Estimation of Molecular Linear Free Energy Relationship Descriptors by a Group Contribution Approach. 2. Prediction of Partition Coefficients

2000 ◽  
Vol 40 (1) ◽  
pp. 71-80 ◽  
Author(s):  
James A. Platts ◽  
Michael H. Abraham ◽  
Darko Butina ◽  
Anne Hersey
Keyword(s):  
Free Energy ◽  
Partition Coefficients ◽  
Group Contribution ◽  
Linear Free Energy Relationship ◽  
Linear Free Energy

Correlation of Human and Animal Air-to-Blood Partition Coefficients With a Single Linear Free Energy Relationship Model

2008 ◽  
Vol 27 (9) ◽  
pp. 1130-1139 ◽  
Author(s):  
Laura M. Sprunger ◽  
Jennifer Gibbs ◽  
William E. Acree ◽  
Michael H. Abraham
Keyword(s):  
Free Energy ◽  
Partition Coefficients ◽  
Linear Free Energy Relationship ◽  
Linear Free Energy ◽  
Relationship Model

Correlation and estimation of gas–chloroform and water–chloroform partition coefficients by a linear free energy relationship method

1999 ◽  
Vol 88 (7) ◽  
pp. 670-679 ◽  
Author(s):  
Michael H. Abraham ◽  
James A. Platts ◽  
Anne Hersey ◽  
Albert J. Leo ◽  
Robert W. Taft
Keyword(s):  
Free Energy ◽  
Partition Coefficients ◽  
Linear Free Energy Relationship ◽  
Linear Free Energy

Development of polyparameter linear free energy relationship models for octanol–air partition coefficients of diverse chemicals

2017 ◽  
Vol 19 (3) ◽  
pp. 300-306 ◽  
Author(s):  
Xiaochen Jin ◽  
Zhiqiang Fu ◽  
Xuehua Li ◽  
Jingwen Chen
Keyword(s):  
Free Energy ◽  
Partition Coefficients ◽  
Linear Free Energy Relationship ◽  
Linear Free Energy ◽  
Different Temperatures

This study develops pp-LFER models to predict octanol–air partition coefficients at different temperatures for diverse chemicals.

scholarly journals Applicability Domain of Polyparameter Linear Free Energy Relationship Models for Predicting Equilibrium Partition Coefficients

2022 ◽  
Author(s):  
Satoshi Endo
Keyword(s):  
Free Energy ◽  
Partition Coefficients ◽  
Training Data ◽  
Applicability Domain ◽  
Linear Free Energy Relationship ◽  
Prediction Errors ◽  
Calibration Data ◽  
Data Set ◽  
Linear Free Energy ◽  
Equilibrium Partition

Polyparameter linear free energy relationships (PP-LFERs) are accurate and robust models to predict equilibrium partition coefficients (K) of organic chemicals. The accuracy of predictions by a PP-LEFR depends on the composition of the respective calibration data set. It is generally expected that extrapolation outside the model calibration domain is less accurate than interpolation. In this study, the applicability domain (AD) of PP-LFERs is systematically evaluated by calculation of the leverage (h), a measure of distance from the calibration set in the descriptor space. Repeated simulations with experimental data show that the root mean squared error of predictions increases with h, and that large prediction errors (>3 SDtraining, the standard deviation of training data) occur more frequently when h exceeds the common threshold of 3 hmean, where hmean is the mean h of all training compounds. Nevetheless, analysis also shows that well-calibrated PP-LFERs with many (e.g., 100), diverse, and accurate training data are highly robust against extrapolation; extreme prediction errors (> 5 SDtraining) are rare. For such PP-LFERs, 3 hmean may be too strict as the cutoff for AD. Evaluation of published PP-LFERs in terms of their AD using 25 chemically diverse, environmentally relevant chemicals as AD probes indicated that many reported PP-LFERs do not cover organosiloxanes, per- and polyfluorinated alkylsubstances, highly polar chemicals, and/or highly hydrophobic chemicals in their AD. It is concluded that calculation of h is useful to identify model extrapolations as well as the strengths and weaknesses of the trained PP-LFERs.

A general linear free energy relationship for predicting partition coefficients of neutral organic compounds

Chemosphere ◽  
2020 ◽  
Vol 247 ◽  
pp. 125869
Author(s):  
Deliang Chen ◽  
Qingyun Wang ◽  
Yibao Li ◽  
Yongdong Li ◽  
Hui Zhou ◽  
...  
Keyword(s):  
Free Energy ◽  
Organic Compounds ◽  
Partition Coefficients ◽  
General Linear ◽  
Linear Free Energy Relationship ◽  
Linear Free Energy ◽  
Neutral Organic Compounds

Linear free-energy relationship between partition coefficients and the aqueous solubility of organic liquids

1968 ◽  
Vol 33 (1) ◽  
pp. 347-350 ◽  
Author(s):  
Corwin Hansch ◽  
John E. Quinlan ◽  
Gary L. Lawrence
Keyword(s):  
Free Energy ◽  
Partition Coefficients ◽  
Aqueous Solubility ◽  
Organic Liquids ◽  
Linear Free Energy Relationship ◽  
Linear Free Energy

Linear Free Energy Relationship Analysis of Solvent Effects on Singlet Oxygen Reactions

2003 ◽  
Vol 7 (9) ◽  
pp. 799-819 ◽  
Author(s):  
Else Lemp ◽  
Antonio Zanocco ◽  
Eduardo Lissi
Keyword(s):  
Free Energy ◽  
Singlet Oxygen ◽  
Solvent Effects ◽  
Linear Free Energy Relationship ◽  
Relationship Analysis ◽  
Linear Free Energy

Synthesis and characterization of a series of 1-methyl-4-[2-aryl-1-diazenyl]piperazines and a series of ethyl 4-[2-aryl-1-diazenyl]-1-piperazinecarboxylates

2004 ◽  
Vol 82 (8) ◽  
pp. 1294-1303 ◽  
Author(s):  
Vanessa Renée Little ◽  
Keith Vaughan
Keyword(s):  
Free Energy ◽  
Chemical Shifts ◽  
Linear Free Energy Relationship ◽  
Piperazine Ring ◽  
Linear Free Energy ◽  
In Series ◽  
Methylene Groups ◽  
Diazonium Coupling ◽  
The Difference

1-Methylpiperazine was coupled with a series of diazonium salts to afford the 1-methyl-4-[2-aryl-1-diazenyl]piperazines (2), a new series of triazenes, which have been characterized by 1H and 13C NMR spectroscopy, IR spectroscopy, and elemental analysis. Assignment of the chemical shifts to specific protons and carbons in the piperazine ring was facilitated by comparison with the chemical shifts in the model compounds piperazine and 1-methylpiperazine and by a HETCOR experiment with the p-tolyl derivative (2i). A DEPT experiment with 1-methylpiperazine (6) was necessary to distinguish the methyl and methylene groups in 6, and a HETCOR spectrum of 6 enabled the correlation of proton and carbon chemical shifts. Line broadening of the signals from the ring methylene protons is attributed to restricted rotation around the N2-N3 bond of the triazene moiety in 2. The second series of triazenes, the ethyl 4-[2-phenyl-1-diazenyl]-1-piperazinecarboxylates (3), have been prepared by similar diazonium coupling to ethyl 1-piperazinecarboxylate and were similarly characterized. The chemical shifts of the piperazine ring protons are much closer together in series 3 than in series 2, resulting in distortion of the multiplets for these methylenes. It was noticed that the difference between these chemical shifts in 3 exhibited a linear free energy relationship with the Hammett substituent constants for the substituents in the aryl ring. Key words: triazene, piperazine, diazonium coupling, NMR, HETCOR, linear free energy relationship.

Absorption Spectra of Substituted 2-Phenylindan-1,3-Dion-2-YL Radicals in Solution

1983 ◽  
Vol 38 (12) ◽  
pp. 1337-1341
Author(s):  
J. Zechner ◽  
N. Getoff ◽  
I. Timtcheva ◽  
F. Fratev ◽  
St. Minchef
Keyword(s):  
Free Energy ◽  
Absorption Spectra ◽  
Flash Photolysis ◽  
Bathochromic Shift ◽  
Substitution Effects ◽  
Linear Free Energy Relationship ◽  
Linear Free Energy

Abstract Flash photolysis of a series of 2-phenylindandione-1,3 derivatives substituted in the 4′ position results in both the formation of stable benzylidenephthalides and of phenylindan-1,3-dion-2-yl radicals. The u. v. absorption maxima of these radicals are dependent on the solvent and show a bathochromic shift upon substitution. These substitution effects were correlated by means of a linear free energy relationship. Attempts were made to draw conclusions concerning the changes in the gap of the states involved and their curvature due to substitution.

Kinetics and linear free energy relationship of wittig reaction between substituted benzaldehydes and substituted benzylidenetriphenylphosphorane

Tetrahedron ◽  
1986 ◽  
Vol 42 (15) ◽  
pp. 4161-4167 ◽  
Author(s):  
Li Donxia ◽  
Wu Dexian ◽  
Li Yaozhong ◽  
Zhao Huaming
Keyword(s):  
Free Energy ◽  
Wittig Reaction ◽  
Linear Free Energy Relationship ◽  
Linear Free Energy ◽  
Substituted Benzaldehydes ◽  
Relationship Of
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