The selective addition of water to C=C bonds; enzymes are the best chemists

Water is the liquid of life. Nature has therefore evolved countless enzymes that catalyse the addition of water to C=C bonds, isolated or conjugated. These reactions are regio- and enantioselective, they are part of primary metabolism as well as the secondary metabolism. The enzymes that catalyse these reactions (hydratases or hydro-lyases) are applied industrially in selected cases. However, they are not generally used in the laboratory although they outperform all currently available catalytic chemical methodologies. This feature article highlights the potential that hydratases have for chemistry compared to the acid catalysed addition of water.     

Chemical control of the photochromic reactivity of diarylethene derivatives

Photochemically inactive diarylethene derivatives having a N-(O-hydroxyphenyl) group underwent photochromic reaction when they were esterified by the addition of acetic anhydride.     

Factors affecting the rates of addition of free radicals to alkenes-determination of absolute rate coefficients using the persistent aminoxyl method

The rate of coupling of alkyl radicals with the persistent aminoxyl radical 1,1,3,3-tetramethylisoindolin-N-oxyl (1) has been used as a kinetic probe to determine absolute rate coefficients for the addition of alkyl radicals to methyl acrylate. The results are discussed in terms of the role of the structure and functionalization of the attacking radical on the rates of addition, particularly as they affect steric, polar, and enthalpic factors. The aminoxyl method is assessed against other methods for determining free radical addition rate coefficients.     

Addition reactions of thiazol-5(4H)-ones—IV : Synthesis,tautomerism and addition reactions of 2-phenylthiazole-5-thiols

4-Substituted 2-phenylthiazole-5-thiols 3 undergo addition reactions of a different type from those of their oxygen analogues, the oxazol- and thiazol-5(4$\text{H}$)-ones, since they exist in solution entirely in the thioenol tautomeric form. Their addition reactions involve only the exocyclic sulphur atom, and they behave as typical heteroaromatic thiols towards unsaturated systems, giving sulphides. A mesoionic thiazole-5-thiol, however, is shown to possess cycloaddition reactivity, undergoing cycloaddition-extrusion reactions with unsaturated systems comparable with well-established reactions of oxygen analogues.     

Applications of Zwitterions and Zwitterionic Polymers for Li-Ion Batteries

A zwitterion is a neutral compound that has both a cation and an anion in the same molecule. Quaternary ammonium cations are frequently used for zwitterions. Zwitterions with quaternary ammonium cations are also common in biological molecules, such as phospholipids, which are the main components of cell membranes. Chemically, they have broad applicability because they are dielectric, non-volatile, and highly polar compounds with a large dipole moment. In addition, after salt addition, ion exchange does not occur in the presence of zwitterions. Owing to these characteristics, zwitterions have been applied as novel electrolyte materials targeting high ionic conductivity. In this review, application of zwitterions and their polymers for Li-ion batteries is addressed.     

Oxidative addition of phenyl bromide to Pd(BINAP) vs Pd(BINAP)(amine). Evidence for addition to Pd(BINAP)

[STRUCTURE: SEE TEXT] The rates of oxidative addition of phenyl bromide to [Pd(BINAP)2] have been measured in the presence and absence of added amine to assess a previous hypothesis that addition to [Pd(BINAP)(amine)] is faster than addition to [Pd(BINAP)]. These data show that addition to the amine complex is not faster than addition to [Pd(BINAP)]. Instead, they are consistent with oxidative addition, even in the presence of amine, to [Pd(BINAP)] as the major pathway. These data underscore the value of studying the stoichiometric reactions of isolated complexes when assessing the mechanism of a catalytic process.     

Catalyzed Addition of Aldehydes to Activated Double Bonds—A New Synthetic Approach

In the presence of cyanide ions as catalyst, aromatic and heterocyclic aldehydes can be smoothly added to α,β-unsaturated ketones, esters, and nitriles in aprotic solvents to form γ-diketones, 4-oxo carboxylic esters, and 4-oxo nitriles. Thiazolium salts in the presence of bases are also suitable catalysts; they permit not only addition of aromatic and heterocyclic aldehydes but also the addition of aliphatic aldehydes.     

Reaction of Sulfinic Acids with Heteroconjugated Alkenes

Abstract

The nucleophilic addition reactions of arenesulfinic acids with heteroconjugated alkenes have been studied. The structures of the sulfones thus obtained were confirmed by microanalytical and spectral methods. Kinetic parameters of the nucleophilic addition reactions were determined. Interactions are second-order reactions, but they are first order regarding each reagent. The influence of various substituents at the carbon–carbon double bond on the nucleophilic activity was studied.     

Amines as antiknock compounds. Phenomenological approach

For enhancing octane number and improving ecological characteristics of internal combustion engines nitrogen-containing compounds of amine class are applied. Although these additives are inferior to the additives based on iron and managanese organoelement compounds (iron dicuyclopentadienyl, manganese methylcyclopentadienyltricarbonyl and others), but superior to oxygen-containing additives (low alcohols, methyl tert.-butyl ether and alone and mixed with tert-butanol and others). The nitrogen-containing compounds are ashess addition agents, thus they are advantageous over the addition agents based on organometallic compounds. A significant advantage of these additives is polyfunctionality. Being effective enough antiknock agents, they also possess antioxidant, stabilizing and anticorrosive properties.     

Construction of a new type of chiral bidentate NHC ligands: copper-catalyzed asymmetric conjugate alkylation

We synthesized in three steps simple chiral bidentate NHC compounds that carry an achiral coordinating group as N-substituent and revealed that they serve as efficient chiral auxiliaries for the copper-catalyzed asymmetric conjugate addition of dialkylzinc to acyclic enones (up to 97% ee).     

Switching the Photochromic Activity of Acenaphthylene Derivatives through a Tandem Nucleophile‐Promoted Addition Reaction

New acenaphthylene‐based dithienylethenes have been prepared. Surprisingly they did not show photochromism. However, they readily underwent a tandem addition of a nucleophile and an electrophile, leading to a small library of dearomatized colourless analogues, which, on the contrary, were endowed with photochromic activity. In the absence of the electrophile, the intermediate obtained by C‐attack readily aromatizes to give, surprisingly, a final product of direct aromatic nucleophilic substitution, which was not photochromically active.     

Palladacyclic catalysts in C-C and C-heteroatom bond-forming reactions

Palladacycles are amongst the most active catalysts in Heck-type carbon-carbon bond formation and related carbon-heteroatom bond forming reactions. For instance they have recently emerged as showing the highest activity in the Suzuki coupling of electronically challenging aryl chloride substrates. In addition to the high activity they display, their ease of synthesis, facile modification and comparative stability all act to enhance their appeal.     

Review Article: Anionic Conjugate Addition Reactions for the Preparation of Substituted Monosaccharides and Disaccharides

1. INTRODUCTION

Conjugate addition reactions are widely used synthetic tools in general organic chemistry,¹ and starting in the early 1960s they were introduced into carbohydrate chemistry. Since then a considerable number of publications have described the utilisation of different types of conjugate addition reactions in the field of carbohydrate chemistry but to date this area has not been reviewed.     

共轭二烯烃定向加成研究进展

以1,3-丁二烯为代表的共轭二烯烃是重要的有机合成原料,在有机合成领域有重要的应用价值.综述了以1,3-丁二烯等为代表的共轭二烯烃定向加成的研究进展,并展望了其发展和应用前景.     

Poly(trialkoxysilyltricyclononenes): A New Type of Polymers for Membrane Gas Separation

New metathesis and addition polymers containing Si–O–C groups were synthesized from 3-tri(n-propoxy) silyltricyclo[4.2.1.0^2.5]non-7-ene. It was shown for the first time that metathesis polymer was more permeable than the addition polymer. The prepared polymers showed high selectivity in the butane/methane separation controlled by solubility; therefore, they are promising for membrane separation of hydrocarbon mixtures.     

Oxidative addition of aryl tosylates to palladium(0) and coupling of unactivated aryl tosylates at room temperature

Aryl tosylates are attractive substrates for Pd-catalyzed cross-coupling reactions, but they are much less reactive than the more commonly used aryl triflates. We report the oxidative addition of aryl tosylates to Pd(PPF-t-Bu)[P(o-tolyl)3] and to Pd(CyPF-t-Bu)[P(o-tolyl)3] at room temperature to produce the corresponding palladium(II) aryl tosylate complexes. In the presence of added bromide ions, arylpalladium(II) bromide complexes were formed. The rate of oxidative addition was accelerated by addition of either coordinating or weakly coordinating anions, and the reactions were faster in more polar solvents. The mild conditions for oxidative addition allowed for the development of Pd-catalyzed Kumada couplings and amination reactions of unactivated aryl tosylates at room temperature. The catalysts for these mild couplings of aryl tosylates were generated from palladium precursors and the sterically hindered Josiphos-type ligands that induced oxidative addition of aryl tosylates to Pd(0) at room temperature.     

Solvation of halide ions and the iodine molecule in binary mixtures of water + oxydipropionitrile application to extraction

In water-rich mixtures, the addition of oxydipropionitrile (ODPN) does not alter the solvation of halide ions, they are preferentially solvated by water. In ODPN-rich media, the addition of water to the poor solvent increases the solvation of halide ions by forming hydrogen bonds with water molecules. The iodine molecule is solvated mainly by ODPN and addition of water to the solvent has little influence. The triiodide complex, a highly polarisable species behaves in the same way as the iodine molecule. On demixing, the halide ions are solvated in a similar way in the water-rich phase and very differently in the solvent-rich phase. Advantage is taken of this property to extract cationic complexes quantitatively from their aqueous solutions with ODPN.     

Synthesis of 12-alkoxycarbonylmethylene-1,15-pentadecanolides

Six novel 12-alkoxycarbonylmethylene-1,15-pentadecanolides (3) were synthesized from 2-nitrocyclo-dodecanone by the Michael addition with acrolein followed by ring enlargement,Nef reaction and Wittig-Horner reaction.Their structures were confirmed by ~1H NMR,IR and elemental analysis.The preliminary bioassay showed that they have some fungicidal activity.     

Chemical modification of polymeric hydrocarbons

Although polymeric hydrocarbons (PCH) carry no functions, they can be modified in many ways. Unsaturated PCH undergo addition reactions as hydrogenation, halogenation, epoxidation and thiol addition. Saturated PCH can be substituted with various functions, notably halogen and chlorosulfonyl groups. All PCH can be modified, by a grafting mechanism, with functional monomers as maleic anhydride. Some modified PCH play a major role in multiphase systems as blends, rubber-modified thermoplastics and thermoplastic elastomers. Attractive grafting procedures involve in-situ grafting in PCH/monomer solutions and during reactive blending processes.     

Polymer-induced recovery of nanoparticles from microemulsions

A new isothermal approach to the recovery of inorganic nanoparticles (NPs) is demonstrated. The NPs can be incorporated into a background microemulsion (ME) supporting fluid, and they can be recovered by addition of non-adsorbing polymer. A clean liquid-liquid (L-L) phase transition can be readily induced by addition of polymer to the MEs. Furthermore, the L-L transitions are also observed in the presence of added NPs, but now the nanoparticles concentrate in the lower co-existing ME phases. Once recovered, the NPs can be redispersed by adding extra ME as a solvent.