Trihexyl tetradecyl phosphonium bromide as an effective catalyst/extractant in ultrasound-assisted extractive/oxidative desulfurization.

Phosphonium-based ionic liquid (PIL) has been used as a catalyst and extractant. Here, the PIL, trihexyl tetradecyl phosphonium bromide ([THTDP]Br) was utilized for the S-removal of model oil (MO) and acted as the reaction-induced self-separation catalyst. The influence of oxidant to sulfur molar ratio (n(O/S)), mass ratio of model oil to ionic liquid (m(MO/IL)), sonication time, and temperature was observed to investigate the optimal conditions for the ultrasound-assisted extractive/oxidative desulfurization (UEODS) catalyzed by [THTDP]Br. A kinetic study was performed, and the reaction rate constant and half-life were calculated as the oxidation reaction was following pseudo-first-order reaction kinetics. Moreover, the oxidation reactivity and selectivity of various sulfur substrates were in the following order: DBT > BT > TH > 3-MT. The DBT removal with various initial S-content was observed to be constant, which makes it feasible for practical application. The interaction energy between [THTDP]Br and S-compounds was examined using Density Functional Theory. The sulfur removal of base oil (BO) was also examined using various desulfurization systems at DBT optimized conditions. The highest desulfurization efficiency of BO was obtained during the UEODS process, which made it industrially feasible. [THTDP]Br was regenerated and recycled six times with a slight variation in efficiency.

Spectral and DFT studies of anion bound organic receptors: Time dependent studies and logic gate applications.

New colorimetric receptors R1 and R2 with varied positional substitution of a cyano and nitro signaling unit having a hydroxy functionality as the hydrogen bond donor site have been designed, synthesized and characterized by FTIR, 1H NMR spectroscopy and mass spectrometry. The receptors R1 and R2 exhibit prominent visual response for F- and AcO- ions allowing the real time analysis of these ions in aqueous media. The formation of the receptor-anion complexes has been supported by UV-vis titration studies and confirmed through binding constant calculations. The anion binding process follows a first order rate equation and the calculated rate constants reveal a higher order of reactivity for AcO- ions. The 1H NMR titration and TDDFT studies provide full support of the binding mechanism. The Hg2+ and F- ion sensing property of receptor R1 has been utilized to arrive at "AND" and "INHIBIT" molecular logic gate applications.