Synthesis of 2‐alkyl‐4,5‐aryl‐2H‐[1λ6,2,3,6]‐thiatriazine‐1,1‐dioxides

Sulphamoyl chlorides and chlorosulphonyl isocyanate react with monosubstituted hydrazones and alkylhydrazonates to sulphamoyl hydrazones and sulphamoyl hydrazonates respectively. Reaction of benzil monoalkylhydrazones with chlorosulphonyl isocyanate results in formation of 2‐alkyl‐4,5‐aryl‐2H‐ [1λ⁶,2,3,6]‐thiatriazine‐1,1‐dioxides.     

Synthesis and biological activities of cis and trans 5‐amino‐3‐[(6‐chloro‐3‐pyridyl)methyl]amino‐1‐(5,5‐dimethyl‐2‐oxo‐4‐substitutedphenyl‐1,3,2‐dioxaphosphinan‐2‐yl)‐4‐cyano(ethoxycarbonyl)‐1H‐pyrazoles

A series of novel title compounds have been designed and synthesized by a multi‐step reaction, the stereochemistry of the reaction was investigated, the structures of all compounds prepared have been confirmed by ¹H NMR, IR, EI‐MS spectroscopy and elemental analysis. The crystal structures of cis 6b and trans 6b were determined by single crystal X‐ray diffraction. The results of preliminary bioassay indicate that some compounds possess a certain extent inhibition effect against aphides at the concentration of 250 ppm.     

The synthesis of symmetrical (2‐indolyl)ethynes and reduced congeners via palladium‐catalyzed couplings of 2‐bromoindole precursors

Starting from a series of 2‐bromo‐1‐methylindole precursors ( 1b‐e ) activated in the 3‐position with aldehyde, ester, or amide functionality, two approaches have been developed toward the synthesis of 2,2′‐bis(indolyl)ethynes and reduced congeners via palladium(0)‐ or palladium(II)‐catalyzed couplings. The first approach utilized Sonogashira coupling of (trimethylsilyl)acetylene to introduce the two‐carbon linker followed by desilylation and further coupling with starting 2‐bromoindole. A second shorter and more efficient route engaged the starting 2‐bromoindole in a double Stille coupling with bis(tributylstannyl) acetylene or (E)‐1,2‐bis(tributylstannyl)ethylene to provide desired homodimers in one step. Subsequent transformations of dimeric intermediates led to target acids 7a‐c and derived amides 8a‐c and 9 . When tested against a panel of tyrosine kinases, each target compound was found to be inactive.     

Kinetics of the Thermal and Thermo‐Oxidative Degradation of a Polystyrene–Clay Nanocomposite

Summary: Thermogravimetry and differential scanning calorimetry have been used to study the thermal and thermo‐oxidative degradation of polystyrene (PS) and a PS–clay nanocomposite. An advanced isoconversional method has been applied for kinetic analysis. Introduction of the clay phase increases the activation energy and affects the total heat of degradation, which suggests a change in the reaction mechanism. The obtained kinetic data permit a comparative assessment of the fire resistance of the studied materials.

The change in activation energy for the degradation of PS and the PS–clay nanocomposite with the extent of polymer conversion.     

Modification of poly(vinyl alcohol) through reaction with phosphorus-containing reactants

Crosslinked products of the form: and have been formed from the interfacial condensation of phosphorus diacid halides with poly(vinyl alcohol). Product yield and amounts of phosphorus reactant included in the product increases as the amount of base increases. Product stability in aqueous systems decreases in the order neutral > base > acid.     

Water‐Soluble Electrostatic Complexes of C60‐Anchored Anionic Polymers and Cationic Porphyrins

The preparation of novel highly water‐soluble electrostatic complexes from C₆₀‐anchored multi‐armed poly(acrylic acid)s and cationic porphyrin derivatives was demonstrated. The UV‐vis absorption and photoluminescence (PL) of these complexes show that the absorption of soret band exhibits a remarkable red shift and the emission of the Q band indicates an apparent quenching effect in comparison with that of the parent cationic porphyrin. These results imply a remarkable ground state and excited state interaction between the porphyrin ring and the C₆₀ moiety.

     

Silica‐Protected Micron and Sub‐Micron Capsules and Particles for Self‐Healing at the Microscale

A generalized silica coating scheme is used to functionalize and protect sub‐micron and micron size dicyclopentadiene monomer‐filled capsules and polymer‐protected Grubbs' catalyst particles. These capsules and particles are used for self‐healing of microscale damage in an epoxy‐based polymer. The silica layer both protects the capsules and particles, and limits their aggregation when added to an epoxy matrix, enabling the capsules and particles to be dispersed at high concentrations with little loss of reactivity.

     

High yield synthesis of 4H‐1,4‐benzothiazine‐1,1‐dioxide derivatives

4H‐1,4‐Benzothiazine‐1,1‐dioxide derivatives were synthesized through a sequence of almost quantitative reactions. The commercial starting material 2‐(methylsulfanyl)aniline was Boc‐protected, N‐acylated and oxidized at the sulfur atom to obtain a sulfonyl derivative. An anionic transposition of the acyl group followed by asimultaneous deprotection‐cyclization gave the title products in excellent yields. All products and intermediates were fully characterized.     

Preparation of 6‐azaoxindole (6‐azaindol‐2(3H)‐one) and substituted derivatives

A general synthesis of 6‐azaoxindoles, substituted in the 3‐ and 5‐position, has been developed starting from 4‐methoxycarbomethyl‐3‐nitropyridine, via hydrogenation of the nitro group and cyclisation of the resulting 3‐amino‐4‐methoxycarbomethyl‐pyridine.     

Synthesis and characterization of 4‐aryl‐5‐(1‐aryl‐2‐methyl‐2‐nitropropyl)‐1,2,3‐selenadiazoles

The synthesis of a new set of selenadiazoles, 4‐aryl‐5‐(1‐aryl‐2‐methyl‐2‐nitropropyl)‐1,2,3‐selenadiazoles ( 4 ) derived from 2‐[4‐methyl‐4‐nitro‐1,3‐diarylpentylidene]‐1‐hydrazinecarboxamide ( 3 ) has been reported. THF has been found to be the solvent of choice for this reaction. Structural features of 3 and 4 have been analyzed by NMR and X‐ray techniques.     

The reaction of aryl and heteroarylhydrazines with aryl‐trifluoromethyl β‐diketones

We report the results obtained when five aromatic or heteroaromatic hydrazines react with six β‐diketones bearing trifluoromethyl and aryl substituents. Forty‐two compounds have been isolated corresponding to two isomeric trifluoromethyl pyrazoles and the intermediate 5‐CF₃, 5‐OH pyrazolines. The results have provided useful information for establishing the mechanism of the synthesis of pyrazoles.     

Poly(2‐vinylpyridine)‐block ‐Poly(ϵ‐caprolactone) Single Crystals in Micellar Solution

Self‐assembly of poly(2‐vinylpyridine)‐block‐poly(ϵ‐caprolactone) (P2VP‐b‐PCL) diblock copolymer in the presence of a selective solvent is investigated by transmission electron microscopy and atomic force microscopy. Addition of water into a P2VP‐b‐PCL solution in N,N‐dimethylformamide at 20 °C produces elongated truncated lozenge shaped single crystals of uniform size and shape in large quantities. The single crystals are composed of PCL single‐crystal layer sandwiched between two P2VP layers tethered on the top and bottom basal surfaces. The formation of the single crystals is found to depend on the temperature. These findings provide a facile approach to the preparation of uniform single crystals in large quantities.

     

Automated Parallel Temperature Optimization and Determination of Activation Energy for the Living Cationic Polymerization of 2‐Ethyl‐2‐oxazoline

Sixteen parallel polymerization reactions of 2‐ethyl‐2‐oxazoline have been performed at different temperatures in an automated synthesizer that allowed individual heating of each reactor. During the reactions samples were taken automatically, which were characterized by means of both online GPC and offline GC, in order to optimize the reaction temperature and to determine the activation energy of the polymerization.

     

Self‐healing in Nanocomposite Hydrogels

Polymer hydrogels with characteristics distinct from those of solid materials are one of the most promising candidates for smart materials. Here, we report that a nanocomposite hydrogel (NC gel) consisting of a unique polymer/clay network structure, can exhibit complete self‐healing through autonomic reconstruction of crosslinks across a damaged interface. Mechanical damage in NC gels can be repaired without the use of a healing agent, and even sections of NC gels separated by cutting, from whichever the same or different kinds of NC gel, perfectly (re‐)combine by just contacting the cut surfaces together at mildly elevated temperatures. In NC gels, the autonomic fusion of cut surfaces as well as the self‐healing could be achieved not only immediately after being cut but also after a long waiting time.

     

NMR Reveals Non‐Distributed and Uniform Character of Network Chain Dynamics

Results of different NMR investigations of elastomers are reviewed with respect to their significance for statistical models of rubber elasticity. In contrast to earlier work based on lineshape analysis and relaxometry, results of recent multiple‐quantum experiments indicate that the NMR‐detected dynamic chain order parameter, which reflects the conformational space of individual monomer units at which the signal is detected locally, is a rather narrowly distributed quantity. Constraints to the dynamics and the conformations of a network chain thus act uniformly and appear as a dynamic average over chains of different length and with different end‐to‐end separations. All our findings are in good agreement with large‐scale computer simulations. Anomalies on swelling such as chain desinterspersion at the early stages and the appearance of heterogeneities, are also discussed.

     

Palladium‐catalyzed cyclization of 3‐bromopyridine‐4‐carbaldehyde with carbon monoxide and carboxylic acids

3‐Bromopyridine‐4‐carbaldehyde is cyclized with carboxylic acids in acetonitrile at 100° under carbon monoxide pressure in the presence of a catalytic amount of a palladium catalyst along with a base to afford the corresponding 3‐oxo‐1,3‐dihydrofuro[3,4‐c]pyridine‐1‐yl alkanoates in moderate to good yields.     

Synthesis of Well‐Defined Polybenzamide‐block‐Polystyrene by Combination of Chain‐Growth Condensation Polymerization and RAFT Polymerization

Well‐defined diblock copolymers composed of poly(N‐octylbenzamide) and polystyrene were synthesized by reversible addition‐fragmentation chain transfer (RAFT) polymerization of styrene with a polyamide chain transfer agent (CTA) prepared via chain‐growth condensation polymerization. Synthesis of a dithioester‐type macro‐CTA possessing the polyamide segment as an activating group was unsatisfactory due to side reactions and incomplete introduction of the benzyl dithiocarbonyl unit. On the other hand, a dithiobenzoate‐CTA containing poly(N‐octylbenzamide) as a radical leaving group was easily synthesized, and the RAFT polymerization of styrene with this CTA afforded poly(N‐octylbenzamide)‐block‐polystyrene with controlled molecular weight and narrow polydispersity.