Reactions of arylcarbamoyl chlorides—II : Reaction with aromatic amines

The reaction of N-arylcarbamoyl chlorides with anilines in acetonitrile initially gives isocyanates, which can react with primary or secondary amines to give N,N-diaryl ureas. The rate of HCl elimination fits the Bronsted catalysis law with β ≈ 1, suggesting that there is extensive proton transfer in the transition state. Plots of log k against σ have ? ≈ 0 when the aryl substituent has a negative σ and ? ≈ 1 when it has a positive σ value. These observations and the kinetic deuterium isotope effect suggest that with electron attracting substituents, an initial proton transfer gives an ion pair which then loses chloride ion, but with electron releasing substituents, these steps become more concerted.     

Analysis of sulphonyl chlorides by polarovoltric titration with sodium sulphide

A method has been developed for the rapid analysis of aliphatic and aromatic sulphonyl chlorides by polarovoltric titration with a standardised sodium sulphide solution. Visual end-point determination is also possible in more concentrated solution.     

Desolvation tips the balance: solvent effects on aromatic interactions

The folding behaviour of the molecular torsion balance framework is rationalised by considering the effects of solvation using the alpha/beta H-bond parameter scheme for estimating the free energies of pairwise functional group interactions in solution.     

Aminolysis of aryl chlorothionoformates with anilines in acetonitrile: effects of amine nature and solvent on the mechanism

The aminolysis of aryl chlorothionoformates (7, YC(6)H(4)OC(=S)Cl) with anilines (XC(6)H(4)NH(2)) in acetonitrile at 5.0 degrees C has been investigated. The rates are slower than those for the corresponding reactions of aryl chloroformates (6, YC(6)H(4)OC(=O)Cl). This rate sequence is a reverse of that for alkyl chloroformates (1-4) in water, for which rate-limiting formation of a tetrahedral intermediate, T(+/-), is predicted. On the basis of the large negative cross-interaction constant, rho(XY) = -0.77, failure of the reactivity-selectivity principle, normal k(H)/k(D) values involving deuterated nucleophiles (XC(6)H(4)ND(2)), and low DeltaH(not equal) with large negative DeltaS(not equal) values, a concerted mechanism with a four-membered hydrogen bonded cyclic transition state (11) is proposed for the title reaction series. It has been shown that the solvent change from water to acetonitrile for the aminolysis of 6 and 7 causes a mechanistic change from stepwise to concerted.     

钯催化下三正丁基杂环基锡和酰氯及取代芳烃偶联反应的研究

本文研究了在Pd(PPh3)2Cl2(1)催化下的三正丁基-2-呋喃基锡(6a), 三正丁基-2-噻吩基锡(6a), 三正丁基-2-(N-甲基)吡咯基锡(6c)和菊酰氯(5), 肉桂酰氯(7)的交联反应。发现除了三正丁基-2-(N-甲基)吡咯与5的不寻常反应得到2, 5-二取代的吡咯衍生物外, 其余反应皆以70～87%的产率得到交叉偶联产物。本文同时还报道了钯催化下有机锡试剂与取代卤代芳烃反应, 高收率地得到了不对称的杂环基芳烃和双杂环化合物。在合成的交联产物中, 化合物2, 8, 9, 15, 16与17均为新化合物。     

Electrophilic aromatic fluorination with fluorine: meta-Directed fluorination of anilines

Anilines are mainly or selectively fluorinated in the meta-position with F₂ when dissolved in triflic acid, sometimes in the presence of small quantities of antimony pentafluoride. The regioselectivity is increased when an electron-donating substituent is present at the para-position.     

Statistical study of solvent effects—II: Analysis of some empirical parameters of solvent polarity

A definition of the polarity of a solvent as due only to the physicochemical properties of the pure solvent is proposed. The physicochemical properties involved are the dipole moment, the dielectric constant, the molar refraction and Hildebrand's δ. A multivariate statistical analysis shows that about 90% of the variance of E_T, AN, Z (but only 70% of the variance of Π^*) are explained by these properties. The first three parameters should be considered as genuine solvent polarity parameters.     

On the correlations between empirical lewis acid-base solvent parameters and the thermodynamic parameters of ion solvation

Assuming a straight-line dependence of the chemical potential of anions (cations) on empirical Lewis acid (base) parameters of solvents, the values of the change of the chemical potential of ions and the change of the surface potential between water and non-aqueous solvents have been calculated and briefly discussed. On the basis of the results obtained and literature data the dependence of the standard emf of the cell Pt,H₂ |HCl|AgCl|Ag|Pt′ on the function of empirical Lewis acid-base parameters has been analysed and discussed.     

Amination of aromatic olefins with anilines: a new domino synthesis of quinolines

A new catalytic amination of aromatic olefins with anilines is presented. In a domino reaction, substituted quinoline derivatives are obtained in the presence of cationic rhodium complexes, such as [Rh(cod)2]BF4, and PPh3. Ethylbenzene is formed as a by-product in this new oxidative reaction. The first transition metal catalyzed anti-Markovnikov hydroamination of styrene with anilines occurs as a side reaction. Mechanistic investigations strongly support the regioselective oxidative amination of styrene as the key reaction step.     

Theoretical investigation of the electronic spectra of aromatic nitrosooxides with allowance for solvent effects

Density functional theory methods correctly describe some properties of nitrosooxides. Electronic spectral data have been calculated for seven para-substituted aromatic nitrosooxides in different solvents using the UB3LYP/6-311+G(d,p) approximation. The calculated positions of maxima in UV spectra correlate with experimental data with high coefficient. Equations are suggested for predicting the positions of absorption maxima for the para-R-C₆H₄-NOO under study.     

Reactions of metal tert-butoxides with aromatic sulfonyl chlorides. A new synthesis of di-tert-butyl ether

Di-tert-butyl ether was synthesized in good yields by the S_N reactions of lithium tert-butoxide with tosyl and p-bromobenzenesulfonyl chlorides under mild conditions.     

A new theoretical approach to the empirical resonance energies of the aromatic hydrocarbons

In the framework of the Hückel MO approximation, the differences in total binding energy between a given molecule and the corresponding distorted Kekulé-type structure are calculated for a variety of benzenoid hydrocarbons. The total binding energy is assumed to be given by the sum of the -electron and -electron binding energies. It is shown that there is a good linear relationship between the calculated differences in total binding energy and the -electron delocalization energies (DE) as obtained by using the simple Hückel MO method. This provides a physical basis for the use of the -electron DE as a theoretical index to the empirical resonance energy (RE). Further, by examining the changes in -electron binding energy between a given molecule and the corresponding distorted Kekulé-type structure, it is concluded that in benzenoid hydrocarbons the main contributor to the RE is not the -electron DE but the compressional energy of bonds.     

溶剂效应的TLSER描述及其在几类异构化反应中的应用

建立了适合于描述党溶剂效应的理论线性溶剂化能相关(TLSER)模型。并用该模型对四类异构化反应在不同溶剂下的反应自由能或活化自由能与溶剂的分子结构之间的关系进行了研究,确证了模型的合理性。     

Reactions of 2-thiophenesulphonyl chloride with anion and neutral nucleophiles: Solvent effects on nucleophilic reactivity correlations

The reaction kinetics of 2-thiophenesulphonyl chloride with anion and neutral nucleophiles was studied in H₂O, D₂O and in protic solvents-H₂O (10% $\text{v}\text{v}$) and aprotic solvents-H₂O (10% $\text{v}\text{v}$) mixtures at 25°. Analysing the rate constants measured in water by Bronsted, Ritchie and Edwards equations the conclusion drawn that, for the nucleophilic order against the sulphonyl sulphur, basicity is of prime importance, although there may well be some dependence on polarizability and solvation. Solvent isotope effects show that the reactions occur by nucleophilic catalysis rather than by a general base mechanism. Water is the solvent in which there is the greater reactivity than in either protic solvents or aprotic-protic mixtures. By solubility measurements and applying Parker's equation the contributions of solvation energies of both reactants and transition states to the free energy of activation are calculated. Solvent effects on nucleophilic reactivities are discussed in terms of S parameters (similar to Ritchie N₊ parameters), and by the approach of multiparameter empirical correlations. The data point out that solvation plays a large role on nucleophilic order. A complete comprehension of the problem would require an equation that takes into some account solvent effects. The homogeneous comparison of 2-thiophenesulphonyl chloride data with those of α-disulphone, p-anisyl p-methoxybenzenesulphinyl sulphone and benzenesulphonyl chloride shows that the same factors are involved in driving the nucleophilic reactivity for these compounds.     

Reactions of diborane with aromatic heterocycles—21: Reactions with nitrogen-containing heterocycles related to pyridine

The reactions of solutions of B₂H₆ in ethers with a variety of aromatic heterocycles containing one or more six-membered rings with only one nitrogen per ring have been examined. Quinoline and isoquinoline form monoborane adducts which hydroborate in the presence of an excess of B₂H₆. Protonolysis gives the 1,2,3,4-tetrahydro-compounds in both cases. N-Methylquinolinium and N-methylisoquinolinium iodides both hydroborate. Hydroboration and halogen loss occur with 2-, 3- or 4-haloquinolines (chlorine or bromine). Prior to hydroboration 8-hydroxyquinoline forms a borane adduct which rapidly eliminates one equivalent of hydrogen in a probable intramolecular ring closure. Sodium 8-hydroxyquinolinate combines with B₂H₆ in an unsymmetrical cleavage reaction to form B₂H₇^? or BH₄^?, and the same ring closed product formed by 8-hydroxyquinoline. Phenanthridine and N-methylphenanthridinium iodide both readily undergo hydroboration. The products formed by the latter with B₂H₆ are 5-methyl-5,6-dihydrophenanthridine-borane and an iodoborane etherate. 1,8-Naphthyridine forms a transient borane complex which rapidly undergoes hydroboration; protonolysis gives 1,2,3,4-tetrahydro-l,8-naphthyridine. 2,2′-Bipyridyl undergoes a complex reaction with one equivalent of BH₃ giving a mixture of bpy·2BH₃ and hydroborated products, but 4,4′-bipyridyl does not appear to hydroborate. 1,10- and 1,7-Phenanthroline both hydroborate giving a mixture of reduced products on protonolysis. Pyridine-borane and 2-phenylpyridine-borane both decompose in refluxing diglyme, but protonolysis gives no reduced products in either case.     

氮氧自由基的研究VIII. 关于溶剂极性经验参数的讨论

作者测定了有机溶剂-水二元混合溶剂体系中2,2,6,6-四甲基哌啶1-氧自由基(TMPO)的ESRaN 值. 这类混合溶剂体系中aN-m关系可归属有机二元混合溶剂体系的四种典型线关系. 比较了几种溶剂极性经验参数, 说明各种经验极参数-m关系图的差异是特定模型反痘中溶剂分子与溶质分子间相互作用不同的反映. 对二元混合溶剂体系而言, aN-Er(30),aN-Z一般不具有线线性关系, 认为溶剂极性经验参数是溶剂(包括溶剂混合物)对模型化合物溶剂化能力的标度, 给出了在各种溶剂体系中的aN 测定值, 作为溶剂对中性偶极分子相对溶剂化能力的经验标度.