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  • Open access
  • 81 Reads
Microwave-Assisted Oxidation of Alcohols Using Urea Hydrogen Peroxide
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The oxidations of some simple secondary alcohols by hydrogen peroxide urea adduct (UHP) using microwaves as an energy source is described. The reaction results in appropriate carbonyl compound. The observed higher yield and shortening of the reaction time was observed for microwave-assisted process comparing to the conventional conditions.
  • Open access
  • 49 Reads
On the Mechanism of Microwave Initiated Reactions
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Microwave irradiation becomes a widely used method to synthesize many useful organic chemicals rapidly, with good yields and high selectivity. A great many of relevant works suggest only thermal nature of the microwave action, that means that microwaves are considered to be a method to heat chemical reagents rapidly and without any overheating. Some other works describe specific non-thermal effects. And the effects are likely to exist. Sometimes the effects are thought to be only specific forms of heat effects, but not always. We have recently observed some of the effects in the microwave initiated polymerizations and oxidations when the microwave power was quite low [1-3]. Here we shall try to discuss briefly possibilities that can be useful to explain the microwave effects. The discussion suggests selection of theoretical ideas that will serve a basis for future theories of the microwave-initiated reactions.
  • Open access
  • 69 Reads
A Comparison of Microwave-Accelerated and Conventionally Heated Iodination Reactions of Some Arenes and Heteroarenes, Using Ortho-Periodic Acid as the Oxidant
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A fast and simple method for the oxidative iodination of some activated arenes and heteroarenes, either under microwave irradiation or by conventional heating, is reported, using diiodine and ortho-periodic acid as the oxidant. The reactions were carried out in hot 95% ethanol under a reflux condenser. For the microwave assisted reactions, the reaction times were always notably shortened, but the yields were nearly the same as those afforded by the conventional method.
  • Open access
  • 71 Reads
Microwave Assisted and Conventional Mono Aryl Substitution of Diazabicycloalkanes by Palladium Coupling
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The typical synthetic routes to the mono-aryl substituted piperazines are palladium catalyzed C-N coupling of piperazine or protected piperazines with aryl halides. In this work we describe the synthesis of aryl piperazines and aryl diazabicycles utilizing Pd catalyzed coupling reactions using protected and unprotected piperazines and diazobicycles performed both conventionally and by microwave assisted organic synthesis (MAOS).
  • Open access
  • 45 Reads
Simple and Convenient Reduction under Microwave Irradiation
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New method for reduction nitro and nitroso group attached to heterocyclic moiety was developed. The yields are high and the products are of high purity. Hydrazine hydrate as a reductive agent and microwave irradiation greatly facilitate the reaction.
  • Open access
  • 81 Reads
Calculations on Solvents and Co Solvents of Single-Wall Carbon Nanotubes: Cyclopyranoses
1-Octanol–, cyclohexane– and chloroform–water partition coefficients (Po, Pch and Pcf) allow calculating molecular lipophilicity patterns, which show that, for a given atom, normalized logPo–ch–cf are sensitive to the presence in the molecule of other atoms–groups, e.g., C70, where logPa–c atomic contributions are greater than logPd–e are. CDHI does not differentiate non-equivalent atoms. (10,10) Single-wall carbon nanotube (SWNT), the most favourite SWNT, presents consistency between a relatively small aqueous solubility and great Po–ch–cf. SWNT solubility is studied in various solvents, finding a class of non-hydrogen-bonding Lewis bases with good solubility. Solvents grouped in three classes. SWNTs in some organic solvents are positively charged, while in water–Triton X are negative.
  • Open access
  • 36 Reads
An Organometallic Selective Synthesis of Conjugated Polymers with Improved Physical Properties
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Conjugated polymers have attracted much interest in recent years due the many possibilities for their applications in opto-electronics and as non-linear optical materials. Synthetic efforts have been made, on the hand, to improve the properties of well-known oligomers and conjugated polymers and on the other, to prepare new polymers, containing original chain units, from a variety of unsaturated monomers. In this paper we present a selective synthesis of conjugated materials based on thiophene by oxidative polymerization of various silyl monomers. The high sensitivity of the silicon atom offers new synthetic route. As shown by GPC, IR, Raman and photoluminescence criteria, Silicon activates the selective coupling of unsaturated monomers, leading to highly conjugated polymers with improved properties for specific applications.
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