Methacrolein And Their Dervatives Potential Energy Surface Crossing Dynamics Research

Acrolein is α β unsaturated aldehydes (ketones) is one of the most simple structuremodel, he can be a research model to study the simplest α β unsaturated aldehydes (ketones).Acrolein is widespread and the environment, in addition, he also widely exists in cigarettes, suchas flue gas is another main source comes from the kitchen lampblack, so for the housewife’shealth also constitute a threat. In addition, through a series of biochemical reactions in organicbody generates acrolein and α β unsaturated aldehydes (ketones), these often cause a variety ofdiseases.Acrolein, there are two active group, so his reaction activity is very strong, he is a kind ofimportant chemical intermediates, in biological molecules, he can happen adduct directly withmany biological molecules, such as nucleic acid bases of purine, pyrimidine compounds, etc.And acrolein and DNA adduct between can also, its adducts can cause gene mutations, may alsocause cancer, such as smoking caused lung cancer and so on, thus acrolein caught the attentionof an increasing number of experts, the relevant report is also more and moreIn the research of this paper system, isobutylene aldehyde acrolein basic structure iscontained in material structure, and because the acrolein belongs to toxic chemicals, not easy toour experiment testing, so choose isobutylene aldehyde as this article research system, in order tofind different substituent for its no radiation decay of photochemical reaction channel regulation.This paper adopts resonance Raman spectroscopy and combines the density functional theoryand the complete active space self-consistent field theory method to study the isobutylenealdehyde (MA),2-amino-2-methyl-3-dimethyl acrolein (DAMAP),3-amino-2-methylacrolein (AMA) in different solvents, reaction kinetics and can stimulate the situational facecross theory research, made a great contribution in the following areasMethyl acrolein and isobutylene aldehyde, it is an important chemical synthesis of reactiveintermediates. For isobutylene aldehyde in different solvents resonance Raman spectracharacteristics of carbonyl stretching vibration mode is very strong, combined with densityfunctional theory and the complete active space self-consistent field theory method to calculate the preliminary conclusion: isobutylene aldehyde by S2state before and after the opticalexcitation no radioactive decay, by S2state through the S1/S2intersection back to S1state, bythe intersection of S1state and S0state back to the ground state. Through a series of calculationand the experimental evidence that isobutylene aldehyde S2state non radioactive decay processthrough the intersection of the process.(1) obtain methacrolein (MA) at B3LYP/6-31+G(d) level in the gas phase conditions forcomputing Raman comparing with Fourier infrared, Fourier transform Raman, throughcalculation, the symmetry of isobutylene aldehyde is Cs point group, A total of27vibrationmodes, A ’irreducible and A "irreducible representation of18,9respectively. The calculatedRaman and Fourier Raman fits well and resonance Raman spectra for us identify provides Apowerful evidence. Resonance Raman active vibration mode with A total of eight, including A’irreducible and A" irreducible representation respectively7and1, respectively, A ’: ν6(1703cm-1) C1O5stretching vibration, ν7(1636cm-1) C2O3stretching vibration+H8C3H7shear typevibration, ν11(1361cm-1) C1H6in-plane swing+H8C3H7shear type vibration, ν13H9C4H10(1028cm-1) methyl swing+C-14H10in-plane swing, ν15(807cm) C1C2C4symmetric stretchingvibration, ν16(606cm-1) O5C1C2shear type vibration, ν17(417cm-1) C2C3swinging insidesurface; A ": ν20(1442cm-1) H9C4H10outside surface to swing+C4H10outside surface.Obtained in208.8,217.8,223.1,217.8nm respectively under the excitation wavelength incyclohexane, acetonitrile, methanol solvent resonance Raman spectroscopy, and the208.8nmrespectively in cyclohexane under excitation wavelength, acetonitrile, methanol solventresonance Raman spectra of the identified, identifies eight fundamental frequency and theircombination of frequency doubling, flood frequency and frequency.Obtained in CAS (6,5)/6-31g (d) level of isobutylene aldehyde S0and S1, S2, T1stateexcited state optimization configuration and S1/S2, S0/T1, S0/S1, S1/T2, T2/T3, S2/T3, S1/T1, T1/T2related potential energy surface intersection, it is not difficult to find that, whenexcited molecules to S2state, the first is along the reaction coordinate C=C double bond, whenthe excitation situation to be able to achieve a S1/S2surface potential energy surface crossingeven more to the C=O, the potential energy surface reaction along the C=O coordinates, by S1,S2situation can surface optimization point can be seen that, thus well explain the resonanceRaman spectra of carbonyl peak intensity big reason. (2) This thesis investigates the electron excitation of3-amino-2-methylacrylaldehyde(AMA) ultraviolet spectrum in different solvents. The electronic transition energies werecalculated by density functional theory; In addition, since the AMA has four kinds of isomerstructures, this thesis used density functional theory and the complete active space self-consistentfield theory method (CASSCF) to calculate four kinds of isomer structures, five kinds ofisomerizations and five corresponding S(ππ*)/S0conical intersection configuration. According tothe structure energy, configuration, bond length, bond Angle and dihedral Angle parameters, weconcluded that the AMA decayed from the excited state to the S(ππ)/S0conical intersection viathe non-radioactive decay. These conical intersection points can return to the correspondingisomerization point, and then through the way back to the ground state. We find that the conicalintersection points are more likely returning to0-2,2,1-1A isomerization point than to0-1,2-1Aisomerization point.(3) Through2-methyl-3-dimethyl amine (DMAMP) ultraviolet spectrum diagram ofacrolein in cyclohexane three kinds of solvents, acetonitrile, methanol band shape there is noobvious change, but the maximum absorption peaks in the proton solvent (methanol) has a slightred shift, this is due to the effect of hydrogen bond makes DMAMP the ground-state energyincreases, thus making spectra occurred red shift, but in general it can be seen that the solvent forultraviolet spectrum and electron transition has no significant effect, absorption band for πH→πL*transition, the transition can be seen: methyl in conjugate can affect the vibrationrestructuring.DMAMP structure reaction kinetics mainly along the ν22(1396cm-1)/C7+C8-methylumbrella vibration, ν24(1364cm-1)/C4-methyl umbrella vibration, ν35(874cm-1)/C3H10surfaceoscillation, ν36(840cm-1)/C7N5C8+C4C2C1symmetry extension reaction coordinate, ν13inmethanol solvent (1588cm-1)/C2C3stretching vibration is activated, the ν12(1655cm-1)/C1O6stretching vibration has been severely weakened, on the contrary, in acetonitrile solvent inmethanol solvent, on the role of hydrogen bonding was hindered the carbonyl lone pair electronsin an electron transfer to the orbit of π*, so Sπ state than Sn state is stable, and no extra decaychannels, and N atoms in the conjugate.