296 research outputs found
Efficient Syntheses of Biobased Terephthalic Acid, p-Toluic Acid, and p-Methylacetophenone via One-Pot Catalytic Aerobic Oxidation of Monoterpene Derived Bio-p-cymene.
An efficient elevated-pressure catalytic oxidative process (2.5 mol % Co(NO3)2, 2.5 mol % MnBr2, air (30 bar), 125 °C, acetic acid, 6 h) has been developed to oxidize p-cymene into crystalline white terephthalic acid (TA) in ∼70% yield. Use of this mixed Co2+/Mn2+ catalytic system is key to obtaining high 70% yields of TA at relatively low reaction temperatures (125 °C) in short reaction times (6 h), which is likely to be due to the synergistic action of bromine and nitrate radicals in the oxidative process. Recycling studies have demonstrated that the mixed metal catalysts present in recovered mother liquors could be recycled three times in successive p-cymene oxidation reactions with no loss in catalytic activity or TA yield. Partial oxidation of p-cymene to give p-methylacetophenone (p-MA) in 55-60% yield can be achieved using a mixed CoBr2/Mn(OAc)2 catalytic system under 1 atm air for 24 h, while use of Co(NO3)2/MnBr2 under 1 atm O2 for 24 h gave p-toluic acid in 55-60% yield. Therefore, access to these simple catalytic aerobic conditions enables multiple biorenewable bulk terpene feedstocks (e.g., crude sulfate turpentine, turpentine, cineole, and limonene) to be converted into synthetically useful bio-p-MA, bio-p-toluic acid, and bio-TA (and hence bio-polyethylene terephthalate) as part of a terpene based biorefinery
Sustainable catalytic epoxidation of biorenewable terpene feedstocks using H<sub>2</sub>O<sub>2Â </sub>as an oxidant in flow microreactors
Fluorescence based Tool to Detect Endogenous Peroxynitrite in M1-Polarized Murine J774.2 Macrophages
Oxidative
stress and inflammation are intrinsically linked to each
other. In addition, they are implicated in the evolution and progression
of noncommunicable diseases (NCDs). Large amounts of reactive oxygen
species (ROS) are generated as part of the immune response toward
NCDs. Among all of the ROS species, peroxynitrite (ONOO<sup>–</sup>) has the shortest half-life with <20 ms under typical physiological
conditions. Hence, detecting ONOO<sup>–</sup> and studying
its generation in vitro allows for a better understanding of inflammatory
processes. We demonstrate that peroxyresorufin-1 (PR1) is a selective
and sensitive ONOO<sup>–</sup> fluorescence-based sensor in
J774.2 macrophages. PR1 was able to detect changes in ONOO<sup>–</sup> production upon investigation of different factors: enhanced generation
of ONOO<sup>–</sup> through LPS and IFN-γ as well as
diminished ONOO<sup>–</sup> production with the introduction
of superoxide scavengers and nitric oxide synthase inhibitors. Our
study validates PR1 as an effective tool for the detection of ONOO<sup>–</sup> in J774.2 murine macrophages and should allow for
further elucidation of ROS biology and chemistry
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