Organic Chemistry of Explosives

Jai Prakash Agrawal is the former Director of Materials of the Indian Defence Research and Development Organization. He obtained his PhD in Chemistry from the Gorakhpur University, India, and did postdoctoral work at the University of Saint-Etienne, France, and at the Cavendish Laboratory of the University of Cambridge, UK. In recognition of his achievements Dr. Agrawal was appointed a Fellow of the Royal Society of Chemistry, London. The focus of his scientific and professional career is on research and development in the field of propellants, explosives and inhibitory materials. He has written a monograph on "Composite Materials" and is recipient of several honours including the prestigious DRDO Technology Award. Together with Robert Hodgson he has authored the book "Organic Chemistry of Explosives", John Wiley & Sons.

Foreword page xiii

Preface xv

Abbreviations xvii

Acknowledgements xxv

Background xxvii

1 Synthetic Routes to Aliphatic C-Nitro Functionality 1

1.1 Introduction 1

1.2 Aliphatic C-nitro compounds as explosives 2

1.3 Direct nitration of alkanes 2

1.4 Addition of nitric acid, nitrogen oxides and related compounds to unsaturated bonds 3

1.4.1 Nitric acid and its mixtures 3

1.4.2 Nitrogen dioxide 4

1.4.3 Dinitrogen pentoxide 5

1.4.4 Nitrous oxide and dinitrogen trioxide 6

1.4.5 Other nitrating agents 6

1.5 Halide displacement 7

1.5.1 Victor Meyer reaction 7

1.5.2 Modified Victor Meyer reaction 9

1.5.3 Ter Meer reaction 10

1.5.4 Displacements using nitronate salts as nucleophiles 13

1.6 Oxidation and nitration of C–N bonds 14

1.6.1 Oxidation and nitration of oximes 14

1.6.2 Oxidation of amines 19

1.6.3 Nitration of nitronate salts 21

1.6.4 Oxidation of pseudonitroles 23

1.6.5 Oxidation of isocyanates 23

1.6.6 Oxidation of nitrosoalkanes 24

1.7 Kaplan–Shechter reaction 24

1.8 Nitration of compounds containing acidic hydrogen 27

1.8.1 Alkaline nitration 27

1.8.2 Acidic nitration 31

1.9 Oxidative dimerization 32

1.10 Addition and condensation reactions 33

1.10.1 1,2-Addition reactions 33

1.10.2 1,4-Addition reactions 35

1.10.3 Mannich reaction 43

1.10.4 Henry reaction 44

1.11 Derivatives of polynitroaliphatic alcohols 46

1.12 Miscellaneous 49

1.12.1 1,1-Diamino-2,2-dinitroethylenes 49

1.12.2 Other routes to aliphatic nitro compounds 50

1.12.3 Selective reductions 51

1.13 Chemical stability of polynitroaliphatic compounds 51

1.13.1 Reactions with mineral acids 52

1.13.2 Reactions with base and nucleophiles 52

References 55

2 Energetic Compounds 1: Polynitropolycycloalkanes 67

2.1 Caged structures as energetic materials 67

2.2 Cyclopropanes and spirocyclopropanes 68

2.3 Cyclobutanes and their derivatives 69

2.4 Cubanes 71

2.5 Homocubanes 74

2.6 Prismanes 78

2.7 Adamantanes 79

2.8 Polynitrobicycloalkanes 82

2.8.1 Norbornanes 82

2.8.2 Bicyclo[3.3.0]octane 84

2.8.3 Bicyclo[3.3.1]nonane 85

References 85

3 Synthetic Routes to Nitrate Esters 87

3.1 Nitrate esters as explosives 87

3.2 Nitration of the parent alcohol 90

3.2.1 O-Nitration with nitric acid and its mixtures 90

3.2.2 O-Nitration with dinitrogen tetroxide 93

3.2.3 O-Nitration with dinitrogen pentoxide 93

3.2.4 O-Nitration with nitronium salts 94

3.2.5 Transfer nitration 95

3.2.6 Other O-nitrating agents 96

3.3 Nucleophilic displacement with nitrate anion 97

3.3.1 Metathesis between alkyl halides and silver nitrate 97

3.3.2 Decomposition of nitratocarbonates 98

3.3.3 Displacement of sulfonate esters with nitrate anion 98

3.3.4 Displacement with mercury (I) nitrate 99

3.4 Nitrate esters from the ring-opening of strained oxygen heterocycles 99

3.4.1 Ring-opening nitration of epoxides 99

3.4.2 1,3-Dinitrate esters from the ring-opening nitration of oxetanes with dinitrogen pentoxide 102

3.4.3 Other oxygen heterocycles 103

3.5 Nitrodesilylation 103

3.6 Additions to alkenes 104

3.6.1 Nitric acid and its mixtures 104

3.6.2 Nitrogen oxides 105

3.6.3 Metal salts 106

3.6.4 Halonitroxylation 106

3.7 Deamination 106

3.8 Miscellaneous methods 107

3.9 Synthetic routes to some polyols and their nitrate ester derivatives 108

3.10 Energetic nitrate esters 112

References 117

4 Synthetic Routes to Aromatic C-Nitro Compounds 125

4.1 Introduction 125

4.2 Polynitroarylenes as explosives 126

4.3 Nitration 128

4.3.1 Nitration with mixed acid 129

4.3.2 Substrate derived reactivity 131

4.3.3 Effect of nitrating agent and reaction conditions on product selectivity 138

4.3.4 Other nitrating agents 139

4.3.5 Side-reactions and by-products from nitration 143

4.4 Nitrosation–oxidation 144

4.5 Nitramine rearrangement 145

4.6 Reaction of diazonium salts with nitrite anion 148

4.7 Oxidation of arylamines, arylhydroxylamines and other derivatives 149

4.7.1 Oxidation of arylamines and their derivatives 149

4.7.2 Oxidation of arylhydroxylamines and their derivatives 155

4.8 Nucleophilic aromatic substitution 157

4.8.1 Displacement of halide 158

4.8.2 Nitro group displacement and the reactivity of polynitroarylenes 167

4.8.3 Displacement of other groups 169

4.8.4 Synthesis of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) 172

4.9 The chemistry of 2,4,6-trinitrotoluene (TNT) 174

4.10 Conjugation and thermally insensitive explosives 176

References 180

5 Synthetic Routes to N-Nitro Functionality 191

5.1 Introduction 191

5.2 Nitramines, nitramides and nitrimines as explosives 192

5.3 Direct nitration of amines 195

5.3.1 Nitration under acidic conditions 195

5.3.2 Nitration with nonacidic reagents 202

5.4 Nitration of chloramines 207

5.4.1 Nitration of dialkylchloramines 207

5.4.2 Nitration of alkyldichloramines 207

5.5 N-Nitration of amides and related compounds 208

5.5.1 Nitration with acidic reagents 208

5.5.2 Nitration with nonacidic reagents 211

5.6 Nitrolysis 213

5.6.1 Nitrolysis of amides and their derivatives 213

5.6.2 Nitrolysis of N-alkyl bonds 217

5.6.3 Nitrolysis of nitrosamines 221

5.7 Nitrative cleavage of other nitrogen bonds 223

5.8 Ring-opening nitration of strained nitrogen heterocycles 225

5.8.1 Aziridines 226

5.8.2 Azetidines 227

5.9 Nitrosamine oxidation 228

5.10 Hydrolysis of nitramides and nitroureas 229

5.11 Dehydration of nitrate salts 232

5.12 Other methods 233

5.13 Primary nitramines as nucleophiles 234

5.13.1 1,4-Michael addition reactions 234

5.13.2 Mannich condensation reactions 235

5.13.3 Condensations with formaldehyde 239

5.13.4 Nucleophilic displacement reactions 240

5.14 Aromatic nitramines 240

5.15 The nitrolysis of hexamine 243

5.15.1 The synthesis of RDX 243

5.15.2 The synthesis of HMX 247

5.15.3 Effect of reaction conditions on the nitrolysis of hexamine 250

5.15.4 Other nitramine products from the nitrolysis of hexamine 252

References 255

6 Energetic Compounds 2: Nitramines and Their Derivatives 263

6.1 Cyclopropanes 263

6.2 Cyclobutanes 264

6.3 Azetidines – 1,3,3-trinitroazetidine (TNAZ) 265

6.4 Cubane–based nitramines 268

6.5 Diazocines 269

6.6 Bicycles 271

6.7 Caged heterocycles – isowurtzitanes 273

6.8 Heterocyclic nitramines derived from Mannich reactions 276

6.9 Nitroureas 277

6.10 Other energetic nitramines 282

6.11 Energetic groups 284

6.11.1 Dinitramide anion 284

6.11.2 Alkyl N,N-dinitramines 286

6.11.3 N-Nitroimides 287

References 288

7 Energetic Compounds 3: N-Heterocycles 293

7.1 Introduction 293

7.2 5-Membered rings – 1N – pyrroles 294

7.3 5-Membered rings – 2N 294

7.3.1 Pyrazoles 294

7.3.2 Imidazoles 296

7.3.3 1,3,4-Oxadiazoles 297

7.3.4 1,2,5-Oxadiazoles (furazans) 297

7.3.5 Benzofurazans 302

7.3.6 Furoxans 302

7.3.7 Benzofuroxans 303

7.4 5-Membered rings – 3N 307

7.4.1 Triazoles 307

7.4.2 Triazolones 312

7.4.3 Benzotriazoles 313

7.5 5-Membered rings – 4N 314

7.6 6-Membered rings – 1N – pyridines 317

7.7 6-Membered rings – 2N 318

7.8 6-Membered rings – 3N 320

7.9 6-Membered rings – 4N 321

7.10 Dibenzotetraazapentalenes 324

References 326

8 Miscellaneous Explosive Compounds 333

8.1 Organic azides 333

8.1.1 Alkyl azides 333

8.1.2 Aromatic azides 338

8.2 Peroxides 339

8.3 Diazophenols 340

8.3.1 Diazophenols from the diazotization of aminophenols 340

8.3.2 Diazophenols from the rearrangement of o-nitroarylnitramines 341

8.4 Nitrogen-rich compounds from guanidine and its derivatives 343

References 346

9 Dinitrogen Pentoxide – An Eco-Friendly Nitrating Agent 349

9.1 Introduction 349

9.2 Nitrations with dinitrogen pentoxide 350

9.3 The chemistry of dinitrogen pentoxide 351

9.4 Preparation of dinitrogen pentoxide 351

9.5 C-nitration 353

9.6 N-nitration 355

9.7 Nitrolysis 357

9.8 O-nitration 359

9.9 Ring cleavage nitration 360

9.10 Selective O-nitration 361

9.10.1 Glycidyl nitrate and NIMMO – batch reactor verses flow reactor 362

9.11 Synthesis of the high performance and eco-friendly oxidizer – ammonium dinitramide 363

References 364

Index 367