The First, General, Highly Efficient Method for Preparing Tetrasubstituted Epoxides Using HOF×CH<sub>3</sub>CN.

Rozen, Shlomo; Golan, Elizabeth

doi:10.1002/chin.200337043

Cited by 2 publications

(2 citation statements)

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“…Hypofluorous acid, HOF can be synthesized by controlled oxidation of water with molecular fluorine and is used as a selective oxidant. , A recent theoretical study had focused on a range of singlet excited states of HOF . At the CCSD(T)/aug-cc-pVQZ level of theory, its first excited triplet (A″) state of (π*,σ*) type is calculated to be 42.2 kcal mol –1 above the singlet ground state.…”

Section: Results and Discussionmentioning

confidence: 99%

(π,σ), (σ,π) and Rydberg Triplet Excited States of Hydrogen Peroxide and Other Molecules Bearing Two Adjacent Heteroatoms

Hill

Bucher

2014

J. Phys. Chem. A

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The properties of the lowest triplet excited states of a series of small molecules containing two or more adjacent heteroatoms have been investigated. High-level coupled cluster and MRCI+Q calculations were employed to probe the properties of the triplet excited states of hydrogen peroxide, hydrazine, hydroxylamine, fluoroamines, oxygen difluoride, hypofluorous acid, chlorine, fluorine, and disulfane. All of the molecules investigated except hydroxylamine are predicted to have bound lowest triplet excited states that are either (π*,σ*) or (σ*,π*) as in H2O2, HOF, OF2, H2S2, Cl2, NH2F, NHF2, or NF3, or are Rydberg states (hydrazine, also H2O2 and H2S2). The heteroatom-heteroatom bond dissociation enthalpies of the triplet states range from very small values as predicted for hydrogen peroxide or fluorine, to BDEs around 8-9 kcal mol(-1) that should allow for an experimental observation of the triplet state, such as in disulfane or monofluoroamine. For all triplet minima investigated except NF3 and F2, CCSD(T) gave results in agreement with the multireference method MRCI+Q, and in excellent agreement with available experimental data (BDEs, ground-state geometries). Due to multireference problems, CCSD(T) does not provide a good description for longer heteroatom-heteroatom distances, and in some cases (e.g., Cl2) it wrongly predicts the presence of a transition state for bond formation on the triplet spin manifold, where the reaction is known experimentally and, as predicted by MRCI+Q, is known to be barrierless. Finally, the (3)Π(u) state of F2 is poorly described by CCSD(T) theory, the equilibrium bond distance is significantly underestimated relative to MRCI+Q, and CCSD(T) places the triplet state above the energy of two fluorine atoms. The T1 diagnostic, frequently used to assess the quality of CCSD(T) calculations, does not appear to provide a valid criterion for the systems studied. The formation of H2O2 on the triplet potential energy hypersurface might possibly open up an additional channel for formation of hydrogen peroxide from two hydroxyl radicals. Due to a low density of states in triplet H2O2, and due to competing formation of water + O((3)P) from a hydrogen-bridged HO···HO triplet radical pair, such a reaction channel probably only can play a role at low temperatures.

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Section: Results and Discussionmentioning

confidence: 99%

(π,σ), (σ,π) and Rydberg Triplet Excited States of Hydrogen Peroxide and Other Molecules Bearing Two Adjacent Heteroatoms

Hill

Bucher

2014

J. Phys. Chem. A

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“…Similarly, tetraphenylcyclopentadienone (3) and 2-cyclopentylidenecyclopentanone (4) were converted to the corresponding diepoxides 5 and 6 in 85% and 92% yields, respectively (Scheme 1). 20 Another interesting comparison with DMDO is the epoxidation of cyclooctatetraene (7). In the past, it was fully epoxidized to the tetraoxide 8 by excess of dioxirane, but that was achieved only after 17 days (almost 15 × 10 5 s).…”

Section: ■ Epoxidationsmentioning

confidence: 99%

HOF·CH₃CN: Probably the Best Oxygen Transfer Agent Organic Chemistry Has To Offer

Rozen

2014

Acc. Chem. Res.

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The complex HOF·CH3CN is readily obtained by bubbling dilute fluorine into aqueous acetonitrile solution. It does not have to be purified or isolated, and its solution can react as is, after the concentration has been establish by any iodometric method. It is the only reagent possessing a distinctive positive oxygen species. This enables electrophilic oxygen transfer with results no other reagent can match. HOF·CH3CN demonstrates its ability in epoxidations that either could not be performed before or could only obtained 5 orders of magnitude slower. This complex is also an excellent tool for oxygenation of compounds at the α position of a carbonyl, including the synthesis of some hard-to-come-by indanediones, which are important for fingerprint visualization on paper. HOF·CH3CN proves itself as a very efficient reagent for oxygenating tertiary nitrogen atoms both in aliphatic (including azides) and in aromatic amines, which could not be accomplished despite many attempts in the last 50 years. Oxygenation of two tertiary nitrogen atoms in the same molecule also becomes feasible as demonstrated for various phenanthrolines, bipyridines, diazafluorenones, and quinoxalines. It was also used to oxygenate primary amines, and because of the exceptionally mild conditions, it could transform vicinal aliphatic diamines to vicinal dinitro derivatives as well as amino acids to the corresponding nitro ones, practically unknown transformations before. Its ability to react with azines and hydrazones and convert them to the original carbonyls helped to establish these groups as good protecting tools for a variety of carbonyls. HOF·CH3CN excels in oxygenation of various sulfur and selenium compounds that could not be oxygenated in the past. The selectivity of the oxidation is quite good, and if there are alcohols, double bonds, and sulfides in the same molecule, usually the sulfur atom will be attacked first. Of special interest is the reaction with oligothiophenes resulting at will in either [all]-S,S-dioxooligothiophenes or in partially oxygenated ones. Some of these last derivatives have the narrowest HOMO-LUMO gap of all oligothiophenes tested, a very desirable feature. This reagent can also oxidize thiols or disulfides to either sulfonic or sulfinic acids at will, all in seconds and in very high yields. Since the oxygen atom of HOF·CH3CN originates in water, it is very easy and relatively inexpensive to introduce the heavy oxygen isotope in many sites of a variety of molecules, some of them quite important. The (18)O tirapazamine and any desirable alcohol, R(Ar)(18)OH, are two examples.

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The First, General, Highly Efficient Method for Preparing Tetrasubstituted Epoxides Using HOF×CH₃CN.

Cited by 2 publications

References 1 publication

(π,σ), (σ,π) and Rydberg Triplet Excited States of Hydrogen Peroxide and Other Molecules Bearing Two Adjacent Heteroatoms

(π,σ), (σ,π) and Rydberg Triplet Excited States of Hydrogen Peroxide and Other Molecules Bearing Two Adjacent Heteroatoms

HOF·CH₃CN: Probably the Best Oxygen Transfer Agent Organic Chemistry Has To Offer

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The First, General, Highly Efficient Method for Preparing Tetrasubstituted Epoxides Using HOF×CH3CN.

Cited by 2 publications

References 1 publication

(π*,σ*), (σ*,π*) and Rydberg Triplet Excited States of Hydrogen Peroxide and Other Molecules Bearing Two Adjacent Heteroatoms

(π*,σ*), (σ*,π*) and Rydberg Triplet Excited States of Hydrogen Peroxide and Other Molecules Bearing Two Adjacent Heteroatoms

HOF·CH3CN: Probably the Best Oxygen Transfer Agent Organic Chemistry Has To Offer

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The First, General, Highly Efficient Method for Preparing Tetrasubstituted Epoxides Using HOF×CH₃CN.

(π,σ), (σ,π) and Rydberg Triplet Excited States of Hydrogen Peroxide and Other Molecules Bearing Two Adjacent Heteroatoms

(π,σ), (σ,π) and Rydberg Triplet Excited States of Hydrogen Peroxide and Other Molecules Bearing Two Adjacent Heteroatoms

HOF·CH₃CN: Probably the Best Oxygen Transfer Agent Organic Chemistry Has To Offer