Diphenyl Selenoxide Research Articles

Diphenyl selenoxide: Unraveled peculiarities in methanol and acetonitrile solutions

We hereby report the volumetric, spectroscopic (UV–Vis, FTIR), and voltammetric properties together with the comprehensive atomistic simulations of diphenyl selenoxide (Ph2SeO) in acetonitrile (ACN) and methanol (MEOH). The solvation effects manifested through densimetry, UV–Vis, and FTIR spectra have been rationalized for the first time. The anodic oxidation and cathodic reduction of Ph2SeO proceeded more easily in a polar aprotic solvent, such as ACN, compared to a polar protic solvent, such as MEOH. The independent atomistically precise simulation studies examining the universe of the stationary point molecular configurations provided solid proof for a substantially better solvation performance of MEOH relative to ACN. The higher degree of conformational flexibility of the MEOH molecules, their strong hydrogen bonding with the seleneoxide group, and sterical confinement of the electrophilic interaction center of Ph2SeO unraveled via numerous low-energy molecular configurations altogether stand beyond a higher maximum homogeneous concentration of the amphiphilic seleneoxide solute in MEOH than in ACN. The reported results reveal the peculiarities of the diphenyl seleneoxide-containing solutions. They are addressed to the researchers representing the field of solution chemistry.

Reactions of diphenyl selenide and diphenyl selenoxide with cumene hydroperoxide

The reaction products of selected organoselenium compounds, diphenyl selenide and diphenyl selenoxide with model lipid hydroperoxide, cumene hydroperoxide, were studied using gas chromatography-mass spectrometry and high-performance liquid chromatography methods, as well as the release of free radicals was determined by the inhibitor method. It has been established, that the reaction products of the studied organoselenium compounds and cumene hydroperoxide are dimethylphenylcarbinol, acetophenone and α-methylstyrene, and the reaction sequentially continues until the formation of diphenylselenone. It was also confirmed by the inhibitor method that these reactions proceed without the formation of free radicals.

Stabilizing effect of intramolecular lewis base toward racemization of optically active selenoxides

Abstract2‐(Methylchalcogenomethyl)diphenyl selenoxides 1 and 2‐{2′‐(N,N‐dimethylamino)ethyl}phenyl alkyl (or aryl) selenoxides 2, which were expected to be stabilized toward racemization by intramolecular coordination, were synthesized and optically resolved into their enantiomers on an optically active column using high‐performance liquid chromatography. Relationship between the absolute configurations and the chiroptical properties of the enantiomers was clarified by comparing with those of sulfur analogues. Stabilities toward racemization of optically active selenoxides 1a and 1b were nearly equal to that of 2‐{(N,N‐dimethylamino)methyl}diphenyl selenoxide and mesityl phenyl selenoxide. The rates of racemization for optically active selenoxides 2 were found to be faster than that of 2‐{(N,N‐dimethylamino)methyl}phenyl alkyl (or aryl) selenoxides. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:301–311, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20299

Deoxygenation and Other Photochemical Reactions of Aromatic Selenoxides1

Atomic oxygen O(3P) is a potent oxidant that has been well-studied in the gas phase. However, exploration of its reactivity in the condensed organic phase has been hampered by the lack of an appropriate source. Dibenzothiophene-S-oxide (DBTO) and related derivatives have been promoted as photochemical O(3P) sources but suffer from low quantum yields. Photolysis of dibenzoselenophene-Se-oxide (DBSeO) results in the formation of dibenzoselenophene and oxidized solvent in significantly higher quantum yields, ca. 0.1. The oxidation product ratios from toluene obtained from the photolysis of dibenzothiophene-S-oxide and the corresponding selenoxide are the same, strongly suggesting a common oxidizing intermediate, which is taken to be O(3P). An additional product, proposed to be the corresponding selenenic ester, is also observed under deoxygenated conditions. The photochemistry of diphenyl selenoxide includes a minor portion of oxidant-forming deoxygenation, in contrast to previous conclusions (Yamazaki, Y.; Tsuchiya, T.; Hasegawa, T. Bull. Chem. Soc. Jpn. 2003, 201-202).

Selenoxides as Catalysts for the Activation of Hydrogen Peroxide. Bromination of Organic Substrates with Sodium Bromide and Hydrogen Peroxide.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Selenoxides as Catalysts for the Activation of Hydrogen Peroxide. Bromination of Organic Substrates with Sodium Bromide and Hydrogen Peroxide

Diphenyl selenoxide (7), dibenzyl selenoxide (8), and several aryl benzyl selenoxides (9−13) are catalysts for the bromination of organic substrates in two-phase systems of CH2Cl2 and pH 6 phosphate buffer containing 2.0 M NaBr and 2.6 M H2O2. The catalysts are effective at 2.5 mol % relative to the organic substrates. In the bromination of 4-pentenoic acid, electron-donating substituents in the selenoxides accelerate the reaction, while electron-withdrawing substituents slow the reaction. Benzyl 2-((dimethylamino)methyl)phenyl selenoxide (13), with a chelating dimethylamino group, was the most effective catalyst and was used in the preparative bromination of 4-pentenoic acid, 2,2-diphenyl-4-pentenoic acid, 1,3,5-trimethoxybenzene, N,N-dimethylaniline, and N-phenylmorpholine.

Donor-Acceptor Reactions of Anhydrous Uranium Tetrachloride with Organic O-Bases

Reactions of anhydrous uranium tetrachloride with tributyl phosphate, dimethyl sulfoxide, diisoamyl methylphosphonate, hexamethylphosphoramide, diamyl sulfoxide, trioctylphosphine oxide, triisoamylphosphine oxide, dioctoxyphenyl selenoxide, diphenyl selenoxide, triphenylarsine oxide, and trioctylamine oxide in acetone and acetophenone were studied. The 1 : 1 and 1 : 2 complexes were revealed by conductometric titration in acetone and acetophenone solutions. The enthalpies of donor-acceptor reactions of O-bases with UCl4 in acetone and acetophenone were determined. These enthalpies in acetone linearly depend on the donor number of the O-base.

Selective Deoxygenation of Aryl Selenoxides by Triaryl Phosphites. Evidence for a Concerted Transformation

AbstractFor Abstract see ChemInform Abstract in Full Text.

Selective deoxygenation of aryl selenoxides by triaryl phosphites. Evidence for a concerted transformation

Triaryl phosphites selectively reduce aryl selenoxides to selenides. The Hammett plot of the reactions of para-phenyl substituted triaryl phosphites with diphenyl selenoxide gave ρ=+2.3, whereas with bis( p-methoxyphenyl) selenoxide, ρ=−2.1. The results are consistent with a concerted mechanism for the oxygen transfer from Se to P.

The Electrochemical Oxidation of Organic Selenides and Selenoxides

The electrochemical oxidation of alkyl and aryl selenides was investigated in acetonitrile. The oxidation of diphenyl selenide and di(4‐methylphenyl) selenide led primarily to the formation of their respective selenoxides, which were identified by exhaustive coulometric oxidation and and analysis of the products. The selenoxide itself was not observed in the cyclic voltammetry of the selenide for two reasons: first, the protonation of the selenoxide by the acid formed from the reaction of water with the cation radical and second, the formation of a selenoxide hydrate. The formation of the hydrate with diphenyl selenoxide was verified by isolation of the dimethoxy derivative. In addition to the selenoxide, selenonium compounds, formed by the coupling of the oxidized material, were also observed. The alkyl selenides were generally oxidized at a lower potential than the aryl selenides. This trend is different from the sulfur analogues, where the aryl sulfides are easier to oxidize than their alkyl counterparts. As a result, the difference in their redox potentials is relatively small. These differences may occur because the oxidation of aryl sulfides is more likely to take place on the aromatic ring, which leads to a greater yield of the coupled products (about 100%) when compared to the selenide analogue.

ChemInform Abstract: Syntheses of Natural Coumarinolignans: Oxidative Coupling of 7,8‐Dihydroxycoumarins and Phenylpropenes in the Presence of Diphenyl Selenoxide.

AbstractOxidation of fraxetin (IIa) or daphnetin (IIb) with diphenyl selenoxide in the presence of coniferyl alcohol (Ia), sinapyl alcohol (Ib), or isoeugenol (V) yields the trans‐adducts (IV) and (VI) after acetylation with acetic anhydride (III).

Syntheses of Natural Coumarinolignans: Oxidative Coupling of 7,8-Dihydroxycoumarins and Phenylpropenes in the Presence of Diphenyl Selenoxide

Oxidative coupling of 7,8-dihydroxycoumarins and phenylpropenes using Ph 2 SeO as oxidizing agent resulted in remarkably efficient synthesis of naturally occurring coumarinolignans (cleomiscosin A, aquillochin (cleomiscosin C), daphneticin, and propacin

ChemInform Abstract: THE REACTIONS OF PHENYLMAGNESIUM HALIDES WITH SELENINYL CHLORIDE, DIPHENYL SELENOXIDE, AND DIBROMODIPHENYLSELENIUM

AbstractDurch Reaktion von Seleninylchlorid mit Phenylmagnesiumhalogeniden und nachfolgende Hydrolyse mit wäßriger HBr wurde die Triphenylselenoniumverbindung (I) neben (II) und (III) dargestellt, deren Ausb. stark von dem molaren Verhältnis der Reaktanten und die Art des Halogens beeinflußt wird.

The Reactions of Phenylmagnesium Halides with Seleninyl Chloride, Diphenyl Selenoxide, and Dibromodiphenylselenium

Abstract Triphenylselenonium halides were readily prepared in good yields by the one-step reaction of seleninyl chloride with phenylmagnesium halides, followed by treatment with hydrogen halides. The yields of triphenylselenonium halides are markedly affected by the molar ratio of seleninyl chloride to the phenylmagnesium halides. In order to interpret the above results, some probable intermediates, such as diphenyl selenoxide, dibromodiphenylselenium, and diphenyl selenide, were investigated by allowing them to react with the phenylmagnesium halides. A pathway which consists of competitive and successive reactions is discussed.

Selective catechol oxidations with diphenyl selenoxide. Applications to phenolic coupling.

Diphenyl selenoxide was used as a mild and selective oxidant in the synthesis of aporphines and homoaporphines. An intramolecular coupling between a phenol and a catechol is believed to proceed via catechol selenurane intermediates.

ChemInform Abstract: A CONVENIENT SYNTHESIS OF SELENONIUM YLIDES

AbstractDas Selenonium‐N‐p‐toluolsulfonimid (I) ergibt mit den aktiven Methylenverbindun gen (IIa) und (IIb) die Selenonium‐Ylide (III) neben (IV) in guten Ausbeuten, mit (IIc) erfolgt keine Reaktion.

ChemInform Abstract: BEHAVIOUR OF SOME SELENIUM BASES IN DISULPHURIC ACID. CONDUCTOMETRIC AND CRYOSCOPIC STUDIES OF SELENIDES, SELENOXIDES AND SELENONES IN DISULPHURIC ACID

Dimethylselenoxide is fully ionized in disulphuric acid whereas diphenyl selenoxide and its nitro derivatives behave as weak bases. In the case of selenones, alkyl selenones are completely ionized in disulphuric acid, diphenyl selenone and its nitro derivatives behave as weak electrolytes. From the extent of protonation it is observed that selenones are stronger bases than the corresponding sulphones. Amongst the selenides, diphenyl selenide is sulphonated whereas its nitro derivatives behave as weak bases in it.

Behaviour of Some Selenium Bases in Disulphuric Acid. Conductometric and Cryoscopic Studies of Selenides, Selenoxides and Selenones in Disulphuric Acid

Abstract Dimethylselenoxide is fully ionized in disulphuric acid whereas diphenyl selenoxide and its nitro derivatives behave as weak bases. In the case of selenones, alkyl selenones are completely ionized in disulphuric acid, diphenyl selenone and its nitro derivatives behave as weak electrolytes. From the extent of protonation it is observed that selenones are stronger bases than the corresponding sulphones. Amongst the selenides, diphenyl selenide is sulphonated whereas its nitro derivatives behave as weak bases in it.

A CONVENIENT SYNTHESIS OF SELENONIUM YLIDES

Abstract The treatment of selenonium N-p-toluenesulfonimides and selenoxides except diphenyl selenoxide with active methylene compounds readily afforded the corresponding stable selenonium ylides in relatively high yields.

Hydrogen bonding in some adducts of oxygen bases with acids. Part 7.—Thermodynamic study by infra-red spectroscopy of the association of chloroacetic acids with some oxygen bases

The association between the chloroacetic acids (mono-, di-, and tri-) and a series of bases (dimethyl, dibenzyl, diphenyl sulphoxide, triphenylphosphine oxide, diphenyl selenoxide) in carbon tetrachloride was studied using the absorbance of the OH stretching band of the free acid. Kas, ΔGo, ΔHo and ΔSo of association were derived from the spectrophotometric data. A linear relationship between ΔHo and the pKa of the acids was found. The thermodynamic quantities reflect also the basicity of the proton acceptors but not in a simple relation. The strongest hydrogen bond is formed between trichloroacetic acid and diphenyl selenoxide, –ΔHo being ∼67 kJ/mol.