Topics in Stereochemistry, Volume 17

311 Pages·1987·8.124 MB·English

TOPICS
IN
STEREOCHEMISTRY
17
VOLUME
ADVISORY BOARD
STEPHEN J. ANGYAL, University of New South Wales, Sydney, Australia
ALAN R. BATTERSBY, Cambridge University, Cambridge, England
GIANCARLO BERTI, University of Pisa, Pisa, Italy
F. ALBERT COTTON, Texas A. & M University, College Station, Texas
JOHANNES DALE, University of Oslo, Oslo, Nonvay
DAVID GINSBURG, Technion, Israel Institute of Technology, Hago, Israel
JEAN-MARIE LEHN, Cofl2ge de France, Paris, France
JAN MICHALSKI, Centre of Molecular and Macromolecular Studies,
Polish Academy of Sciences, hdz, Poland
KURT MISLOW, Princeton University, Princeton, New Jersey
MICHINORI GKI, Tokyo University, Tokyo, Japan
VLADIMIR PRELOG, Eidgeniissische Technische Hochschule, Zurich,
Switzerland
GmTHER SNATZKE, Ruhruniversitiit, Bochum, Federal Republic of
Germany
JOHN B. STOTHERS, University of Western Ontario, London, Ontario,
Canada
HANS WYNBERG, University of Groningen, Groningen, The Netherlands
TOPICS IN
STEREOCHEMISTRY
EDITORS
ERNEST L. ELIEL
Professor of Chemistry
University of North Carolina
Chapel Hill, North Carolina
SAMUEL H. WILEN
Professor of Chemistry
City College, City University of New York
New York, New York
VOLUME 17
AN INTERSCIENCE a~ PUBLICATION
JOHN WILEY & SONS
New York Chichester Brisbane Toronto Singapore
An Interscience" Publication
Copyright 0 1987 by John Wiley & Sons, Inc.
All rights reserved. Published simultaneously in Canada.
Reproduction or translation of any part of this work
beyond that permitted by Section 107 or 108 of the
1976 United States Copyright Act without the permission
of the copyright owner is unlawful. Requests for
permission or further information should be addressed to
the Permissions Department, John Wiley & Sons, Inc.
Library of Congress Catalog Card Number: 67-13943
0471-85282-1
ISBN
Printed in the United States of America
10 9 8 7 6 5 4 3 2 1
INTRODUCTION TO THE SERIES
It is patently impossible for any individual to read enough of the journal
literature so as to be aware of all significant developments that may impinge on
his or her work, particularly in an area such as stereochemistry, which knows
no topical boundaries. Stereochemical investigations may have relevance to an
understanding of a wide range of phenomena and findings irrespective of their
provenance. Because stereochemistry is important in many areas of chemistry,
comprehensive reviews of high quality play a special role in educating and
alerting the chemical community to new stereochemical developments.
The above considerations were reason enough for initiating a series such as
this. In addition to updating information found in such standard monographs as
Srereochemisrry of Carbon Compounds (Eliel, McGraw-Hill, 1962) and Con-
formational Analysis (Eliel, Allinger, Angyal, and Momson, Interscience, 1965;
reprinted by American Chemical Society, 1981) as well as others published
more recently, the series is intended also to deal in greater detail with some of
the topics summarized in such texts. It is for this reason that we have selected
the title Topics in Stereochemistry for this series.
The series is intended for the advanced student, the teacher, and the active
researcher. A background of the basic knowledge in the field of stereochemistry
is assumed. Each chapter is written by an expert in the field and, hopefully,
covers its subject in depth. We have tried to choose topics of fundamental
importance aimed primarily at an audience of inorganic and organic chemists
but involved frequently with basic principles of physical chemistry and molec-
ular physics, and dealing also with certain stereochemical aspects of biochem-
istry.
It is our intention to produce future volumes at intervals of one to two years.
The editors will welcome suggestions as to suitable topics.
We are fortunate in having been able to secure the help of an international
board of editorial advisors who have been of great assistance by suggesting
topics and authors for several chapters and by helping us avoid, in so far as
possible, duplication of topics appearing in other, related monograph series. We
are grateful to the editorial advisors for this assistance, but the editors and
authors alone must assume the responsibility for any shortcomings of Topics in
Stereochemistry.
E. L. ELIEL
S. H. WILEN
V
PREFACE
In contrast to previous volumes, Volume 17 contains only three chapters.
We shall not bore the reader with the circumstances that led to such brevity; it
certainly is not because there is a lack of suitable material or an absence of
activity in the field of stereochemistry. We hope that the quality of the chapters
will make up for their lesser quantity.
The first chapter, by Mario Farina of the city of Milan, Italy, the former
home of Giulio Natta and the place of gestation of many ideas in polymer
stereochemistry, treats this subject in a comprehensive manner. There are other
books dealing with the unraveling of the configuration of stereoregular polymers
by nuclear magnetic resonance spectroscopy and there are edited collections
dealing with the synthesis of optically active polymers. However, to the best of
our knowledge, there is no other text where all these subjects relating to polymer
stereochemistry are treated collectively. At a time when polymer chemistry is
experiencing a resurgence, this collection of valuable information should be
welcomed by practicing chemists from a wide variety of fields other than
polymer science.
The second chapter, by T. B. Freedman and L. A. Nafie, on the stereo-
chemical aspects of vibrational optical activity, deals with a subject that is just
beginning to come of age. In contrast to the previous chapter, which reviews a
mature field, this chapter is designed to introduce chemists at large to a relatively
new stereochemical technique, which will probably become very useful for the
determination of configuration and conformation.
The third chapter, by J. F. Stoddart, is concerned with a very “hot” subject,
namely, the stereochemical aspects of crown ether chemistry. Many chapters
have been written on this topic; Stoddart’s concentrates on the synthesis of a
variety of chiral crown ethers and surveys some of their uses in different areas
of physical, chemical, and biological science.
Even though we continue to enjoy the help of an excellent group of editorial
advisors, we invite our readers to send us suggestions for future chapters and
authors.
ERNEST L. ELIEL
SAMUEL H. WILEN
Chapel Hill, North Carolina
New York, New York
January 1987
vii
CONTENTS
STEREOCHEMISTRY OF LINEAR
THE
MACROMOLECULES 1
by Mario Farina,
Dipartimento di Chimica Organica e Industriale,
Universita di Milano,
Milan, Italy
STEREOCHEMICAL ASPECTS OF VIBRATIONAL
OPTICAL ACTIVITY 113
by Teresa B. Freedman and Laurence A. Nafie,
Department of Chemistry,
Syracuse University,
Syracuse, New York
CHIRAL CROWN ETHERS 207
by J. Fraser Stoddart,
Department of Chemistry,
The University,
Shefleld, United Kingdom
SUBJECT INDEX 289
CUMULATIVE INDEX, VOLUMES 1-17
3011
ix
TOPICS
IN
STEREOCHEMISTRY
VOLUME 17
Topics in Stereochemisty, Volume1 7
Edited by Ernest L. Eliel, Samuel H. Wilen
Copyright © 1987 by John Wiley & Sons, Inc.
The Stereochemistry of Linear Macromolecules
MARIO FARINA
Dipartimento di Chimica Organica e Industriale
Universitd di Milano
Milano, Italy
1. Introduction ............................................... 1
II. Stereoisomerism of Macromolecular Chains
A. Isotactic and Syndiotactic Polymers . .
Other Stereoregular Polymers ................................. 8
B.
C. Nonconventional Stmctures ............................ . 14
D. Microtacticity ........................................... 18
Ill. The Contribution of NMR Spectroscopy to Macromolecular Stereochemistry ..... 27
A. A Pioneering Research Problem: Poly(methy1 methacrylate)
The Present Level of Spectral Analysis .............
B.
Conformational Analysis .............. .. .......... 42
TV.
A. Conformations of Crystalline Polymers ................. ..... 46
Disordered Conformations ................
B.
C. New Methods and New Problems ....................
V. Chirality in Polymers ......................................... 66
A. Prediction of Chirality in Flexible Macromolecular Systems ............. 67
B. Synthesis of Optically Active Polymers from Chiral Monomers
C. Asymmetric Polymerization ...............
D. Properties and Uses of Optically Active Polymers
VI. Stereochemical Control During Polymerization ......
Conclusions ............................................... 93
VII.
Addendum ......... .... ......... .. 94
Acknowledgments .... ............................... 96
References ................................ ............ 96
I. INTRODUCTION
The discovery of the polymerization processes promoted by transition metal
catalysts and the foundation of macromolecular stereochemistry represents a
major breakthrough in chemistry in the second half of this century. Since the
first discoveries by Ziegler in Miilheim and in Milan there has been an
Natta
enormous development of fundamental and applied research that still continues
1
2 THE STEREOCHEMISTRY OF LINEAR MACROMOLECULES
after more than 30 years (1). This is not the place to deliberate on the role
played by this research in the development of the petrochemical and plastics
industry during the 1960s and 1970s, nor is it the place to illustrate all the
resultant benefits of scientific knowledge produced in many fields of chemistry
(organometallic and coordination chemistry, homogeneous and heterogeneous
catalysis, etc.). In the following pages I shall try to shed some light on only
one aspect of this subject, namely, the impact that polymer chemistry has had
on classic organic stereochemistry.
In brief, we can say that the study of macromolecular compounds has intro-
duced a new dimension into organic stereochemistry. This is true not only in
the spatial sense if one considers the shape of the macromolecule, but also in
the time sense if one examines the process of polymerization and the transmis-
sion of stereoregularity and chirality within each macromolecule. Finally, the
study of macromolecules has necessitated the introduction of concepts and meth-
ods (e.g., the statistical approach), which are usually not pertinent to the ste-
reochemistry of low molecular weight compounds (4).
The of these pages is twofold: first, to fill the gap existing between the
aim
language and the experience of organic stereochemists and polymer chemists
and second, to show how macromolecular stereochemistry can be discussed and
defined using the concepts and criteria of fundamental stereochemistry. I shall
also try to illustrate the role of the conformational analysis of polymers as a
nodal point in determining structure-property relationships. From among the
experimental techniques, greatest emphasis will be given to NMR spectroscopy,
particularly I3C NMR, in its most recent developments.
The reader will find no description of the many individual polymers studied.
I have preferred to give major emphasis to the general aspects of the subject,
illustrated in each instance by a few chosen examples.
Given the vastness of the subject matter I have limited myself to dealing with
.
the structural (or static) aspects of macromolecular stereochemistry An adequate
treatment of the stereochemistry of polymerization, with specific regard to the
polymerization of olefins and conjugated diolefins, would have occupied so
much space and called for such a variety of additional information as to make
this article excessively long and complex. I trust that others will successfully
dedicate themselves to this task. However, the connection between polymer
structure and polymerization mechanism is so important that the fundamentals
of dynamic macromolecular stereochemistry cannot be completely ignored in
this chapter.
Macromolecular stereochemistry has been treated in this series only once,
more than 15 years ago, in a chapter by Goodman (6). Reference may be made
to this review and to a contemporary treatise on the same subject, edited by
Ketley (7), to know the state of the art at the end of the 1960s, at the end, that
is, of the most creative era in the development of this field.