Theoretical Studies on the Mechanism of Mannich Reaction Involving Iminium Salt as Potential Mannich Reagent(1)——Use Acetaldehyde as Pseudo-acid Component

ＴｈｅｏｒｅｔｉｃａｌＳｔｕｄｉｅｓｏｎｔｈｅＭｅｃｈａｎｉｓｍｏｆＭａｎｎｉｃｈＲｅａｃｔｉｏｎＩｎｖｏｌｖｉｎｇＩｍｉｎｉｕｍＳａｌｔａｓＰｏｔｅｎｔｉａｌＭａｎｎｉｃｈＲｅａｇｅｎｔ（１）——ＵｓｅＡｃｅｔａｌｄｅｈｙｄｅａｓＰｓｅｕｄｏ┐ａｃ...     

Theoretical Study on the Reaction Mechanism of F2 ＋ 2HBr = 2HF ＋ Br2

1 INTRODUCTION The replacement reactions between halide and hy- drogen halide, or halide and halide are basic reac- tions in chemistry. Goldfinger et al. have speculated by experiment that the gas reaction between chlorine and hydrogen bromide might be a two-step intermo- lecular reaction[1, 2]. But gas reactions between other halides and hydrogen halides haven’t been reported experimentally so far. About theoretical investiga- tion, colinearity quantum mechanics, vibrational tran- sitio…     

Theoretical and Experimental Studies on the Reaction Mechanism of Cl2 ＋ I2- 2ICl

1 INTRODUCTION The reactions between halogen and halogen are basic reactions in chemistry. Especially, in the syn- thesis of iodo-substituted aromatic hydrocarbon, the reaction Cl2 I2 = 2ICl could heighten the usage of iodine atom to 100%. So far, to the best of our know- ledge, the studies about halogen-halogen reaction mechanisms are very few. In detail, only the struc- ture and stability studies of X2Y- (X, Y = Cl, Br and I) ions by calculating reaction potential energy sur- face…     

Theoretical Study on the Mechanism of VO2^＋ ＋ H2 Reaction in the Gas Phase

The mechanism of VO2+ + H2 reaction in the gas phase was investigated by using density functional theory (DFT) at the CCSD//B3LYP/6-311G(2d, p) level. According to our calculation results, the different reaction mechanisms were found for the singlet and triplet potential energy surfaces (PESs). Especially, the crossing points (CPs) among different PESs were located by means of the intrinsic reaction coordinate (IRC) approach presented by Yoshizawa et al., and the structures and energies of the corresponding minimum energy crossing points (MECPs) were obtained by the mathematical algorithm proposed by Harvey et al. Finally, the frontier molecular orbital (FMO) interaction analyses about MECP1 and MECP2 were used to prove our calculation results.     

Studies on the Reaction Mechanism of Br2 ＋ I2 = 2IBr

1 INTRODUCTION Interhalogen compounds have played an impor- tant role in environment and chemical engineering production. During the course of ozone exhaustion induced by sunlight in polar region, Br2, BrCl and HOBr are all precursors of Br atom[1]. Lately, scien- tists have detected that the content of BrCl in polar region sunlight was 35 ppt, larger than that of Br2 (25 ppt). Previous studies suggested that the con- centration of BrCl and O3 exhibits obvious negative correlation: w…     

Theoretical Study on the Structures and Electronic Spectra of the Derivatives of C_(60)-P-2,4,6-Triphenyl Borazinc

1 INTRODUCTION The electron-transfer reaction of C60 derivatives, especially light-induced electron-transfer reaction, has been an active research field for a long time. Many researches are focused on the long-live charge- separated state caused by electron-transfer[1]. And several electron-transfers between electron donor and C60 or intramolecular electron-transfer have been confirmed. As an example, TTF-C60 is proved to be a short-live charge-separated compound[2].Due to the excelle…     

Theoretical Study on the Reaction Mechanism of Ketene CH2CO with Isocyanate NCO Radical

The bimolecular single collision reaction potential energy surface of an isocyanate NCO radical with a ketene CH2CO molecule was investigated by means of B3LYP and QCISD（T） methods. The computed results indicate that two possible reaction channels exist on the surface. One is an addition-elimination reaction process, in which the CH2CO molecule is attacked by the nitrogen atom at its methylene carbon atom to lead to the formation of the intermediate OCNCH2CO followed by a C-C rupture channel to the products CH2NCO＋CO. The other is a direct hydrogen abstraction channel from CHzCO by the NCO radical to afford the products HCCO＋HNCO. Because of a higher barrier in the hydrogen abstraction reaction than in the addition-elimination reaction, the direct hydrogen abstraction pathway can only be considered as a secondary reaction channel in the reaction kinetics of NCO＋ CH2CO. The predicted results are in good agreement with previous experimental and theoretical investigations.     

Theoretical Studies on the Abstraction Reaction of Atomic O（^3p） with Si2H6

The hydrogen abstraction reaction of O(^3P) with Si2H6 has been studied theoretially. Two transition states of ^3A″ and ^3A′ symmetries have been located for this abstraction reaction. Geometries have been optimized at the UMP2 leve with 6-311G (d) basis set. G3MP2 has been used for the final single-point energy calculation. The rate constants have been calculated over a wide temperature range of 200-3000K using canonical variational transition-state sheory (CVT) with small curvature tunneling effect(SCT). The calculated CVT/SCT rate constants match well with the experimental value.     

Theoretical Studies on the Intermonomer Interaction of F~-·(H_2O)_n (n = 1, 2)

1 INTRODUCTION Hydrogen bond plays an important role in the fields of physics, biology and chemistry. It has cap- tured the interest of chemists for a long time and reports about its theory and experiment have been well represented[1～6]. Concerning its theoretical inves- tigations, most of the emphases are placed on the weak interaction energy of intramolecular hydrogen bond. But studies on its spectrum behavior are rela- tively rare. These years spectrum behavior led by hydrogen bond h…     

Studies on Mechanism of Chemiluminescence Reaction of 2, 6, 7-Trihydroxyl-9-(4'-chlorophenyl )-3-fluorone

1INTRoDUCTIONPhenylfluoroneisanimportanttypeofreagentinanalytica1chemistry"~'>.Themoleculesofthisreagenthavearigidplanarstructuret5'6i,sotheenergyofmolecularorbitsofthereagentscanbecalculatedbyHuckelmolecularorbitalmethod(HMO).WehadtriedtoassigndissociationconstantsforsomesuchreagentsbyacombinedspectrophotometricandHMOmethodt7'8i.Them.thodissimpleandtheresultsaresatisfactory.Inthispaper,apossiblemechanismforcatalyticchemiluminescencere-actionofCl-PFisproposedonthebasisofstudyingchemil…     

Theoretical Study on the Isomerization Mechanism of Enol Ester from 2-Acyl-1, 3-cyclohexanediones

The present paper employed density function theory to investigate two reaction pathways for isomerization of enol ester proposed by Yang(path a) and the present authors(path a), respectively. The base catalytic effects of solvent triethylamine on these two reactions were also evaluated. It is demonstrated that path B is more preferable than path a due to low barrier height for the rate-determining step.     

Novel Stereoselective Synthesis of (E)- α，β-Unsaturated Esters by the Tandem Reaction of Deprotonation-Oxidation-Wittig Reaction from Phosphonium and Arsonium Salt

Phosphonium or arsonium salt 1 can undergo the tandem reaction of deprotonation -oxidation-Wittig reaction with alcohol 2 in the presence of sodium hydroxide and manganese dioxide,which affords a general simplified method for the stereoselective synthesis of (E)- α-β-unsaturated esters 3.     

Theoretical and Experimental Studies on the Metal Complex of Diethylenetriamino-trioxo-molybdenum(VI) [MoO_3(NH_2C_2H_4NHC_2H_4NH_2)]

1 INTRODUCTION Molybdenum is a biologically important trace ele- ment that occurs in the redox-active sites of moly- bdoenzymes involving in nitrogen, sulfur or carbon metabolism. The structural chemistry of molybde- num complexes has aroused considerable interest in view of its higher oxidation states to form a number of compounds containing MoO groups, and informa- tion on these is very useful in understanding the behavior of MO groups generally[1~3]. Molybdenum oxide-based solids hav…     

Synthesis of A New Reagent 1-(6-Nitro-2-Benzothiazolyl)-3-(4-Nitrophenyl)-Triazene and Study on Its Color Reaction with Cadmium

Thetriazenereagentswereusedf0rthedeterminationofcadmium,mercuryandzinc.Somereagentscontainingdiaz0amin0az0benzenehavebeenreported'-'.Wehavesynthesizedreagentscontainingdiaz0aminonitrobenzene4'5.Recently,anewreagentNBTNPThasbeensynthesizedin0urlab0ratoryanditscolorreactionwithcadmiumwasstudied.Resultsshowthatthisreagenthashighsensitivitywithmetallicions.Theproposedmeth0dhasbeenaPpliedt0thedeterminati0nofcadmiuminhumanhairandwastewaterwithsatisfact0ryresults.Theprocedureofsynthesis0fNBTNPT…     

Ab initio Studies on the Reaction of M~ CH_4→M~ CH_2 H_2(M＝Sc,Y,La)

ＡｂｉｎｉｔｉｏＳｔｕｄｉｅｓｏｎｔｈｅＲｅａｃｔｉｏｎｏｆＭ~＋＋ＣＨ_４→Ｍ~＋ＣＨ_２＋Ｈ_２（Ｍ＝Ｓｃ，Ｙ，Ｌａ）ＺＨＵＲｏｎｇ－ｓｈｕｎ；ＤＡＩＳｈｕｓｈａｎ；ＨＵＡＮＧＪｉａｎ－ｈｕａａｎｄＹＥＳｏｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅｍｉｓｔ?..     

Photochemically Catalyzed Diels-Alder Reaction of Azadienes with 2,3-Dihydrofuran by 2, 4, 6-Triphenylpyrylium Salt： Synthesis of Styrylfuroquinoline Derivatives

Photochemically promoted Diels-Alder reactions of 1, 4-diaryl-1-azabutadienes with 2,3-dihydrofuran were achieved by using 2, 4, 6-triphenylpyrylium tetrafluoroborate as catalyst to produce corresponding styrylfuroquinolines in high yield.     

Axially Dissymmetric Chiral (R)-N,N′-Bis(2-hydroxy-3,5-di-tert-butyl-arylmethyl)-1,1′-binaphthalene-2,2′-diamine as Chiral Ligands in the Reaction of Diethylzinc to Aldehydes

ＩｎｔｒｏｄｕｃｔｉｏｎＡｘｉａｌｌｙｄｉｓｓｙｍｍｅｔｒｉｃ 1,1′ ｂｉｎａｐｈｔｈｙｌａｎｄ 1,1′ ｂｉ ｐｈｅｎｙｌｌｉｇａｎｄｓｂｅａｒｉｎｇｔｗｏｉｄｅｎｔｉｃａｌｇｒｏｕｐｓｉｎｔｈｅ 2 ,2′ ｐｏｓｉｔｉｏｎｈａｖｅｐｒｏｖｅｄｔｏｂｅｒｅｍａｒｋａｂｌｙｕｓｅｆｕｌｉｎｅｎａｎｔｉｏｓｅ ｌｅｃｔｉｖｅｃａｔａｌｙｓｉｓ ,ｗｉｔｈｏｐｔｉｃａｌｙｉｅｌｄｓｃｌｏｓｅｔｏ 10 0 %ｅｎａｎ ｔｉｏｍｅｒｉｃｅｘｃｅｓｓ (ｅｅ)ｏｂｔａｉｎｅｄｉｎｓｅｖｅｒａｌｐｒｅｐａｒａｔｉｖｅｌｙｉｍ ｐ…     

Studies on the Properties of Schiff Base Type of Aryl mercury Compounds( Ⅰ )——~1H NMR Spectra of Some Schiff Base Type Aryl mercury Compounds and Substituted Benzyl ideneanilines

1H NMR spectra of 16 Schiff base type of arylmercury compounds and 4 -substituted benzylideneanilines have been studied. It was found that the p-substituents of the N-phenyl ring do not affect the δ values of methine proton, whereas the o-substitutents influence the δ values of methine proton, whereas the o-substituents influence the δ values of methine proton significantly. These changes can be reasonably interpreted in terms of the steric inhibition of o-substituents and intramolecular coordination of imino nitrogen with mercury. The influence of the m-or p-substituent of the C-phenyl ring on the δ values of methine proton exhibited a linear correlation with Hammett constants σp or σm. It was also confirmed that in the molecules of Schiff base type of arylmercury compounds there exists an intramolecular coordination via a four-membered ring.     

Theoretical Studies on the Cu-Cu Interaction and Stability of [Cu_a(Ph_2Ppy)_b(CH_3CN)_c]~(a+) (a=1～2,b=1～3,c=0～2)

To study the Cu-Cu interaction and stability of the title complexes,the structures of complexes [Cu(Ph2Ppy)(CH3CN)]+ 1,[Cu(Ph2Ppy)]+ 2,[Cu2(Ph2Ppy)2(CH3CN)2]2+ 3,[Cu2(Ph2Ppy)2(CH3CN)]2+ 4,[Cu2(Ph2Ppy)2]2+ 5 and [Cu2(Ph2Ppy)3(CH3CN)]2+ 6 were calculated by density functional theory PBE0 method,and the following conclusions can be drawn:(1) There is no orbital overlapping between two Cu atoms,indicating no Cu-Cu orbital interaction exists in complexes 3～6.Due to a breakdown of the closed shell configuration of Cu atoms,the weak Cu-Cu interactions result from the 3dCu → 4sCu' charge-transfer in 4～6.The Cu-Cu interaction strength follows 5 6 4,implying that there are stronger Cu-Cu interactions in the complexes with fewer CH3CN or more Ph2Ppy ligands.(2) The calculated interaction energies suggest that the coordination of Cu to Ph2Ppy is stronger than that to CH3CN.In 3～6,there are weaker interactions between Cu and CH3CN or Ph2Ppy in the complexes with more CH3CN or Ph2Ppy ligands.(3) The P-Cu and N-Cu interactions are much stronger than the Cu-Cu interaction,so we mainly attribute the stabilities of the binuclear complexes to the eight-membered rings Cu2P2N2C2.     

Ca(NO3)2•4H2O-catalysed Biginelli Reaction: One-pot Synthesis of 1,2,3,4-Tetrahydropyrimidin-2-ones/pyrimidine-2-thiones under Solvent-free Conditions

The synthesis of 1,2,3,4-dihydropyrimidinone/thione derivatives was achieved in good to excellent yields using calcium(II) nitrate as catalyst to promote the Biginelli three-component condensation reaction from a diversity of aromatic aldehydes, β-keto compounds and urea or thiourea. The reaction was carried out under solvent-free conditions.