PHOTOCHEWIICAL RE ACTIONS OF CHLORO AROMATIC COMPOUNDS A Thesis Presented to The Faculty of Graduate Studies of The University of Guelph by ALEXANDRE KONSTANTINOV In partial fiilfillment of requirements for the degree of Doctor of Philosophy January, 1999 @ Alexandre Konstantinov, 1999 National Library Bibliothèque nationale du Canada Acquisitions and Acquisitions et Bibliographie Services services bibliographiques 395 Wellington Street 395. nie Wellington Ottawa ON KIA ON4 Ottawa ON K1A ON4 Canada Canada Your Ma Voue derence Our Ne Nom reterem The author has granted a non- L'auteur a accordé une licence non exclusive licence ailowing the exclusive permettant a la National Library of Canada to Bibliothèque nationale du Canada de reproduce, loan, distribute or sen reproduire, prêter, distribuer ou copies of this thesis in microfom, vendre des copies de cette thèse sous paper or electronic formats. la fome de microfiche/flm, de reproduction sur papier ou sur format électronique. The author retains ownership of the L'auteur conserve la propriété du copyright in this thesis. Neither the droit d'auteur qui protège cette thèse. thesis nor substantial extracts fiom it Ni la thèse ni des extraits substantiels may be printed or otherwise de celle-ci ne doivent être imprimés reproduced without the author's ou autrement reproduits sans son permission. autorisation. PHOTOCHEMICAL REACTIONS OF CHLOROAROMATIC COMPOUNDS Alexandre Konstantinov Advisor: University of Guelph, 1998 Dr. N.J. Bunce A novel reaction of successive photocyanation cornmon for various classes of highly chlo~atedaromatic compounds was discovered. The products of photolysis of polychlorinated aromatics in the presence of sodium cyanide were polycyanated hydroxychlorocompounds with various degrees of chlorine replacement. Products from some substrates were isolated, identified and characterized. The quantum yields of disappearance in the presence of sodium cyanide were determined for a number of structurally diverse chloroaromatic compounds. The quantum efficiency of photocyanations was found to increase with the number of chlorine substituents on a substrate. Sensitization and quenching experiments established the triplet excited state to be reactive for al1 tested compounds, consistent with the suggested SN2Ar* mechanism for the successive photocyanation. To date, the synthetic potential of the reaction is low because of low selectivity. In related work, a method for on-site destruction of dioxins in smd quantities of liquid laboratory waste using UV light was developed and applied to both standard congeners and waste sarnples from an analytical laboratory. The novel feaiure was the use of a low power, low pressure mercury arc as the radiation source. The problem of poor matend balance in photolysis of dioxins was resolved by photolyzing tritiated 2,3,7,8-TCDD as a tracer compound and locating the missing material in the polar fractions. These products were identified by ES-MS as hydroxylated aromatic compounds, indicating that as much as 80% of the photolysis proceeds by C-O rather than C-Cl homolysis. Biological assays demonstrated that the products formed upon photolysis of 2,3,7,8-TCDD lost the toxic effects associated with dioxins' receptor binding ability and did not bind to the estrogen receptor. This information is very important for the practical applications of the UV treatment methods, because it shows that the photolysis products are Likely to have low toxicity, and cm therefore be disposed of by conventional means. I would like to thank a number of people who directly or indirectly contributed to the success of this project. First of dl, Dr. N. J. Bunce, who was an outstanding supervisor during my M.Sc. and Ph.D. studies at the University of Guelph. His thorough knowledge in various fields of chemistry and open-minded style of guidance were a great deal of help in my research. I would like to thank my committee members Dr. 3. Lipkowski, R. McCrindle and M. Tchir for their assistance, usefûl advise, and encouragement. Special thanks to Dr. C. Kingsmill and Dr. D. Suh f?om Laboratory Services Division, University of Guelph, for prompt analysis on a number of samples using the Electrospray Mass Spectrometer. Kudos to Dr. G. Ferguson for x-ray crystallography and to Valerie Robinson for running 2-D NMR experiments. My appreciation to Brian Cox and John Petrulis for successfbl CO-operationin biochemicai assay experiments, and thanks to my other lab-mates for being nice people. 1 would also like to express my gratitude to the outstanding suppon staff of the Department of Chemistry and Biochemistry, including Teny White - workshop, Yves Savoret - glassblowing, Karen Shiell -purchasing, Uwe Oehler, Ian Renauld and Steve Seifried - network support and electronics shop. My very special thanks to my wife Svetlana for support and patience. 2.3. Conclusions ............................................................................................................ 82 2.4. Expenmental ........................................................................................................... 83 2.4.1. Generai ....................................... ,.. .......................................................... 83 2.4.2. Irradiations .................................................................................................... 83 2.4.3. Andysis ........................................................................................................ 83 2.4.4. Mass Spectrometv ...................................................................................... 84 2.4.5. Photochernical Cyanation of Hexachlorobenzene......................................... 85 2.4.5.1. Measurement of Quantum Yield of Disappearance of HCB ............ -85 2.4.5.2. Photolysis of Hexachlorobenzene in the Presence of NaCN for Various Penods of Time ................................................................... 87 2.4.5.3. Sensitization of HCB Photocyanation by Acetone and Acetophenone, and Oxygen Removal .............................................. 88 2.4.5.4. Quenching of HCB Photocyanation by Ferrocene ............................ 89 2.4.5.5. Photolysis of HCB at Various Concentrations of Sodium Cyanide .. -89 2.4.5.6. Influence of Water on Photocyanation of HCB ................................ 90 2.4.5.7. Determination of Isosbestic Point in Cyanation of Hexachlorobenzene ......................................................................... 91 2.4.5.8. Dependance of Quantum Yield of Cyanation of HCB on the Initial Concentration of HCB ........................................................ 92 2.4.5.9. Photocyanation of HCB on Preparative Scale ..................................... 92 2.4.6. Synthesis of 2,3,4,5,6-pentachlorobenzonitrile............................................. -96 2.4.6.1. Iodination of 4-chloroaniline ............................................................ 96 2.4.6.2. Polychlorination of 1-iodo-4chlorobenzene .................................... 96 2.4.6.3 Cyanation of Pentachloroiodobenzene.............................................. 97 2.4.7. Reactions of 2,3,4,5, 6-Pentachlorobenzonitnlewith Sodium Cyanide .........-97 2.4.8. Calculation of Quantum Yield of Disappearance of Pentachlorobenzonitnle98 2.4.9. Synthesis and Ground-State Reactions of 1,4 -Dichloro-2,3,5, 6- Tetracyanobenzene and a Trichloro-Tncyanobenzene..................... 99 2.4.10. Competitive Photocyanation of HCB, Pentachlorobenzene and 1,2,3, 4-Tetrachlorobenzene ..........................~..........................................100 2.4.1 1. Photocyanation of 1,4-Dicyanobenzene and 1,2,4,5-Tetracyanobenzene. .. 10 1 2.4.12. Photocyanation of Decachlorobiphenyl .................................................... 103 2.4.12.1. Photolysis of Decachlorobiphenyl in the Presence of Sodium Cyanide for Various Penods of Time ........................................... 103 2.4.12.2. Measurement of Quantum Yield of Disappearance of Decachlorobiphenyl ..................................................................... 104 2.4.12.3. Quenching of Cyanation of DCB by Ferrocene ............................ 105 2.4.12.4. Photocyanation of DCB at Various Concentrations of Water ....... 1O6 2.4.12.5. Photolysis of Decachlorobiphenyl at Various Concentrations of Sodium Cyanide ........................................... 106 . 2.4.12.6. Sensitization of DCB Photocyanation by Acetone, Acetophenone and Oxygen Rernoval................................................................... 107 2.4.12.7. Competitive Photolysis of Three Hexachlorobiphenyls ................ 108 2.4.12.8. Photolysis of 2,3,4,5, 6-Pentachlorobiphenyl in the Presence of Sodium Cyanide for Various Periods of Time .............................. 110 List of Figures Figure 1. Charge Distribution in Ground and Singlet Excited States . of 4-NitrocatechoI ............................................................................................ 8 Figure 2 . Para-Directing Effect of Nitro Group in the Photo-Smiles Rearrangernent ...... -9 Figure 3 . Net charges and the H orbital coefficients of the Tl state and net charges of the radical anion of 4-nitrophenol ............................................................... 10 Figure 4 . Pathways of Photocyanation of LMethoxynaphthalene .................................. 19 Figure 5 . Mechanism of Nucleophilic Substitution of Haloanisoles in Aqueous t-BuOH ........................................................................................ 21 Figure 6 . Mechanism of