Cover image for Computational approaches for the prediction of pKa values
Title:
Computational approaches for the prediction of pKa values
Series:
QSAR in environmental and health sciences ; 4
Publication Information:
Boca Raton : CRC Press, 2014.
Physical Description:
xix, 155 p. : ill. ; 24 cm.
ISBN:
9781466508781
Abstract:
"The book describes how one can calculate the acidities and basicities of chemicals (pKa is the dissociation constant). Many drugs, industrial chemicals, biochemicals and pollutants dissociate to form new species under different conditions. The nature of the species present has a profound effect on how the species act, and it is important to be able to estimate which species will be present under different conditions. No other book summarizes how one can estimate the natures of the species present using modern theoretical methods. This book fills that need"-- Provided by publisher.
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30000010328077 QD477 S54 2014 Open Access Book Book
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Summary

Summary

The pKa of a compound describes its acidity or basicity and, therefore, is one of its most important properties. Its value determines what form of the compound--positive ion, negative ion, or neutral species--will be present under different circumstances. This is crucial to the action and detection of the compound as a drug, pollutant, or other active chemical agent. In many cases it is desirable to predict pKa values prior to synthesizing a compound, and enough is now known about the salient features that influence a molecule's acidity to make these predictions.

Computational Approaches for the Prediction of pKa Values describes the insights that have been gained on the intrinsic and extrinsic features that influence a molecule's acidity and discusses the computational methods developed to estimate acidity from a compound's molecular structure. The authors examine the strengths and weaknesses of the theoretical techniques and show how they have been used to obtain information about the acidities of different classes of chemical compounds.

The book presents theoretical methods for both general and more specific applications, covering methods for various acids in aqueous solutions--including oxyacids and related compounds, nitrogen acids, inorganic acids, and excited-state acids--as well as acids in nonaqueous solvents. It also considers temperature effects, isotope effects, and other important factors that influence pKa. This book provides a resource for predicting pKa values and understanding the bases for these determinations, which can be helpful in designing better chemicals for future uses.


Author Notes

George Shields, Ph.D., is currently a professor of chemistry and dean of the College of Arts and Sciences at Bucknell University. His research uses computational chemistry to investigate atmospheric and biological chemistry.

Paul Seybold, Ph.D. , has been has been a faculty member and department chair (1999-2004) in the Department of Chemistry at Wright State University in Ohio and a visiting scholar and visiting professor at a number of universities in the United States and Europe. His research interests center on chemical and biochemical applications of quantum chemistry, molecular structure-activity relationships, luminescence spectroscopy, and cellular automata models of complex systems.


Table of Contents

Series Introductionp. ix
Forewordp. xi
Acknowledgmentsp. xiii
About the Authorsp. xvii
Prefacep. xix
Chapter 1 Introductionp. 1
Chapter 2 Absolute pK a Calculationsp. 3
2.1 Thermodynamic Cyclesp. 3
2.1.1 Limiting Experimental Valuesp. 6
2.2 Gas Phase Gibbs Free Energy Calculationsp. 10
2.3 Solvation Gibbs Free Energy Calculationsp. 12
2.4 Pitfalls and Lessons from the Literaturep. 21
2.5 Concluding Remarks on Absolute pK a Calculationsp. 24
Chapter 3 Relative pK a Calculationsp. 27
Chapter 4 Quantitative Structure-Acidity Methodsp. 31
4.1 Basic Principles of the QSAR Approachp. 31
4.2 Hammett and Taft Constantsp. 35
4.3 The Search for Useful Quantum Chemical Descriptorsp. 37
4.4 Alternative Approachesp. 41
4.5 Free and Commercial Programsp. 41
Chapter 5 Oxyacids and Related Compoundsp. 43
5.1 Alcohols, Phenols, and Carboxylic Acidsp. 43
5.2 Phosphonic Acidsp. 50
5.3 Hydroxamic Acids and Oximesp. 52
5.4 Silanolsp. 53
5.5 Thiolsp. 54
Chapter 6 Nitrogen Acidsp. 57
6.1 Aliphatic Aminesp. 57
6.2 Anilinesp. 60
6.3 Azoles and Some Other Heterocyclicsp. 62
6.4 Amino Acidsp. 65
6.5 Pyridines and Related Heterocyclicsp. 68
6.6 Purines and Pyrimidinesp. 69
Chapter 7 Additional Types of Acidsp. 73
7.1 Carbon Acidsp. 73
7.2 Inorganic Acidsp. 77
7.3 Polyprotic Acidsp. 81
7.4 Superacidsp. 84
7.5 Excited-State Acidsp. 86
Chapter 8 Acidities in Nonaqueous Solventsp. 89
8.1 Deuterium Oxidep. 89
8.2 Dimethyl Sulfoxidep. 92
8.3 Acetonitrilep. 94
8.4 Tetrahydrofuranp. 95
8.5 1,2-Dichloroethanep. 96
8.6 Other Solvents and Commentaryp. 96
Chapter 9 Additional Factors Influencing Acidity and Basicityp. 99
9.1 Thermodynamicsp. 99
9.2 Temperature Effects on Acidityp. 100
9.3 Steric Effects and Hydrogen Bondingp. 103
9.4 Isotope Effectsp. 104
Chapter 10 Conclusionsp. 107
Referencesp. 109
Indexp. 143