The zwitterionic intermediate created from the reaction between dichlorocarbene and acetylenic esters is trapped by aromatic aldehydes to afford poly functionalized furans in fairly good yields...

Nano-Ag as a green heterogeneous catalyst was utilized for the synthesis of furans by the three-component reaction of phenylglyoxal, dimethyl acetylenedicarboxylate, and primary amines. The best results were obtained in the presence of 4 mol% of nano-Ag in CH2Cl2 at room temperature. The nanocatalyst was characterized by UV-VIS, FT-IR, XRD, SEM and EDS. Ag nanostructures were prepared using extract of Echium amoenum. Some of the substantial features of this method include experimental simplicity, wide range of products, excellent yields in short reaction times, reusability of the catalyst, and low catalyst loading.

Monitoring and evaluation of transformers are essential to prevent their insulation failure. In this paper, the use of 2-furan-carboxaldehyde (2-FAL) and methanol (MeOH) concentrations as the main products of paper insulation degradation, and insulation condition markers, has been studied. In order to study the degradation process and production of degradation products, the thermal aging process of the transformer insulation system was implemented in laboratory conditions. The results of laboratory studies show that in the early stages of degradation the amount of MeOH is significant compared to 2-FAL. Also, the estimation of the degree of polymerization (DP) in the early stages of degradation (DP>800) through MeOH concentration and with decreasing DP (DP <800) through 2-FAL concentration is closer to the real value. The results of studies performed on 35 distribution transformers confirm the production of significant amounts of MeOH in the early stages of degradation. Also, the estimated DP values for the studied transformers were obtained through 2-FAL and MeOH concentration. The results show that estimating the amount of DP through MeOH concentration is associated with a probability of error of about 9% compared to estimating DP through 2-FAL concentration.

A study on polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (dl-PCBs) was conducted in a pooled sample of breast milk from 27 first-time mothers (primiparous) living in twelve locations at mesoregion industrial area, southern of Rio de Janeiro, Brazil, between August 2012 and July 2014. Questionnaires with questions regarding to food habits, social and economic conditions, places of dwelling were applied. Mothers were breast-feeding only one infant and milk was collected between 4 and 6 weeks after delivery. TEQs of PCDDs/Fs, and dl-PCBs were 10.6, 4.77, 6.96 TEQ pg/g, respectively. The understanding and identification of pollution sources may be helpful for taking better counter measures against breast milk dioxin contamination. It’s important for pregnant women to have a diet free as possible of contaminants chemical. Further research must be undertaken in the context of epidemiological investigations to more accurately assess the effects of these compounds.

Background and Objective: Dioxins and Furans are dangerous and highly toxic compounds entering to the environment from natural and manmade sources. Having high stability and half-life, these compounds remain for a long period in the medium and bring about severe effects on human beings and the environment. The aim of this study was to identify dioxins and furans emission sources in Iran and to estimate their contribution in emission rate.Materials and Methods: First, we identified the emission sources of dioxins and furans and then necessary data was gathered by referring to the authorized organizations and filling the prepared UNEP questionnaires. We used Excel software to analyze the data collected.Results: According to the results obtained, total dioxins and furan emission in Iran in 2010, was 1957 g TEQ/yr; out of this amount, 705.8 g TEQ is emitted to the atmosphere and 643.2 g TEQ is residual ash. Therefore, dioxins and furans emission rate was 26.4 mg TEQ/capita in Iran. The most rates of emissions were associated with uncontrolled open burning (732.8 g TEQ/yr) and ferrous and nonferrous metal production (635.7 g TEQ/yr) such as cupper, iron, and steel.Conclusion: Our findings showed that the emission rate of Dioxins and Furans is much higher in Iran compared with other countries and appropriate management strategies are required to control these dangerous pollutants.

Herein, we critically present theoretical modeling of toxic molecular compounds from biomass pyrolysis using the density functional theory formalism at the B3LYP level of theory coupled to 3-21G basis set. Detailed molecular modeling – geometry optimization, global hardness, and chemical potentials of the selected phenols and furans are reported. The thermal energy changes and reactivity are estimated from Gaussian’09 and Chemissian computational platforms. The formation of phenol and cresols are attributed to the thermally induced fragmentation of tyrosine via the rapture of the C-C bond (β-fission) which occurs via an endethermicity of +231.58 kJ/mol. The decarboxylation of tyrosine proceeds exothermally following an energy release of -14.36 kJ/mol. Subsequently, furans were formed from radical recombination during the thermal fragmentation of monomeric cellulose and tyrosine. The mechanistic formation of toxic molecular species from the thermal degradation of representative biomass materials has been proposed. From the global hardness data, it was noted that p-cresol was more reactive compared to phenol whereas alkylated benzofurans were more reactive than benzofuran because of their lower HOMO-LUMO energy gaps.