W. E. Billups

Birch reduction of graphite. Edge and interior functionalization by hydrogen.

The Birch reduction (lithium in liquid ammonia) of graphite gives a highly reduced, exfoliated product that is free of lithium. Edge and interior hydrogenation were demonstrated by solid-state (13)C NMR spectroscopy. Elemental analysis of a carefully purified sample allows the chemical composition to be expressed as (C(1.3)H)(n). Atomic force microscopy images showed that the reduced graphene was highly exfoliated. Hydrogen mapping by electron energy loss spectroscopy showed that the entire surface of the reduced sample was covered by hydrogen, consistent with the NMR studies also indicating that hydrogen was added in interior positions of the graphene lattice as well as along the edge. A large band gap (4 eV) further establishes the high level of hydrogenation.

Palladium Catalyzed Allylation of Indole

Abstract The palladium catalyzed transfer of allyl groups between active hydrogen compounds is well documented,1 and recent applications of the intramolecular counterpart of this reaction as key steps in the total synthesis of exaltolide2 and desethyli-bogamine3 demonstrate useful synthetic applications of the method. We now wish to report some of our results describing the palladium catalyzed allylation of indole.

The Synthesis and Characterization of Fullerene Hydrides

The syntheses and characterization of fullerene hydrides prepared from C60 and C70 are reviewed. Methods of isolation and characterization are discussed, particularly MS and NMR, including 3He nuclear magnetic resonance spectroscopy. The higher hydrides are discussed in terms of novel structural features and their unusual spectroscopic properties.

3He NMR spectra of highly reduced C60

Two signals were observed in the 3He NMR spectrum of 3He@C60H36. The major signal corresponds with the 3He chemical shift calculated for a structure with D3d′ symmetry.

Uses of adsorbed reagents in the synthesis of reactive molecules via elimination reactions

Abstract The synthesis of reactive molecules (in vacuo) using reagents adsorbed on inert surfaces to effect elimination reactions has been investigated. Potassium t-butoxide adsorbed on Chromosorb W can be used to generate methylenecyclopropene from 2-chloromethylenecyclopropane and 1-vinylcyclopropene from either 1,4-dichlorospiropentane or 1-chloro-2-vinylcyclopropane. Both compounds can be characterized at low temperature using NMR and IR spectroscopy. Methyllithium on glass helices has been used in the reductive elimination of halogen from vicinal cyclopropyl dihalides to yield cyclopropenes. β-Halocyclopropylsilanes can be converted in high yield to the corresponding cyclopropene using tetra-n-butylammonium fluoride deposited on glass helices. The fluoride route has been used to generate bicyclo[4.1.0]hept-(1,6)-ene and bicyclo[4.1.0]hept-(1,7)-ene in the gas phase under conditions which allow either spectroscopic characterization or trapping as Diels-Alder adducts.

Reduction of C60 using anhydrous hydrazine

Abstract Buckminsterfullerene (C 60 ) can be reduced by anhydrous hydrazine to yield a mixture of C 60 H 2 , C 60 H 4 and other more highly reduced fullerenes.

1-bromo-2-chlorocyclopropene--A new cycloproparene synthon. Synthesis of 1H-Cyclopropa[b]phenanthrene

Abstract Treatment of 1-bromo-2,2-dichloro(trimethylsilyl)cyclopropane (2) with tetra- n -butylammonium fluoride in tetrahydrofuran yields 1-bromo-2-chlorocyclopropene (1). 1H-Cyclopropa[b]phenanthrene (3) can be prepared by aromatization of the Diels-Alder adduct of 1 and 1,2-dimethylene-3,5,6,7,8,9-hexahydronaphthalene (6) using DDQ followed by potassium t -butoxide in tetrahydrofuran.

Water-Soluble Nanodiamond

Reduction of the graphenic edges of annealed nanodiamond by sodium in liquid ammonia leads to a nanodiamond salt that reacts with either alkyl or aryl halides by electron transfer to yield radical anions that dissociate spontaneously into free radicals and halide. The free radicals were observed to add readily to the aromatic rings of the annealed nanodiamond. Nanodiamonds functionalized by phenyl radicals were sulfonated in oleum, and the resulting sulfonic acid was converted to the sodium salt by treatment with sodium hydroxide. The solubility of the salt in water was determined to be 248 mg/L. Nanodiamond functionalized by carboxylic acid groups could be prepared by reacting 5-bromovaleric acid with the annealed nanodiamond salt. The solubility of the sodium carboxylate in water was found to be 160 mg/L.

Generation of simple methylenecyclopropenes as reactive intermediates

Abstract The dehydrochlorination of either 1,2 - dichloro - 1 - methylcyclopropane or 1 - bromo - 2 - chloro - 2 - methylcyclopropane with potassium t-butoxide yields 2 - t - butoxy - 1 - methylenecyclopropane. These results are interpreted in terms of methylenecyclopropene as a reactive intermediate which is trapped by addition of nucleophile (t-butoxide) to the cyclopropenyl double bond. The introduction of methanethiol to the reaction medium yields 2 - thiomethyl - 1 - methylenecyclopropene 2,2 - Dichloro - 1 - methylenecyclopropane reacts with potassium t-butoxide in tetrahydrofuran to yield trans- and cis - t - butoxybut - 1 - ene - 3 - yne. The addition of thiomethide ion results in the formation of 2,2 - bis(thiomethyl) - 1 - methylenecyclopropane and 2 - t - butoxy - 2 - thiomethyl - 1 - methylenecyclopropane. Other evidence for simple methylenecyclopropenes as reactive intermediates comes from the observation that nucleophiles add nonregiospecifically to the reactive intermediate produced by the dehydrohalogenation of 2 - halo - 1 - alkylidenecyclopropanes. Novel methylenecyclopropane→ cyclopropene transformations were found in the reaction of 2 - halomethylenecyclopropanes with thiomethide ion.

Pathways for the thermally induced dehydrogenation of C60H2

Abstract The thermolysis of C 60 H 2 to yield C 60 and H 2 was studied by hybrid density functional theory (B3LYP/6-311G**//B3LYP/3-21G). The concerted loss of dihydrogen requires an activation energy of 92 kcal mol −1 at T =452 K. An alternative radical mechanism, which is first order in the C 60 H 2 concentration, has an activation energy at 452 K of only 61 kcal mol −1 . Monitoring of the C 60 H 2 decomposition in 1,2-dichloro-[D 4 ]-benzene solution by NMR spectroscopy indicates a pseudo first-order reaction with an activation energy of 61.38±2.35 kcal mol −1 .