Recoverable and thermally stable superhydrophobic silica coating

A facile route to methyltrimethoxysilane (MTMS) based recoverable superhydrophobic silica coatings with dual-scale roughness obtained through the single step base catalyst sol–gel process. Superhydrophobic silica coatings have shown static water contact angle near about 170 ± 1° and dynamic water contact angle up to 2 ± 1°. Superhydrophobic-superhydrophilic switching feature also achieved by alternating heat treatment and bath surface modification with Trimethylchlorosilane (TMCS) at room temperature (26 °C). Furthermore, the superhydrophobic state could be transformed into superhydrophilic state by slow rate heat treatment. These studies present a very simple strategy for the fabrication of recoverable superhydrophobic surfaces.     

Reaction of 3,6-diphenyl-1,2,4,5-tetrazine with cis,cis-1,5-cyclooctadiene : An attempt at preparing some dihydropyridazine derivatives

The reaction of 3,6-diphenyl-1,2,4,5-tetrazine 1 with cis,cis-cycloocta-1,5-diene 7 has been studied with a view to preparing some interesting dihydropyridazine derivatives. Refluxing a mixture of 1 with excess of 7 in benzene solution for 8hr resulted in the formation of a mixture of products consisting of 1,4-diphenyl-10a-hydroperoxy-4a, 5,6,9,10,10a-hexahydrocycloocta[d]pyridazine (8, 27%) and 2,4a,5,6,8,10a,11,12-octahydro-1,4,7,10-tetraphenyldipyridazo[4,5-a:4',5'-e]cyclooctene ( However, when the reaction of 1 with 7 was carried out in refluxing benzene for nearly 40 hr, the products formed were a 14% yield of 8, a 17% yield of 9 and a 37% yield of 1,4-diphenyl-5,6,9,10-tetrahydrocycloocta[d]pyridazine (10). Neat heating of 1 with 7 around 150° for 10 hr, on the other hand, gave a 20% yield of 9, as the only isolable product. Thermolysis of 8 around 155° gave a mixture of products consisting of 2-oxocyclooct-5-enyl phenyl ketone N-benzoylhydrazone (15,30%) and 1H-3-phenyl-4,5,8,9-tetrahydrocycloocta[d]pyrazole (16, 22%). Nickel peroxide-oxidation of the adduct 9 gave a 67% yield of 1,4,7,10-tetraphenyldipyridazo[4,5-a:4',5'-e]cyclooctene (27). Acetylation of 9, on the other hand, gave a 70% yield of 2,3,8,9-tetraacetyl-2,3,5,6,8,9,11,12-octahydro-1,4,7,10-tetraphenyldipyridazo[4,5-a:4',5'-e]cyclooctene(28).     

Heterogeneous Pd catalysts and microwave irradiation in heck arylation

Pd metal dispersed on supports like γ-Al₂O₃, C, MgO and CaCO₃ is an efficient and recyclable catalyst in Heck arylation of several olefins. This reaction is also effective in microwave environment. IPCL Communication No. 294     

Synthesis of selectively deuterated fulvenes and indenes from enediynes

A facile enediyne--> fulvene--> indene transformation provides a route to all possible isotopomers of substituted fulvenes and indenes.     

A Stability Indicating LC Method for Deferasirox in Bulk Drugs and Pharmaceutical Dosage Forms

A novel, sensitive, stability indicating RP-LC method has been developed for the quantitative determination of deferasirox, its related impurities in both bulk drugs and pharmaceutical dosage forms. Efficient chromatographic separation was achieved on a C18 stationary phase with simple mobile phase combination delivered in an isocratic mode and quantitation was by ultraviolet detection at 245 nm. The mobile phase consisted of buffer, acetonitrile and methanol (50:45:5, v/v) delivered at a flow rate of 1.0 mL min^?1. Buffer consisted of 10 mM potassium dihydrogen orthophosphate monohydrate, pH adjusted to 3.0 by using orthophosphoric acid. In the developed LC method the resolution (R _s ) between deferasirox and its four potential impurities was found to be greater than 2.0. Regression analysis showed an r value (correlation coefficient) greater than 0.999 for deferasirox and its four impurities. This method was capable to detect all four impurities of deferasirox at a level of 0.002% with respect to test concentration of 0.5 mg mL^?1 for a 10 μL injection volume. The inter- and intra-day precision values for all four impurities and for deferasirox was found to be within 2.0% RSD. The method showed good and consistent recoveries for deferasirox in bulk drugs (98.3–101.1%), pharmaceutical dosage forms (100.2–103.1%) and for its all the four impurities (99.7–102.1%). The test solution was found to be stable in methanol for 48 h. The drug was subjected to stress conditions of hydrolysis, oxidation, photolysis and thermal degradation. Considerable degradation was found to occur in acid stress hydrolysis. The stress samples were assayed against a qualified reference standard and the mass balance was found close to 99.95%. The developed RP-LC method was validated with respect to linearity, accuracy, precision and robustness.     

Topological investigations of binary and ternary mixtures: excess isentropic compressibilities

The speed of sound, U_ij 1,3-dioxolane (D) in binary mixtures (ij) with benzene, cyclohexane, n-hexane or n-heptane and U_ijk for 1,3-dioxolane in ternary mixtures (ijk) with the same hydrocarbons have been measured as a function of composition at 298.15 K. The observed data have been utilised to evaluate excess isentropic compressibility of binary, (κ_s^E)_ij and ternary (κ_s^E)_ijk mixtures using density and speed of sound values of the binary and ternary mixtures. The Moelyn-Huggins concept of interaction between the molecular surfaces of the components of a binary mixture [Polymer 12 (1971) 389] has been extended to evaluate excess isentropic compressibility of the studied binary and ternary mixtures. It has been observed that κ_s^E values predicted by a graph-theoretical approach using connectivities of third degree for binary mixtures compare reasonably well with their corresponding experimental values and κ_s^E for ternary mixtures are of the same sign and order of magnitude.     

Polymer‐Infiltrated Aligned Carbon Nanotube Fibers by in situ Polymerization

Carbon nanotube–polymer composite fibers are obtained by infiltration of a monomer liquid into aligned carbon nanotube aerogel fibers with subsequent in situ polymerization. The monomer, methyl methacrylate (MMA), was infiltrated into the aerogel fibers of multi‐walled carbon nanotubes (MWNTs) at room temperature and subsequently polymerized at 50 °C into poly(methyl methacrylate) (PMMA). Cross‐sections of the PMMA/MWNT composite fibers showed that the PMMA filled the spaces of the nanotube fibers and bound the nanotubes together. PMMA in the composite fibers exhibited local order. The resultant composite fibers with 15 wt.‐% nanotube loading exhibited a 16‐fold and a 49‐fold increase in tensile strength and Young's modulus, respectively, compared to the control PMMA.

     

Efficient and Convenient Method for Synthesis of Benzofuran-3-acetic Acids and Naphthafuran-acetic Acids

Herein, we report an efficient and convenient method for synthesis of benzofuran-3-acetic acids and naphthafuran-acetic acids 5a–p by the reaction of substituted-4-bromomethylcoumarins with aqueous sodium hydroxide at refluxing temperature. The obtained products are characterized by infrared, ¹H NMR, ¹³C NMR, and mass spectral data. Structures 5a and 5e are confirmed by their single x-ray diffraction studies. The advantages of this method are good yields, easy workup, and no chromatographic purifications.     

First Total Synthesis of N‐(3‐Guanidinopropyl)‐2‐(4‐hydroxyphenyl)‐2‐oxoacetamide

The first total synthesis of the α‐oxo amide‐based natural product, N‐(3‐guanidinopropyl)‐2‐(4‐hydroxyphenyl)‐2‐oxoacetamide ( 3 ), isolated from aqueous extracts of hydroid Campanularia sp., has been achieved. The α‐oxo amide 12 , prepared via the oxidative amidation of 1‐[4‐(benzyloxy)phenyl]‐2,2‐dibromoethanone ( 9a ) with 4‐{[(tert‐butyl)(dimethyl)silyl]oxy}butan‐1‐amine ( 10a ), has been used as the key intermediate in the total synthesis of 3 as HBr salt. On the way, an expeditious total synthesis of polyandrocarpamide C ( 2c ), isolated from marine ascidian Polyandrocarpa sp., was carried out in four steps.