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The bipyridinium herbicides
PES.FlClDE
BIOCHEMISTRY
AND
PHYSIOLOGY
15,
99-100 (1981)
Book Reviews The Bipyridinium Herbicides. L. A. Summers, Academic Press, London/New York/Toronto/ Sydney/San Francisco, 1980. 449 pp., $69.00. This work attempts, with great success, to bring together and integrate the relevent literature on all aspects of the bipyridinium herbicides and related compounds. The book introduces the bipyridinium compounds with the discovery of their herbicidal properties which overshadowed their historical importance as oxidation-reduction indicators. The first four chapters are very complete in their coverage of the literature and are written in a clear and understandable manner with many chemical structures and tables interspersed throughout the text to enhance comprehension of the points being discussed. The literature relevent to the structure and chemistry of the 2,2’- and 4.4’-bipyridines is effectively separated throughout the work which should be an aid to those interested in only one class of the compounds. Synthesis, chemical and physical properties, purification, and nomenclature of all of the diquatemary salts are discussed. Techniques for synthesis of radiolabeled compounds are included for those with interest in this area. Chemical structure and herbicidal activity are treated in depth in Chapter 5. Not unexpectedly much discussion centers on the importance of radical formation, molecular configuration, and oxidation-reduction potential as these determine herbicidal activity. Patent compounds are mentioned but not discussed since knowledge from similar compounds would suggest a lack of herbicidal activity. The latter half of the book concentrates on the commercial bipyridinium herbicides, paraquat, diquat, and morfamquat. The clarity of the first half of the book where the many figures help to visualize structures and reactions contrasts with the verbal presentation in the last chapters. A fairly detailed treatise is presented on fate of the bipyridiniums in soil, water, plants, and animals; analytical techniques and problems in all substrates; herbicidal applications; physiology and mode of action: and toxicology and the environment. Literature on paraquat and diquat adsorption by clay minerals is informatively integrated with literature on charge distribution within the bipyridiniums and the need for more definitive studies is implied. Impairment of soil fertility by saturation of the exchange sites in soil or leaching of the diquatemary cations to groundwater is extensively discussed and summarized. The fate of the bipyridiniums in other substrates and contamination of the food chain is
likewise discussed and the margins of safety of these herbicides when used as intended is indicated. The analytical methods for detection of the bipyridinium herbicides are extensively reviewed in a separate chapter and the informative discussion on their associated problems should prove useful to analysts. The physiology and mode of action of the bipyridinium herbicides are presented in detail but the judicial use of figures would have more succinctly presented the information. Repetition among chapters is quite evident which appears deliberate since the author intended the work to serve as a reference source and for supplementary reading for scientists and students in their respective disciplines. In most cases a good summary of pertinent points is found at the end of each section. The repetition contributed to the length of the book but many chapters contain statements which present no information except to include a reference to the literature. Some minor spelling, editing, and grammatical errors were found but considering the length of the treatise these were not serious and did not detract from an understanding of the subject matter. A notable example is found in Chapter 9, where the reporting of concentrations was inconsistent and in some cases the units had been omitted. One obvious omission in the discussion relates to possible nitrosamine formation with the bipyridiniums or their metabolites. Reference is made to the observation that some plant species accumulate nitrite when treated with photosynthetic-inhibiting herbicides yet no discussion or mention of possible nitrosamine formation is presented. Considering the late interest in this subject the lack of data on nitrosation of metabolites of the bipyridinium herbicides or the need fat further research deserved comment. The objective of the author to produce a single work uniting all aspects of the bipyridinium compounds has been accomplished. Those working with the bipyridinium herbicides will find the book a valuable single reference source while those associated with weed science and related disciplines will find selected chapters useful for supplementary reading. Unfortunately, the book will have limited utility because of its narrow subject matter and cost. JOHN
GAYNOR
Reseurch St&ion Agriculture Cunudu Hurrobv, Ontario NOR
IGO.
Cnnudo
99 004%3575/81/010099-02$02.00/O Copyright 0 1981 by Academic Press. Inc. All rights of reproduction in any form reserved.
BIOCHEMISTRY
AND
PHYSIOLOGY
15,
99-100 (1981)
Book Reviews The Bipyridinium Herbicides. L. A. Summers, Academic Press, London/New York/Toronto/ Sydney/San Francisco, 1980. 449 pp., $69.00. This work attempts, with great success, to bring together and integrate the relevent literature on all aspects of the bipyridinium herbicides and related compounds. The book introduces the bipyridinium compounds with the discovery of their herbicidal properties which overshadowed their historical importance as oxidation-reduction indicators. The first four chapters are very complete in their coverage of the literature and are written in a clear and understandable manner with many chemical structures and tables interspersed throughout the text to enhance comprehension of the points being discussed. The literature relevent to the structure and chemistry of the 2,2’- and 4.4’-bipyridines is effectively separated throughout the work which should be an aid to those interested in only one class of the compounds. Synthesis, chemical and physical properties, purification, and nomenclature of all of the diquatemary salts are discussed. Techniques for synthesis of radiolabeled compounds are included for those with interest in this area. Chemical structure and herbicidal activity are treated in depth in Chapter 5. Not unexpectedly much discussion centers on the importance of radical formation, molecular configuration, and oxidation-reduction potential as these determine herbicidal activity. Patent compounds are mentioned but not discussed since knowledge from similar compounds would suggest a lack of herbicidal activity. The latter half of the book concentrates on the commercial bipyridinium herbicides, paraquat, diquat, and morfamquat. The clarity of the first half of the book where the many figures help to visualize structures and reactions contrasts with the verbal presentation in the last chapters. A fairly detailed treatise is presented on fate of the bipyridiniums in soil, water, plants, and animals; analytical techniques and problems in all substrates; herbicidal applications; physiology and mode of action: and toxicology and the environment. Literature on paraquat and diquat adsorption by clay minerals is informatively integrated with literature on charge distribution within the bipyridiniums and the need for more definitive studies is implied. Impairment of soil fertility by saturation of the exchange sites in soil or leaching of the diquatemary cations to groundwater is extensively discussed and summarized. The fate of the bipyridiniums in other substrates and contamination of the food chain is
likewise discussed and the margins of safety of these herbicides when used as intended is indicated. The analytical methods for detection of the bipyridinium herbicides are extensively reviewed in a separate chapter and the informative discussion on their associated problems should prove useful to analysts. The physiology and mode of action of the bipyridinium herbicides are presented in detail but the judicial use of figures would have more succinctly presented the information. Repetition among chapters is quite evident which appears deliberate since the author intended the work to serve as a reference source and for supplementary reading for scientists and students in their respective disciplines. In most cases a good summary of pertinent points is found at the end of each section. The repetition contributed to the length of the book but many chapters contain statements which present no information except to include a reference to the literature. Some minor spelling, editing, and grammatical errors were found but considering the length of the treatise these were not serious and did not detract from an understanding of the subject matter. A notable example is found in Chapter 9, where the reporting of concentrations was inconsistent and in some cases the units had been omitted. One obvious omission in the discussion relates to possible nitrosamine formation with the bipyridiniums or their metabolites. Reference is made to the observation that some plant species accumulate nitrite when treated with photosynthetic-inhibiting herbicides yet no discussion or mention of possible nitrosamine formation is presented. Considering the late interest in this subject the lack of data on nitrosation of metabolites of the bipyridinium herbicides or the need fat further research deserved comment. The objective of the author to produce a single work uniting all aspects of the bipyridinium compounds has been accomplished. Those working with the bipyridinium herbicides will find the book a valuable single reference source while those associated with weed science and related disciplines will find selected chapters useful for supplementary reading. Unfortunately, the book will have limited utility because of its narrow subject matter and cost. JOHN
GAYNOR
Reseurch St&ion Agriculture Cunudu Hurrobv, Ontario NOR
IGO.
Cnnudo
99 004%3575/81/010099-02$02.00/O Copyright 0 1981 by Academic Press. Inc. All rights of reproduction in any form reserved.