Secondary Kinetic Isotope Effects in Bimolecular Nucleophilic Substitutions. VI. Effect of α and β Deuteration of Alkyl Halides in their Menschutkin Reactions with Pyridine in Nitrobenzene

Abstract

A survey of kinetic, secondary deuterium isotope effects, for a, ,!I, and y deuterated alkyl halides reacting with pyridine in nitrobenzene solvent has been made. a-Deuterium effects have been measured for eight compounds, P-deuterium effects for four compounds, and one rate ratio for y-deuteration is reported. The possible errors in the rate ratios for b-deuterated compounds, resulting from the elimination side reaction have been determined. The results are discussed in terms of transition state structure.Une etude sur la cinetique des effets isotopiques secondaires du deuterium a kt6 effectuee sur les halogenures d'alkyle a, /I, et y deuteres qui reagissent avec la pyridine dans le nitrobenzine. Les effets du deuterium en a ont ete mesures au moyen de huit composes, les effets du deuterium en au moyen de quatre composes, et on rapporte un rapport de vitesse pour la deuteration en y. Leserreurs possibles dans les rapports de vitesse pour les composes ,!I-deuterts, et qui resultent d'une reaction annexe d'elimination, ont ete determinees. Les resultats sont discutes en fonction de la structure de I'etat de transition.Canadian Journal of Chemistry, 50,986 (1972) Introduction Although many secondary deuterium isotope effects have been measured for nucleophilic substitutions at saturated carbon, systematic studies involving changes in the leaving group, the alkyl group, and the position of deuteration are not common. Robertson and co-workers (1-4) have provided the most complete set of data for sclvolysis reactions in water of alkyl halides and sulfonates, and Brown and McDonald (5) have reported a series of measurements on various substituted deuterated pyridines reacting with alkyl iodides in nitrobenzene solvent. This paper presents a set of isotopic rate ratios for the reaction of a single nucleophile pyridine, with various deuterated alkyl compounds in the same solvent, nitrobenzene.

Secondary kinetic deuterium isotope effect in oxidative addition reaction of cycloplatinated(II) complexes with MeI

“…These are typical values for an S N 2 reaction [23e26] and also is consistent with the earlier results obtained for similar reactions such as the Menschutkin-type reactions of methyl halides with different nucleophiles [27,28] (KIEs ¼ 0.93e1.11), the reduction of MeI with hydride ion [29] (KIEs ¼ 0.98e1.056), the oxidative addition reaction of Vaska's compound, (Ph 3 P) 2 Ir(CO)Cl, with MeI ¼ 0.91e1.11). It should also be noted that higher KIE values are usually expected for reactions between metal complexes and MeI when proceeding by a radical mechanism [29].…”

SN2 and E2 Branching of Main-Group-Metal Alkyl Intermediates in Alkane CH Oxidation: Mechanistic Investigation Using Isotopically Labeled Main-Group-Metal Alkyls

“…In contrast, from 8 , the E2-type reaction involves cleavage of a C–H bond and the ratio of 4 to 7 would be expected to be more similar to that from the putative intermediate, EtTl­(TFA) 2 . No attempts at highly accurate quantitative analyses of the difference among 4 , 10 , and 7 from 2 or 8 were made, as secondary kinetic isotope effects (SKIEs) could be possible on both the S N 2 and E2-type pathways. , The SKIEs observed with 2 and 8 are consistent with literature reports for S N 2 and E2 reactions from alkyl halides. − When these functionalizations are carried out at room temperature, the intermediate species 5 and 6 are observed immediately after mixing, in both cases, in an ∼1:1 ratio (Figure , spectrum B for 2 and spectrum D for 8 ). This is evidence for the formation of free ethylene, as CH 2 CD 2 generated from either 2 or 8 should add to Tl­(TFA) 3 in a 1:1 ratio as the SKIE for addition would be expected to be small.…”

Study of the Diels–Alder and retro-Diels–Alder reaction between furan derivatives and maleimide for the creation of new materials

“…For this study, the temperature, which is the easier way for industrialization, has been chosen. Systems such as the urethane group, 4 nitroso group, 5 ester group, 6 ionene complex, [7][8][9][10] azlactone-phenol adduct 11,12 and, lastly, the Diels-Alder adduct [13][14][15][16][17][18] allow the formation of reversible covalent bonds under high temperature conditions. The Diels-Alder system was chosen for this project, in spite of existing studies, 14,[19][20][21] because this is the most famous and the easier system.…”