Analysis of Substituent Effects in Naphthalene Skeleton

2004 ◽  
Vol 69 (12) ◽  
pp. 2297-2314
Author(s):  
Patrik Pařík ◽  
Miroslav Ludwig
Keyword(s):  
Dissociation Constants ◽  
Comprehensive Evaluation ◽  
Substituent Effects ◽  
Principal Component ◽  
Alternative Interpretation ◽  
Point Of View ◽  
Carboxylic Group ◽  
Resonance Effects ◽  
The Individual

The dissociation constants of 45 substituted 1- and 2-naphthoic acids in six organic solvents (methanol, ethanol, acetonitrile, dimethylformamide, dimethyl sulfoxide, pyridine) have been used to evaluate the substituent effects in the naphthalene skeleton. The dissociation constants data have been treated traditionally by using Dewar-Grisdale equation and the Taft DSP equation, and the alternative interpretation of substituent effects (AISE) method. Quantitative comparison of substituent effects and their transmission from different positions, combination of inductive and resonance effects from various positions, and effects of solvents are discussed. Best results are predominantly provided by the AISE. Substituent effects are stronger in the case of substituents affecting from ring of the naphthalene skeleton bearing carboxylic group than from ring not bearing carboxylic group, and there are no substantial differences between the individual positions of this ring. The contribution of resonance effects at 4α and 8β positions distinctly changes with the medium. Special quality of substituent H was found in comparison with other substituents presumably due their bulkier character. The principal component analysis (PCA) has been also applied to treat the mean dissociation constants using the single substituent property approach. The dissociation together with reactivity data for other naphthalene derivatives have been tested for comprehensive evaluation using PCA. There was found a large similarity of naphthalene reactivity data tested from the point of view of substituent effects.

Chemometric Analysis of Substituent Effects. VIII. Alternative Interpretation of Substituent Effects (AISE)

1995 ◽  
Vol 60 (9) ◽  
pp. 1502-1528 ◽  
Author(s):  
Oldřich Pytela
Keyword(s):  
Multiple Bond ◽  
Substituent Effects ◽  
Alternative Interpretation ◽  
Class I ◽  
Reaction Centre ◽  
Correlation Equations ◽  
Class Iii ◽  
Substituent Constant ◽  
Chemical Models ◽  
The Individual

Alternative interpretation of substituent effects (AISE) starts from the presumption that a substituent only possesses a single property described by a single substituent constant. This property is transmitted to the reaction centre by three different ways depending on the interaction type in the triad reaction centre - basic skeleton - substituent. For interpretation it is substantial whether or not the substituent has p electrons at the atom adjacent to the basic skeleton. If it has none, the substituent belongs to class I and operates only by its basic effect described by the mentioned single substituent constant. Substituents of class II possess a free electron pair at the atom adjacent to the basic skeleton, and those of class III have a multiple bond between the first and the second atoms which is polarized in the direction from the basic skeleton. Substituent effects in class I are described by a substituent constant identical with σI constant. Substituents in classes II and III show additional effects proportional to the same constant. Hence, a separate treatment of substituent effects in the individual classes provides three straight lines intersecting in a common point. Mathematically, the description of substituent effects in this approach is expressed by a family of lines with a single explaining variable. The point of intersection, which is referred to as the iso-effect point, is not identical with the classic standard substituent - hydrogen - but is near to CN substituent. The approach given has the advantage of adopting a single substituent constant whose scale can be adjusted relatively precisely. Its drawback (like in the case of the correlation equations derived from the principle of separation of substituent effects) lies in a more extensive set of substituents needed for a correlation. The AISE principle has been applied to 318 series of experimental data describing effects of 32 substituents in a large variety of chemical models (aliphatic, alicyclic, aromatic, heteroaromatic, with or without direct conjugation between reaction centre and substituent) in both chemical reactions and equilibria. A comparison with two other correlation relations with two and three substituent constants for interpretation of substituent effects based on the principle of separation of the individual substituent effects showed that the closeness of AISE based correlations is comparable with that of the correlation equations currently used. It was somewhat less successful in the models with direct conjugation between reaction centre and substituent but the AISE principle can be used even in these cases.

Effects of Medium and Substituents on Dissociationof 4,4'-Disubstituted Bis(benzenesulfon)imides

1996 ◽  
Vol 61 (8) ◽  
pp. 1205-1214 ◽  
Author(s):  
Miroslav Ludwig ◽  
Pavel Štverka
Keyword(s):  
Latent Variables ◽  
Dissociation Constants ◽  
Substituent Effects ◽  
Principal Component ◽  
H Nmr ◽  
Base Process ◽  
Elemental Analyses ◽  
Substituent Constants ◽  
Model Substances ◽  
Strong Acids

Ten 4,4'-disubstituted bis(arenesulfon)imides of the general formula XC6H4SO2NHSO2C6H4X have been synthesized and their structures confirmed by their 1H NMR spectra. Elemental analyses are presented for the compounds not yet described. The dissociation constants of these model substances have been measured potentiometrically in pyridine, dimethylformamide, methanol, ethanol, propylene carbonate, acetone, acetonitrile, 1,2-dichloroethane and tetramethylene sulfone. The pKHA values obtained have been correlated with three sets of the Hammett substituent constants and the results have been used to discuss the solvent and substituent effects on the dissociation of the compounds studied. Sulfonimides with electron-acceptor substituents behave as rather strong acids in some solvents (pyridine, dimethylformamide, methanol and ethanol), whereas normal substituent dependences are found in other solvents. The experimental data have also been interpreted with the help of the statistical methods based on latent variables. From the calculations it follows that only the first principal component, which correlates well with the substituent constant sets adopted, is statistically significant in describing the substituent effect on the acid-base process studied.

scholarly journals Research on Liquor Storage Based on Statistical Analysis Model

2021 ◽  
Vol 5 (3) ◽  
Author(s):  
Xuhua Xu
Keyword(s):  
Index System ◽  
Comprehensive Evaluation ◽  
Principal Component ◽  
Evaluation Index System ◽  
Classification Model ◽  
Analysis Model ◽  
The Index System ◽  
Storage Methods ◽  
Physical And Chemical

According to the physical and chemical indexes of different periods, different storage containers and different storage sites, a two overall T test was used to show that there were significant differences in physical and chemical indexes of liquor body in different detection sites. Correlation analysis of wine storage in different storage methods by Spearman correlation coefficient. By using the principal component analysis method, the comprehensive evaluation index system of the quality of the wine body was constructed, and the classification model of the detection location based on the comprehensive evaluation was established by using the index system. The detection sites were classified, and the results showed that the detection sites were divided into four grades.

scholarly journals Utilization of factor analysis in waterworks engineering

2004 ◽  
Vol 52 (2) ◽  
pp. 121-128
Author(s):  
Petra Nováková
Keyword(s):  
Water Quality ◽  
Factor Analysis ◽  
Quality Indicators ◽  
Water Reservoir ◽  
Statistical Processing ◽  
Point Of View ◽  
Water Quality Indicators ◽  
Quality Of Water ◽  
The Individual

The aim of the work was to elaborate and evaluate the water quality of water reservoir Vranov nad Dyjí. Fresh water was sampled in five different locations of the reservoir (three important tributaries, dam and water captation locality). Ten, the most essential water quality indicators were selected. From the point of view of water quality indicators complexity the most integrated samples were taken in the water captation locality (period 1984 – 2002). At other locations, there were missing dates from the eightieth, but their volume was sufficient for statistical processing.Correlation analyses for the individual locations and dimensions were done as so as determination coefficients for all localities during the time period of 1994 – 2002. The results demonstrate very good allocation of the water captation from the point of view of the water flow.Multiples and factor analysis was done for the period of 1984 – 2002 in the locality Jelení zátoka where the object of water captation is situated. The results of the analysis are nine factors, which influence the water quality of the reservoir. From the point of view of the importance three factors were interpreted.The analyses and results are part of my Ph.D. thesis. The results will be used for other evaluations of the water quality in the reservoir and tributaries, for activities in the catchment’s area and for proposal processing other zones of second level of protected areas.

Effect of Se Enrichment on Improving the Quality of Camellia Oil from Different Source Varieties

2020 ◽  
Vol 14 (5) ◽  
pp. 657-663
Author(s):  
Jie Liu ◽  
Lichao Wu ◽  
Yimin Tan
Keyword(s):  
Comprehensive Evaluation ◽  
Wide Spectrum ◽  
Biological Effects ◽  
Principal Component ◽  
Acid Value ◽  
Fertilizer Application ◽  
Tocopherol Content ◽  
Camellia Oil ◽  
Functional Components

Se-enriched camellia oil has received increasing attention because it can improve the Se intake of diet for Se deficiency areas and has a wide spectrum of biological effects. Six main cultivars of camellia oil in Guangxi, including Camellia oleifera cenxiruanzhi 2 (CR2), CR3, C. oleifera xianglin 4 (XL4), XL40, C. oleifera changlin 1 (CL1), and CL210, were selected for fertilization experiment to produce Se-enriched camellia oil and investigated the effect of Se enrichment on quality. The Se content in camellia oil of six varieties was significantly increased by Se fertilizer application. CR2 had the maximum Se content and raise ratio compared to CK, which was 0.87 mg kg−1 and fourfold, respectively. The Se contents in XL1, XL210, CR3, CL4, and CL40 improved by 2.14-, 2.77-, 3.58-, 2.56-, and 3.79-fold, respectively. Se fertilizer reduced the acid and peroxide values and increased the squalene and tocopherol contents. The acid value decreased by 38.29%–61.30%, the peroxide value decreased by 20.66%–61.79%, the tocopherol content increased by 7.76%–32.78%, and the squalene content increased by 13.53%–77.39%. The quality indices were significantly different among camellia oil varieties. Principal component analysis showed that CR2 obtained the highest score by comprehensive evaluation. Se fertilization, particularly for CR2 species, can significantly increase the contents of Se as well as functional components, such as squalene and tocopherol, and thus improve the quality of camellia oil

scholarly journals Evaluation of Two Parts of Lithocarpus polystachyus Rehd. from Different Chinese Areas by Multicomponent Content Determination and Pattern Recognition

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Min Wei ◽  
Yangling Tuo ◽  
Ye Zhang ◽  
Qi Deng ◽  
Cuiying Shi ◽  
...  
Keyword(s):  
Evaluation System ◽  
High Performance ◽  
Comprehensive Evaluation ◽  
Principal Component ◽  
Dry Weight ◽  
Quantification Analysis ◽  
Development And Utilization ◽  
Array Detection ◽  
Accurate Quantification

The purpose of this work is to establish a new method using high-performance liquid chromatography-diode array detection (HPLC-DAD) with chemometrics analysis to determine the content of catechin, isoquercetin, astragalin, phloridzin, trilobatin, and phloretin for one flavanol and five flavonoids, filter out the key compounds, and evaluate the quality of 26 batches of tender leaves and flower spikes of Lithocarpus polystachyus Rehd. (LP) from ten areas in China. The result showed that the HPLC-DAD method had excellent performance for accurate quantification analysis. S3 (tender leaf from Lushan, Sichuan) had the highest contents for six measured chemicals with trilobatin content of up to 27.82% in dry weight. S22 (flower spike from Liangping, Chongqing) had the highest content of phloridzin (up to 7.28%). All samples were divided into three types based on spatial distribution using principal component analysis. The result showed that the tender leaves and flower spikes from the same areas had many similar properties, and there were significant differences between the samples from different regions. Furthermore, phloridzin and trilobatin were identified as chemical markers for quality evaluation of two parts with different tender leaves and flower spikes of LP from geographical areas by orthogonal partial least squares discrimination analysis. These results will be helpful to establish an effective and comprehensive evaluation system of the development and utilization of LP resources.

A framework of characteristics identification and source apportionment of water pollution in a river: a case study in the Jinjiang River, China

2012 ◽  
Vol 65 (11) ◽  
pp. 2071-2078 ◽  
Author(s):  
Haiyang Chen ◽  
Yanguo Teng ◽  
Jinsheng Wang
Keyword(s):  
Water Pollution ◽  
Water Quality ◽  
Source Apportionment ◽  
Comprehensive Evaluation ◽  
Principal Component ◽  
Anthropogenic Pollution ◽  
Ammonia Nitrogen ◽  
Support Vector ◽  
Jinjiang River

A framework for characteristics identification and source apportionment of water pollution in the Jinjiang River of China was proposed in this study for evaluation. A total of 114 water samples which were generated between May 2009 and September 2010 at 13 sites were collected and analysed. First, support vector machine (SVM) and water quality pollutant index (WQPI) were used for water quality comprehensive evaluation and identifying characteristic contaminants. Later, factor analysis with nonnegative constraints (FA-NNC) was employed for source apportionment. Finally, multi-linear regression of the absolute principal component score (APCS/MLR) was applied to further estimate source contributions for each characteristic contaminant. The results indicated that the water quality of the Jinjiang River was mainly at the third level (65.79%) based on national surface water quality permissible standards in China. Ammonia nitrogen, total phosphorus, mercury, iron and manganese were identified as characteristic contaminants. Source apportionment results showed that industrial activities (63.16%), agricultural non-point source (16.50%) and domestic sewage (12.85%) were the main anthropogenic pollution sources which were influencing the water quality of Jinjiang River. This proposed method provided a helpful framework for conducting water pollution management in aquatic environment.

scholarly journals A New Strategy for Quality Evaluation and Identification of Representative Chemical Components in Polygonum multiflorum Thunb.

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Yun-xia Li ◽  
Xiao-hong Gong ◽  
Mei-chen Liu ◽  
Cheng Peng ◽  
Peng Li ◽  
...  
Keyword(s):  
Quality Evaluation ◽  
Comprehensive Evaluation ◽  
Principal Component ◽  
Chemical Compounds ◽  
Chemical Components ◽  
Health Food ◽  
Polygonum Multiflorum ◽  
New Strategy ◽  
Novel Method

Polygonum multiflorum Thunb. (HSW) is widely used as herb medicine and health food additive. Recently, a series of HSW-induced hepatotoxicities have been reported and many studies have been carried out to investigate it. But contradictory conclusions were drawn that might be caused by the inconsistent quality of market decoction pieces. Therefore, the HSW decoction pieces quality was evaluated with a developed novel method in the paper. 25 batches of raw HSW (RHSW) and 21 batches of processed HSW (PHSW) samples were purchased from different provinces of China. HPLC determination was performed to identify and detect the contents of 16 chemical compounds in herbal material. Fingerprint similarity was analyzed using chromatography information and the results showed that most herbs were in good similarity. Then, a comprehensive evaluation strategy based on principal component analysis with representative quality control indicators was developed to evaluate the quality of HSW samples. And the rationality of the developed method was verified by HCA analysis. The results showed that the herb from Dabashan, Sichuan Province, no matter RHSW or PHSW had the best quality. Different representative components were selected for RHSW or PHSW decoction pieces which might be caused by the chemical reaction during processing. And most PHSW were unqualified according to the requirement of Chinese Pharmacopeia which might take the responsibility for the toxicity of HSW.

A Study of Transmission Effects of Sulfonyl and Carbonyl Groups

1995 ◽  
Vol 60 (5) ◽  
pp. 841-850 ◽  
Author(s):  
Miroslav Ludwig ◽  
Patrik Pařík ◽  
Jiří Kulhánek
Keyword(s):  
Latent Variables ◽  
Dissociation Constants ◽  
Substituent Effects ◽  
Principal Component ◽  
Carbonyl Groups ◽  
H Nmr ◽  
Deviation Analysis ◽  
Substituent Constants ◽  
The Difference ◽  
Latent Structures

Seventeen p-substituted N-phenylsulfonylbenzamides of general formulas XC6H4SO2NHCOC6H5 and C6H5SO2NHCOC6H4X have been synthesized and their structure has been confirmed by elemental analysis and 1H NMR spectra. The dissociation constants of all the compounds have been measured by potentiometric titration in methanol, acetonitrile, dimethylformamide, dimethyl sulfoxide, and pyridine. The obtained pKHA values have been correlated with three sets of Hammett substituent constants using simple or double linear regression. The solvent and substituent effects are discussed on the basis of experimental results, and the difference between the substituent effects from sulfonamide and benzamide sections is evaluated. It has been found that due to the extensive delocalization of negative charge in the conjugated base the transmission effects of carbonyl and sulfonyl groups on the transmission of substituent effect are roughly the same. The experimental data have been interpreted by the methods with latent variables: the principal component analysis (PCA), the conjugated deviation analysis (CDA), and the method of projection to latent structures (PLS). The results obtained by these procedures were similar.

Separation of the Enthalpic and Entropic Contributions to Substituent Effects for the Equilibrium Constants of Aromatic Acids

1975 ◽  
Vol 53 (23) ◽  
pp. 3622-3633 ◽  
Author(s):  
T. M. Krygowski ◽  
W. R. Fawcett
Keyword(s):  
Substituent Effect ◽  
Equilibrium Constants ◽  
Substituent Effects ◽  
Point Of View ◽  
Aromatic Acids ◽  
Resonance Effects ◽  
Equation Analysis ◽  
Reaction Constant ◽  
Enthalpy And Entropy Changes ◽  
Substituent Constants

Separation of the substituent effect ρσ into entropie ρSσS and enthalpic ρHσH contributions is presented within the framework of the general Hammett equation. Analysis of the experimental data for aromatic acids shows that, in general, entropie effects are the major contribution to the total substituent effect, the entropic reaction constant being approximately equal to the normal Hammett ρ A comparison of the present results with those based on a separation of inductive and resonance effects shows that the entropie and inductive effects are directly related. On the other hand, strongly resonance interacting substituents were found to be enthalpy controlled. The substituent effect on enthalpy and entropy changes is discussed from a molecular point of view and related to inductive and resonance effects. A list of 16 enthalpic (σH) and entropie (σS) substituent constants are presented.

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