salicylaldehyde azine, it's obvious that the meta methoxy has great influence to the reaction. The theoretical analysis also indicated that the group of phenyl has some influence at certain extent.3. crystal structureFurfural azine was synthesized by the reaction of furfural with hydrazine hydrate and its crystal structure was determined by single-crystal X-ray diffraction method. The crystal belongs to the orthorhombic system, space group Pbca,with cell parameters: a=6.887(2)A,b=9.001(3)A,c=15.195(5)A, α = β= γ =90° ,V=942.0(5)A 3,Z=4,DC=1.327g/cm^-3,F(000)=392, R₁=0.0498,wR₂=0.1155.4. The mechanism of the reaction of aromatic aldehyde and hydrazine hydrateThe mechanism of the reaction of salicylaldehyde and hydrazine hydrate has been examined in detail by ab initio method at B3LYP/6-31G** level, obtained three stable intermediate and four transition states. The theoretical analysis indicated that the intermediate geometry is a stable structure and the transitions state are all right. The potential profile for this reaction was obtained by the calculation of IRC. The theoretical results have proved that the activation energy of the third process is high, so the third process is the key process of the whole reaction.At the same time, the mechanism of the reaction of furfural and hydrazine hydrate,o-vanillin and hydrazine hydrate has been also examined by ab initio method at AMI level respectively, the result shows that its mechanism is similar to the mechanism of the reaction of salicylaldehyde and hydrazine hydrate: three stable intermediate and four transition states have been obtained. And we conclude that the third process is the key process of the whole reaction.