Interaction of β-Cyclodextrin Catalyst with p-Chlorobenzonitrile for the Synthesis of 5-Substituted 1H-tetrazoles in n,n-Dimethylformamide:a DFT Study

The synthesis of 5-substituted 1H-tetrazoles in n,n-dimethylformamide(DMF) with b-cyclodextrin(b-CD) as catalyst can get an excellent yield in short reaction time.The interaction of b-CD with p-chlorobenzonitrile plays an important role in this process.This paper studies the complex of b-CD with p-chlorobenzonitrile using density functional theory(DFT) method.The minimum energy structure is investigated in water,DMF and DMSO.Hydrogen bonds are researched on the basis of natural bonding orbital(NBO) analysis.The relative position between p-chlorobenzonitrile and b-CD in DMF is confirmed by 1H nuclear magnetic resonance(1H NMR).The data from 13 C and 15 N spectra indicate that more positive charges focus on the carbon atom of cyanogroup(C11) and more negative charges concentrate on the nitrogen atom of cyanogroup(N12) upon complexation.The results from frontier molecular orbitals and Mulliken charge reveal that β-CD catalyst improves the reactivity and electrophilicity of p-chlorobenzonitrile.Meanwhile,the functional group of p-chlorobenzonitrile is easier to be attacked by azide ions in the presence of β-CD as catalyst.     

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 study on the reaction mechanism of CN radical with ketene

The bimolecular single collision reaction potential energy surface of CN radical with ketene (CH2CO) was investigated by means of B3LYP and QCISD(T) methods. The calculated results indicate that there are three possible channels in the reaction. The first is an attack reaction by the carbon atom of CN at the carbon atom of the methylene of CH2CO to form the intermediate NCCH2CO followed by a rupture reaction of the C-C bond combined with -CO group to the products CH2CN CO. The second is a direct addition reaction between CN and CH2CO to form the intermediate CH2C(O)CN followed by its isomerization into NCCH2CO via a CN-shift reaction, and subsequently, NCCH2CO dissociates into CH2CN CO through a CO-loss reaction. The last is a direct hydrogen abstraction reaction of CH2CO by CN radical. Because of the existence of a 15.44 kJ/mol reaction barrier and higher energy of reaction products, the path can be ruled out as an important channel in the reaction kinetics. The present theoretical computation results, which give an available suggestion on the reaction mechanism, are in good agreement with previous experimental studies.     

Chemical Reactions and Kinetics of the Carbon Monoxide Coupling in the Presence of Hydrogen

The chemical reactions and kinetics of the catalytic coupling reaction of carbon monoxide to diethyl oxalate were studied in the presence of hydrogen over a supported palladium catalyst in the gaseous phase at the typical coupling reaction conditions. The experiments were performed in a continuous flow fixed-bed reactor. The results indicated that hydrogen only reacts with ethyl nitrite to form ethanol, and kinetic studies revealed that the rate-determining step is the surface reaction of adsorbed hydrogen and the ethoxy radical (EtO-). A kinetic model is proposed and a comparison of the observed and calculated conversions showed that the rate expressions are of rather high confidence.     

Synthesis and characterization of hyperbranched polyurethane-benzyltetrazole

A series of hyperbranched polyurethane-benzyltetrazoles（H-PBTZs） with different linkage structures were synthesized via the polycondensation of hexamethylenediisocyanate as an A₂ type monomer with（4-（1H-tetrazol-5- yl）benzyl）-diethanolamine（TBDEA） as a BB’₂ type monomer in the absence of catalyst at different temperatures.The FTIR, and ¹³C and ¹H-NMR spectroscopy were used to characterize the molecular structures of TBDEA and H-PBTZs as well as the counterpart linear polyurethane-benzyltetrazole（L-PBTZ）.The molecular composition was determined by the reaction selectivity that the isocyanate group reacted with the hydroxyl group in diethanolamine segment or the active hydrogen atom on tetrazole ring.Raising reaction temperature was propitious to the reaction of isocyanate group with the active hydrogen atom on tetrazole ring.The degrees of branching（DB） for H-PBTZs obtained from the ¹H-NMR spectra increased with raising reaction temperature.The wider molecular weight distribution of 1.7-2.9 for H-PBTZs was obtained via GPC analysis.TGA results showed that H-PBTZs had high thermal stability compared with L-PBTZ.     

CATALYTIC ACTIVITY OF Pd-Sn COMPLEX CARBONYLATION OF ACETYLENE

The influence of different concentration of HO, SnCl2, Cl- and n-BuOH on the carbonylation of acetylene has been studied. The results show that the yield of n- butyl propionate increases with the increase of HC1 concentration and the catalytic activity is depressed when Cl" concentration increases. However, the stability of catalytic complex is promoted by Cl-. The key to the carbonylation of acetylene lies in the addition of SnCl2, which promotes the formation of the complex of C2H2, CO with catalyst and plays an important role in the hydrogen removal from n-BuOH. The hydrogen removed from n BuOH is the hydrogen source of this reaction. Meanwhile, the principle of the effect of HCl, Cl- and SnCl2 on reaction has been discussed. The reaction model has also been proposed.     

THEORY OF GAS-PHASE ACIDITY(Ⅰ)CORRELATION OF DEPROTONATION ENERGY WITH HYDROGEN CHARGE

The charge distributions of various acids and their conjugate bases are calculated by using CNDO/2 and MNDO with full geometry optimization.The deprotonation energy is found to be better correlated with the charge on the acidic hydrogen than with the charge on the atom linking to the hydrogen and with the charge on the nucleophilic atom of the conjugate base.This shows that the charge on the acidic hydrogen has an important effect on acidity,whereas the effect of the charge on the linking atom and on the nucleophilic atom of the conjugate base is not important.It can thus be deduced that the view of stabilization of the anio'n due to dispersion of the negative charge is not a significant explanation of acidity.     

Remarkably Enhanced Hydrogen Oxidation Reaction Activity of Carbon-supported Pt by Facile Nickel Modification

Developing high activity catalysts for hydrogen oxidation reaction(HOR)under alkaline condition remains a challenge in the exchange membrane fuel cell(AEMFC).Herein,we report that the activity of carbon-supported platinum(Pt/C)towards the hydrogen oxidation reaction(HOR)in alkaline media can be remarkably enhanced by simple immersion of Pt/C in nickel chloride solution.The adsorption of hydrogen on the catalyst surface is weakened by modification of nickel.The HOR activity on the Pt/C after immersion possesses an excellent mass current density of 33.4 A/gmetal,which is 18%higher than that(28.3 A/gmetal)on Pt/C.     

H2-induced CO adsorption and dissociation over Co/Al2O3 catalyst

The activation of adsorbed CO is an important step in CO hydrogenation. The results from TPSR of pre-adsorbed CO with H2 and syngas suggested that the presence of H2 increased the amount of CO adsorption and accelerated CO dissociation. The H2 was adsorbed first, and activated to form H＊ over metal sites, then reacted with carbonaceous species. The oxygen species for CO2 formation in the presence of hydrogen was mostly OH^＊, which reacted with adsorbed CO subsequently via CO^＊＋OH^＊ → CO2^＊＋H^＊; however, the direct CO dissociation was not excluded in CO hydrogenation. The dissociation of C-O bond in the presence of H2 proceeded by a concerted mechanism, which assisted the Boudourd reaction of adsorbed CO on the surface via CO^＊＋2H^＊ → CH^＊＋OH^＊. The formation of the surface species （CH） from adsorbed CO proceeded as indicated with the participation of surface hydrogen, was favored in the initial step of the Fischer-Tropsch synthesis.     

STUDIES ON ORGANOPHOSPHORUS COMPOUNDS——OXIDATIVE PHOSPHINYLATION——A NEW ROUTE TO DIALKYLPHOSPHINIC ACID DERIVATIVES

A new method is reported for the preparation of dialkylphosphinic acids and their derivatives based on the reaction of dialkylphosphinous acid with a nucleophile and base in the presence of carbon tetraehloride. The influence of the reaction conditions and the structure of nueleophiles on the yield of the oxidative phosphinylation is examined. It is proposed that the reaction operates by an ionic process rather than a radical mechanism.     

Studies on organophosphorous compounds: IX. C-Phosphorylation of compounds bearing an active methylene group

The behaviour of carbanions of para-substituted benzylcyanides and ambident enolates toward phosphorylation has been examined. In the former case the C-phosphorylation proceeded smoothly, while the ambident enolate ions derived either from β-diketones or from β-ketoesters gave exclusively regiospecific O-phosphorylation products on reaction with diethyl phosphoryl chloride. The experimental results are well supported by reaction selectivity in terms of E_qo/E_C.OC/ based on EHMO calculation.     

Diastereoselectivity in the Mukaiyama-Michael Reaction Employing alpha-Acyl beta,gamma-Unsaturated Phosphonates

The unique electronic and structural nature of the alpha-acylphosphonate functional group affords both dimeric and chelated complexes of diethyl crotonyl phosphonate (1; DECP) with stannic chloride (SnCl(4)). The dimeric complex, SnCl(4).(DECP)(2) (5) results from the coordination of two DECP molecules, ligated via the phosphoryl oxygens to the tin atom. The chelated complex, SnCl(4).(DECP) (6), is best represented with both phosphoryl and carbonyl oxygens coordinated to the metal center. Both metal ligated and chelated complexes have unique (13)C (31)P, and (119)Sn NMR spectra. In complex 5, the (13)C NMR resonances attributed to the carbonyl carbons were shifted upfield of free DECP. A monocoordinating Lewis acid, BF(3).OEt(2), produced a similar chemical shift trend in both the (13)C and (31)P NMR spectra of the BF(3).DECP complex. Essentially quantitative yields and moderate diastereomeric excesses favoring anti (or trans) diethyl 6-phenyl-4,5-dimethyl-6-(trimethylsilyloxy)-2-dihydropyranphosphonate (3) and diethyl 5-phenyl-3,4-dimethyl-1,5-dioxopentanephosphonate (4) were obtained from both chelated and dimeric SnCl(4).(DECP)(n) (n = 1, 2) when treated with either diastereomeric (Z)- or (E)-1-phenyl-1-(trimethylsilyloxy)-1-propene 2. Diethyl crotonylphosphonate (1), 3, and 4 were fully characterized.     

五氯化磷辅助下氨基酸的自组装成肽反应研究

L-α-氨基酸和D-α-氨基酸可与五氯化磷直接发生磷酰化反应，随后自组装成多肽，但β-氨基酸不能成肽，DL-α-氨基酸成肽困难；在SOCl2存在下，α-氨基酸也不能成肽，用电喷雾质谱研究了氨基酸的自组装反应，反应过程中有五元环状的氨基酸五配位磷中间体生成，使用硅烷基保护的氨基酸，在^31PNMR中可观察到五配位磷中间体。     

天然紫草萘醌类化合物与苯胺和苯硫酚的亲核反应

研究了天然紫草萘醌类化合物β-二甲基丙烯酰阿卡宁在没有还原剂和有还原剂存在下与亲核试剂的反应,合成了七个新的萘茜类衍生物。比较了β-二甲基丙烯酰阿卡宁与合成衍生物的生物活性。     

3－芳基－6－三氯甲基－1，2，4－三唑并[3,4-b]-1,3,4-噻二唑的合成与波谱表征

首次报道3－芳基－4－氨基－5－巯基－1，2，4－三唑与三氯乙酸在三氯氧磷 存在下关环，合成了3－芳基－6－三氯甲基－1，2，4－三唑并[3,4-b]－1，3，4 －噻二唑，标题化合物结构经元素分析、红外光谱、核磁共振氢谱、碳谱与质谱确 证。     

二(四氢糠基茚)稀土氯化物的合成及晶体结构

将四氢糠基茚锂分别与无水三氯化钇和无水三氯化钆以摩尔比2;1反应,除去不溶物和溶剂后,将产物在甲苯/THF中冷冻得到晶体(C₄H₇OCH₂C₉H₆)₂LnCl[Ln=Y(1);Ln=Gd(2)].这两种配合物都是单分子无溶剂化合物,在空气中稳定.配合物1和2的晶体结构都属于正交晶系,P2₁2₁2₁空间群,晶胞参数分别为a=1.04252(9)nm,b=1.47455(12)nm,c=1.49799(13)nm,Z=4,Dc=1.508g/cm³;a=1.03701(10)nm,b=1.47233(12)nm,c=1.51354(14)nm,Z=4,Dc=1.699g/cm³.它们的结构相似,但空间构象不同.稀土中心离子分别与两个茚中的五元环和两个氧原子及氯原子成键,形成九配位结构.     

β-CD与间羧基苯磺酰氯及Fe^3^+构筑氧化还原酶

用β-CD与间羧基苯磺酰氯及三氯化铁反应, 制得了双(6-氧-间羧基苯磺酰基)-β-CD.Fe^3^+配合物, 以此配合物作催化剂, 将苯甲醇高速率氧化成苯甲醛和苯甲酸, 其反应速率是三氯化铁的1.4×10^4倍。     

氢气存在下一氧化碳偶联反应的化学和性能

实验研究了在氢气存在下，一氧化碳与亚硝酸乙酯偶联合成草酸二乙酸反应体系在典型操作条件下的化学反应和反应性能，结果表明氢气只与反应体系中的亚硝酸乙酯反应生成乙醇。由于氢气与一氧化碳在催化剂表面竞争吸附，并且氢的存在打破了生成草酸二乙酯所必需的正常的氧化还原过程：Pd^0→Pd^2 →Pd^0，因此氢的引入使一氧化碳转化率及草酸二乙酯选择性下降。此外，化学吸附测试结果表明氢气和一氧化碳是在催化剂表面同一活性中心上吸附。     

Synthesis and Spectral Characterization of Some Novel Phosphonyl‐ and Phosphoryl Pyrazole Compounds

1,3‐Diphenyl‐1H‐pyrazole‐4‐carbaldehyde ( 1 ) reacted with aniline, 2‐substituted anilines, and P,P‐dimethylphosphinic hydrazide in the presence of diethyl phosphite to give acyclic α‐aminophosphonate 2 , cyclic α‐aminophosphonates 4–6 , and α‐hydrazinophosphonate 7 , respectively. Also, treatment of aldehyde 1 with cyanoaceto‐hydrazide, acetophenone, and malononitrile afforded the condensation products 8 , 16 , and 21 , respectively, which in turn, reacted with diethyl phosphite and P,P‐dimethylphosphinic hydrazide. The reaction of diethyl phosphite with the hydrazone 8 and chalcone 16 yielded the novel phosphorus heterocycles 13 and 18 , respectively, while its reaction with the dicyanoarylidene 21 produced the dicyanopyrazolyl phosphonate 22 . On the other hand, treatment of the hydrazone 8 with P,P‐dimethylphosphinic hydrazide gave the unexpected P,P‐dimethylphosphinic hydrazone 15 , which reacted with diethyl phosphite forming α‐hydrazinophosphonate 7 . Furthermore, the interesting N‐phosphoryl pyrazoles 20 and 24 were resulted in good yield via cycloaddition of P,P‐dimethylphosphinic hydrazide to the chalcone 16 and dicyanoarylidene 21 , respectively. Structures of all newly synthesized compounds were confirmed by considering the data of IR spectroscopy, MS, and ¹H‐, ¹³C‐, and ³¹P‐NMR spectroscopy, as well as that of elemental analyses.     

Synthesis and Transformations of 5-Substituted 2-Furoyl Phosphonates

5-Chloromethyl-2-furoyl chloride when treated with triethyl phosphite has given 5-chloromethyl-2-furoyl phosphonate. This compound has reacted with sodium azide in the presence of potassium iodide to give 5-azidomethyl-2-furoyl phosphonate. Treatment of 5-chloromethyl-2-furoyl phosphonate with secondary amines even under mild conditions has caused cleavage of P–C bond with liberation of diethyl hydrogen phosphite and formation of 5-chloromethyl-2-furancarboxamide. Butanthiol in the presence of potassium carbonate in acetonitrile has converted the chloromethyl group into the butylthiomethyl one and simultaneously split the P–C bond with the formation of the corresponding thioester. Under the action of S-methylthiuronium iodide and triethylamine, 5-chloromethyl-2-furoyl phosphonate has been unexpectedly reduced into the 5-methyl derivative. 5-Butylthiomethyl- and 4-(N-morpholinomethyl)-2-furoul chlorides have been phosphorylated with triethyl phosphite into the corresponding 5-functionalized 2-furoyl phosphonates. The prepared furoyl phosphonates have reacted with resonance-stabilized phosphoranes to give phosphorylated derivatives of 3-(furyl)acrylates and 4-(furyl)but-3-en-2-one with trans-location of phosphoryl and carbonyl groups with respect to the double bond.