Research Summary

• In this study, Gold nanorods with different aspect ratios were synthesized and characterized in large quantities

• Also Gold nanostars with different sizes were synthesized

• Laser initiation studies of high energy materials are successfully conducted by using gold nanorods

Decomposition Mechanism of Hexanitrohexaazaisowurtzitane (CL-20) by Coupled Computational and Experimental Study

(Journal of Physical Chemistry A, 2019, 123, 4014-4020) 

• A novel degradation pathway of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) was identified using computational and experimental methods

• Based on the indications from computational and experimental results, the cleavage of the strained fragment from CL-20 was identified instead of NO2 or HONO elimination as in conventional high energy materials. 

• This fragmentation results in the formation of two energetic species, dinitrodihydropyrazine and dinitroformimidamide, which makes CL-20 one of the most powerful energetic materials. 

• This novel degradation pathway of CL-20 will be useful in understanding the decomposition of cage molecules, design of new practical energetic molecules, and development/improvement of thermokinetic codes used for energetic property calculations.

Sn-Pd bimetallic catalyst supported by nanocrystalline ZSM-5 for aqueous nitrate reduction

(Applied Catalysis B: Environmental, 2016, 187, 37-46)

• Novel bimetallic catalysts supported by nanocrystalline beta zeolite (NBeta) were firstly developed for the complete and selective reduction of nitrate to environment-friendly nitrogen.

• Sn-Pd-NBeta showed highest reduction kinetics (k = 19.09×10-2×min-1) followed by In-Pd-NBeta (k = 2.89×10-2×min-1) and Cu-Pd-NBeta (k = 2.31×10-2×min-1).

• The NBeta-supported Cu-Pd, In-Pd, and Sn-Pd catalysts also showed a complete NO3- reduction with consistent N2 selectivity in successive and regenerated cycles.

Reductive dechlorination of trichloroethylene by polyvinylpyrrolidone stabilized nano-scale zero valent iron particles with Ni

(Journal of Hazardous Materials, 2017, 340, 399-406)

• A new metal-free protocol is described for the synthesis of terminal acetals by tandem oxidative rearrangement of olefins using oxone as an oxidant in the presence of iodine.

• Moreover, a one-pot procedure for the preparation of glycol mono esters from olefins is also presented for the first time using the same reagent system.

• The reaction mechanism was investigated using in situ Mass, in situ NMR, Computational studies and Isotopic labeling techniques.

N-Alkylation of amines with alcohols over nanosized zeolite beta

(Green Chemistry, 2013, 15 (12), 3474-3483)

• Direct N-alkylation of amines with alcohols was successfully performed by using nanosized zeolite beta, which showed the highest catalytic activity among other conventional zeolites.

• This method has several advantages, such as broad substrate scope, high atom economy (only water is a side product), reusability of catalyst, environmentally benign, higher yields of the desired products and simple work-up procedure, which make it an attractive and useful methodology for organic synthesis.

• In addition, imines were also efficiently prepared from the tandem reactions of amines with nitrobenzyl alcohols using nanosized zeolite beta.

Oxybromination of aromatic compounds

(Synthesis, 2010, 1629-1632)

• A simple, efficient and mild method for the selective bromination of activated aromatic compounds using ammonium bromide as the source of bromine and Oxone as the oxidant in methanol or water as solvent is reported.

• The reaction proceeds at ambient temperature in yields ranging from moderate to excellent without a catalyst.

• The advantage of this system over other methods for the bromination of aromatic compounds is that the use of a catalyst is not required to enhance the reactivity of the reagents, control the regioselectivity or to improve the yield.

• Another notable benefit of this system is that regioselective conversion of resorcinol into its para-brominated product is achieved in excellent yield compared to earlier reports.

Oxybromination of carbonyl compounds

(Tetrahedron letters, 2012, 53, 191-195)

•  A highly efficient, environmentally safe and economic method for selective α-monobromination of aralkyl, cyclic, acyclic, 1,3-diketones and β-keto esters and α,α-dibromination of 1,3-diketones and β-keto esters without catalyst is reported using ammonium bromide as a bromine source and oxone as an oxidant.

• The reaction proceeds at ambient temperature and yields range from moderate to excellent.

• Bromination of unsymmetrical ketones takes place at the less substituted α-position predominantly.

• Aromatisation of tetralones is also carried out with this reagent system.

Oxybromination of olefins

                            (Tetrahedron Letters, 2012, 53, 1401-1405)

                                       (Synthetic Communications, 2013, 43, 3121-3129)

• An efficient protocol for the synthesis of vicinal bromohydrins, alkoxybromides and dibromides from olefins is presented.

• Various olefins are regio- and stereoselectively hydroxybrominated, alkoxybrominated and dibrominated with anti fashion, following Markonikov’s rule, using eco-friendly, non-toxic, and stable reagents such as      NH4Br and oxone in CH3CN/H2O (1:1), alcohols and CH3CN without employing catalyst in moderate to excellent yields.

• Bromohydrins are formed instantaneously. It is noteworthy that the present method provides a new route for the bromohydroxylation of olefins.

Vapour phase synthesis of annelated pyridines over modified zeolite Beta

(Catalysis Letters, 2015, 145, 1922-1930)

• Vapor phase synthesis of annelated pyridines was carried out over various zeolite molecular sieves.

• The present protocol demonstrates Pbβ zeolite as an effective catalyst for the synthesis of 1,2,3,4,5,6,7,8-octahydroacridine, 9-substituted octahydroacridines and other annelated pyridines using simple reactants such as cyclic ketones, aliphatic aldehydes and ammonia under vapor phase conditions.

• Notable advantages offered by this method are single step (step economic) synthesis of annelated pyridines, inexpensive and environmentally friendly catalysts and commercially available reactants makes this method valuable from a preparative point of view.

Catalyst-free synthesis of amines from cyclic ketones and formamides in superheated water

(Synthetic Communications, 2016, 46 (6), 516-522)

• A novel and environmentally benign protocol for the synthesis of amines from cyclic ketones and formamides is demonstrated.

• The reaction proceeds under catalyst-free and superheated water conditions and yields range from moderate to excellent.

• This methodology is applicable to variety of cyclic ketones and formamides.