No abstract

-The compound R-(+)limonene is available and cheap than its oxidized products. Consequently, the selective oxidation of R(+)limonene has attracted attention as a promising process for the production of compounds with a higher market value, such as cis/trans-1,2-limoneneoxide, cis/trans-carveol and/or carvone. One of the these processes, described in the recent literature, is submission of R-(+)limonene to an oxidation reaction catalyzed by neutral or cationic Metal(Salen) complexes, in the presence of effective terminal oxidants such as NaOCl or PhIO. These reactions are commonly carried out in organic solvents (dichromethane, ethyl acetate, acetonitrile or acetone). Thus, the main objective of the present work was to study the effect of several factors (type of oxidant, catalyst, solvent and time) on reaction selectivity for the high-priced compounds referred to above. For this purposes, experimental statistical multivariate analysis was used in conjunction with a complete experimental design. From the results it was observed that for the three targeted products (1,2-limoneneoxide, carveol or carvone) some factors, including the nature of the terminal oxidant and the catalyst, were significant for product selectivity (with a confidence level of 95%). Therefore, this statistical analysis proved to be suitable for choosing of the best reaction conditions for a specific desired product.

AbstractsThe Mn(Salen)Cl and Ni(Salen)-catalyzed oxidation of limonene has been carried out. The catalytic cycle involved PhIO via a rebound mechanism. In all cases the use of organic solvents resulted in reasonable selectivities of oxidized products. The use of supercritical carbon dioxide (SCCO 2 ) led at least to comparable results in terms of conversions, but showed different selectivities. In ordinary solvents epoxidation appears to predominate over allylic oxidation. This tendency, in SCCO 2 , appears only after 4 h of reaction. Shorter reaction times (2 h) appear to lead to opposite selectivity. These results showed the advantages of using SCCO 2 as solvent in these reactions. SCCO 2 is much more compatible with green technology than are organic solvents.

Due to environmental and economic problems, we need to seek and investigate renewable energy sources. Worldwide, we have a predominant use of energy derived from fossil fuels. In Brazil, much of the energy comes from hydroelectricity. However, it is known that to be dependent predominantly from a main source, could cause logistical problems. A solution to this situation, in Brazil, are sugarcane plants. These plants are normally self-sufficient in terms of energy, but they can still have their energetic and exegetics efficiencies increased. This paper intends to present by simulation (using free software, COCO) that if all machines in the process, steam-powered, were replaced by machines powered by electricity, the yield should increase. We also show that if we replace the turbines by other, working in higher pressures, the energy will have an even greater increase.