Theoretical Investigation Into The Cooperativity Effect Of Cl~-for Benzonitrile Hydrate

Aromaticity, which is one of the most fundamental conception in organic chemistry. Ithas been used frequently as a stability measure of many organic and inorganic molecules. Inrecent years, it has attracted much attention on theory and experiment about the Benzene andits homologue. It is most important to invest the aromaticity of cyanide compounds using thequantum chemistry method for the future waste water treating. In this dissertation，All themonomer, two complex, three complex are investigated using the B3LYP and MP2(full)methods, which include the structure, energy, and the Aromaticity. In addition, the reactionmechanism of hydroxyl anion and benzonitrile or benzonitrile H2O has been studied at theBHandHLYP/6-311++G**level of theory.In chapter1, the source of the cyanide, harmful and current research status conclude thedevelopment of the conception of aromaticity are presented. The theoretical methods used inthis work are described in chapter2.In the three chapter, The cooperativity effects between the O/C–H Cl–anionicH-bonding and O–H N and C–H O H-bonding interactions, thermodynamic properties andaromaticities in Cl–benzonitrile H2O complexes are investigated using the B3LYP andMP2(full) methods. The result shows that the influence of the O/C–H Cl–anionic H-bondinginteraction on the C–H O is more pronounced than that on the O–H N interaction. Thecooperativity effect appears in the linear conformation while the anti-cooperativity effect isfound in the cyclic structure. The enthalpy change is the major factor driving the cooperativityin forming the linear ternary complex while entropy change turns into the favorable factor informing the cyclic system. The aromaticity of the benzonitrile ring is weakened and the π�'π*conjugative effect between the ring and C≡N bond is strengthened upon the ternary-complex formation. To our interest, the cooperativity effect correlates well with Rc(NICS(1)ternary/NICS(1)binary), ΔΔ (Δ ternary–Δ binary), Rc ((NICS(1)ternary–NICS(1)binary)/NICS(1)binary) and RBDE(C–CN)(BDE(C–CN)ternary/BDE(C–CN)binary),respectively. AIM (atoms in molecules) analysis confirms the existence of cooperativity. Inaddition, the shifts and RDG investigation also confirms the interactions in three compkex aremore enhanced than in two complex.In the four chapter, The cooperativity effects between the new O/C–H O H-bonding andO–H N and C–H O H-bonding interactions, thermodynamic properties and aromaticities inOH–benzonitrile H2O complexes are investigated using the B3LYP and MP2(full) methods.The result shows that the influence of the new O/C–H O H-bonding interaction on theC–H O or O–H N is more pronounced. The cooperativity effect appears in the linearconformation while the anti-cooperativity effect is found in the cyclic structure. The enthalpychange is the major factor driving the cooperativity in forming the linear ternary complexwhile entropy change turns into the favorable factor in forming the cyclic system. When exitsthe O/C–H O H-bonding, The aromaticity of the benzonitrile ring is weakened and theπ�'π*conjugative effect between the ring and C≡N bond is strengthened upon theternary-complex formation. But, when exits the C O interaction, the results is on the contrary.To our interest, the cooperativity effect correlates well with RBDE(C–CN)(BDE(C–CN)ternary–BDE(C–CN)binary), respectively. AIM, RDG (atoms in molecules)analysis confirms the existence of cooperativity.In the five chapter, The reaction mechanism of hydroxyl anion and benzonitrile orbenzonitrile H2O has been studied at the BHandHLYP/6-311++G**level of theory. Thegeometries of the reactants, products and the transition states were optimized, and thetransition states were confirmed by the vibrational frequencies analysis and the intrinsicreaction coordinate (IRC) method. The result shows that the in the OH–benzonitrile reaction,there are three types of reactions which are the hydrogen abstraction reaction, namely R1, R2,R3. The potential barriers of that are84.647、86.958、84.036, respectively. So, themeso-position hydrogen is hard to be abstracted. In the (benzonitrile H2O) OH reaction, there are five types of reaction which are the hydrogen abstraction reaction, namely S1, S2,S3, S4, S5. The potential barriers of that are–104.274、–99.350、–101.768、–138.440、–150.356, respectively. So, the meso-position hydrogen is easy to be abstracted. In addition,we used the Conventional transition state theory(CTST) to evalued the rate constant at theroom temperature, which using the Wigner correction. The rate constants of the R1, R2, R3is3.52×1020、4.01×1020、4.55×1021, respectively. In the (benzonitrile H2O) OH–reaction, TheK is in the rage of2.79×1019~1.85×1027.