Synthesis of 6-Membered-Ring Fused Thiazine-Dicarboxylates and Thiazole-Pyrimidines via One-Pot Three-Component Reactions

A facile and efficient one-pot three-component reaction method for the synthesis of thiazine-dicarboxylates is reported. Reaction of an isocyanide and dialkyl acetylenedicarboxylate with 2-amino-4H-1,3-thiazin-4-one derivatives containing both an acidic proton and an internal nucleophile gave the products in good yields of 76–85%. The reactivity of dialkyl acetylenedicarboxylates was further tested in the synthesis of thiazole-pyrimidines where a two-component reaction of 2-aminothiazole with dialkyl acetylenedicarboxylates was successfully converted to a more efficient three-component reaction of a thiourea, α-haloketone and dialkyl acetylenedicarboxylate (DMAD/DEtAD) to give thiazole-pyrimidines in good yields of 70–91%.

Crystal Structure of Novel Terephthalate Salt of Antiarrhythmic Drug Disopyramide

1:1 salt of Disopyramide (DPA) with Terephthalic acid (TA) was obtained by the slow solvent evaporation and the slurry crystallization methods. X-ray single crystal diffraction of DPA:TA confirmed the formation of salt by the transfer of an acidic proton from one of the carboxylic acidic groups of TA to the tertiary amino group of the chain moiety (N3-nitrogen atom) of the DPA molecules. DPA:TA salt crystals crystalize in the triclinic system with space group P-1. The asymmetric unit, comprising one protonated DPA and one TA anion, are linked by a strong charge assisted N+–H∙∙∙O¯ hydrogen bond and a C–H∙∙∙O¯ hydrogen bond. Moreover, structural characterization of DPA:TA salt was carried out using Fourier transform infrared spectroscopy, differential scanning calorimeter, thermogravimetric analysis, and powder X-ray diffraction techniques

Accelerating water dissociation in bipolar membranes and for electrocatalysis

Catalyzing water dissociation (WD) into protons and hydroxide ions is important both for fabricating bipolar membranes (BPMs) that can couple different pH environments into a single electrochemical device and for accelerating electrocatalytic reactions that consume protons in neutral to alkaline media. We designed a BPM electrolyzer to quantitatively measure WD kinetics and show that, for metal nanoparticles, WD activity correlates with alkaline hydrogen evolution reaction activity. By combining metal-oxide WD catalysts that are efficient near the acidic proton-exchange layer with those efficient near the alkaline hydroxide-exchange layer, we demonstrate a BPM driving WD with overpotentials of <10 mV at 20 mA·cm−2 and pure water BPM electrolyzers that operate with an alkaline anode and acidic cathode at 500 mA·cm−2 with a total electrolysis voltage of ~2.2 V.

Influence of residual water and cation acidity on the ionic transport mechanism in proton-conducting ionic liquids

There will be a transition between vehicular and cooperative transport mechanisms in highly acidic proton conducting ionic liquids.

Monitoring the structure–reactivity relationship in epoxidized perilla and safflower oil thermosetting resins

The reactivity of epoxidized perilla oil and epoxidized safflower oil with two aromatic dicarboxylic acids was studied. The presence of S–S bonding at the β position of the carboxylic group increases the reactivity of the acidic proton toward epoxy ring opening.

Influence of the acid–base stoichiometry and residual water on the transport mechanism in a highly-Brønsted-acidic proton-conducting ionic liquid

There is a transition between prevailing vehicular and cooperative transport mechanism in base-excess Brønsted-acidic proton-conducting ionic liquids depending on stoichiometry.

Anionic Polymerization of β-Butyrolactone Initiated with Sodium Phenoxides. The Effect of the Initiator Basicity/Nucleophilicity on the ROP Mechanism

It was shown that selected sodium phenoxide derivatives with different basicity and nucleophilicity, such as sodium p-nitrophenoxide, p-chlorophenoxide, 1-napthoxide, phenoxide and p-methoxyphenoxide, are effective initiators in anionic ring-opening polymerization (AROP) of β-butyrolactone in mild conditions. It was found that phenoxides as initiators in anionic ring-opening polymerization of β-butyrolactone behave as strong nucleophiles, or weak nucleophiles, as well as Brønsted bases. The resulting polyesters possessing hydroxy, phenoxy and crotonate initial groups are formed respectively by the attack of phenoxide anion at (i) C2 followed by an elimination reaction with hydroxide formation, (ii) C4 and (iii) abstraction of acidic proton at C3. The obtained poly(3-hydroxybutyrate) possesses carboxylate growing species. The ratio of the observed initial groups strongly depends on the basicity and nucleophilicity of the sodium phenoxide derivative used as initiator. The proposed mechanism of this polymerization describes the reactions leading to formation of observed end groups. Moreover, the possibility of formation of a crotonate group during the propagation step of this polymerization is also discussed.

Examining the Influence of Anion Nucleophilicity on the Polymerisation Initiation Mechanism of Phenyl Glycidyl Ether

The reaction of phenyl glycidyl ether (PGE) with 1‐ethyl‐3‐methylimidazolium acetateand 1‐ethyl‐3‐methylimidazolium thiocyanate to initiate the polyetherification reaction wasexamined using thermal and spectral analysis techniques. The influence of the nucleophilicity of theanions on the deprotonation of the 1‐ethyl‐3‐methylimidazolium cation determined the reactionpathway. The thermal degradation of the ionic liquid liberated the acetate ion and led, subsequently,to the deprotonation of the acidic proton in the imidazole ring. Thus, polymerisation of PGEoccurred via a carbene intermediate. The more nucleophilic thiocyanate anion was not sufficientlybasic to deprotonate the 1‐ethyl‐3‐methylimidazolium cation, and thus proceeded through directreaction with the PGE, unless the temperature was elevated and a competing carbene mechanismensued.