Ions, viii

Levsen, K. Heimbach, H. Shaw, G.J. MUne, G.W.A. Isomerization of Hydrocarbon Ions. VIII. The Electron Impact Induced Decomposition of n-Dodecane. Org. Mass Spectrom. 1977, 72, 663-670. 

Winstein and coworkers14 have introduced a variable termed the driving force, L, attributable to participation of a neighboring group in the rate-determining step, which is a measure of the decrease in free energy attended by the conversion of an open carbonium ion (VIII) to the cyclic carbonium ion (VII). The driving force was defined as... 

VII, and kc is the specific, rate constant for the ionization to the open carbonium ion VIII. In order to calculate the driving force L for the ions... 

The key to Favorskii transpositions is a transient cyclopropanone. In this case, the cyclopropanone would be obtained by means of an odd, although not unprecedented, route based on the interaction of carbene and epoxide as indicated in Scheme 43.2. In fact, we observed for the first time some years ago that diazoketone VI was converted to enone IX upon exposure to copper bronze in refluxing benzene, presumably via oxetonium ion VIII. ... 

Perhaps Wemer s tour de force in the area of polynuclear cobalt(III) complexes was his successful resolution of the hexoP ion (VIII). He prepared this ion and its ethylenediamine analog by heating a basic solution of m-diaquotetramminecobalt(III) sulfate and deduced its structure by observing that the acid cleavage gave back the cis-diaquo complex and cobaltous ion (37). He later resolved the ion into its optical antipodes with d-camphor sulfonic acid and d-bromocamphor sulfonic acid and obtained the D- and l- forms as the bromides (35). His successful resolution... 

Smith, G.P., L.C. Lee, and P.C. Cosby, Photodissociation and photodetachment of molecular negative ions, VIII. Nitrogen oxides and hydrates. J Chem Phys 71, 4464, 1979. 

AHR7LAR] Ahrland, S., Larsson, R., Rosengren, K., On the complex chemistry of the uranyl ion VIII. The complexity of uranyl fluoride, Acta Chem. Scand., 10, (1956), 705-718. Cited on page 283. 

F. J. Field, Reactions of gaseous ions. VIII. Multiple-order Ion-molecule reactions in the ultra-high-pressure mass spectrum of ethylene, J. Am. Chem. Soc. 83, 1523-1534 (1961). 

The acylium ion is particularly stable and generally does not easily undergo rearrangement reactions unlike F-C alkylations. If the acylium ion VIII can produce an especially stable carbocation and reacted with an arene of modest reactivity, side products can form via a competing F-C alkylation pathway. An example of such is the competing F-C acylation-alkylation pathways in the attempted pivaloylation of neat benzene versus anisole. The reaction of benzene with pivaloyl chloride in the presence of AICI3 catalyst produces ter/-butylbenzene as the major product, whereas the reaction of... 

Simple olefins are very inert to attack by nucleophiles. However, an olefin coordinated to an electrophile, as in the bromium or mercurinium ions (VIII, X = Br+ or Hg ), is well known to be readily attacked by nucleophiles, and... 

In a neutral or alkaline medium containing water, a 1,2-cis halide is replaced by hydroxyl with inversion. In the 1,2- mns situation, a hydroxyl ion can combine with the orthoester ion (VIII) to give a 1,2-hydrogen orthoacetate (IX) (66) which then isomerizes to a 2,3,4,6-tetra-O-D-glycopyranosyl acetate (X) without inversion of the carbon atom at position 1. In alcohol the situation is the same except that the alkyl orthoacetate (XI) is stable (67), Additional support for these speculations is given by Ness, Fletcher, and Hudson (71) in their work on replacement reactions with the tri-O-benzoylaldopentopyranosyl halides (see p. 198). 

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