Synthesis of cetyltrimethylammonium tribromide (CTMATB) and its application in the selective oxidation of sulfides to sulfoxides

The bright yellow crystalline cetyltrimethylammonium tribromide (CTMATB) reagent has been synthesized from the reaction of CTMAB and KBr with H₂MoO₄·H₂O, H₂O₂ and H₂SO₄ in the molar ratio 1:2:0.01:4:0.93. CTMATB selectively oxidizes a variety of dialkyl and alkyl aryl sulfides to the corresponding sulfoxides in high yields under mild conditions.     

Conjugate base catalysed one-pot synthesis of pyrazoles from β-formyl enamides

A novel one-pot synthesis of pyrazoles has been accomplished by the reaction of β-formyl enamides with hydroxylamine hydrochloride catalysed by potassium dihydrogenphosphate in acid medium.     

Ab initio study on the noncovalent adsorption of camptothecin anticancer drug onto graphene, defect modified graphene and graphene oxide

The application of graphene and related nanomaterials like boron nitride (BN) nanosheets, BN-graphene hybrid nanomaterials, and graphene oxide (GO) for adsorption of anticancer chemotherapeutic camptothecin (CPT) along with the effect on electronic properties prior to functionalization and after functionalization has been reported using density functional theory (DFT) calculations. The inclusion of dispersion correction to DFT is instrumental in accounting for van der Waals π–π stacking between CPT and the nanomaterial. The adsorption of CPT exhibits significant strain within the nanosheets and noncovalent adsorption of CPT is thermodynamically favoured onto the nanosheets. In case of GO, surface incorporation of functional groups result in significant crumpling along the basal plane and the interaction is basically mediated by H-bonding rather than π–π stacking. Docking studies predict the plausible binding of CPT, CPT functionalized graphene and GO with topoisomerase I (top 1) signifying that CPT interacts through π stacking with AT and GC base pairs of DNA and in presence of nano support, DNA bases preferentially gets bound to the basal plane of graphene and GO rather than the edges. At a theoretical level of understanding, our studies point out the noncovalent interaction of CPT with graphene based nanomaterials and GO for loading and delivery of anticancer chemotherapeutic along with active binding to Top1 protein.     

A facile microwave assisted synthesis of spiro-1,3-oxazines from N-(2-(cyclohex-1-en-1-yl)ethyl)amides

A mild and efficient methodology has been developed for the synthesis of spiro-1,3-oxazine derivatives by the microwave assisted cyclization of N-2-(1′-cyclohexenyl)ethyl-acetamides/benzamides. The reaction was catalyzed by in situ generated trimethylsilyl iodide and featured by its very short reaction time. The starting materials were easily obtained by the condensation of substituted acetic/benzoic acids with 2-(1′-cyclohexenyl)ethyl amine.     

Some results on a special case of a general continued fraction of Ramanujan

We derive a new special case C(q) of a general continued fraction recorded by Ramanujan in his Lost Notebook. We give a representation of the continued fraction C(q) as a quotient of Dedekind eta-function and then use it to prove modular identities connecting C(q) with each of the continued fractions \(C(-q)\), \(C(q^{2})\), \(C(q^{3})\), \(C(q^{5})\), \(C(q^{7})\), \(C(q^{11})\), \(C(q^{13})\) and \(C(q^{17})\). We also prove general theorems for the explicit evaluation of the continued fraction C(q) by using Ramanujan’s class invariants.     

Solution of approximate gluon evolution equation for small-x at fixed ‘ρ’

A simple method has been applied to solve the approximate gluon evolution equation for small-x at fixedρ(≡√ln(x ₀/x)/ln[ln(Q ²/Λ²)/ln(Q ₀ ² /Λ²)]. Numerical comparison is made with the predictions from ‘double asymptotic scaling’ and fit. Better agreement is found between our solution and fit nearρ=1. The solution gives approximate double scaling in this region having ‘hard’ pomeron with small contamination.     

Supported dual‐acidic 1,3‐disulfoimidazolium chlorozincate@HZSM‐5 as a promising heterogeneous catalyst for synthesis of indole derivatives

HZSM‐5‐supported Brönsted and Lewis acidic ionic solid 1,3‐disulfoimidazolium chlorozincate materials ([dsim]₂[ZnCl₄]@HZSM‐5) were synthesized with various ratios (3, 6, 9, 17 and 50% w/w). The heterogeneous materials were characterized via a variety of spectroscopic techniques. Dual acidity of these materials was determined using specified techniques. These acidic solids were examined as stable heterogeneous catalysts for the Fischer indole reaction of equimolar amounts of phenylhydrazine hydrochloride and various aliphatic or aromatic ketones at 80–90°C in neat condition to produce substituted indole derivatives. The efficient 17% ionic salt‐loaded HZSM‐5 composite was easily reused for ten consecutive cycles with a slight loss of its activity. The recycled catalyst was further analysed using powder X‐ray diffraction and inductively coupled plasma optical emission spectrometric techniques.     

Influence of Sn on the hydration of tricalcium aluminate, Ca3Al2O6

Tricalcium aluminate (Ca₃Al₂O₆, C₃A) containing 0?C5% of Sn was synthesized by solid-state method, and the products were characterized by XRD technique. Differential thermo-analytical technique (DTA) along with X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) were applied to study the hydration behaviour of different C₃A samples with and without the presence of gypsum. Results indicate that C₃A can accommodate small amount of Sn in its structure and remaining amount forms SnO₂. Hydration studies of the synthesized C₃A shows that the additions of 0.5 and 1% Sn increase and 2% Sn decrease the reactivity of C₃A at the initial period (<3?h) of hydration. Increasing additions of Sn also increase the amounts of amorphous phases and hexagonal calcium aluminate hydrates in the cement pastes. The stabilities of these hydration products also increase with increasing content of Sn in C₃A at the experimental conditions. The presence of Sn significantly changes the hydration of C₃A and gypsum solid mixture at the initial period of hydration by enhancing the formation of more amounts of AFt and AFm phases. However, at the later stage of hydration (on or after 3?days), the hydration products in C₃A and gypsum pastes with and without the presence of Sn are almost similar.     

Chemistry of trichlorofluoromethane: synthesis of chlorofluoromethyl phenyl sulfone and fluoromethyl phenyl sulfone and some of their reactions.

It was observed that the reaction of CFCl3 with thiophenoxide gave only 10% of the corresponding thioether. On the other hand, these thioethers could be prepared in excellent yield from diaryl disulfides and CFCl3 in the presence of sodium hydroxymethanesulfinate in aqueous DMF at 4 atm pressure of nitrogen. Dechlorination of the thioether (PhSCFCl2) with different reducing agents were studied. Most of the reducing agents eliminated both fluorine and chlorine functionalities or gave the hydrolyzed products. But its sulfone on treatment with Zinc in methanol gave monochlorofluoromethyl and fluoromethyl phenyl sulfone in good yields. Darzens reaction of these compounds was also studied.     

Motional dispersions and ratchet effect in inertial systems

We obtain ratchet effect in inertial structureless systems in symmetric periodic potentials where the asymmetry comes from the non-uniform friction offered by the medium and driven by symmetric periodic forces. In the adiabatic limit the calculations are done by extending the matrix continued fraction method and also by numerically solving the appropriate Langevin equation. For finite frequency field drive the ratchet effect is obtained only numerically. In the transient time scales the system shows dispersionless behaviour as reported earlier when a constant force is applied. In the periodic drive case the dispersion behaviour is more complex. In this brief communication we report some of the results of our work.