Investigations into the Functionalisation of Polyisobutylene by Simon James Perry • A thesis submitted to the University of York for the degree of Doctor of Philosophy Department of Chemistry University of York February 2000 Abstract The work described in this thesis is concerned with the functionalisation of polyisobutene (PIB). which is an important intermediate in the production of oil additives for the automotive industry. These include dispersants which derive their dispersency from the polar endgroups attached to an alkyl chain. A number of problems are encountered with the present synthetic procedures and this thesis details investigations into the nature of some of these problems and their possible solutions. The complex nature of pm makes it a difficult substrate to employ for mechanistic studies. To circumvent this problem a number of model alkenes have been employed to mimic the behaviour ofPIB. Chapter 1 contains a general introduction to oil additives concentrating on the formation of dispersants from pm. and also contains a summary of the halogenation of alkenes and of the Alder-ene reaction. In Chapter 2 the halogenation of the model alkenes has been studied using chlorine, bromine and interhalogen compounds such as ICI and IBr. The selectivity of the halogenation process, and the consequent incorporation of chlorine into the fmal product has been studied and ways of eliminating the problem of residual chlorine are reported. Chapter 3 details experiments concerned with the formation of diamines from the epoxides derived from the model alkenes. This it was hoped might provide a new route to functionalised PIB. Although, ring-opening of the model alkene epoxides was usually not a problem, attempts to synthesis diamines from the resultant amino-alcohols proved unsuccessful. Chapter 4 is concerned with an investigation into the preparation of polyisobutylene succinic anhydride (PIBSA), which is manufactured by the thermal ene reaction between maleic anhydride (MA) and PIB. The production of coloured by-products from this reaction have been studied using two alkenes as models. The experiments show that the intensity of the colour in the reaction mixture depends on the proportion of MA used. However, attempts to isolate and identify the coloured components were not completely successful. It is suggested that the decomposition of MA or related material results in the formation of involatile coloured resin. Chapter 5 contains details of the experiments studying the thermal decomposition of ii MA. The synthesis of polymeric MA by radical and base initiated routes has been effected in the hope that this would aid the identification of the coloured polymer. Finally, Chapter 6 contains the detailed experimental procedures used in Chapters 2 to 5. iii Contents Abstract 11 Contents IV Acknowledgements ix Abbreviations x 1. Introduction. 1 Introduction 1 1.1 Composition of engine oil 2 1.2 The chemical composition of lubricants and the role of additives 1.2.1 Base oil 3 1.2.2 Viscosity index (VI) improve / pour point depressants 5 1.2.3 Friction modifiers / anti-wear additives 6 1.2.4 Corrosion inhibitors 7 1.2.5 Anti-oxidants 7 1.3 Detergents and dispersants 8 1.3.1 Detergents 9 1.3.2 Dispersants 10 1.4 Polyisobutene 14 1.5 Model systems 14 1.6 Reaction of electrophiles with alkenes 15 1.6.1 Reaction sequence,' intermediate formation 16 1.6.1.1 Addition of bromine to alkenes 21 1.6.1.2 Addition of chlorine to alkenes 23 1.6.1.3 Addition of iodine electrophiles to alkenes 24 1.6.2 Reaction sequence; bridged halonium ion or open p-halocarbocation 25 1.6.3 Productforming step; substitution versus addition 27 iv 1.7 Alder-Ene reactions 30 1. 7.1 Reaction conditions 32 1.7.2 Mechanism 33 1.8 Addition of carboxylic acids to alkenes 38 1.9 Aims 39 2. Electrophilic addition of halogens to alkenes. 2 Introduction 41 2.1 Electrophilic addition of chlorine to the model alkenes 41 2.1.1 Solvent halogenation 44 2.1.2 Halogenation o/the model alkenes 48 2.1.2.1 Chlorination of l-octene 49 2.1.2.2 Chlorination of 2,4,4-trimethyl-l-pentene (TMP-1) 53 2.1.2.3 Chlorination of 2,4,4-trimethyl-2-pentene (TMP-2) 54 2.1.2.4 Chlorination of 3-methyl-2-pentene 55 2.2 Addition of bromine to the model alkenes 56 2.2.1 Bromination 0/1-octene 57 2.2.2 Bromination 0/2,4,4-trimethyl-1-pentene ([,MP-1) 61 2.2.3 Bromination 0/2. 4. 4-trimethyl-2-pentene ([,MP-2) 66 2.2.4 Bromination of3-ethyl-2-pentene 67 2.3 Addition of iodine electrophiles to the model alkenes 67 2.3.1 Reaction o/iodine monochloride with the model alkenes 68 2.3.2 Reaction o/iodine monobromide with the model alkenes 71 2.3.3 Reaction ofiodine monochlorideformed in-situ with TMP-1 72 2.4 Summary and conclusions 73 3. Formation of diamines from epoxides. 3 Introduction 76 3.1 Epoxidation of the model alkenes 77 3.2 Ring-opening reactions of epoxides 79 3.3 Preparation of diamines 82 3.4 Preparation of aziridines 85 v 3.5 Summary and conclusions 86 4. Investigations into the pmSA reaction. 4 Introduction 88 4.1 Reaction of MA with l-octadecene 90 4.1.1 Separation ofthe coloured by-products 93 4.1.2 UV-Vis spectrometry ofthe crude reaction mixture 94 4.1.3 Liquid chromatography (HPLC) 96 4.2 Preparation of diisobutylene succinic anhydride 97 4.2.1 Analysis ofthe residual solid produced in the TMP-l/MA ene reaction 102 4.3 Reactions of diisobutylene succinic anhydride (DIBSA) 103 4.3.1 Hydrolysis ofdiisobutylene succinic anhydride 103 4.3.2 Lactonisation ofdiisobutylene succinic anhydride 106 4.3.3 Intramolecular acylation ofdiisobutylene succinic anhydride 109 4.4 Ge/MS analysis of the ene reaction residue 111 4.5 Thermal decomposition of diisobutylene succinic anhydride 116 4.6 Thermal decomposition of of the lactones (4.10) produced . from diisobutylene succinic anhydride 117 4.7 EPR studies 118 4.8 Summary 122 5. Thermal decomposition of maleic anhydride. 5 Introduction 124 5.1 Autoclave experiments 125 5.1.1 Thermolysis ofneat maleic anhydride 125 5.1.2. IH NMR analysis o/the MA pyrolysis reaction mixture 128 5.1.3 Analysis o/the MA thermolysis reaction mixture using LC/MS 132 5.1.4 Thermolysis ofmaleic acid and/umaric acid 134 5.1.5 Thermolysis ofsuccinic acid and succinic anhydride 135 vi 5.3 Formation ofpoly(maleic anhydride) (PMA) 136 5.3.1 Initiation by free radicals 137 5.3.2 Synthesis ofPMA 138 5.3.3 Excited species and radical-catalysed PMA 142 5.3.4 Initiation by organic bases 143 5.4 Summary and conclusions 145 6. Experimental procedures. 6.1 General 155 6.1.1 Chemicals 155 6.1.2 Instrumentation 156 6.2 Chapter 2: Addition of halogens to Alkenes 158 6.2.1 Chlorination reactions 158 6.2.2 Bromination reactions 164 6.2.3 Interhalogen reactions 176 6.3 Chapter 3: Formation of diamines from epoxides 184 6.3.1 Epoxidation reactions 184 6.3.2 Epoxide ring-opening reactions 185 6.3.3 Attempted preparation ofdiamines 189 6.3.4 Attempted preparation ofaziridines 190 6.4 Chapter 4: Ene-reactions between maleic anhydride and the model alkene 192 6.4.1 Preparation ofcompounds from diisobutylene succinic anhydride 194 6.4.2 Preparation ofcompounds from isobutylene succinic anhydride 197 6.4.3 EPR experiments 201 6.4.4 'Spin trap' experiments 202 6.5 Chapter 5: Thermal decomposition of maleic anhydride 202 6.5.1 Procedurefor the thermolysis ofmaleic anhydride and derivatives 202 6.5.2 Preparation ofpoly(maleic anhydride) (PMA) 203 vii 6.5.3 Inhibition ofpoly(maleic anhydride) formation 203 6.5.2 Thermolysis ofMA in the presence ofadditives 204 References. 205 viii Acknowledgements Firstly, I would like to acknowledge Dr Barry Thomas for his advice and encouragement throughout my period of study. My gratitude goes to Adibis for sponsoring this project, especially Dr Dave Morton for his support and countless discussions. I would like to thank all the technical staff, particularly Trevor Dransfield, Barbara Chamberlain, Ben Glennie and John Lowe. I would also like to acknowledge Adrian Whitwood for running the EPR experiments contained within this thesis. There are many people who I would like to thank personally although there is not space for you all, the 'Ziggy's committee'! My gratitude goes to Marriott and Alec for helping sort out many of the problems encountered during the last three years. The past and present members of C 178 and founder members of the mighty 'championees' (what a line up!) Harrison, Largo, Pettifer, Pons, Schmarriott and Willy; supporters Haydn, Whittaker, Wilson and Neha; substitutions due to retirements - Upeandran (Bala) and Paul; not forgetting the 'others' Alec, Badger, Kathryn, Des, Florian, Mark, Maurice, Natalie, Porter, Sarah, Scrowelly, Silvester (Wig' ead) and Tim. Outside chemistry, for their continued friendship and encouragement throughout my education, I would like to thank Chris, Colin, Dave, Graham, Mitch, Paul and Rob. I am also grateful to Jo for helping me through the last three years and kicking me out of bed in the morning. Finally, I would like to thank my family, especially Mwn and Dad, for their support and for always being there. ix Abbreviations ASA Alkenyl succinic anhydride atm atmospheres br broad(NMR) Cl Chemical Ionization CTC Charge-Transfer Complex DIBSA Diisobutylene Succinic Anhydride d doublet (NMR) dd doublet of doublets (NMR) ddt doublet of doublet of triplets (EPR) DMF N,N-Dimethyl formamide El Electron Impact EPR Electron Paramagnetic Resonance ESI Electrospray Ionisation FAB Fast Atom Bombardment FID Flame Ionisation Detector FM Friction Modifier GC Gas Chromatography GCIMS Gas ChromatographylMass Spectrometry HOMO Highest Occupied Molecular Orbital HPLC High Perfonnance Liquid Chromatography HR High resolution IR Infra-red AMAX absorption maximum LCIMS Liquid ChromatographylMass Spectrometry LUMO Lowest Unoccupied Molecular Orbital m multiplet (NMR) m- meta (as in m-CPBA, meta-Chloroperbenzoic acid) MA Maleic Anhydride MI Molecular Ion mmHg millimetres of mercury x MsCl Mesyl Chloride NMP 2,2-Methylnitrosopropane NMR Nuclear Magnetic Resonance p- para pm Polyisobutylene pmSA Polyisobutylene Succinic Anhydride PMA Poly(Maleic Anhydride) p.p.m.