Methods for Oxidation of Organic Compounds. Alcohols, Alcohol Derivatives, Alky Halides, Nitroalkanes, Alkyl Azides, Carbonyl Compounds Hydroxyarenes and Aminoarenes

466 Pages·1988·5.65 MB·English

by  Alan Haines (Auth.)

BEST SYNTHETIC M E T H O DS
Series Editors
A. R. Katritzky O. Meth-Cohn C. W. Rees
University of Florida Sterling Organics Ltd Imperial College of Science
Gainesville, Florida Newcastle upon Tyne and Technology
USA UK London, UK
Richard F. Heck, Palladium Reagents in Organic Syntheses, 1985
Alan H. Haines, Methods for the Oxidation of Organic Compounds: Alkanes, Alkenes,
Alkynes, andArenes, 1985
Paul N. Rylander, Hydrogenation Methods, 1985
Ernest W. Colvin, Silicon Reagents in Organic Synthesis, 1988
Andrew Pelter, Keith Smith and Herbert C. Brown, Borane Reagents, 1988
Basil Wakefield, Organolithium Methods, 1988
Alan H. Haines, Methods for the Oxidation of Organic Compounds: Alcohols, Alcohol
Derivatives, Alkyl Halides, Nitroalkanes, Alkyl Azides, Carbonyl Compounds,
Hydroxyarenes and Aminoarenes, 1988.
In preparation
I. Ninomiya and T. Naito, Photochemical Synthesis, 1988
Methods for the Oxidation
of Organic Compounds
Alcohols, Alcohol Derivatives,
Alkyl Halides, Nitroalkanes,
Alkyl Azides, Carbonyl Compounds,
Hydroxyarenes and Aminoarenes
Alan H. Haines
School of Chemical Sciences
University ofEastAnglia
Norwich, England
1988
Academic Press
Harcourt Brace Jovanovich, Publishers
London San Diego New York Berkeley
Boston Sydney Tokyo Toronto
ACADEMIC PRESS LIMITED
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US Edition published by
ACADEMIC PRESS INC.
San Diego, CA 92101
Copyright © 1988 by
ACADEMIC PRESS LIMITED
All rights Reserved
No part of this book may be reproduced in any form by photostat, microfilm, or any other
means, without written permission from the publishers
This book is a guide providing general information concerning its subject matter; it is not
a procedural manual. Synthesis of chemicals is a rapidly changing field. The reader should
consult current procedural manuals for state-of-the-art instructions and applicable govern­
ment safety regulations. The publisher and the author do not accept responsibility for
any misuse of this book, including its use as a procedural manual or as a source of specific
instructions
British Library Cataloguing in Publication Data
Haines, Alan H.
Methods for the oxidation of organic
compounds: alcohols, alcohol derivatives,
alkyl halides, nitroalkanes, alkyl azides,
carbonyl compounds, hydroxyarenes and
aminoarenes.
1. Organic compounds. Oxidation
I. Title II. Series
547'.23
ISBN 0-12-315502-9
Typeset in Great Britain by EJS Chemical Composition, Bath
Printed in Great Britain by St Edmundsbury Press Limited, Bury St Edmunds, Suffolk
For Carol, Neal, and Mark
In memory of Austin and Annie
Foreword
There is a vast and often bewildering array of synthetic methods and
reagents available to organic chemists today. Many chemists have their own
favoured methods, old and new, for standard transformations, and these can
vary considerably from one laboratory to another. New and unfamiliar
methods may well allow a particular synthetic step to be done more readily
and in higher yield, but there is always some energy barrier associated with
their use for the first time. Furthermore, the very wealth of possibilities
creates an information-retrieval problem. How can we choose between all
the alternatives, and what are their real advantages and limitations? Where
can we find the precise experimental details, so often taken for granted by
the experts? There is therefore a constant demand for books on synthetic
methods, especially the more practical ones like Organic Syntheses, Organic
Reactions, and Reagents for Organic Synthesis, which are found in most
chemistry laboratories. We are convinced that there is a further need, still
largely unfulfilled, for a uniform series of books, each dealing concisely with
a particular topic from a practical point of view—a need, that is, for books
full of preparations, practical hints and detailed examples, all critically
assessed, and giving just the information needed to smooth our way pain­
lessly into the unfamiliar territory. Such books would obviously be a great
help to research students as well as to established organic chemists.
We have been very fortunate with the highly experienced and expert
organic chemists who, agreeing with our objective, have written the first
group of volumes in this series, Best Synthetic Methods. We shall always be
pleased to receive comments from readers and suggestions for future
volumes.
A.R.K., O.M.-C, C.W.R.
ix
Preface
When I was collecting information for the contribution on oxidation to the
Best Synthetic Method Series, the need became clear, in view of the
extremely wide range of oxidative methods employed by organic chemists,
to divide the subject matter between two volumes in order to provide the
practical information in books of convenient size for use in the laboratory.
The first volume dealt with the oxidation of hydrocarbons under the
headings of alkanes, alkenes, alkynes, and arenes, and the present volume
deals with the oxidation of alcohols, alcohol derivatives, alkyl halides,
nitroalkanes, alkyl azides, carbonyl compounds, hydroxyarenes and
aminoarenes. No attempt has been made in either volume to include
oxidation at heteroatoms such as sulphur or nitrogen, unless it forms a part
of an oxidation process of the type already described.
Most of the oxidative techniques considered here are illustrated with
detailed experimental procedures taken from the literature. The original
procedures have been edited and rewritten to ensure uniformity of style.
Although every attempt has been made to ensure that all pertinent
information is included, consultation of the original literature may be
advisable in some cases.
The number of experimental procedures that may be described fully is
clearly limited by the availability of space, and, to alleviate this problem,
tables containing several examples of each type of oxidation are included.
These tables, numbered so as to indicate the chapters with which they are
associated, are placed together in an appendix. Each entry in a table
summarizes an experiment for which, in nearly every case, a good, fully
detailed procedure is described in the original reference.
I am indebted to Professor A. McKillop for critically reading the entire
manuscript and for his valuable comments.
My thanks go to my wife Carol for typing the manuscript with great speed
and accuracy and for providing valuable support and encouragement during
the period of writing. My thanks go also to my children Neal and Mark, who
helped to check the manuscript and who showed great understanding
regarding the claims placed on my time by the whole undertaking.
ALAN H. HAINES
xi
- 1-
Introduction
Scope and Organization of Material
The compilation of a series of recommended methods for the controlled
oxidation of organic compounds is a daunting task. The number of oxidants
that have been employed by organic chemists is very large, and often many
reagents effect the same type of transformation, albeit with differing
efficiencies and under different conditions. An important and particularly
difficult decision for the author of a general laboratory text on the oxidation
of organic compounds is the selection and organization of material, both of
which are essential to bring order to the vast amount of available data, and to
ensure that the user will quickly find a procedure best suited to his needs.
Many of the previous books and reviews on oxidation have dealt with
oxidants by type, but it is clear that in order to meet the requirements of this
series, a treatment based primarily on chemical transformations is more
desirable. In this book, therefore, as with the companion volume covering
the oxidation of alkanes, alkenes, alkynes and arenes [1], each chapter deals
with a different class of substrate, and the sections of each chapter deal with
the formation of a particular type of compound or grouping from that
substrate. Sections are further subdivided, generally on the basis of
reagents, or the types of reaction that may be used to form that particular
type of compound or grouping. The first part of each such subsection is in the
form of a general but brief introduction to the reagent or procedure, in
which the scope, advantages and disadvantages are discussed, and several
typical examples illustrating its synthetic utility are given in tabular form.
The second part gives, in detail, an example of a typical procedure for
achieving that type of oxidation, when such data are available. Often,
potentially useful procedures lack precise experimental details for
preparative purposes; if this is the case, examples of the procedures are
omitted. References are collected at the end of each subsection.
The definition of the state of oxidation of an organic compound is not
entirely straightforward, yet obviously this problem needs to be addressed in
order to determine which reactions constitute oxidative processes. The
1
2 1. INTRODUCTION
TABLE 1.1
Some Simple Functional Groups Arranged According to their Oxidation State
Increasing state of oxidation »
RH —C=C— —C==C— RCOOH C0
2
ROH RCOR RCOOR CC1
4
RC1 RCH=NOH RCONH etc.
2
RNH RC~CR RfeN
2 2 I I 2
HO OH
etc. etc.
RC-CR
2 I I 2
CI CI
etc.
concepts of electron transfer and oxidation numbers, which prove so useful
in organic chemistry, are generally less easily applied in organic chemistry.*
In this book the oxidative series shown in Table 1.1 is used as a basis for
defining an oxidative transformation, and oxidation is classed as the
conversion of a functional group to one of a higher category. Generally,
compounds that are related by the addition or removal of a molecule of
water or its equivalent are regarded as being in the same oxidation state, but
this is not always the case. Thus when elements of water are removed from
an aldoxime, a nitrile is produced and a change in oxidation level from an
aldehyde to an acid is thereby achieved. On the other hand, dehydration of
an amide to a nitrile causes no change in oxidation level.t
The replacement of an electronegative group at a carbon atom by another
electronegative group, for example in the conversion of a geminal dichloride
RCHC1 into a geminal diacetoxy compound RCH(OAc), causes no major
2 2
change in the overall oxidation level of the carbon atom in the functional
group. On the other hand, replacement of a hydrogen atom attached to
carbon by a substituent that is more electronegative than hydrogen results in
an oxidation at that carbon atom. Thus the substitution of hydrogen in an
alkane or arene by halogen, or the addition of halogen to an alkene, are
strictly oxidative processes. However, in common with most other books
and review articles on oxidation, reactions of these types are not included
* An earlier book on the oxidation of organic compounds [2] does, however, classify oxidations
on the basis of the number of electrons transferred to the oxidant,
t In the oxime-to-nitrile conversion the number of bonds from the electronegative nitrogen
atom to the carbon atom of the functional group increases from two to three, but in both the
amide and nitrile there are three bonds to the carbon atom from electronegative atoms
(nitrogen and oxygen, and nitrogen, respectively).
SCOPE AND ORGANIZATION OF MATERIAL 3
unless they form an integral part of another oxidative process. Oxidation at
a heteroatom in an organic substrate is not discussed, unless it forms part of
a process leading to oxidation at carbon.
Constraints on space and the overall aims of the series have made it
necessary for the author to be extremely selective in the material presented
and to omit many mechanistic aspects of the reactions presented. In spite of
this, it is hoped that the procedures that have been included will provide
useful models on which to base the design of related transformations that
may be required by synthetic organic chemists in their everyday research.
REFERENCES
[1] A. H. Haines, Methods for the Oxidation of Organic Compounds: Alkanes, Alkenes,
Alkynes, andArenes. Academic Press, London, 1985.
[2] L. J. Chinn, Selection of Oxidants in Synthesis. Dekker, New York, 1971.
- 2-
Oxidation of Alcohols
2.1. Formation of Carbonyl Compounds
A great number of oxidizing agents can affect the conversion of an alcohol
to a carbonyl compound (Scheme 1, (1) -> (2)), and the synthetic chemist
is faced, apparently, with a bewildering choice of methods for this reaction.
R ^ C H OH — R ^ CO
(1) (2)
Scheme 1
However, the susceptibility of aldehydes (2, R1 = H, R2 = alkyl or aryl)
to further oxidation narrows the choice of reagents for the oxidation of
primary alcohols to the carbonyl level in good yield, and if the alcohol group
is part of a complex molecule that is sensitive to acidic or basic reagents then
the choice of effective oxidants is narrowed still further. The discovery of
oxidants that are able to achieve the alcohol-to-carbonyl conversion in high
yield in a variety of substrates has been of key importance to the develop­
ment of the synthesis of complex natural products.
Catalytic dehydrogenation of alcohols, either with or without a hydrogen
acceptor present,* is especially suited to the large-scale production of the
simpler carbonyl compounds [1-5] and has been used, for example, for the
preparation of formaldehyde, acetaldehyde, acetone and 2-butanone on an
industrial scale [6]. Although of lesser importance in the laboratory, the
technique has found valuable application in the selective oxidation of
polyhydroxylated compounds using platinum-oxygen as the reagent
combination [7-9].
A most useful method for the conversion of alcohols (usually, but not
always, secondary) to carbonyl compounds is the Oppenauer oxidation
* Oxygen is considered here to be a hydrogen acceptor, but often such catalytic reactions
carried out in the presence of oxygen are termed catalytic oxidations. Clearly an intimate
knowledge of the reaction mechanism is required to allow a decision as to the best
terminology.
5