The phenylselenyl radical and its reaction with molecular oxygen

2017 ◽  
Vol 19 (40) ◽  
pp. 27384-27388 ◽  
Author(s):  
Artur Mardyukov ◽  
Yetsedaw A. Tsegaw ◽  
Wolfram Sander ◽  
Peter R. Schreiner
Keyword(s):  
Molecular Oxygen ◽  
Noble Gas ◽  
Oxidation Products ◽  
First Time ◽  
Primary Oxidation

The phenylselenyl radical and its primary oxidation products phenylselenyl peroxy and phenylselenoyl radicals were generated and subsequently isolated in solid noble gas matrices for the first time.

Spectroscopic identification of the phenyltelluryl radical and its reactivity toward molecular oxygen

2019 ◽  
Vol 21 (46) ◽  
pp. 25797-25801
Author(s):  
Felix Keul ◽  
Artur Mardyukov ◽  
Peter R. Schreiner
Keyword(s):  
Molecular Oxygen ◽  
Noble Gas ◽  
Oxidation Products ◽  
Spectroscopic Identification ◽  
First Time ◽  
Primary Oxidation

Phenyltelluryl radical and its primary oxidation products phenyltelluro peroxy and phenyl telluroyl radicals were generated and characterized spectroscopically in solid noble gas matrices for the first time.

scholarly journals Novel Photoinduced Squalene Cyclic Peroxide Identified, Detected, and Quantified in Human Skin Surface Lipids

Antioxidants ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1760
Author(s):  
Saoussane Khalifa ◽  
Masaru Enomoto ◽  
Shunji Kato ◽  
Kiyotaka Nakagawa
Keyword(s):  
Molecular Oxygen ◽  
Skin Surface ◽  
Oxidation Products ◽  
Human Organism ◽  
Isolation And Purification ◽  
Surface Lipids ◽  
Skin Abnormalities ◽  
Skin Surface Lipids ◽  
First Time ◽  
Cyclic Peroxide

Skin surface lipids (SSLs) form the first barrier that protects the human organism from external stressors, disruption of the homeostasis of SSLs can result in severe skin abnormalities. One of the main causes of this disruption is oxidative stress that is primarily due to SSLs oxidation. Squalene (SQ), the most abundant lipid among SSLs, was shown to first undergo singlet molecular oxygen (1O2) oxidation to yield 6 SQ-monohydroperoxide (SQ-OOH) isomers as the primary oxidation products. However, due to the instability and lability of hydroperoxides, we found that when total SQ-OOH isomers are further photooxidized, they form a unique higher molecular weight secondary oxidation product. To generate the compound, we photooxidized total SQ-OOH isomers in the presence of ground state molecular oxygen (3O2), after its isolation and purification, we studied its structure using MS/MS, NMR, derivatization reactions, and chemical calculations. The compound was identified as 2-OOH-3-(1,2-dioxane)-SQ. Photooxidation of individual SQ-OOH isomers revealed that 6-OOH-SQ is the precursor of 2-OOH-3-(1,2-dioxane)-SQ and indicated the possibility of the formation of similar cyclic peroxides from each isomer following the same photoinduced chain reaction mechanism. An HPLC-MS/MS method was developed for the analysis of 2-OOH-3-(1,2-dioxane)-SQ and its presence on the skin was confirmed in SSLs of six healthy individuals. Its quantity on the skin correlated directly to that of SQ and was not inversely proportional to its precursor, indicating the possibility of its accumulation on the skin surface and the constant regeneration of 6-OOH-SQ from SQ’s oxidation. In general, research on lipid cyclic peroxides in the human organism is very limited, and especially on the skin. This study shows for the first time the identification and presence of a novel SQ cyclic peroxide “2-OOH-3-(1,2-dioxane)-SQ” in SSLs, shedding light on the importance of further studying its effect and role on the skin.

scholarly journals Groundwater N<sub>2</sub>O emission factors of nitrate-contaminated aquifers as derived from denitrification progress and N<sub>2</sub>O accumulation

2008 ◽  
Vol 5 (5) ◽  
pp. 1215-1226 ◽  
Author(s):  
D. Weymann ◽  
R. Well ◽  
H. Flessa ◽  
C. von der Heide ◽  
M. Deurer ◽  
...  
Keyword(s):  
Emission Factor ◽  
Noble Gas ◽  
N2o Emission ◽  
Emission Factors ◽  
N2o Emissions ◽  
Northern Germany ◽  
Stable Component ◽  
Sand And Gravel ◽  
First Time ◽  
Ipcc Default

Abstract. We investigated the dynamics of denitrification and nitrous oxide (N2O) accumulation in 4 nitrate (NO−3) contaminated denitrifying sand and gravel aquifers of northern Germany (Fuhrberg, Sulingen, Thülsfelde and Göttingen) to quantify their potential N2O emission and to evaluate existing concepts of N2O emission factors. Excess N2 – N2 produced by denitrification – was determined by using the argon (Ar) concentration in groundwater as a natural inert tracer, assuming that this noble gas functions as a stable component and does not change during denitrification. Furthermore, initial NO−3 concentrations (NO−3 that enters the groundwater) were derived from excess N2 and actual NO−3 concentrations in groundwater in order to determine potential indirect N2O emissions as a function of the N input. Median concentrations of N2O and excess N2 ranged from 3 to 89 μg N L−1 and from 3 to 10 mg N L−1, respectively. Reaction progress (RP) of denitrification was determined as the ratio between products (N2O-N + excess N2) and starting material (initial NO−3 concentration) of the process, characterizing the different stages of denitrification. N2O concentrations were lowest at RP close to 0 and RP close to 1 but relatively high at a RP between 0.2 and 0.6. For the first time, we report groundwater N2O emission factors consisting of the ratio between N2O-N and initial NO−3-N concentrations (EF1). In addition, we determined a groundwater emission factor (EF2) using a previous concept consisting of the ratio between N2O-N and actual NO−3-N concentrations. Depending on RP, EF(1) resulted in smaller values compared to EF(2), demonstrating (i) the relevance of NO−3 consumption and consequently (ii) the need to take initial NO−3-N concentrations into account. In general, both evaluated emission factors were highly variable within and among the aquifers. The site medians ranged between 0.00043–0.00438 for EF(1) and 0.00092–0.01801 for EF(2), respectively. For the aquifers of Fuhrberg and Sulingen, we found EF(1) median values which are close to the 2006 IPCC default value of 0.0025. In contrast, we determined significant lower EF values for the aquifers of Thülsfelde and Göttingen. Summing the results up, our study supports the substantial downward revision of the IPCC default EF5-g from 0.015 (1997) to 0.0025 (2006).

Kinetic study on the linalool ozonolysis reaction in the atmosphere

2012 ◽  
Vol 90 (4) ◽  
pp. 353-361 ◽  
Author(s):  
Xiaomin Sun ◽  
Chenxi Zhang ◽  
Yuyang Zhao ◽  
Jing Bai ◽  
Maoxia He
Keyword(s):  
Rate Constants ◽  
Transition State Theory ◽  
State Theory ◽  
Oxidation Products ◽  
Tunneling Effect ◽  
Total Rate ◽  
Variational Transition State Theory ◽  
Atmospheric Lifetime ◽  
Ozone Addition ◽  
First Time

In the atmosphere, linalool ozonolysis will generate a series of oxidation products and then form particles through nucleation. In this study, the linalool ozonolysis mechanisms were studied and some of the main products detected from experiment are verified. The Rice–Ramsperger–Kassel–Marcus (RRKM) theory and the canonical variational transition state theory (CVT) with small curvature tunneling effect (SCT) are used to calculate rate constants over the temperature range of 200∼800 K. The total rate constant for the reaction of ozone with linalool is 4.50 × 10−16 cm3 molecule–l s–l, and the addition of ozone to (CH3)2C=CH– is the main ozone addition position. Furthermore, the Arrhenius formulas are fitted and the lifetimes of reaction species in the troposphere are discussed for the first time. The total atmospheric lifetime of linalool relative to O3 is 2.30 h. The O3-initiated atmospheric lifetimes of P1, P3, and P6 are 2.64 months, 16.67 days, and 15.5 h, respectively.

The Course of Enzymatically Induced Lipid Peroxidation in Homogenized Porcine Kidney Tissue

1998 ◽  
Vol 53 (5-6) ◽  
pp. 431-438 ◽  
Author(s):  
Uwe Kießling ◽  
Gerhard Spiteller
Keyword(s):  
Lipid Peroxidation ◽  
Octadecadienoic Acid ◽  
Tissue Injury ◽  
Kidney Tissue ◽  
Oxidation Products ◽  
Mammalian Tissue ◽  
Porcine Kidney ◽  
Octadecanoic Acid ◽  
Biological Environment ◽  
Primary Oxidation

Homogenization of mammalian tissue - exemplified by porcine kidney - causes enzymatically induced lipid peroxidation (LPO) processes proven by measuring the amounts of the typical lipid peroxidation products 9- and 13-hydroxy-octadecadienoic acid (HODE) either after homogenization in aqueous (activation of enzymes) or an organic (inactivated enzymes) solvent. A kinetic study revealed that the level of the 9- and 13-isomer reached maximum values 6 hours after tissue injury. Within one day the amount of these primary oxidation products was reduced fast, indicating that they undergo degradation in their biological environment. In contrast, the level of 10-hydroxy-octadecanoic acid - obviously derived from LPO of oleic acid - increased continuously even after one day. These observations reflect that the generation and degradation of hydroperoxides occurs at different rates which might be of interest in pathological processes connected with tissue injury, e.g. myocardial infarction.

scholarly journals Oxidation of Alkylaromatics

2007 ◽  
Vol 4 (1) ◽  
pp. 1-13 ◽  
Author(s):  
T. S. S. Rao ◽  
Shubhra Awasthi
Keyword(s):  
Transition Metal ◽  
Benzoic Acid ◽  
Oxidation Product ◽  
Alkali Metals ◽  
Oxidation Products ◽  
Metal Salts ◽  
Acid Oxidation ◽  
Transition Metal Salts ◽  
Strong Acids ◽  
Primary Oxidation

Hydroperoxide atα-position to the aromatic ring is the primary oxidation product formed. In all cases monoalkylbenzenes lead to the formation of benzoic acid. Oxidation in the presence of transition metal salts not only accelerate but also selectively decompose the hydroperoxides. Alkyl naphthalenes mainly produce the corresponding naphthalene carboxylic acids. Hock-rearrangement by the influence of strong acids converts the hydroperoxides to hemiacetals. Peresters formed from the hydroperoxides undergo Criegee rearrangement easily. Alkali metals accelerate the oxidation while CO2as co-oxidant enhances the selectivity. Microwave conditions give improved yields of the oxidation products.

Comparative study of microbiological, chemical and sensory properties of kefirs produced in Estonia, Latvia and Lithuania

2016 ◽  
Vol 83 (1) ◽  
pp. 89-95 ◽  
Author(s):  
Dea Anton ◽  
Piret Raudsepp ◽  
Mati Roasto ◽  
Kadrin Meremäe ◽  
Sirje Kuusik ◽  
...  
Keyword(s):  
High Performance ◽  
Ion Trap ◽  
Chemical Properties ◽  
Principal Component ◽  
Bacterial Count ◽  
Starter Cultures ◽  
Oxidation Products ◽  
Total Bacterial Count ◽  
Codex Standard ◽  
Primary Oxidation

In the current study the microbiological, sensory and chemical properties of 24 kefirs (12 producers) from Estonian, Latvian and Lithuanian retail market were determined using gas chromatography (GC), high performance liquid chromatography (HPLC-MS/MS-Q-TOF and LC-ion trap MS/MS), spectrophotometry and other methods. Antihypertensive, angiotensin-converting enzyme (ACE) inhibiting, antioxidant and antibacterial peptides were found in the kefir samples. According to the results of principal component analysis of 200 most abundant compounds obtained with HPLC-MS/MS-Q-TOF analysis, Estonian kefirs differed from the rest. Kefirs of Latvian and Lithuanian origin showed similarities in several characteristics, probably related to the starter cultures and technological processes. The fatty acids composition of all Baltic kefirs was uniform. The antioxidant capacity of the kefirs varied slightly, whereas intermediate positive correlation (r= 0·32,P< 0·05) was found between antioxidativity and total bacterial count. The lipid oxidation level, estimated as the content of linoleic and oleic acid primary oxidation products, oxylipins, was very low in all studied kefirs. Only one third of analysed kefirs met the requirements of the minimum sum of viable microorganisms, indicated in the Codex Standard for Fermented Milks.

scholarly journals Time-Resolved Infrared Spectroscopy in Supercritical Fluids

1999 ◽  
Vol 19 (1-4) ◽  
pp. 133-139 ◽  
Author(s):  
Michael W. George ◽  
Martyn Poliakoff ◽  
Xue-Zhong Sun ◽  
David C. Grills
Keyword(s):  
Infrared Spectroscopy ◽  
Supercritical Fluids ◽  
Room Temperature ◽  
Noble Gas ◽  
Fast Time ◽  
Metal Carbonyls ◽  
Time Resolved ◽  
Organometallic Reactions ◽  
Time Resolved Infrared Spectroscopy ◽  
First Time

We have used fast Time-resolved Infrared Spectroscopy (TRIR) to probe organometallic reactions in supercritical fluids on the nanosecond time-scale. This has allowed us to identify, for the first time in solution at room temperature, organometallic noble gas complexes which are formed following irradiation of metal carbonyls in supercritical noble gas solution. We have found that these complexes are surprisingly stable and have comparable reactivity to organometallic alkane complexes. We have also studied the coordination of CO2 to metal centres in supercritical CO2 (scCO2) and provide the first evidence for the formation and reactivity of ɳ1-O bound metal CO2 complexes in solution at or above room temperature.

Determination of stigmasterol primary oxidation products by high-performance liquid chromatography

2003 ◽  
Vol 80 (3) ◽  
pp. 415-421 ◽  
Author(s):  
Suvi Säynäjoki ◽  
Susanna Sundberg ◽  
Laura Soupas ◽  
Anna-Maija Lampi ◽  
Vieno Piironen
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
High Performance ◽  
Oxidation Products ◽  
Primary Oxidation
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