The experimental study of the oxidation of the three linear isomers of hexene was performed in a quartz isothermal jet-stirred reactor (JSR) at temperatures ranging from 500 to 1100 K including the negative temperature coefficient (NTC) zone, at quasi-atmospheric pressure (1.07 bar), at a residence time of 2 s and with dilute stoichiometric mixtures. The fuel and reaction product mole fractions were measured using online gas chromatography. In the case of 1-hexene, the JSR has also been coupled through a molecular-beam sampling system to a reflectron time-of-flight mass spectrometer combined with tunable synchrotron vacuum ultraviolet photoionization. A difference of reactivity between the three fuels, which varies with the temperature range has been observed and is discussed according to the changes in the possible reaction pathways when the double bond is displaced. An enhanced importance of the reactions via the Waddington mechanism and of those of allylic radicals with HO2 radicals can be noted for 2- and 3-hexenes compared to 1-hexene.
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http://dx.doi.org/10.1021/jp4107102 | DOI Listing |
Se Pu
February 2025
School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, China.
To evade legal controls, new psychoactive substances (NPS), which have been designed as substitutes for traditional and synthetic drugs, are gradually dominating the drug market. Synthetic cannabinoids (SCs), which account for the majority of NPS, are rapidly being derivatized; consequently, controlling increasing abuse by merely listing individual compounds is difficult. Therefore, China has included the entire SC category of SCs listed as legal controlled substances since July 1, 2021.
View Article and Find Full Text PDFAnal Chim Acta
February 2025
Department of Archaeology and Anthropology, School of Humanities, University of Chinese Academy of Sciences, 100049, Beijing, China. Electronic address:
Background: Pottery lipid residue analysis has been extensively practiced worldwide as an important part of archaeometry studies, but in some cases, the complexity of archaeological residue cannot be fully revealed by one-dimensional gas chromatography (1D GC) separation. Although the development of comprehensive two-dimensional gas chromatography (GCxGC) has offered another way to achieve better separation and higher resolution, GCxGC separation has rarely been applied to pottery residue analysis. Clearly, GCxGC separation needs to be explored to examine and scrutinize the complexity of pottery lipid residue profile as well as rapid data treatment workflow.
View Article and Find Full Text PDFAmino Acids
January 2025
Faculty of Natural Sciences, University of SS Cyril and Methodius, 91701, Trnava, Slovakia.
Four aliphatic amino acids-α-aminobutyric acid (AABA), β-aminobutyric acid (BABA), α-aminoisobutyric acid (AAIBA) and β-aminoisobutyric acid (BAIBA) were investigated in water as a solvent by two quantum chemical methods. B3LYP hybrid version of DFT was used for geometry optimization and a full vibrational analysis of neutral molecules, their cations and anions in the canonical and zwitterionic forms (6 forms for each species). Ab initio DLPNO-CCSD(T) method was applied in the geometry pre-optimized by B3LYP.
View Article and Find Full Text PDFJ Pharm Biomed Anal
January 2025
Key Laboratory of Forensic Medicine, Ministry of Justice, Shanghai Forensic Service Platform, Shanghai Key Laboratory of Forensic Science, Academy of Forensic Science, Guangfu West Road 1347, Shanghai 200063, China. Electronic address:
Etomidate and its structural analogues, which have anesthetic effects, are classified as controlled psychotropic drugs. Electronic cigarettes (e-cigarettes) have become more and more popular. With the increase of adding etomidate and its analogues to electronic liquids (e-liquids), there is a trend of abuse, which is a tough problem urgently need to be solved.
View Article and Find Full Text PDFJ Chromatogr Sci
January 2025
Nutrition and Bromatology Group, Department of Analytical Chemistry and Food Science, Faculty of Science, Universidade de Vigo, E-32004 Ourense, Spain.
An efficient reverse-phase high-performance liquid chromatographic method, based on the design of the experiment approach, was developed for the simultaneous determination of capsiate isomers. Critical method parameters, i.e.
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