Free radical reaction model for n-pentane pyrolysis

A mathematical mechanism of the n-pentane pyrolysis process based on free radical reaction model was presented.The kinetic parameters of n-pentane pyrolysis are obtained by quantum chemistry and the reaction network is established. The solution of the stiff ordinary differential equations in the n-pentane pyrolysis model is completed by semi implicit Eular algorithm. Then the pyrolysis mechanism based on free radical reaction model is built,and the computational efficiency increases 10 times by algorithm optimization. The validity of this model and its solution method is confirmed by the experimental results of n-pentane pyrolysis.

Liver Nuclear Activation of Carbon Tetrachloride or Bromotrichloromethane to Trichloromethyl and Trichloromethylperoxyl Free Radicals.Their Reactions With Lipids and Proteins

The formation of·CCl3 radicals in liver nuclei was suggested by spin trapping of them with N-t-butyl-α-phenylnitrone followed by GC/MS detection of the resulting adduct. Comparison of its formation in microsomal biotransformation of CCl4 was made. In aerobic nuclear activation mixtures containing NADPH and CCl4, significant decrease in the arachidonic acid content of nuclear lipids was observed (27. 8%, compared to control), the intensity of this decrease was lower than that occurring in the corresponding microsomal incubation mixtures (29.1%). Significant decreases in arachidonic acid content of nuclear and endoplasmic reticulum lipids were also observed in animals at 6 hours of poisoning with the haloalkane. During aerobic nuclear metabolism of CCl4 or CBrCl3, cholesterol oxidation products were detected: a ketocholesterol, an epoxide like structure and 7-ketocholesterol. Nuclear protein carbonyl formation was not promoted during nuclear CCl4 biotransformation. NADPH by itself may lead to protein carbonyl formation during prolonged periods of incubation. CBrCl3 in contrast, led to decreased protein carbonyl formation. No increase in nuclear protein carbonyl formation was observed in CCl4 intoxicated animals during periods of time between 1 to 6 hours after treatment. The results indicate that during nuclear biotransformation of CCl4 or CBrCl3 reactive free radicals, PUFA degradation, reactive aldehydes and cholesterol oxidation products are formed, nearby DNA and regulatory proteins.

Theoretical insights of the pharmaceutical compound fluoxetine in water:Role in direct photolysis and indirect photolysis by free radicals

The frequent detection of pharmaceutical compounds in the environment has led to a growing awareness,which may pose a major threat to the aquatic environment.In this study,photodegradation(direct and indirect photolysis)of two different dissociation states of fluoxetine(FLU)was investigated in water,mainly including the determination of photolytic transition states and products,and the mechanisms of indirect photodegradation with·OH,CO_(3)^(*-)and NO_(3)^(*).The main direct photolysis pathways are defluorination and C–C bond cleavage.In addition,the indirect photodegradation of FLU in water is mainly through the reactions with·OH and NO_(3)^(*),and the photodegradation reaction with CO_(3)^(*-)is relatively difficult to occur in the water environment.Our results provide a theoretical basis for understanding the phototransformation process of FLU in the water environment and assessing its potential risk.

Theoretical Study on the Reaction Mechanism of F_2+2HBr = 2HF+Br_2

The gas phase reaction mechanism of F2 ＋ 2HBr = 2HF ＋ Br2 has been investigated by （U）MP2 at 6-311G＊＊ level, and a series of four-center and three-center transition states have been obtained. The reaction mechanism was achieved by comparing the activation energy of seven reaction paths, i.e. the dissociation energy of F2 is less than the activation energy of the bimolecular elementary reaction F2 ＋ HBr → HF ＋ BrF. Thus it is theoretically proved that the title reaction occurs more easily in the free radical reaction with three medium steps.

Polyaniline-supported tungsten-catalyzed oxidative deoximation reaction with high catalyst turnover number

Polyaniline-supported tungsten(W@PANI)was easily prepared by immersing polyaniline(PANI)in the aqueous solution of Na2WO4.It was found to be an efficient catalyst for oxidative deoximation reaction,the very important transformation for pharmaceutical industry.Besides the green features,the method employed very few of catalytic tungsten(0.048 mol%vs.oxime substrates),resulting in the high turnover numbers(TONs)of the catalyst(ca.103 mol/mol)and the low metal residues in product(<0.1 ppm).The reaction is applicable for a variety of substrates,including those containing heterocycles,which are key intermediates in medicine synthesis.It has also been successfully magnified to kilogram scale production to afford the desired carbonyl products smoothly.

硅氢加成反应与研究

本文指出硅氢反应加成的反应机理,加成方式及产物的重要用途。

Frequency Effects on 2-Chlorobiphenyl Sonication

In order to better understand sonication, this paper studies the effect of sound frequency on the 2-chlorobiphenyl (2-CB) sonication and analyzes two prevailing hypotheses. Four frequencies 205, 358, 618, and 1071 kHz were tested. The 2-CB degradation kinetics, dechlorination, and inhibition by a free radical scavenger were examined. The results show that sonication effectively degrades 2-CB, and the first order rate constants using 0.4 W/cm3 sonication are 0.214, 0.508, 0.454, and 0.248 min1 at 205, 358, 618, and 1071 kHz, respectively. Good dechlorination was also achieved. 358 kHz frequency provided the most effi-cient 2-CB degradation, but the worst dechlorination, and was most sensitive to the free radical scavenger. Detailed analyses show that thermolysis is relatively stable at these frequencies while the free radical reac-tion depends strongly on the sound frequency.