Alkaloids of the Australian Rutaceae: Lunasia quercifolia. II. The Nature of Lunasine

1959 ◽  
Vol 12 (3) ◽  
pp. 458 ◽  
Author(s):  
JR Price
Keyword(s):  
Oxygen Atom ◽  
Methyl Iodide ◽  
Principal Component ◽  
Alkyl Halides ◽  
Water Soluble ◽  
Methyl Group

The principal component of the mixture of water-soluble alkaloids of Lunasia quercifolia is shown to be the quaternary 4-methoxy-1-methylquinolinium structure IV corresponding to the 1-methyl-4-quinolone alkaloid lunacrine. The formation of IV from lunacrine and methyl iodide involves addition of the methyl group to the quinolone oxygen atom. It is suggested that this, as with the γ-pyrones, is the usual mode of reaction of 4-quinolone with alkyl halides. The properties of 4-methoxyquinolinium salts are discussed in relation to the conversion of furoquinoline alkaloids to the iso-alkaloids.

scholarly journals Size-Segregated Atmospheric Humic-Like Substances (HULIS) in Shanghai: Abundance, Seasonal Variation, and Source Identification

Atmosphere ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 526
Author(s):  
Tianming Sun ◽  
Rui Li ◽  
Ya Meng ◽  
Yu Han ◽  
Hanyun Cheng ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Size Distribution ◽  
Principal Component ◽  
Water Soluble ◽  
Atmospheric Particulate Matter ◽  
Biomass Combustion ◽  
Vehicle Exhaust ◽  
Total Suspended Particulates ◽  
Condensation Mode ◽  
Water Soluble Organic Carbon

Humic-like substances (HULIS) are of great interest due to their optical and chemical characteristics. In this study, a total of 180 samples of atmospheric particulate matter (PM) of different sizes were collected from summer 2018 to spring 2019, in order to analyze the size distribution, to investigate the seasonal variation and then to identify the key sources of HULIS. The annual mean concentration of HULIS in the total suspended particulates reached 5.12 ± 1.42 μg/m3. The HULIS concentration was extremely higher in winter (8.35 ± 2.06 μg/m3) than in autumn (4.88 ± 0.95 μg/m3), in summer (3.62 ± 1.68 μg/m3) and in spring (3.36 ± 0.99 μg/m3). The average annual ratio of water-soluble organic carbon (WSOC) to OC and the ratio of HULIS to WSOC reached 0.546 ± 0.092 and 0.56 ± 0.06, respectively. Throughout the whole year, the size distributions of WSOC and HULIS-C were relatively smooth. The peaks of WSOC appeared at 1.8~3.2 μm and 0.56~1.0 μm, while the peaks of HULIS-C were located at 3.2~5.6 μm, 1.0~1.8 μm and 0.18~0.32 μm. The distribution of the HULIS particle mode was similar in spring, summer and autumn, while there was a lower proportion of the coarse mode and a higher proportion of the condensation mode in winter. By using the comprehensive analysis of principal component analysis (PCA), air mass backward trajectories (AMBTs) and fire point maps, key sources of WSOC and HULIS in Shanghai were identified as biomass combustion (48.42%), coal combustion (17.49%), secondary formation (16.07%) and vehicle exhaust (5.37%). The remaining part might be contributed by crustal dust sources, marine sources and/or other possible sources. This study provides new insight into the characteristics and size distribution of HULIS in Shanghai, thereby providing a practical base for further modeling.

scholarly journals Characterization of Ambient Particulate Matters in an Industry-Intensive Area in Central Taiwan

Atmosphere ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 926
Author(s):  
Hsing-Wang Li ◽  
Kang-Shin Chen ◽  
Chia-Hsiang Lai ◽  
Ting-Yu Chen ◽  
Yi-Ching Lin ◽  
...  
Keyword(s):  
Principal Component Analysis ◽  
Principal Component ◽  
Component Analysis ◽  
Water Soluble ◽  
High Tech ◽  
Particulate Matters ◽  
Metallic Elements ◽  
Soluble Ions ◽  
Water Soluble Ions ◽  
Central Taiwan

Atmospheric particulate matters (PMs) were measured in an industry-intensive region in central Taiwan in order to investigate the characteristics and possible sources of PMs. The samplings were simultaneously conducted using a 10- and 3-stage Micro Orifice Uniform Deposit Impactor (MOUDI) from 2017 to 2018. In this study, the characteristics of PMs in this region were evaluated by measuring the mass concentration of PMs and analyzing water-soluble ions and metallic elements, as well as dioxins. Additionally, principal component analysis (PCA) was used to identify the potential sources of PMs. The results showed that the mean concentration of coarse (>1.8 μm), fine (0.1–1.8 μm), and ultrafine (<0.1 μm) particles were 13.60, 14.38, and 3.44 μg/m3, respectively. In the industry-intensive region, the size distribution of ambient particles showed a bi-modal distribution with a high concentration of coarse particles in the spring and summer, while fine particles were dominant in the autumn and winter. The most abundant water-soluble ions of PMs were NO3−, Cl−, and SO42−, while the majority of metallic elements were Na, Fe, Ca, Al, and Mg in different particle sizes. The results of Pearson’s correlation analysis for metals indicated that the particles in the collected air samples were related to the iron and steelmaking industries, coal burning, vehicle exhausts, and high-tech industries. The dioxin concentration ranged from 0.0006 to 0.0017 pg I-TEQ/Nm3. Principal component analysis (PCA) revealed that the contribution to PMs was associated with sea salt, secondary pollutants, and industrial process.

Methanogenesis from Acetate by Methanosarcina barkeri: Catalysis of Acetate Formation from Methyl Iodide, CO2 , and H2 by the Enzyme System Involved

1987 ◽  
Vol 42 (4) ◽  
pp. 360-372 ◽  
Author(s):  
Kerstin Laufer ◽  
Bernhard Eikmanns ◽  
Ursula Frimmer ◽  
Rudolf K. Thauer
Keyword(s):  
Methyl Iodide ◽  
Condensation Reaction ◽  
Methyl Chloride ◽  
Methanosarcina Barkeri ◽  
Carboxyl Group ◽  
Atpase Inhibitor ◽  
Methyl Group ◽  
Proton Potential ◽  
Acetate Formation ◽  
Reducing Equivalents

Cell suspensions of Methanosarcina barkeri grown on acetate catalyze the formation of methane and CO2 from acetate as well as an isotopic exchange between the carboxyl group of acetate and CO2. Here we report that these cells also mediate the synthesis of acetate from methyl iodide, CO2, and reducing equivalents (H2 or CO), the methyl group of acetate being derived from methyl iodide and the carboxyl group from CO2. Methyl chloride and methyltosylate but not methanol can substitute for methyl iodide in this reaction. Acetate formation from methyl iodide, CO2, and reducing equivalents is coupled with the phosphorylation of ADP. Evidence is pres­ented that methyl iodide is incorporated into the methyl group of acetate via a methyl corrinoid intermediate (deduced from inhibition experiments with propyl iodide) and that CO2 is assimi­lated into the carboxyl group via a C1 intermediate which does not exchange with free formate or free CO. The effects of protonophores, of the proton-translocating ATPase inhibitor N.N′-di- cyclohexylcarbodiimide, and of arsenate on acetate formation are interpreted to indicate that the reduction of CO2 to the oxidation level of the carboxyl group of acetate requires the presence of an electrochemical proton potential and that acetyl-CoA or acetyl-phosphate rather than free acetate is the immediate product of the condensation reaction. These results are discussed with respect to the mechanism of methanogenesis from acetate.

Application of Laser-Excited Raman Spectroscopy to Organic Chemistry. II. Conformers of Some Isochromans

1970 ◽  
Vol 24 (1) ◽  
pp. 42-43 ◽  
Author(s):  
Stanley K. Freeman
Keyword(s):  
Organic Chemistry ◽  
Raman Spectroscopy ◽  
Oxygen Atom ◽  
Aromatic Ring ◽  
Raman Spectra ◽  
Liquid State ◽  
Methyl Group ◽  
Methyl Analog

Raman spectra of 4-methyl isochroman and its aromatic ring substituted derivatives indicate the presence of two conformers in the liquid state and only one in the solid, while the 1- and 3-methyl analog assume one conformation only in both states. The presence of a methyl group adjacent to the ring oxygen atom sterically prevents adoption of one of the two possible conformations due to 1,3-interaction. No such restriction is imposed on the 4-methyl compounds.

Ambident Heterocyclic Reactivity: Alkylation of 4-Substituted and 2,4-Disubstituted Benzimidazoles

1994 ◽  
Vol 47 (8) ◽  
pp. 1523 ◽  
Author(s):  
MR Haque ◽  
M Rasmussen
Keyword(s):  
Hydrogen Bonding ◽  
Transition State ◽  
Electrostatic Field ◽  
Transition States ◽  
Alkyl Halides ◽  
Methyl Group ◽  
Site Selectivity ◽  
Leaving Group ◽  
Standard Set ◽  
Specific Association

The N1/N3-alkylation patterns of 4-amino-, 4-methyl- and 4-nitro-benzimidazole anions, and their 2-methyl analogues, with a standard set of primary alkyl halides (in dimethylformamide, 30°) have been determined and compared. The observed regioselectivities are dominated by proximal effects-electrostatic field, non-bonded steric and in some cases specific association (hydrogen bonding)-the interplay of which is critically dependent on the (variable) geometries of the SN2 transition states involved, in particular on the N---C distance of the developing N-alkyl bonds. The presence of a symmetrically placed 2-methyl group produces an enhanced N1/N3 site selectivity, very sensitive to the loose-tight nature of the transition state. Halide leaving group effects on butylation regioselectivities of 2-unsubstituted, 2-ethoxy-, 2-methyl- and 2-chloro-4-methylbenzimidazole anions, whilst small, are consistent with a Bell-Evans-Polanyi analysis of SN2 transition state variations, with the earlier transition states of CH3(CH2)3I leading to reduced regioselectivities.

Binding of alkyl halides in water-soluble cavitands with urea rims

2018 ◽  
Vol 42 (12) ◽  
pp. 9945-9948 ◽  
Author(s):  
Yang Yu ◽  
Yong-Sheng Li ◽  
Julius Rebek
Keyword(s):  
Alkyl Halide ◽  
Alkyl Halides ◽  
Water Soluble

Alkyl halide guests in cavitands move rapidly and maintain halide to contact with the aryl surfaces of the host.

scholarly journals DSC, FTIR and Raman Spectroscopy Coupled with Multivariate Analysis in a Study of Co-Crystals of Pharmaceutical Interest

Molecules ◽  
2018 ◽  
Vol 23 (9) ◽  
pp. 2136 ◽  
Author(s):  
Patrycja Garbacz ◽  
Marek Wesolowski
Keyword(s):  
Principal Component ◽  
Water Soluble ◽  
Crystal Formation ◽  
Multivariate Statistical ◽  
Molar Ratios ◽  
Pharmaceutical Ingredients ◽  
Multivariate Statistical Approach ◽  
And Cluster Analysis ◽  
Dsc Curves ◽  
Physical Mixtures

Co-crystals have garnered increasing interest in recent years as a beneficial approach to improving the solubility of poorly water soluble active pharmaceutical ingredients (APIs). However, their preparation is a challenge that requires a simple approach towards co-crystal detection. The objective of this work was, therefore, to verify to what extent a multivariate statistical approach such as principal component analysis (PCA) and cluster analysis (CA) can be used as a supporting tool for detecting co-crystal formation. As model samples, physical mixtures and co-crystals of indomethacin with saccharin and furosemide with p-aminobenzoic acid were prepared at API/co-former molar ratios 1:1, 2:1 and 1:2. Data acquired from DSC curves and FTIR and Raman spectroscopies were used for CA and PCA calculations. The results obtained revealed that the application of physical mixtures as reference samples allows a deeper insight into co-crystallization than is possible with the use of API and co-former or API and co-former with physical mixtures. Thus, multivariate matrix for PCA and CA calculations consisting of physical mixtures and potential co-crystals could be considered as the most profitable and reliable way to reflect changes in samples after co-crystallization. Moreover, complementary interpretation of results obtained using DSC, FTIR and Raman techniques is most beneficial.

scholarly journals Observation and Source Apportionment of Trace Gases, Water-Soluble Ions and Carbonaceous Aerosol During a Haze Episode in Wuhan

Atmosphere ◽  
2019 ◽  
Vol 10 (7) ◽  
pp. 397 ◽  
Author(s):  
Zhengxu Gao ◽  
Xiaoling Wang ◽  
Lijuan Shen ◽  
Hua Xiang ◽  
Honglei Wang
Keyword(s):  
Organic Carbon ◽  
Air Pollutants ◽  
Principal Component ◽  
Water Soluble ◽  
Vehicle Exhaust ◽  
Soluble Ions ◽  
Secondary Formation ◽  
Water Soluble Ions ◽  
Haze Episode ◽  
Haze Days

As the new core region of the haze pollution, the terrain effect of sub-basin and water networks over the Twin-Hu Basin (THB) in the Yangtze River Middle-Reach (YRMR) had great impacts on the variations and distributions of air pollutants. In this study, trace gases (NH3, HNO3, and HCl), water-soluble ions (WSIs), organic carbon (OC), and elemental carbon (EC) were measured in PM2.5 from 9 January to 27 January 2018, in Wuhan using monitoring for aerosols and gases (MARGA) and a semi-continuous OC/EC analyzer (Model RT-4). The characteristics of air pollutants during a haze episode were discussed, and the PM2.5 sources were quantitatively analyzed on haze and non-haze days using the principal component analysis/absolute principal component scores (PCA/APCS) model. The average PM2.5 concentration was 122.61 μg·m−3 on haze days, which was 2.20 times greater than it was on non-haze days. The concentrations of secondary water soluble ions (WSIs) including NO3−, SO42−, and NH4+ increased sharply on haze days, which accounted for 91.61% of the total WSIs and were 2.43 times larger than the values on non-haze days. The heterogeneous oxidation reactions of NO2 and SO2 during haze episodes were proven to be the major sources of sulfate and nitrate in PM2.5. On haze days, the concentrations of EC, primary organic carbon (POC), and secondary organic carbon (SOC) were 1.68, 1.69, and 1.34 times larger than those on non-haze days, the CO, HNO3, and NH3 concentrations enhanced and relatively low SO2, O3, and HNO2 levels were observed on haze days. The diurnal variations of different pollutants distinctly varied on haze days. The PM2.5 in Wuhan primarily originated from the secondary formation, combustion, dust, industry, and vehicle exhaust sources. The source contributions of the secondary formation + combustion sources to PM2.5 on haze days were 2.79 times larger than the level on non-haze days. The contribution of the vehicle exhaust + combustion source on haze days were 0.59 times the value on non-haze days. This description is supported by a summary of how pollutant concentrations and patterns vary in the THB compared to the variations in other pollution regions in China, which have been more completely described.

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