Fast Synthesis of Substituted N‐Phenylanthranilic Acids Using Ullmann Condensation Under Microwave Irradiation in Dry Media

Substituted N‐phenylanthranilic acids using the Ullmann condensation under microwave irradiation in dry media were obtained in good yield and short reaction times.     

DESORPTION OF VOCs FROM POLYMERIC ADSORBENTS UNDER MICROWAVE FIELD

1. INTRODUCTION Nowdays the volatile organic compounds (VOCs) have become important pollutants to air [1]. The source of these wastes is very wide. The leakage of the VOCs from chemical and pharmaceutical manufacturing, printing processes, paint and adhesive manufacturing and applications, composites and fiberglass molding etc. is the source of the pollutants. A number of adsorbents are capable of capturing a wide range of VOCs. However, the conventional process of regenerating …     

Clean and fast oxidative transformation of thiols to disulfides under solvent-free conditions

We present here a fast, solvent-free synthesis of symmetrical disulfides using solid supported catalyst (Al₂O₃/KF). The reaction was performed at room temperature, by gentle heating or under MW irradiation. This efficient and improved method is general for liquid thiols, affording the disulfides in good to excellent yields. The catalytic system can be re-used two times without previous treatment and with comparable activity.     

An Acid‐Catalyzed Fragmentation Reaction of a Triamine‐Linked Acridine Dimer

An acid‐catalyzed cleavage of the C‐N^? bond from N^?‐(2,3,4,5‐tetrahydroxyvaleryl) substituted side chain and/or its acetonide form of a triamine‐linked acridine dimer is de scribed. An envisaged multi‐neighboring group‐assisted solvolysis reaction mechanism is proposed.     

Erlenmeyer azlactone synthesis with aliphatic aldehydes under solvent-free microwave conditions

2-Phenyl-5(4H)-oxazolone (azlactone) reacts with aliphatic aldehydes upon adsorption on neutral alumina and irradiation with microwaves (<2 min). The corresponding condensation products are obtained in good yields (62-78%), indicating the satisfactory resolution of a long-standing problem plaguing the classical Erlenmeyer synthesis (poor results with aliphatic aldehydes). Plausible mechanistic reasons for the success of the procedure are discussed.     

Synthesis of C-C bonded dimeric steroids by olefin metathesis

Five new C-C bonded steroidal homodimers derived from deoxycholic acid, pregnenolone, and progesterone were synthesized by an olefin metathesis reaction assisted by microwave heating. Microwave improved the yield and accelerated the reaction allowing the use of less catalyst with good results (2.5 mol %). Due to the bulky nature of the steroidal skeleton the more favorable E-dimers were formed as the sole or major products depending on the linker length.     

Microwave Assisted Synthesis of Sodium Sulfonates Precursors of Sulfonyl Chlorides and Fluorides

We describe the use of a microwave reaction for the conversion of various bromides to sodium sulfonates that have been further elaborated to sulfonyl chlorides. This new approach leads to much improved yields and shorter reaction times. Representative sulfonyl chlorides serve as precursors for the respective sulfonyl fluorides that are potent inhibitors of the fatty acid amide hydrolase.     

Novel magneto-oscillatory behavior of confined electrons at a twin boundary in ZnSe and at an interface in GaAs/AlGaAs heterostructures

Electronic properties of confined electrons at naturally formed twin boundaries in ZeSe have been investigated by microwave absorption measurements. Cyclotron resonance signal of the confined electrons was observed. On the cyclotron resonance peak, novel oscillation of the absorption intensity was observed. Similar oscillatory behavior was also observed in GaAs/AlGaAs heterostructures near cyclotron resonance filed at which new Shubnikov–de Haas-like oscillation was observed by Zudov. The oscillatory structure has a period not in inverse magnetic field but magnetic field. The origin of the oscillation observed is caused by Rayleigh interference of two-dimensional electron gas.     

The Newman-Kwart rearrangement re-evaluated by microwave synthesis

The Newman-Kwart rearrangement (NKR) has been re-evaluated by microwave heating. Microwave technology has proven to be ideal for investigating this high temperature rearrangement and facilitated the confirmation of many aspects of this valuable reaction. Comparisons between thermal and microwave results indicate no evidence of a significant microwave effect.     

Amplitude and phase of light scattered by micro-scale aggregates of dielectric spheres: Comparison between theory and microwave analogy experiments

Light scattering is a useful diagnostic tool for characterization of particles. Direct scattering measurements for arbitrarily shaped micro-scale particles is difficult due to small-scale limitations. Microwave analogy is a convenient approach to realize such measurements as it enables realization of analogous experiments with larger model particles in a spectral domain where wavelengths are on centimeter scale. In the present study a test model analogous to light scattering by a micro-scale aggregate of dielectric spheres was constructed and experimentally characterized in the microwave regime. Measured amplitude and phase of the scattered field were compared with theoretical predictions obtained from quasi-exact multiple-scattering T-matrix method and discrete dipole approximation (DDA). Excellent agreement demonstrates the validities of both the experiment and the models.