PREFACE his book contains the full manuscripts of the 23 papers
presented
•*· during the symposium "Advances in Industrial and Laboratory Nitrations" held in Philadelphia on April 7 and 8, 1975, as part of the 169th Downloaded via 5.62.155.134 on September 28, 2018 at 00:52:32 (UTC). See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.
Annual Meeting of the American Chemical Society, under the sponsorship of the Division of Industrial and Engineering Chemistry. T h e E d i tors had the honor of acting as cochairmen of the symposium. Publication of the proceedings will make the papers available to an even wider audience than the large and international one present in Philadelphia. W h y should a meeting on industrial nitration chemistry have been timely? Nitration, particularly of aromatic hydrocarbons, was one of the earliest unit processes to be operated on a large scale when the heavy organic chemical industry first developed last century.
It has played an
equally important part in the development of our present understanding of the mechanism of organic reactions, offering an ideal example of electrophilic substitution and being most elegantly researched
during the
1940's and 1950s in the classic investigations of Professor C . K . Ingold and his associates at University College, London (J. Chem. Soc. (Brit.) 1950, 2400-2473; 1950, 2628-2684; 1952, 28-32; and 1958, 4357-4374). Despite a long history of industrial application and the extensive study of nitration mechanisms, many questions remain to be answered, and the last decade has seen a resurgence of interest in the chemistry of the process, particularly under the conditions employed in industry. Having worked together for a considerable number of years, we came to the conclusion that the time was ripe on both sides of the Atlantic Ocean for a major international meeting aimed at reviewing our present state of knowledge and at convening the chemists and chemical engineers, from both industrial and academic establishments, who have been working on the subject. The Philadelphia symposium was the result. W e were particularly concerned about providing a medium for interaction among all scientists—of whatever discipline or employment—who had something to offer toward a better understanding of nitration reactions under industrial conditions. There have been previous meetings on nitrations, but we feel this to be the first at which such a wide spectrum of sources was sought and obtained. The first group of papers, Chapters 1-10 of this book, emphasize various aspects of the chemistry and the mechanism of different nitrations.
Information on side reactions, including oxidation, and on ipso ix
Albright and Hanson; Industrial and Laboratory Nitrations ACS Symposium Series; American Chemical Society: Washington, DC, 1976.
nitrations is discussed by several authors; such information should be most helpful in clarifying certain features of the overall process.
During
the symposium, the results of Ingold and associates were referred to on numerous occasions; they had clearly shown that the nitronium ion, N0
2
+
,
is an excellent nitrating agent.
They also indicated the nitro-
sonium ion, N O , can be used in the nitration of easily nitratable aro+
matics including phenols or phenol ethers.
Other ions which result in
nitrations have also now been reported in Chapter 1. The
second broad grouping of papers (Chapters 11-16) considers
both the chemistry and physical transfer steps between phases which often occur during nitration. In aromatic nitrations using mixed acids, for example, the presence of two immiscible liquid phases complicates the nitration reaction. Agitation to emulsify the two phases is necessary to obtain adequate contact between the hydrocarbon and the nitrating species.
Transfer of reactants and products, heat transfer, nature of
emulsion, etc. are key factors. Chapters 17-24 consider various aspects of plant operation.
Process
improvements, safety features, and new processes are discussed; in several cases nitration chemistry is also presented. The present volume contains two papers in addition to those formally presented at the symposium. T h e first (Chapter 24)
concerns develop-
ment of an industrial nitration plant employing injectors for mixing the liquid streams. While an offer of this paper was received prior to the symposium, there was insufficient notice for it to be incorporated into the program. Nevertheless, we feel it to be of interest and direct relevance to the symposium and so have included it for the benefit of the reader. The second paper (Chapter 25) is devoted to vapor phase nitrations and was presented at an earlier American Chemical Society meeting. Since the papers presented at the symposium were concerned primarily with liquid phase processes, we thought that, because of their industrial importance, vapor phase nitrations should be included also. In conclusion, we would like to thank all who made possible the symposium and this subsequent publication: firstly, the Division of Industrial and Engineering Chemistry for sponsorship; equally important, the authors, without whom it could never have existed; and finally, those who have worked behind the scenes, particularly our two secretaries, Mrs. Diane Kneile (West Lafayette)
and Mrs. P. A . Matthews (Bradford),
who have been burdened with considerably more than their normal duties as a result. LYLE
CARL HANSON
F . ALBRIGHT
West Lafayette, Ind. U S A
Bradford
October
England
1975 x
Albright and Hanson; Industrial and Laboratory Nitrations ACS Symposium Series; American Chemical Society: Washington, DC, 1976.
