4-Aminoacetophenone Intercalated CoAl Layered Double Hydroxides: Synthesis, Characterization and Adsorptive Removal of Cd(II) ions from Water Samples

In the present study, CoAl-NO3 Layered Double Hydroxides (CoAl-NO3-LDH) was synthesized and an enolate anion of 4-Aminoacetophenone (AAP) was intercalated into LDH following the reconstruction approach. The CoAl-NO3-LDH and CoAl-AAP-LDH were characterized by Fourier-Transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray (EDX) analyses. CoAl-AAP-LDH worked well for adsorption of Cd(II) ions from aqueous samples at optimum pH 7, adsorbent dosage 25 mg, concentration of Cd(II) ions 25 mg L-1 and shaking time 20 min at 25 °C. Different isotherms such as Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherms fitted well to adsorption data with correlation coefficient (R2) of 0.998, 0.982 and 0.992, respectively. Monolayered (Qm) and multi-layered (KF) capacities of CoAl-AAP-LDH for adsorption of Cd(II) ions were calculated and found to be 34.40 and 19.44 mg g-1, respectively. Sorption energy was calculated and found to be 9.13 kJ mol-1, indicating chemisorption or ion exchange sorption mechanism. The method worked well for the adsorption of Cd(II) ions from wastewater samples.

Antifeedant Activity of Pyrazolin-5-One Derivatives

A series of substituted 4-{1-aza-2-[(aryl) amino)]}-3-methyl-2-pyrazolin-5-ones has been synthesized and evaluated for their biological activity. The title compounds (4a-l) were prepared by the diazotization of substituted anilines (1a-l) to form substituted phenyl hydrazine derivatives (2a-l) which synthesized substituted 4-{1-aza-2-[(aryl) amino)]}-3-methyl-2-pyrazolin-5-ones (4a-l) by Michael addition reaction, which is a nucleophilic addition of enolate anion to the carbon-carbon double bond of a α, β–unsaturated carboxylic acid derivatives. Twelve different pyrazolinone derivatives (4a to 4l) were synthesized. Structural assignments of these compounds have been made by elemental analysis, FTIR, 1HNMR and Mass spectral data and the purity of the compounds was determined by TLC. The antifeedant activity of the newly isolated heterocyclic compounds was evaluated against agriculture pest Achoea janata. Compound 4d found to be very effective as antifeedant while rest of the compounds showed a moderate to good degree of antifeedant activity.

INTERACTION OF α-CARBANIONS OF LITHIUM ACYLATES WITH 1,2-DIBROMOALKANES

We have studied the interaction of α-carbanions of lithium acylates with 1,2-dibromoalkanes with different length of the carbon chain in order to establish the direction of the reaction. Interaction of α-carbanions of lithium acylates obtained by metallation of acetic, butyric and isobutyric acids with lithium diisopropylamide and 1,2-dibromoalkanes (1,2-dibromohexane, 1,2-dibromoheptane or 1,2-dibromononane) with a molar ratio of reactants equal to 1: 2: 1 in argon atmosphere in tetrahydrofuran under normal conditions (20-25 °C) for 2 h leads to the products of the oxidative coupling of enolate anions: succinic acid, 2,3-diethylsuccinic acid (mixture of diastereomers of meso- and (±) -form in a ratio of ~ 2: 1) and 2,2,3,3-tetramethylsuccinic acid with 10-70% yields. We didn’t observe any products of sequential nucleophilic substitution in reaction. The yields of dicarboxylic acids depend on the structure of the initial α-carbanion of lithium acylate and on the carbon chain length of 1,2-dibromoalkane involved in the reaction. We established that the oxidative coupling proceeds most effectively in the interaction of 1,2-dibromoalkanes with an α-carbanion containing an anionoid center at the secondary α-carbon atom - α-carbanion of lithium butyrate (2,3-diethylsuccinic acid yields are 31-70%). We suggested the most probable anion-radical scheme of the formation of the products of the oxidative coupling of α-carbanions of lithium acylates through electron transfer from the enolate anion to 1,2-dibromoalkane with the generation of its radical anion. The pathways for the formation of primary bromoalkanes (1-bromohexane, 1-bromoheptane, 1-bromononane) and terminal olefins (hexene-1, heptene-1, nonene-1) that are generated from the corresponding 1,2-dibromoalkanes during the elimination of their radical anions with the loss of the bromine anion and the subsequent stabilization of 1-bromoalkyl radicals by abstraction of the hydrogen atom from the solvent, or by bromine elimination, are shown.

Catalysis of an Aldol Condensation Using a Coordination Cage

The aldol condensation of indane-1,3-dione (ID) to give ‘bindone’ in water is catalysed by an M8L12 cubic coordination cage (Hw). The absolute rate of reaction is slow under weakly acidic conditions (pH 3–4), but in the absence of a catalyst it is undetectable. In water, the binding constant of ID in the cavity of Hw is ca. 2.4 (±1.2) × 103 M−1, giving a ∆G for the binding of −19.3 (±1.2) kJ mol−1. The crystal structure of the complex revealed the presence of two molecules of the guest ID stacked inside the cavity, giving a packing coefficient of 74% as well as another molecule hydrogen-bonded to the cage’s exterior surface. We suggest that the catalysis occurs due to the stabilisation of the enolate anion of ID by the 16+ surface of the cage, which also attracts molecules of neutral ID to the surface because of its hydrophobicity. The cage, therefore, brings together neutral ID and its enolate anion via two different interactions to catalyse the reaction, which—as the control experiments show—occurs at the exterior surface of the cage and not inside the cage cavity.

Evidence of single electron transfer from the enolate anion of an N,N′-dialkyldiketopiperazine additive in BHAS coupling reactions

A designed N,N′-dialkyldiketopiperazine (DKP) provides evidence for the role of DKP additives as initiators that act by electron transfer in base-induced homolytic aromatic substitution reactions, involving coupling of haloarenes to arenes.

Theoretical Electronic and Rovibrational Studies for Anions of Interest to the DIBs

The dipole-bound excited state of the methylene nitrile anion (CH2CN−) has been suggested as a candidate carrier for a diffuse interstellar band (DIB) at 803.8 nm. Its corresponding radical has been detected in the interstellar medium (ISM), making the existence for the anion possible. This work applies state-of-the-art ab initio methods such as coupled cluster theory to reproduce accurately the electronic excitations for CH2CN− and the similar methylene enolate anion, CH2CHO−. This same approach has been employed to indicate that 19 other anions may possess electronically excited states, five of which are valence in nature. Concurrently, in order to assist in the detection of these anions in the ISM, work has also been directed towards predicting vibrational frequencies and spectroscopic constants for these anions through the use of quartic force fields (QFFs). Theoretical rovibrational work on anions has thus far included studies of CH2CN−, C3H−, and is currently ongoing for similar systems.