Chemical and electrochemical nitrations of alkenes and dienes

247 Pages·2014·5.58 MB·English

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UNIVERSITY OF SOUTHAMPTON
FACULTY OF SCIENCE
DEPARTMENT OF CHEMISTRY
Doctor of Philosophy
CHEMICAL AND ELECTROCHEMICAL
NITRATIONS OF ALKENES
AND DIENES
by Andrew Jonathan Bloom
ACKNOWLEDGEMENT
I wish to thank the following:
My parents for their support; Dr. John Mellor and Professor
Martin Fleischmann, my supervisors; Dr. Philip Parsons for his faith
and encouragement; Neil Smith, Ivan Pinto, Jeff Buchannan and Neil
Carlson for the proof-reading and Suzanne Salt for the typing.
Financial support from The Procurement Executive, Ministry of Defence,
for my maintenance grant, and NATO, for travel expenses, is gratefully
acknowledged.
Table of Contents
Chapter 1 Introduction 1
I'l Electrochemical Nitration 5
1-1,1 Anodic Oxidation of Dinitrogen Tetroxide 6
1*1,2 Anodic Oxidation of the Nitrite Ion 8
1-1,3 Anodic Oxidation of the Nitrate Ion 10
1-2 The Nitration of Alkenes and Dienes 12
1-2,1 The Reaction of Alkenes with Nitronium Salts 14
1-2,2 The Reaction of Acetyl Nitrate with Alkenes
and Dienes 32
1-2,3 The Reaction of Dinitrogen Pentoxide with
Alkenes and Dienes 46
1-2,4 The Reaction of Nitric Acid with Alkenes
and Dienes 48
1-2,5 The Reaction of Tetranitromethane with Alkenes
and Dienes 55
1-2,6 The Reaction of Nitryl Fluoride with Alkenes 60
1-2,7 The Reaction of Nitryl Chloride and Dinitrogen
Tetroxide-Chlorine with Alkenes and Dienes 61
1-2,8 The Reaction of Nitryl Iodide and Dinitrogen
Tetroxide with Alkenes and Dienes 63
1-2,9 The Reaction of Dinitrogen Tetroxide with Alkenes
and Polyenes 65
1-2,10 The Reaction of Mercuric Nitrite with Alkenes 70
1-3 Initial Objectives 71
Chapter 2 The Electrogeneration of Nitronium Salts and Dinitrogen
Pentoxide and Their Reactions 73
2-1 Introduction and Background 74
2"1,1 Mediated or Redox Catalysed Reactions 74
2-1,2 Electrochemically Generated Reagents 78
2-1,3 Chemical Preparation of Nitronium Salts and
Dinitrogen Pentoxide 82
2-2 Results and Discussion i 84
2-2,1 Choice of Solvents 84
2-2,2 Choice of Electrolyte 85
2-2,3 Cell Design 86
2-2,4 Assay 88
2-2,5 Preparation and Reactions of
Nitronium Tetrafluoroborate in Acetonitrile 89
2-2,6 Preparation and Reactions of Nitronium
Hexafluorophosphate in Nitromethane 96
2-2,7 Generation of Nitronium Tetrafluoroborate in
Sulpholane 101
2-2,8 Generation of Dinitrogen Pentoxide in Acetonitrile
and Dichloromethane 101
2-3 Conclusions 109
Chapter 3 Nitroacetamidation of Alkenes and Dienes 110
3-1 Introduction and Background 111
3-1,1 Acetamidation Reactions: The Reaction of
Electrophiles with Alkenes in Acetonitrile 111
3-1,2 Preparation of Vicinal Nitroamines 120
3-2 Results and Discussion
3-2,1 The Nitroacetamidation of Alkenes 124
3*2,2 The Nitroacetamidation of Dienes 140
3-2,3 Some Transformations of Nitroacetamides 152
3*3 Conclusions 157
Chapter 4 The Preparation of 1-Nitro-l,3-dienes Via the
Nitrotrifluoroacetoxylation of Dienes 158
4*1 Introduction and Background 159
4*1,1 Reactions of Trifluoroacetyl Nitrate 159
4*1,2 Additions Involving the Trifluoroacetate Ion 160
4*1,3 Literature Preparations of 1-Nitro-l,3-Dienes 162
4*2 Results and Discussion 167
4*2,1 The Nitrotrifluoroacetoxylation of Dienes and
the Preparation of 1-Nitro-l,3-dienes 167
4*2,2 The Nitrotrifluoroacetoxylation of Alkenes 174
4*2,3 Nucleophilic Additions to 1-Nitro-l,3-dienes 178
4*3 Conclusions 181
Chapter 5 Experimental Procedures 182
5*1 Materials 183
5*1,1 Purification of Solvents 183
5*1,2 Preparation and/or Purification of Electrolytes 183
5*1,3 Preparation and/or Purification of Starting Materials 183
5*1,4 Handling of Dinitrogen Tetroxide 184
5*1,5 Purification and Handling of Nitronium
Tetrafluoroborate 184
5*1,6 Preparation and/or Purification of Other Reagents 185
5*1,7 Apparatus and Equipment 185
5*2 Electrochemistry Experiments 187
5*2,1 Typical Electrolysis Method 187
5-2,2 Analytical Method 187
5*2,3 Reactions of Electrogenerated Nitronium
Tetrafluoroborate 189
5-2,4 Reactions of Electrogenerated Nitronium
Hexafluorophosphate 191
5*2,5 Reaction of Electrogenerated Dinitrogen Pentoxide 193
5*3 The Nitroacetamidation of Alkenes 193
5*3,1 The Epimerisation of Nitroacetamides 202
5*3,2 The Reduction of Nitroacetamides 204
5*4 The Nitroacetamidation of Dienes 207
5*5 Oxidation and Reduction Reactions 215
5*6 Nitrotrifluoroacetoxylation: The Preparation of Nitrodienes 220
5*6,1 Typical Nitrotrifluoroacetoxylation Procedure 220
5*6,2 Typical Elimination Procedure 222
5*6,3 Nucleophilic Addition Reactions 227
References 230
UNIVERSITY OF SOUTHAMPTON
ABSTRACT
FACULTY OF SCIENCE
CHEMISTRY
Doctor of Philosophy
CHEMICAL AND ELECTROCHEMICAL
NITRATION OF ALKENES AND DIENES
by Andrew Jonathan Bloom
Anodic oxidation of dinitrogen tetroxide in acetonitrile containing lithium
tetrafluoroborate gaue nitronium tetrafluoroborate in high yield and current efficiency.
»
Nitronium hexafluorophosphate in nitromethane and dinitrogen pentoxide in dichloromethane
were similarly prepared. The electrogenerated nitration reagents were found to react
with arenes, alkenes and/or silyenolethers giving the same products in similar yields to
those obtained using the conventionally obtained reagents.
Nitronium tetrafluoroborate in acetonitrile reacted with styrenes giving
nitroacetamide products of Markounikou regiochemistry. trans-1-Phenylpropene and trans-
stilbene underwent a syn addition, whilst cis-1-phenylpropene, cis-stilbene and
1-phenylcyclohexene all underwent an anti addition. The nitroacetamidation of simple
alkenes gaue 1,2 and/or 1,3 adducts in low yield. Electrogenerated nitronium
tetrafluoroborate in acetonitrile reacted with dienes to giue mixtures of 1,2 and 1,4
nitroacetamides. The additions onto isoprene and trans-penta-1,3-diene showed a
preferential attack of the more substituted double bond. The 1,2 addition onto trans-
penta-1,3-diene was syn whilst in both the 1,2 and 1,4 additions onto trans, trans hexa-
2,4-diene were non stereoselective.
Oxidation of nitroacetamides with potassium permanganate or eerie aranonium nitrate
under basic conditions gave acetamidoketones. Reduction of nitroacetamides with
aluminium amalgam proceeded stereospecifically to give aminoacetamides. Heating the
aminoacetamides caused cyclisation giving dihydroimidazoles.
Mixtures of ammonium nitrate and trifluoroacetic anhydride reacted with dienes
forming mixtures of nitrotrifluoroacetates. Treatment of these mixtures with a base such
as potassium acetate gave 1-nitro-1,3-dienes, which were predominantly of the trans
configuration. Attempted nitrotrifluoroacetoxylation of alkenes gave complex mixtures of
products.
The nucleophilic addition of thiophenol to trans-1-nitrobuta-1,3-diene gave mainly
a 1,2 adduct, while the addition of aniline gave only a 1,4 adduct.
Chapter One
Introduction
Nitration, the formation of a nitro-compound from an
unsaturated compound, by reaction with a nitrating agent
is a process of considerable popularity*. The process
is commonly used to make aromatic nitro compounds,
many of which are of industrial importance. Aromatic
nitro compounds are used in the synthesis of explosives,
2
pharmaceuticals, dyes and fragrances, for example .
(DH NO-
NO-
O9N
HO3S SOoH
NO-
Trinitrotoluene Dinoserb an intermediate in
an explosive a herbicide the synthesis of
azo-dyes .
Aliphatic nitro-compounds have considerably less
industrial use. However they have become popular as
3
intermediates in research . This popularity is due to
the diversity of useful reactions undergone by aliphatic
nitro-compounds.