Addition of Di(trimethylsilyl) Phosphite to Schiff Bases of 2,5-Diformylfuran

A series of 2,5-Furanyl-bis-(aminomethylphosphonic Acids) has been synthesized by the addition of di(trimethylsilyl) phosphite to azomethine bond of achiral Schiff bases derved from 2,5-diformylfuran. The stereochemical aspect of this reaction has been studied and compared with the behaviour of achiral terephthalic Schiff bases in similar reaction. Whereas, addition to achiral terephthalic Schiff bases was found to be highly stereoselective, the analogous reaction with achiral 2,5-diformylfuran Schiff bases was stereoselective exclusively in the case when the substituent is benzyl.N/

THERMODYNAMIC ANALYSIS OF SYNTHESIS GAS AND HIGHER HYDROCARBONS PRODUCTION FROM METHANE

This chapter focused on thermodynamic chemical equilibrium analysis using method of direct minimization of Gibbs free energy for all possible methane reactions with oxygen (partial oxidation of methane), carbon dioxide (CO2 reforming of methane), steam (steam reforming of methane), and autothermal reforming. Effects of feed ratios (methane to oxygen, carbon dioxide, and/or steam feed ratio), reaction temperature, and system pressure on equilibrium composition, conversion, and yield were studied. In addition, operating regions of carbon and no carbon formation were also considered at various reaction temperatures and feed ratios in the equilibrium system. It was found that the reaction temperature above 1100 K and CH4/CO2 ratio unity were favorable for synthesis gas production for methane – carbon dioxide reaction. The Carbon Dioxide Oxidative Coupling of Methane reaction to produce ethane and ethylene is less favorable thermodynamically. In addition, steam reforming of methane is the most suitable for hydrogen production from methane with low coke formation from thermodynamic point of view

Superelastic and pH-Responsive Degradable Dendrimer Cryogels Prepared by Cryo-aza-Michael Addition Reaction

Dendrimers exhibit super atomistic features by virtue of their well-defined discrete quantized nanoscale structures. Here, we show that hyperbranched amine-terminated polyamidoamine (PAMAM) dendrimer G4.0 reacts with linear polyethylene glycol (PEG) diacrylate (575 g/mol) via the aza-Michael addition reaction at a subzero temperature (−20 °C), namely cryo-aza-Michael addition, to form a macroporous superelastic network, i.e., dendrimer cryogel. Dendrimer cryogels exhibit biologically relevant Young’s modulus, high compression elasticity and super resilience at ambient temperature. Furthermore, the dendrimer cryogels exhibit excellent rebound performance and do not show significant stress relaxation under cyclic deformation over a wide temperature range (−80 to 100 °C). The obtained dendrimer cryogels are stable at acidic pH but degrade quickly at physiological pH through self-triggered degradation. Taken together, dendrimer cryogels represent a new class of scaffolds with properties suitable for biomedical applications

Utilization of oxygen difluoride for syntheses of fluoropolymers

The reaction oxygen difluoride, OF2, with ethylenically unsaturated fluorocarbon compounds is examined. Depending upon the fluorocarbon material and reaction conditions, OF2 can chain extend fluoropolyenes, convert functional perfluorovinyl groups to acyl fluoride and/or epoxide groups, and act as a monomer for an addition type copolymerization with diolefins

Visible light-mediated gold-catalysed carbon(sp2)-carbon(sp) cross-coupling.

A dual photoredox and gold-catalysed cross-coupling reaction of alkynyltrimethylsilanes and aryldiazonium tetrafluoroborates is described. The reaction proceeds through visible-light mediated oxidative addition of aryldiazoniums, transmetalation of alkynyltrimethylsilanes and aryl-alkynyl reductive elimination. Exclusive selectivity for silyl-substituted alkynes is observed, with no reactivity observed for terminal alkynes

Effects of Fe2O3 addition on the nitridation of silicon powder

The reaction of silicon powder and nitrogen was studied in the range of 1300-1400 C. When an addition of Fe2O3 was more than 0.8wt%, the reaction was linear and compared to samples with no Fe2O3, the reaction velocity increased 5 to 10 times. The reactions were mediated by the process of peeling and cracking in a thin layer of Si2N4 formed on the silicon particles or on the surface of the Fe-Si melts. As the addition of Fe2O3 increased, the reaction activation energy for highly pure samples decreased. Fe2O3 which exceeded the Si3N4 solubility limits was finally converted to d-Fe

Reactivity of the Indenyl Radical (C9 H7 ) with Acetylene (C2 H2 ) and Vinylacetylene (C4 H4 ).

The reactions of the indenyl radicals with acetylene (C2 H2 ) and vinylacetylene (C4 H4 ) is studied in a hot chemical reactor coupled to synchrotron based vacuum ultraviolet ionization mass spectrometry. These experimental results are combined with theory to reveal that the resonantly stabilized and thermodynamically most stable 1-indenyl radical (C9 H7 . ) is always formed in the pyrolysis of 1-, 2-, 6-, and 7-bromoindenes at 1500 K. The 1-indenyl radical reacts with acetylene yielding 1-ethynylindene plus atomic hydrogen, rather than adding a second acetylene molecule and leading to ring closure and formation of fluorene as observed in other reaction mechanisms such as the hydrogen abstraction acetylene addition or hydrogen abstraction vinylacetylene addition pathways. While this reaction mechanism is analogous to the bimolecular reaction between the phenyl radical (C6 H5 . ) and acetylene forming phenylacetylene (C6 H5 CCH), the 1-indenyl+acetylene→1-ethynylindene+hydrogen reaction is highly endoergic (114 kJ mol-1 ) and slow, contrary to the exoergic (-38 kJ mol-1 ) and faster phenyl+acetylene→phenylacetylene+hydrogen reaction. In a similar manner, no ring closure leading to fluorene formation was observed in the reaction of 1-indenyl radical with vinylacetylene. These experimental results are explained through rate constant calculations based on theoretically derived potential energy surfaces