A Novel Approach to the Synthesis of 1,3,4-Thiadiazole-2-Amine Derivatives

The main purpose of the study was the development of a new method for synthesis of 1,3,4-thiadiazol-2-amine derivatives in a one-pot manner using the reaction between a thiosemicarbazide and carboxylic acid without toxic additives such as POCl3 or SOCl2. The reaction was investigated in the presence of polyphosphate ester (PPE). It was found that, in the presence of PPE, the reaction between the thiosemicarbazide and carboxylic acid proceeds in one-pot through three steps with the formation of corresponding 2-amino-1,3,4-thiadiazole. Using the developed approach five, 2-amino-1,3,4-thiadiazoles were synthesized. The structures of all compounds were proven by mass spectrometry, IR, and NMR spectroscopies.

Catalytic Hydrogenation of Sorbic Acid using Pyrazolyl Palladium(II) and Nickel(II) Complexes as Precatalysts

ABSTRACT We have prepared several pyrazolyl palladium and nickel complexes ([(L1)PdCl2](1), [(L2) PdCl2](2), [(L3) PdCl2](3), [(L1) NiBr2](4), [(L2) NiBr2](5) and [(L3) NiBr2](6)) by reacting 3,5-dimethyMH-pyrazole (L1), 3,5-di-ferf-butyl-1ZÏ-pyrazole (L2) and 5-ferrocenyl-1Zf-pyrazole(L3) with [PdCl2(NCMe)2] or [NiBr2(DME)] to afford mononuclear palladium and nickel complexes, respectively. These complexes were then investigated as pre-catalysts in the hydrogenation of 2,4-hexadienoic acid (sorbic acid). The active catalysts from these complexes demonstrate significant activities under mild experimental conditions. Additionally, the active catalysts show that the hydrogenation of sorbic acid proceeds in a sequential manner, where the less hindered C=C bond (4-hexenoic acid) is preferentially reduced over the more hindered C=C bond (2-hexenoic acid). Keywords: Pyrazolyl catalysts, sorbic acid, hydrogenation, selectivity.

Acid-promoted hydride transfer from an NADH analogue to a Cr(iii)–superoxo complex via a proton-coupled hydrogen atom transfer

Acid-promoted hydride transfer from an NADH analogue to a Cr(iii)–superoxo complex in the presence of acid proceeds via the full formation of the NADH analogue radical cation, followed by the decay of the radical, and accompanied then by the formation of NAD+.

The catalytic and radical mechanism for ethanol oxidation to acetic acid

Liquid-phase ethanol oxidation to acetic acid proceeds in two steps: catalytic ethanol oxidation and non-catalytic acetaldehyde autoxidation. The balance between the two-steps coincides in the acetic acid formation and provides information for designing selective catalysts.

Kinetics and mechanism of the Oxidative regeneration of Carbonyl Compounds from Phenylhydrazones by Tetramminecopper(2+) Bis (Permanganate)

The oxidation of aldo- and keto-phenylhydrazones by tetraamminecopper(2+) bis(permanganate) (TACP), in aqueous acetic acid, proceeds through a mechanism involving the formation of a cyclic activated complex, in the rate-determining step.

A study of hydrogenation of benzhydrols in the presence of catalytic amount of triflic acid

The ionic hydrogenation of diarylcarbinols by triethylsilane, in the presence of catalytic amount of triflic acid proceeds via dibenzhydryl ethers. These ethers do not disproportionate to benzophenones and diphenylmethanes but are reduced by triethylsilane to diarylmethanes.Key words: catalytic reduction, benzhydrols, dibenzhydryl ethers, triethylsilane.

Kinetics and Mechanism of the Oxidation of Aliphatic Aldehydes by Benzyltrimethylammonium Chlorobromate

Oxidation of aliphatic aldehydes by benzyltrimethylammonium chlorobromate to the corresponding carboxylic acid proceeds via the transfer of a hydride ion from the aldehyde hydrate to the oxidant.