CCLXVII.—Influence of directing groups on nuclear reactivity in oriented aromatic substitutions. Part II. Nitration of toluene

Abstract

UNTIL four years ago, data for the proportions in which isomerides are simultaneously formed in aromatic hydrogen-substitutions contributed the only direct, quantitative experimental basis for the numerous theories of the process which had at various times been advanced. At the period mentioned the broad lines of the modern view had been laid down; and not only was this view no exception t o the preceding statement, but also many theoretical details which have subsequently been filled in have arisen from the determination of further d.ata of the same type. I n 1927, however, the view that continued development of the theory would require the consideration, not only of proportions of isomerides, but also of relative velocities of substitution, led to the publication of Part I (Ingold and Shaw, J., 1927, 2918), in which data of the latter kind were submitted for a number of benzene derivatives having single orienting substituents of widely differing structural types.Proportions of isomerides, which are also ratios of their rates of formation,? are regarded as giving only the ratios of magnitudes which individually relate t o the effect of the substituent on reactivity at the different nuclear positions. The speed of total substitution relatively to that of benzene, in short, the " reduced " velocity of substitution, yields the sum of such magnitudes. Only when both the ratios and the sum are known can the individual effects be defined, and the influence of the substituent on nuclear reactivity ROTHSTEIN, arid DENIS WARD. * The first of these studies, called Part I in the text, was published in another series under the specific title " A n Attempt further to define the Probable Mechanism of Aromatic Substitution." -f This is true provided that the simultaneous substitutions are reactions of the same order and are irreversible, which are the conditions contemplated ; it is known that normally these conditions are fulfilled for nuclear nitration and halogenation.

Kinetics, Thermodynamics, and the Problem of Selectivity: The Maturation of an Idea

“…Those relative rates, however, will only be time‐independent if the competing reactions are all of the same kinetic order. To my knowledge, this idea was first stated by Ingold et al in 1931 8. If the rates are of different orders, the product ratio in general will change with time, as not all of the concentration terms in the rate equations for the competition will cancel.…”

“…Among these were several studies of allylic rearrangements 26. 8, 27–30 In the interest of brevity, we omit a detailed description of those important results in order to focus on a stereochemical issue of broad significance (Section 7).…”

Kinetik, Thermodynamik und das Problem der Selektivität: vom Reifen einer Idee

“…Hier kann man auf einige wenige frühe Beispiele, z. B. auf einige Arbeiten zu Allylumlagerungen, [26,8,[27][28][29][30] verweisen, in denen sich zeigt, dass eine oder mehrere der Ideen vollauf verstanden worden sind. Wir verzichten hier auf eine eingehende Beschreibung dieser wichtigen Ergebnisse und wenden uns im folgenden Abschnitt stattdessen einem stereochemischen Problem von weitreichender Bedeutung zu.…”

“…[26,38,8,[27][28][29][30] Bis zum Erscheinen eines Artikels von Woodward und Baer im Jahr 1944 über die Diels-Alder-Reaktion [39] gab es aber kaum einen Versuch, die allgemeinen Prinzipien präzise darzulegen. Diese Autoren hatten beobachtetet, dass die Addition von Pentamethylenfulven (3) an Maleinsäureanhydrid (4) [40] und Alder und Trimborn publizierten die Ergebnisse der Dissertation Trimborns letztlich im Jahr 1950.…”

General Introduction

“…The so-called "normal laws" of aromatic substitution have been established mainly as the result of studies of nitration. (Ingold, 1934;Bird and Ingold, 1938;Ingold and Smith, 1938;Ingold, Lapworth, Rothstein and Ward, 1939;Hughes, Ingold and Reed, 1950;Bennett, Brand and Williams, 1946;Bennett, Brand, James, Saunders and Williams, 1947;Roberts, Sandford, Sixma, Cerfontein and Zagt, 1954.) On both theoretical and experimental grounds a directing group (X) attached to the aromatic nucleus in the compound C e H 5 X, may be placed in one of two main categories.…”