Synthesis and Chemistry of Agrochemicals III (Acs Symposium Series) (Vol 3)

470 Pages·1992·6.57 MB·English

by  Don R. Baker

ACS SYMPOSIUM SERIES 504
Synthesis and Chemistry
of Agrochemicals III
1 Don R. Baker, EDITOR
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w ICI Americas Inc.
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99 Joseph G. Fenyes, EDITOR
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1/b Buckman Laboratories International, Inc.
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92 | E. I. du Pont de Nemours and Company
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American Chemical Society, Washington, DC 1992
Library of Congress Cataloging-in-Publication Data
Synthesis and chemistry of agrochemicals III / Don. R. Baker, editor,
Joseph G. Fenyes, editor, James J. Steffens, editor.
p. cm—(ACS symposium series, ISSN 0097-6156; 504)
"Developed from symposia sponsored by the Division of
Agrochemicals of the American Chemical Society."
Includes bibliographical references and index.
01 ISBN 0-8412-2473-0
0
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4.f 1. Pesticides—Synthesis—Congresses. 2. Herbicides—Synthesis-
0 Congresses. 3. Fungicides—Synthesis—Congresses.
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92- I. Baker, Don R., 1933- . II. Fenyes, Joseph G., 1925-
19 III. Steffens, James J., 1942- . IV. American Chemical Society.
k- Division of Agrochemicals. V. Series.
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02 TP248.P47S964 1992
0.1 668'.65—dc20 92-27345
1 CIP
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e Copyright © 1992
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D All Rights Reserved. The appearance of the code at the bottom of the first page of each
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P 1970, for copying beyond that permitted by Sections 107 or 108 of the U.S. Copyright Law.

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PRINTED IN THE UNITED STATES OF AMERICA
1992 Advisory Board
ACS Symposium Series
M. Joan Comstock, Series Editor
V. Dean Adams Bonnie Lawlor
Tennessee Technological Institute for Scientific Information
University
John L. Massingill
Mark Arnold Dow Chemical Company
University of Iowa
Robert McGorrin
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0 David Baker Kraft General Foods
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4.f University of Tennessee
50 Julius J. Menn
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2- Alexis T. Bell Plant Sciences Institute,
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1 University of California—Berkeley U.S. Department of Agriculture
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02 Arindam Bose Vincent Pecoraro
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10. Pfizer Central Research University of Michigan
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2 | Robert F. Brady, Jr. Marshall Phillips
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19 Naval Research Laboratory Delmont Laboratories
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ber Margaret A. Cavanaugh A. Truman Schwartz
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e National Science Foundation Macalaster College
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ate: Dennis W. Hess John R. Shapley
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n Lehigh University University of Illinois
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ati at Urbana—Champaign
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Conoco Inc.
Madeleine M. Joullie
University of Pennsylvania Robert A. Weiss
University of Connecticut
Mary A. Kaiser
Ε. I. du Pont de Nemours and Peter Willett
Company University of Sheffield (England)
Gretchen S. Kohl
Dow-Corning Corporation
Foreword
THE ACS SYMPOSIUM SERIES was first published in 1974 to
provide a mechanism for publishing symposia quickly in book
form. The purpose of this series is to publish comprehensive
books developed from symposia, which are usually "snapshots
in time" of the current research being done on a topic, plus
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0 some review material on the topic. For this reason, it is neces
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4.f sary that the papers be published as quickly as possible.
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05 Before a symposium-based book is put under contract, the
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9 proposed table of contents is reviewed for appropriateness to
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k- the topic and for comprehensiveness of the collection. Some
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1/ papers are excluded at this point, and others are added to
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1 round out the scope of the volume. In addition, a draft of each
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doi: 1 Tpahpise r aisn opneyemr-oreuvsi ewreedv iepwri orp rtoo cefsinsa l iasc cesputapnecrvei seodr rebjeyc tiothne.
92 | organizer(s) of the symposium, who become the editor(s) of the
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2, 1 book. The authors then revise their papers according the the
er 2 recommendations of both the reviewers and the editors,
b prepare camera-ready copy, and submit the final papers to the
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Pu M. Joan Comstock

Series Editor
Preface
IN A WORLD WITH AN EXPANDING POPULATION of approximately 5.5
billion people, where nearly 1.5 billion are underfed or starving, increased
production of food crops and fiber is of utmost importance. In addition
to natural adversities, such as early frost and drought, crops are also
exposed to attack by a variety of fungal, bacterial, and viral diseases and
to competition for nutrients by numerous types of weeds. Even after har
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00 vest the crop needs protection from deterioration. The importance of
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4. using the proper chemical products to ensure a plentiful harvest cannot
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b This is the third volume in our continuing effort to bring
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2 current information concerning the newest developments in agrochemical
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0. research to the attention of those interested in the development of new
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mb symposia reviewing the discovery of new agrochemicals. These symposia
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at This book is organized like the preceding volumes. The first chapters
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We wish to express our appreciation to all of those who have
participated in our symposia and who have shared the results of their
work with us. Special thanks go to those who have toiled at writing the
chapters that appear in this volume. We hope that our readers will find
the contents to be interesting, useful, and, above all, stimulating.
We also wish to thank our employers, Buckman Laboratories
International, Inc., E. I. du Pont de Nemours and Company, and ICI
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Americas Inc.; without their generous support, this volume and the previ
ous two volumes could not have been published.
DON R. BAKER
ICI Americas Inc.
Richmond, CA 94804
JOSEPH G. FENYES
Buckman Laboratories International, Inc.
Memphis, TN 38108
JAMES J. STEFFENS
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0 E. I. du Pont de Nemours and Company
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xii
Chapter 1
Progress in a Time of Change
Don R. Baker1, Joseph G. Fenyes2, and James J. Steffens3
1ICI Americas Inc., 1200 South 47th Street, Richmond, CA 94804
2Buckman Laboratories International, Inc., 1256 North McLean Boulevard,
Memphis, TN 38108
3E. I. du Pont de Nemours and Company, Stine-Haskell Research Center,
Newark, DE 19714
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05 Agrochemicals continue to be the prime method for controlling insects,
92- plant diseases, and weeds throughout the world and will continue as
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k-1 such for the foreseeable future. The increasing world population will
1/b require increased crop production and this will require the use of new
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0 environmentally safe and efficacious agrochemicals. Increasing costs
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0. of registration and re-registration are causing organizations to
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99 product safety provide opportunities for new materials which are safer
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2, and more effective. Increasing knowledge about vital enzyme
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n being used to prepare crop plants which are resistant to certain
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A chemist, like a painter or poet, is a maker of concepts. If these concepts are more
permanent than theirs, it is because they are made with ideas. Ideas are the core of
the chemist's creation. No discussion here can be more than a reflection of each
individual undertaking. Moreover, only by studying how the road was traveled in the
past can we gain an understanding of the future. The case histories we present here,
commercially successful or not, provide that insight into that process which lies
behind that creative leap from the old to the new. These considerations have inspired
our previous volumes on this subject (7,2) and our ongoing ACS Agrochemicals
Division Symposium series on which these volumes are based.
0097-6156/92/0504-O001S06.00/0
© 1992 American Chemical Society
2 SYNTHESIS AND CHEMISTRY OF AGROCHEMICALS III
We seem to be always in a period of change. However, only with change is
progress possible. Concern for man himself and his fate must be the chief interest
of all technical endeavors. The solutions to these unsolved problems coming from
the creations of our minds must be a blessing to mankind and not a curse. The
memory of the Silent Spring should be a reminder of our responsibility to future
generations.
The Environment for New Agrochemicals
In our lifetime we have seen a tremendous change in how science is perceived in the
community (5). In the middle decades of the twentieth century science was a major
vitality in our society. Scientists ranked high in our community and what they said
was believed. Scientific knowledge expanded at a tremendous rate. The world's
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0 problems were finding solution through the application of scientific principles. This
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ch knowledge was making life easier and better than ever before for many groups in the
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0 industrialized world. Even in the developing nations, science in the form of medicine
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2- and agriculture was steadily increasing the life span. Hunger was being conquered.
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9 Everyone had a conviction that even the most difficult problems were solvable. This
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bk- was the time of the start of the space and electronic age. For the average person
21/ there was more and more time to enjoy life.
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0.1 Still the same business goes on today, however, many do not have that
oi: 1 confidence and conviction that we will continue to find solutions to the world's
d problems. Today the scientist has lost that stature that he once enjoyed. At the same
92 | time various groups in society have developed which are poorly informed about a
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1 variety of technical issues. Major decisions are often not made according to rational
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2 principles, but by vague intuition or political expediency. The basis of our society
ber is an informed electorate. And with the vast expansion of knowledge most of society
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e: being opposed to anything nuclear, chemical or genetically engineered. Any
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Mankind has always been faced with a changing variety of risks. Science and
technology have contributed toward the reduction of many of the historic major risks.
Modern medicine has minimized many of the old health risks. Life expectancy has
greatly increased to the point that aging processes are now the major cause of death.
Counteracting the effects of aging is the new medical challenge. Modern
transportation has made mankind much more mobile. However, the increase in speed
has generated a variety of new risks. Technology associated with warfare has
brought its own group of risks. Relations between nations are now much more
critical for an increasing variety of reasons. There is an expanding list of economic
and social risks. The steadily increasing population creates another group of risks.
As society becomes more and more complex and interdependent, new risks and
1. BAKER ET AL. Progress in a Time of Change 3
problems are created. The benefits of modern civilization are many, however, this
has created its own challenges for the future. Increasingly, society seems to be
unwilling to accept many of these new risks, however small, even if the benefit is
great. With this seems to come an ever increasing resistance to change.
The media has fostered a disproportionate awareness of risks in those areas
that create headlines. As an example, if an airliner crashes and kills 100 people,
within a few hours most of the world has heard about it. This increased public
awareness has contributed toward making air travel by far the safest form of
transportation in terms of deaths per mile traveled. The death of a single individual
on the highways receives almost no publicity unless the death is unusual for other
reasons. And yet there are over 100 deaths each day on the U. S. highways without
any apparent recognition. Everyone has heard about Chernobyl and the disaster
resulting from that nuclear power plant. However, nuclear power is still the safest
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0 form of electric power generation in terms of deaths or injury per megawatt of
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50 power?
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2- The politicians of the world in general lean in the direction to which most of
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19 their constituencies belong. In the area of risk versus benefit the public is willing to
bk- accept large risks in certain areas, and in other areas there is great public reaction to
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2 very small risks. In general where the risk involves life style choices much greater
0
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0. risk is accepted by the public. The public knows that hundreds of thousands die each
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oi: year due to smoking but does very little about it. Alcohol is almost as bad and even
92 | d ltehsesr eis i sd opnueb lbicy c tohnec peurnb lfioc.r aH roiwske tvheart, iisn rtehlea tcivaesely o mf aingoror.c hOemnliyc arel lfaotoivde clyo nrteacmenintlayt ihoans,
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2, 1 the public's attention been focused on the influence of diet and exercise on long term
er 2 health and well being. This food risk (4) is far greater than from agrochemical
b contamination of our food.
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ate: However, the costs are great to discover and develop these new alternative products.
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Pu increased costs in the registration and re-registration of products, many organizations

are dropping the registrations on those materials that are less profitable. For farmers
growing so-called minor crops, this usually means that there are fewer and fewer
materials that are available and registered for use on these crops.
In any risk benefit analysis dealing with these major issues of society such as
nuclear power, genetic manipulation, and use of agrochemicals the question becomes
"What is the acceptable risk?" In the light of other risks that everyone faces each
day, the risks inherent with agrochemicals must be evaluated (4-7). As an example,
consider the risk of cancer which is many times greater when eating broiled meat
once a week as compared to eating an apple each week with a certain pesticide
residue. What level of risk is perceived as acceptable?
4 SYNTHESIS AND CHEMISTRY OF AGROCHEMICALS III
Agrochemical Safety
In our previous volume we referred to the changing picture concerned with
agrochemical safety. Earlier we have discussed risk-benefit as it relates to
development of new products. This situation has come about by the changing
standards; new laws and regulations at both the federal and state level. Even local
governments are making their own regulations. These new laws and regulations have
greatly increased the costs associated with the registration and manufacture of
agrochemicals in the U. S. Manufacturers are forced to consider which products to
support in light of the time and effort needed for continued registration of the
product. Some new tests cost millions of dollars for just one environmental
investigation. Only those products worthy of such costs continue to be registered.
For the development of new materials these new environmental requirements such as
01 leaching, soil persistence, volatility, and soil surface loss are important
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99 standpoint. The prime targets are those systems which require small amounts of
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21/ The cause of these increasing regulatory expenses is the public perception of
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2 | traditional reserve and put safety issues to the public in a form that can be
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19 understood.
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resistance to enhanced metabolism (11,12). On the other hand, evidence has shown
that, at least with Photosystem II herbicides, strains resistant by virtue of mutation
at the site of binding of competitive inhibitors may be less fit in the environment in
the absence of selection pressure (13). Compounds, which have as their mode of
action an effect at multiple sites in the organism, develop resistance much more
slowly. The major problem with this type compound is the fact that it may also
effect sites in non-target species and there is then the potential for toxicology
problems.
Historically, most of the broad spectrum foliar fungicides were types which
effect multiple sites in the fungi. Resistance is slow to develop for these materials.
However, most of these compounds have toxicology problems of one type or another.
Resistance management strategies are evolving to accommodate these various types.