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Estimation of Melting Points of Organic Compounds

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Estimation of Melting Points of Organic Compounds Estimation of Melting Points of Organic Compounds Item Type text; Electronic Dissertation Authors Jain, Akash Publisher The University of Arizona. Rights Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. Download date 30/09/2021 11:41:43 Link to Item http://hdl.handle.net/10150/193516 ESTIMATION OF MELTING POINTS OF ORGANIC COMPOUNDS By Akash Jain Copyright © Akash Jain 2005 A Dissertation Submitted to the Faculty of the DEPARTMENT OF PHARMACEUTICAL SCIENCES In Partial Fulfillment of the Requirements For the Degree of DOCTORAL OF PHILOSOPHY In the Graduate College THE UNIVERSITY OF ARIZONA 2005 2 THE UNIVERSITY OF ARIZONA GRADUATE COLLEGE As members of the Dissertation Committee, we certify that we have read the dissertation prepared by Akash Jain entitled Estimation of Melting Points of Organic Compounds and recommend that it be accepted as fulfilling the dissertation requirement for the Degree of Doctor of Philosophy _______________________________________________________________________ Date: (10-17-05) Samuel H. Yalkowsky, Ph.D. _______________________________________________________________________ Date: (10-17-05) Michael Mayersohn, Ph.D. _______________________________________________________________________ Date: (10-17-05) Paul B. Myrdal, Ph.D. _______________________________________________________________________ Date: (10-17-05) Srini Raghavan, Ph.D. _______________________________________________________________________ Date: ( ) Final approval and acceptance of this dissertation is contingent upon the candidate’s submission of the final copies of the dissertation to the Graduate College. I hereby certify that I have read this dissertation prepared under my direction and recommend that it be accepted as fulfilling the dissertation requirement. ________________________________________________ Date: (10-17-05) Dissertation Director: Samuel H. Yalkowsky, Ph.D. 3 STATEMENT BY AUTHOR This dissertation has been submitted in partial fulfillment of requirements for an advanced degree at the University of Arizona and is deposited at the University Library to be made available to borrowers under rules of the Library. Brief quotations from this dissertation are allowable without special permission, provided that accurate acknowledgement of the source is made. Requests for permission for extended quotation from or reproduction of this manuscript in whole or in part may be granted by the copyright holder. AKASH JAIN 4 ACKNOWLEDGEMENTS I would like to express my gratitude to my advisor, Dr Samuel Yalkowsky, for providing me the opportunity and financial support to earn my doctoral degree in Pharmaceutical Sciences. I sincerely thank him for his continued guidance, encouragement and mentorship over the years I spent at the University of Arizona. I will cherish his scientific values, virtues and philosophies for life. I would like to thank my major committee members, Dr Michael Mayersohn and Dr Paul Myrdal, for their guidance and comments in not only preparing this dissertation but for my entire period of education at the University of Arizona. I would also like to express my gratitude to my minor committee members, Dr Srini Ragahvan and Dr Neal Armstrong, for dedicating their time to serve on my committee. I would like to thank my past and present colleagues at the University of Arizona for being there for me whenever I needed them. I will inherit all the good times we have had working together and I am pleased to have made some friends for life. I would like to thank my professors back in India, especially Dr T.R.Saini and Dr. S.C. Chaturvedi, for encouraging me to pursue a doctoral degree in Pharmaceutical Sciences. At last, I would like to thank my family: my parents and sister for their love and inspiration, my fiancée Bhumika for all her love and patience and her family for their care and support. 5 DEDICATION To my parents and Bhumika 6 TABLE OF CONTENTS LIST OF FIGURES……………………………………………………………………….9 LIST OF TABLES……………………………………………………………………….10 ABSTRACT……………………………………………………………………………...11 CHAPTER 1: INTRODUCTION………………………………………………………..12 CHAPTER 2: ENTHALPY OF MELTING……………………………………………..19 INTRODUCTION…………………………………………………………………….19 DATA…………………………………………………………………………………21 MODEL……………………………………………………………………………….22 Group Definition…………………………………………………………………....22 Group Environment………………………………………………………………....23 Proximity Factors…………………………………………………………………...24 METHODS……………………………………………………………………………26 RESULTS AND DISCUSSION………………………………………………………26 SUMMARY…………………………………………………………………………...36 CHAPTER 3: ENTROPY OF MELTING……………………………………………….38 INTRODUCTION…………………………………………………………………….38 DATA………………………………………………………………………………....40 METHODS……………………………..……………………………………………..40 Molecular Rotational Symmetry Number…………………………………………..40 Molecular Flexibility Number……………………………………………………...42 7 TABLE OF CONTENTS – Continued RESULTS AND DISCUSSION………………………………………………………44 SUMMARY….………………………………………………………………………..48 CHAPTER 4: MELTING POINTS………………………………………………………49 INTRODUCTION……………………………………………………………………..49 DATA………………………………………………………………………………… 52 METHODS………………………………………………………………………….... 52 RESULTS AND DISCUSSION……………………………………………………… 53 SUMMARY…………………………………………………………………………... 60 CHAPTER 5: COMPARISON OF TWO METHODS FOR PREDICTING MELTING POINTS…………………………………………………………………………………..61 INTRODUCTION……………………………………………………………………..61 DATA………………………………………………………………………………….61 METHODS………………………………………………………………………….....61 RESULTS AND DISCUSSION……………………………………………………… 63 SUMMARY…………………………………………………………………………... 66 APPENDIX A. Examples of predicting enthalpy of melting (KHm), entropy of melting (KSm) and melting point (Tm) using the developed model………………………………. 67 APPENDIX B. Experimental and predicted enthalpy of melting (KHm) for 1663 organic compounds……………………………………………………………………………….69 8 TABLE OF CONTENTS - Continued APPENDIX C. Rotational symmetry number (L), Flexibility count (Ф), experimental entropy of melting and predicted entropy of melting (KSm) for 1663 organic Compounds……………………………………………………………………………...101 APPENDIX D. Experimental and predicted Melting Points (Tm) for 2230 organic compounds………………………………………………………………………………135 REFERENCES………………………………………………………………………….178 9 LIST OF FIGURES Figure 1.1: UPPER (Unified Physical Property Estimation Relationships) Scheme…... .12 Figure 2.1(a): Sulfonylureas……………………………………………………………...23 Figure 2.1(b): Barbiturates………………………………………………………………. 23 Figure2.2: Molecular environment descriptors in the fragmentation scheme……………24 Figure2.3: Intramolecular hydrogen bonding patterns…………………………………... 25 Figure 2.4: The distribution of errors in predicting enthalpy of melting………………... 35 Figure 3.1: Symmetry numbers for several molecules………………………………….. 42 Figure 3.2: The distribution of errors in predicting entropy of melting………………….45 Figure 3.3: Error distribution as a function of the logarithm of the rotational symmetry number (L)…………………………………………………………………….46 Figure 3.4: Error distribution as a function of the logarithm of the molecular flexibility number (N)……………………………………………………………………. 46 Figure 4.1: Observed versus predicted melting points for 2230 organic compounds……53 Figure 4.2: Error distribution in melting point prediction using the proposed model…... 54 Figure 4.3: Predicted versus observed melting points for 152 drugs (including steroids) in the database………………............................................................56 Figure 4.4: Predicted versus observed melting points for 149 environmental compounds included in the database……………………………………………………..57 Figure 4.5: Proximity factors for intramolecular hydrogen bonding and geminal fluorine atoms in Dinitramine…………………………………………………………… 58 Figure 4.6: Experimental melting points of n-alkanes (C2-C190)……………………….59 Figure 5.1: Observed versus predicted melting points (using UPPER) for 2230 compounds……………………………………………………………………...63 Figure 5.2: Observed versus predicted melting points (using MPBPWIN) for 2230 compounds………………………………………………………………………………. 64 Figure 5.3: AAE in melting point prediction of symmetrical molecules using the two models…………………………………………………………………………... 65 Figure 5.4: AAE in melting point predictions of flexible molecules using the two models…………………………………………………………………………... 65 10 LIST OF TABLES Table 1.1: Experimental melting points (°C) of some homologous series……………….14 Table 1.2: Experimental melting points for some octanes………………………………. 15 Table 1.3: Experimental melting points for isomeric arenes……………………………. 15 Table 1.4: Experimental melting points (°C) for some disubstituted benzenes…………. 15 Table 2.1: A list of molecular fragments and proximity factors along with their enthalpy contribution values…………………………………………………………….. 27 Table 2.2: Frequency distribution of the average absolute errors in enthalpy of melting prediction……………………………………………………………………...... 36 Table 3.1: Examples of some molecular flexibility numbers…………………………….44 Table 3.2: Average absolute errors in entropy of melting prediction at different flexibility count (Ф)……………………………………………………………………... 47 Table 3.3: Frequency distribution of the average absolute errors in entropy of melting prediction……………………………………………………………………….. 47 Table 4.1: Average Absolute Errors in general melting point estimation methods……... 51 Table 4.2: Frequency distribution of the average absolute errors in melting point
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