Autooxidation of diethyl hydroxylamine

The autooxidation of diethyl hydroxylamine (DEHA) has been studied both in solution and in the gas phase between 0° and 60°C. The results obtained are interpreted in terms of a nonchain free radical mechanism in which reaction (1) is the rate-determining step. This reaction is followed by the reaction of HO₂ radicals with DEHA to give hydrogen peroxide. The initial stoichiometry is given by which implies that the hydrogen peroxide reacts with DEHA to give water and diethyl nitroxide radicals. The activation energy of reaction (1) is 16.5 ± 2 kcal/mol, leading to a dissociation energy of 69.5 ± 2 kcal for the O?H bond in DEHA. The oxidation of DEHA in the gas phase is nearly ten times slower than that observed in chlorobenzene solution under similar experimental conditions. This result is related to the stabilization of the free radicals produced by the solvent.     

Hydantoins,thiohydantoins, glycocyamidines—36: 1,5,5- and 3,5,5-triphenyl derivatives

In contrast to the α-chloroamides 1a-c which, when reacted with potassium N-cyanoanilide, furnish anomalous substitution products (2a-c), the related nitrile and ester yields normal substitution products (3a and b) under the same conditions. 1,5,5-Triphenylhydantoin (4a) and a series (5a-8a, 13 and 14) of its derivatives have been prepared starting with 3a and b. Acid hydrolysis of 3a yields, in addition to the normal products (4a and 5a) considerable quantities of the rearranged product 4b. An authentic sample of the latter, as well as a series of its derivatives (5b-8b and 11) have been prepared starting with α,α-diphenylglycinonitrile and 2-methylthio-1,4,4-triphenyl-2-imidazolin-5-one (9). When reacted with ammonia and ammonium iodide, 9 gave, in addition to the normal ammonolysis product 7b, the Dimroth rearrangement product 16, as well as 5,5-diphenylglycocyamidine, by apparent dephenylation of 16. The mass spectra of the imidazole derivatives 4–8, a and b, 9, 11, 13 and 14 are discussed.     

Autooxidation of 8S-Hydroxycedran-13-Al

8S-Hydroxycedran-13-al, subjected to autooxidation in three different solvents, gave eight products, from which the transformation of cedrane skeleton to acorane and decahydroazulene skeltons was observed.     

Autooxidation and stabilization of undoped and doped polyacetylenes

Autooxidations of polyacetylene have been measured by volumetric, infrared, and isothermal TGA weight uptake techniques. The rate of oxygen uptake is 9 × 10^?7 mol (g s)^?1 at 70°C and the overall activation energy is about 10 kcal mol^?1. The maximum oxygen uptake corresponds to [CHO_0.25]_x. Above 100°C there is oxidative degradation of the polymer completely to volatile products. The rate constant for the oxidative degradations at 160°C is ca. 1.5 × 10^?5s. Autooxidation does not result in formation of significant amounts of crosslinking because there are not carbonaceous residues. TGA under a stream of oxygen showed the degradation to be complete at ca. 420°C leaving no residues. Autooxidation is much slower if the polymer is compressed to higher bulk density. Radical scavengers such as BHT and 4010 are effective stabilizers. Hydroperoxide decomposers, such as DSTDP, does not help in the stabilization; spin trap BPN accelerates the oxidation of polyacetylene. Iodine and AsF₅ doped polyacetylenes are oxidatively much more stable than undoped polymers. Perchlorate doped polyacetylenes begin to lose weight as soon as heated above room temperature. Even in an inert atmosphere the polymers often undergo explosive decomposition.     

Synthesis and properties of 3,4-dihydroxy-1,5,5-trimethylimidazolidin-2-one

The synthesis and alkaline cyclization of N-(alkoxycarbonyl) derivatives of 2-methyl-2-methylaminopropanol oxime to 3,4-dihydroxy-1,5,5-trimethylimidazolidin-2-one, which splits out water under the influence of phosphorus pentoxide to give 1,1,2,5,5,6-hexamethyl-3,7-dioxo-4,8,2,3a,6,7a-oxatetraazacyclopenta[f]-hexahydroindan.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1670–1672, December, 1980.     

Autooxidation of tetrachlorohydroquinone in aqueous media

The oxidation of tetrachlorohydroquinone in an aqueous solution at pH 7.40 is an autocatalytic reaction (signoid kinetic curves). The interaction of the tetrachloro-1,4-semiquinone radical anion with dioxygen occurs with the rate constantk ₂ equal to 9±3 L mol⁻¹ s⁻¹ (22–37°C). Superoxide dismutase does not affect the maximum rate of tetrachlorohydroquinone oxidation. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 890–895, May, 1999.     

Autooxidation of Ferrocenylacetic Acid in Organic Solvents

Autooxidation of ferrocenylacetic acid in organic solvents was studied. Several specific features of the process were revealed and discussed.     

Autooxidation of methylheterocycles under phase transfer catalysis conditions

The autooxidation of methyl- and dimethyl-substituted N-, S-, and O-heterocyclic compound derivatives has been studied in 1,2-dimethoxyethane—t-BuOK in the presence of 18-crown-6. Mono- and dicarboxylic acid derivatives of pyrazine, pyridine, pyrimidine, and thiophene have been synthesized.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 959–962, July, 1991.     

Autooxidation of Unsaturated Fatty Acids and Their Esters

The shape of DSC curves of non-isothermal oxidation of fats was explained. Two main exothermic effects overlapped partially are caused by hydroperoxide formation (first peak) and by further oxidation of peroxides (second peak). The oxidation of oils and lipid analogues of various peroxide concentration showed that only the start of the oxidation process is affected by initial concentration of peroxides, other temperatures determined from DSC curves are not connected with this parameter. The computer simulations gave the best agreement of theoretical and experimental data for kinetic scheme of a two-step consecutive reaction with autocatalytic start. The comparison of activation energies calculated for isothermal and non-isothermal autooxidation of unsaturated fatty acids and their esters also confirmed this interpretation. This revised version was published online in July 2006 with corrections to the Cover Date.     

1,4,4a,10b-Tetrahydro-N,N-dimethyl-4-phenanthridinamines and 1,4,4a,5,6,10b-hexahydro-N,N-dimethyl-4-phenanthridinamines

Synthetic procedures to prepare the title compounds are described. Diels-Alder cycloaddition of β-nitrostyrene derivatives 5 to N,N-dimethyl-1,3-butadien-1-amine, 6 , gave 5-aryl-N,N-dimethyl-6-nitro-2-cyclohexen-1-amines 7. Reduction of 7 with zinc in acetic acid gave the diamino derivatives 8 . Schotten-Baumann acylation of 8 gave amides 9 . Treatment of 8 with alkyl isocyanates gave the aminourea derivatives 10 . Bischler-Napieralski cyclodehydration procudure of 9 and 10 gave 1,4,4a,10b-tetrahydrophenanthridinamines 3 and N⁶-alkyl-1,4,4a,10b-tetrahydro-N⁴,N⁴-dimethyl-4,6-phenanthridinediamines 11 , respectively. Condensation of diamines 8 with aryl aldehydes under azeotropic conditions gave imines 12 which on treatment with acids yielded 6-aryl-1,4,4a,5,6,10b-hexahydro-N,N-dimethyl-4-phenanthridinamines 4 . The stereochemistry of these materials is assigned from the proton magnetic resonance studies.     

Autooxidation of 2-isobutyl-5,6-benzo-1,3,2-dioxaborepane

Using PMR, IR, and mass spectrometric methods it was shown that the main autooxidation product upon prolonged storage of 2-isobutyl-5,6-benzo-1,3,2-dioxaborepane is 2,2′-oxybis(5,6-benzo-1,3,2-doxaborepane). A. V. Bogatskii Physicochemical Institute, National Academy of Sciences of Ukraine, Odessa 270080. Organic Chemistry Institute, Ufa Science Center, Russian Academy of Sciences, Ufa 450054. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1418–1421, October, 1998.     

Synthesis and Reactions of 1,4,4a,5,8,8a-Hexahydro-1,4-Methano-5,8-Ethenonaphthalene

The preparation of the titled compound 1 is described. Its photochemical reaction and its formation of a molybdenum carbonyl complex are also reported.     

Autooxidation of hydrocarbons with oxygen in ionic liquids as solvents

The results of hydrocarbons autooxidation process carried out using several ionic liquids (IL) as solvents are demonstrated. Test studies to check the influence of ILs on this process showed that most ILs can accelerate the initiation rate of autooxidation. The results could be very useful for choosing an IL not only for autooxidation processes but also for catalytic oxidation systems. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 287–293, 2008     

A convenient synthesis of enantiopure (4aS,7aR)-1,4,4a,7a-tetrahydrocyclopenta[c]pyran-3,7-dione

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Chemistry of Isodrin Derivatives. The Syntheses of 11- and 12-Hydroxy-1,4,4a,9,9a,10-Hexahydro-Endo,Endo-1,4;9,10-Dimethano-Anthracenes

The titled compounds are synthesized through multi-step sequences involving consecutive [_n4_s + _n2_s] cycloadditions of norbornadiene with two units of chlorinated cyclopentadiene. A dyotropic double hydrogen migration was observed between two closely located double bonds during the process of aromatization of a cyclohexadiene moiety. A hydroxyl group is introduced onto either of the two methylene bridges in order to provide products suitable for solvolytic analyses.     

Diastereoselective preparation of (S)-(1,4,4-trimethylpyrrolidin-3-yl)amine, a new chiral 1,2-diamine for thiourea-type organocatalysts

The enantioselective synthesis of the title compound, its conversion into a thiourea-type organocatalyst and the behavior of this organocatalyst in several enantioselective Michael reactions are described.