C-H bond chlorination and bromination using water soluble nickel(II) guanidine complexes.

Water-soluble nickel(II)-guanidine-based complexes successfully catalyzed the C-H chlorination of a series of hydrocarbons in the presence of NaOCl and acetic acid in water-chloroform (7 : 3, biphasic condition) at room temperature. Majorly chlorinated products (TON ∼680 for cyclohexane) were obtained. Furthermore, C-H bond bromination of cyclohexane, -hexane, and toluene was also carried out using generation of NaOBr.

Eosin Y Catalyzed Photochemical Synthesis of Arylated Phenothiazones.

In the presence of Eosin Y (), the synthesis of substituted phenothiazones was carried out efficiently using various substituted 2-aminothiophenol, diazonium salts, and 1,4-napthaquinones () at room temperature (RT) (condition: green LED of 525 nm, 44 W; reaction time: 8 h, isolated yield: 68-90%). A fluorescence quenching experiment and density functional theory (DFT) calculations suggested that the triplet photoexcited state of EY (EY*; τT = 320 ± 10 ns) converts to EY via oxidative quenching by ArN (-1.11 V vs SCE for EY* to EY) initially.

Keto-enol tautomerism of β-diketo molecules in the presence of graphitic materials through π-π stacking.

The pseudo aromatic structures of the enol forms of β-diketo molecules are stabilized on the surface of graphitic materials through π-π interaction. This phenomenon has been studied through a relative binding energy calculation using density functional theory. The intermolecular interaction as well as the relative stability of the keto or enol tautomer is also influenced by the functional groups attached to the graphitic materials.

Bio-inspired Cu(II) amido-quinoline complexes as catalysts for aromatic C-H bond hydroxylation.

Cu(II) complexes supported by tetradentate amido-quinoline acyclic ligands (L1 & L2) have been synthesized, characterized, and employed as catalysts for aromatic C-H hydroxylation using HO as an oxidant in the absence of an external base with a high selectivity of around 90% for phenols the non-radical pathway (TON ≥720). The KIE value, various spectroscopic studies and DFT calculation supported the involvement of Cu(II)-OOH species.

Photochemical C-H Arylation of Napthoquinones Using Eosin Y.

A visible-light-mediated C-H arylation of substituted 1,4-napthoquinones () and 1,2-napthoquinone () with diazonium salt using a photocatalyst eosin Y at room temperature in a single step (isolated yield of ≥75%) is described in this report. The rate-determining step of the reaction is aryl radical generation, which was trapped by high-resolution mass spectrometry. Cost-effectiveness, operational simplicity, a short reaction time, high atom economy, and a good yield make this photoredox-mediated process a valuable alternative to the transition-metal (Fe, Cu, Pd, etc.

C-H bond chlorination using nickel(II) complexes of tetradentate amido-quinoline ligands.

Ni(II)-tetradentate amido-quinoline complexes effectively catalysed C-H chlorination of a series of hydrocarbons in the presence of NaOCl and acetic acid. The bond dissociation energy of the C(sp)-H bond of the substrates varies from 99.3 kcal mol (cyclohexane) to 87 kcal mol (ethyl benzene).

Visible Light-Mediated Thiolation of Substituted 1,4-Naphthoquinones Using Eosin Y as a Photoredox Catalyst.

In the presence of eosin Y, a visible light-induced one-step procedure (isolated yield of ≥75%) for thiolation of substituted 1,4-naphthoquinones using various aromatic and aliphatic thiols at room temperature is described herein. The rate-determining step of the reaction is thiyl radical generation, and the radical was characterized by high-resolution mass spectrometry. Cost effectiveness, operational simplicity, a short reaction time, high atom economy, and a very good yield make this photoredox-mediated process a useful alternative to the transition metal (e.

Visible-Light-Mediated Synthesis of Substituted Phenazine and Phenoxazinone Using Eosin Y as a Photoredox Catalyst.

This paper describes an efficient, sustainable, one-step procedure for synthesizing substituted phenazines and phenoxazinones from commercially available -substituted aromatic amines with very good yield (≥80%) in water. The procedure uses eosin Y (EY) as a photoredox catalyst at room temperature (RT). The highly reactive -quinone-diimine or -quinone-imine intermediate was characterized by the HR-MS technique.

Phosphorous-Doped Graphitic Material as a Solid Acid Catalyst for Microwave-Assisted Synthesis of β-Ketoenamines and Baeyer-Villiger Oxidation.

Synthesis of phosphorous-doped graphitic materials (P-Gc) using phytic acid as a precursor was done in a microwave oven in a cost- and time-effective green way. The material was used as a solid acid catalyst for microwave (MW)-assisted synthesis of β-ketoenamines and Baeyer-Villiger (BV) oxidation. In the case of BV oxidation, hydrogen peroxide (HO) was used as a green oxidant.

C-C Bond formation catalyzed by natural gelatin and collagen proteins.

The activity of gelatin and collagen proteins towards C-C bond formation via Henry (nitroaldol) reaction between aldehydes and nitroalkanes is demonstrated for the first time. Among other variables, protein source, physical state and chemical modification influence product yield and kinetics, affording the nitroaldol products in both aqueous and organic media under mild conditions. Significantly, the scale-up of the process between 4-nitrobenzaldehyde and nitromethane is successfully achieved at 1 g scale and in good yield.

Hypovalent titanium and Ti(II)-Ti(III) interconversions.

Treatment of pink titanium(iii) triflate (0.045 M) with HF in triflic acid (CH(3)SO(3)H) converts Ti(iii) rapidly to a 1 : 1 mixture of Ti(IV) and green Ti(II): (2 Ti(III) + 4 HF --> TiF(4) + Ti(II) + 4 H(+)). This disproportionation is half complete when [HF] added is 0.

Reactions of aquatitanium(II) with hypervalent chromium species.

Titanium(ii) solutions, prepared by dissolving titanium metal in triflic acid and HF, react readily with derivatives of Cr(vi), Cr(v) and Cr(iv). Reductions of Cr(vi) and Cr(iv), carried out with [Co(NH(3))(5)Br](2+) as a scavenger for Cr(ii), yield no detectable Co(2+), indicating that 2e(-) steps, bypassing Cr(v) and Cr(iii), are not operative. Catalysis by Ti(iv) is observed only for reduction of Cr(vi).

Reductions of oxo species by aquatitanium(II) as catalyzed by titanium(IV).

Titanium(II) solutions, prepared by dissolving titanium wire in triflic acid + HF, contain equimolar quantities of Ti(IV). These preparations react readily with oxidizing species such as VO(2)(+), substituted benzoquinones, and the biguanide complex of Mn(IV). Reactions with excess Ti(II) yield Ti(III).