- Ensemble effects in nanostructured TiO2 used in the gas-phase photooxidation of trichloroethylene
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The effects of crystal size, structure, and crystallinity on the photocatalytic activity of nanostructured TiO2 with different crystal sizes (3, 5, and 6 nm) for the gas-phase heterogeneous photocatalytic oxidation of trichloroethylene (TCE) wa
- Yeung,Maira,Ho,Wei,Stolz,Soria,Chao,Hung,Yue
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- Some Transformations of Mono-and Dichloro(diethoxyphosphoryl)acetaldehydes
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Addition of ethanol and diethyl phosphonate to the carbonyl group of 2,2-dichloro-2-(diethoxyphosphoryl)-acetaldehyde has been studied, and the corresponding α-chloro ether, acetal, and phosphorylated metrifonate have been obtained. α,α-Dichloro-α-phospho
- Allakhverdieva, G. E.,Ismailov, V. M.,Mamedov, I. A.,Sadykhova, N. D.,Yusubov, N. N.
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- Tricyclic base analogues
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Nucleoside analogues have structure (2) wherein Q is H or a sugar moiety or sugar analogue or a modified sugar or a nucleic backbone or backbone analogue, W is an alkylene or alkenylene chain of 0-5 carbon atoms, any of which may carry a substituent R8, X is O or N or NR12or CR10, X′ is O or S or N, provided that when X′ is O or S, then X is C, Y is CH or N, R6is NH2or SMe or SO2Me or NHNH2, each of R7and R8is independently H or F or alkyl or alkenyl or aryl or acyl or a reporter moiety, R12is independently H or alkyl or alkenyl or aryl or acyl or a reporter moiety, and R10is H or ═O or F or alkyl or aryl or a reporter moiety.
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- Evidence for an additional oxidant in the photoassisted Fenton reaction
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The photo-Fenton reaction (Fe3+ + H2O2 + UV) has potential applications in wastewater treatment. This reaction was compared to H2O2 photolysis and other reactions that produce only hydroxyl radicals (OH·) in order to probe for additional or alternative intermediates that may contribute to the recognized potency of photo-Fenton as an oxidant of organic compounds. Distinct differences were found between photo-Fenton and genuine OH· reactions. The kinetic deuterium isotope effect (KDIE) for cyclohexane in the photo-Fenton reaction increases from 1.2 to 1.4 with increasing concentration of OH· scavenger, tert-butyl alcohol; whereas the KDIE in genuine OH· reactions (H2O2/UV, Fe3+/UV, and Fe2+ + H2O2) is 1.1 and unchanged in the presence of tert-butyl alcohol. Photo-Fenton catalyzed the epoxidation of cyclohexene at a much greater rate than H2O2/UV. The relative yields of chlorinated organic acids from 1,1,2-trichloroethane, trichloroethene, and tetrachloroethene oxidation were markedly affected by the presence of iron. Time-resolved laser flash photolysis spectroscopy in the absence of organics revealed a transient, seen only in Fe3+ + H2O2 solutions, with broad absorbance in the visible and a lifetime of ~100 ns. The results suggest the participation of a high-valent oxoiron complex (ferryl) in addition to OH· in organic compound oxidations. Hydrogen peroxide forms a complex with iron, Fe(O2H)2+ (K15 = 1.15 x 10-2), that absorbs in the visible region and could be the precursor of the ferryl complex. The photo-Fenton reaction (Fe3+ + H2O2 + UV) has potential applications in wastewater treatment. This reaction was compared to H2O2 photolysis and other reactions that produce only hydroxyl radicals (OH·) in order to probe for additional or alternative intermediates that may contribute to the recognized potency of photo-Fenton as an oxidant of organic compounds. Distinct differences were found between photo-Fenton and genuine OH· reactions. The kinetic deuterium isotope effect (KDIE) for cyclohexane in the photo-Fenton reaction increases from 1.2 to 1.4 with increasing concentration of OH· scavenger, tert-butyl alcohol; whereas the KDIE in genuine OH· reactions (H2O2/UV, Fe3+/UV, and Fe2+ + H2O2) is 1.1 and unchanged in the presence of tert-butyl alcohol. Photo-Fenton catalyzed the epoxidation of cyclohexene at a much greater rate than H2O2/UV. The relative yields of chlorinated organic acids from 1,1,2-trichloroethane, trichloroethene, and tetrachloroethene oxidation were markedly affected by the presence of iron. Time-resolved laser flash photolysis spectroscopy in the absence of organics revealed a transient, seen only in Fe3+ + H2O2 solutions, with broad absorbance in the visible and a lifetime of approx. 100 ns. The results suggest the participation of a high-valent oxoiron complex (ferryl) in addition to OH· in organic compound oxidations. Hydrogen peroxide forms a complex with iron, Fe(O2H)2+ (K15 = 1.15 × 10-2), that absorbs in the visible region and could be the precursor of the ferryl complex.
- Pignatello, Joseph J.,Liu, Di,Huston, Patrick
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p. 1832 - 1839
(2007/10/03)
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- α-(Acyloxy)dialkylnitrosamines: Effects of structure on the formation of N-nitrosiminium ions and a predicted change in mechanism
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The decay of α-(acyloxy)dialkylnitrosamines in aqueous solutions has been studied with a view toward elucidating mechanistic details and effects of structure on mechanism and reactivity. Rate constants (k1) for the pH-independent decay of 43 α-(acyloxy)dialkylnitrosamines have been determined. Observations from these and other experiments rule out decomposition via an anchimeric assistance mechanism involving the Z isomer that had previously been suggested. All of the reported data for most of the compounds is consistent with a mechanism involving the formation of N-nitrosiminium ions in or before the rate-limiting step. Structure -reactivity correlations indicate that the stability of α-(acyloxy)dialkylnitrosamines is determined by electronic properties of substituents at RN and RC as well as by the ability of substituents RC to engage in hyperconjugative interactions of C-H bonds with the developing cationic center in the transition state for nitrosiminium ion formation. Attachment of substituents of sufficient electron-withdrawing power at RN and RC results in a predicted change in mechanism to what appears to be an acyl group attack mechanism.
- Hongliang, Cai,Fishbein, James C.
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p. 1826 - 1833
(2007/10/03)
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- Process for the hydroxyalkylation of a carbocyclic aromatic ether
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The present invention concerns a process for the hydroxyalkylation of a carbocyclic aromatic ether. The invention preferably relates to the preparation of 3-methoxy-4-hydroxybenzyl alcohol by the hydroxymethylation of guaiacol. It also concerns the oxidation of the hydroxyalkylated ethers obtained, in particular the oxidation of 3-methoxy-4-hydroxybenzyl alcohol to 3-methoxy-4-hydroxybenzaldehyde, commonly known as "vanillin". The process for the hydroxyalkylation of a carbocyclic aromatic ether of the invention consists of reacting the aromatic ether with a carbonyl compound in the presence of a catalyst and is characterized in that the hydroxyalkylation reaction is carried out in the presence of an effective quantity of a zeolite.
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- Some reactions of ammonia and primary amines with propanal, 2-chloroethanal, 2,2-dichloroethanal and 2,2,2-trichloroethanal in acetonitrile
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The reaction of ammonia with propanal in acetonitrile produces the hexahydrotriazine, 1, in good yield. The corresponding reaction of chloroethanal yields the cyclic trimer 16 but only in poor yield. Increasing chloro-substitution in the aldehyde stabilises the initially formed carbinolamines and disfavours trimerisation. Imines formed by reaction of primary amines with the aldehydes are relatively stable. Those formed from aliphatic amines may undergo slow dimerisation by C-C bond formation and this may be accompanied by loss of amine to yield products containing a conjugated double-bond system. Kinetic and equilibrium data are reported for both the forward and reverse reactions involving interconversion of propanal and ammonia with 1 in acetonitrile-water mixtures. The results indicate that dehydration of the carbinolamine is rate determining.
- Crampton, Michael R.,Lord, Simon D.,Millar, Ross
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p. 909 - 914
(2007/10/03)
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- Pharmaceutical composition for inhibiting HIV protease
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A pharmaceutical composition is disclosed which comprises a solution of an HIV protease inhibiting compound in a pharmaceutically acceptable organic solvent comprising a mixture of (1) (a) a solvent selected from propylene glycol and polyethylene glycol or (b) a solvent selected from polyoxyethyleneglycerol triricinoleate, polyethylene glycol 40 hydrogenated castor oil, fractionated coconut oil, polyoxyethylene (20) sorbitan monooleate and 2-(2-ethoxyethoxy)ethanol or (c) a mixture thereof and (2) ethanol or propylene glycol.
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- Pharmaceutical composition
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A solid pharmaceutical composition is disclosed which comprises a pharmaceutically acceptable adsorbent or a mixture of pharmaceutically acceptable adsorbents to which is adsorbed a mixture of (1) a pharmaceutically acceptable organic solvent or a mixture of pharmaceutically acceptable organic solvents, (2) an HIV protease inhibiting compound and (3) one or more pharmaceutically acceptable acids. The solid composition can optionally be encapsulated in a hard gelatin capsule.
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- Reactions of α-Chloro- and α,α-dichloro-β-oxoaldehydes with Anionic Nucleophiles
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The reaction of α-chloro and α,α-dichloro-β-oxoaldehydes with anionic nucleophiles (NaOH, MeONa, PhONa, MeCOOK) proceeds mainly via haloform splitting with elimination of the formyl group; only with the most nucleophilic sodium methoxide, the reaction at the β-carbon atom partially occurs.The intermediate anions react with benzaldehyde to give difficulty accessible polyfunctional compounds.
- Guseinov, F. I.,Tagiev, S. Sh.,Moskva, V. V.
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- Preparation of dichloroacetaldehyde cyclic trimer and its depolymerization
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Dichlorination of paraldehyde followed by hydration gave white crystals of dichloroacetaldehyde(DCA) hydrate which were treated with concd sulfuric acid at 0°C to afford a cyclic trimer of DCA as a quite stable precursor of DCA.
- Wakasugi,Miyakawa,Suzuki,Itsuno,Ito
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p. 1289 - 1294
(2007/10/02)
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- Products and reaction pats in the liquid phase oxidation of trans-1,2-dichloroethene with oxygen
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Ultraviolet initiated liquid phase oxidation of neat trans-1,2-dichloroethene (1a) with oxigen at 30 deg C afforded ca. 45percent of the combined Cl-products CO, CO2, and phosgene as well as nine oxygenated and nine non-oxygenated chlorinated organic products.Major oxigenated products were cis- and trans-2,3-dichlorooxirane (6a, b) and 1,2,2-trichloroethyl formate (13); minor products were e.g., meso and rac bis(1,2,2-trichloroethyl)ether (11c, d) and dichloromethyl 1,2,2,-trichloroethyl ether (12).The mode of formation of all products is rationalized by a unified reaction scheme.
- Griesbaum, Karl,Hayes, Michael P.,Werli, Vera
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p. 1366 - 1370
(2007/10/02)
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- Halogenated Epoxides. 9. Reaction of trans-2,3-Dichlorooxirane with Dimethyl Sulfide
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Reaction of trans-2,3-dichlorooxirane (1) with dimethyl sulfide afforded in high yield dimethyl(1-chloro-2-hydroxyethenyl)sulfonium chloride (2a).The latter was converted into 1-chloro-2-methoxy-1-(methylthio)ethene (3b) and into 2-acetoxy-1-chloro-1-(methylthio)ethene (3c) by reaction with diazomethane and with ketene, respectively.Pyrolysis of 2a gave chloro(methylthio)acetaldehyde (4a) and dichloroacetaldehyde (6), along with a series of minor byproducts.
- Griesbaum, Karl,Scaria, Pallikaparampil M.,Doehling, Thomas
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p. 1302 - 1305
(2007/10/02)
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- Cephalosporin derivatives, and pharmaceutical compositions containing them
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New cephalosporin derivatives, of the formula: STR1 in which R1 is a heterocyclic, phenyl, p-hydroxyphenyl, phenoxy or dichlorophenylthio radical and R2 is a hydrogen atom, or R1 is phenyl or p-hydroxyphenyl and R2 is an amino radical, R3 is hydrogen, phenyl, substituted phenyl, alkylthio or substituted amino or a radical of the structure --A--R'3, which A is --CH2 --, --NH-- or --NHCO-- and R'3 is a substituted pyridinio radical, R is a carboxyl radical or a carboxylato radical if R3 is a --AR'3 radical and X is a sulphur or oxygen atom, the said alkyl moieties or radicals containing 1 to 4 carbon atoms each in their D, L and D,L forms, where these exist, and their salts are narrow-spectrum anti-bacterial agents which are active against gram-positive bacteria.
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- Cephalosporin derivatives
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New cephalosporin derivatives of the formula: STR1 in which R' represents a protected carboxyl radical, Hal represents a halogen atom, X1 represents a sulphur or oxygen atom or a sulphinyl radical and R represents an acyl radical or an amine-protecting radical, are useful as intermediates for the preparation of cephalosporins having antibacterial activity.
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- Small Rings, 42. Attempts to Prepare Oxirenes via Photochemical Cycloreversions
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Photochemically induced cycloreversions, which are ideally suited for the matrix isolation of cyclobutadienes, cannot be used for an analogous preparation and identification of oxirenes.In some cases ketenes are formed instead.
- Maier, Guenther,Sayrac, Tugmac,Reisenauer, Hans Peter
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p. 2202 - 2213
(2007/10/02)
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- ISOMERIZATION OF CHLORINE-SUBSTITUTED α-OXIDES
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During the thermal and catalytic isomerization of chlorine-substituted epoxyethanes to the corresponding carbonyl compounds the reaction rate increases with increase in the number of chlorine atoms in the molecule.Active catalysts are amines, Lewis acids, and sulfuric acid but not hydrochloric acid and carboxylic acids) the type of catalyst (acid or base) affects the direction of isomerization in the unsymmetrical chloroepeoxyethanes.
- Voronina, T. A.,Chernyavskii, A. I.,Dobrov, I. V.,Poluektov, V. A.,Fomina, N. V.
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p. 801 - 805
(2007/10/02)
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- Vincadifformine synthesis process
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The preparation of vincadifformine and some derivatives thereof for use as a starting material for synthesis of the corresponding vincamine derivatives or for synthesis of bisindole alkaloids having clinically important antitumor properties.
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- Synthesis of 16-unsaturated pregnanes from 17-keto steroids
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17-Keto steroids (I) in their protected form (IIa or IIb) are reacted with a metalated olefin (VI) to give a 21-aldehyde (IV) which is readily transformed to a 16-unsaturated pregnane (V) which is useful in the production of commercially important substituted corticoids.
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- Process of preparing α-formyl sulfides and 2-hydrocarbylthioaldoximes therefrom
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An α-formyl sulfide is prepared by a process which comprises reacting in an aqueous medium an α-haloaldehyde of the formula EQU1 wherein R' and R" independently are hydrogen, hydrocarbon radicals of 1 to 18 carbon atoms selected from the group consisting of alkyl, cycloalkyl, alkenyl, cycloalkenyl and aryl, or substituted hydrocarbon radicals of the above group, and X is a halogen selected from the group consisting of chlorine, bromine, and iodine, with a thiol salt of the formula R"'SM, wherein R"' is a hydrocarbon radical of 1 to 18 carbon atoms selected from the group consisting of alkyl, cycloalkyl, alkenyl, cycloalkenyl and aryl or a substituted hydrocarbon radical of the above group; and M is an alkali or alkaline earth metal, thereby forming an α-formyl sulfide of the formula EQU2 Also, 2-hydrocarbylthioaldoximes are prepared by oximating the above α-sulfides by reaction with a source of hydroxylamine. Additionally, 2-hydrocarbylthioaldoximes are prepared by a process which comprises halogenating an aldehyde having the formula EQU3 wherein R' and R" are defined as above, to form an α-haloaldehyde of the formula EQU4 wherein X is defined as above, reacting in an aqueous medium the α-haloaldehyde with a thiol salt of the formula R"'SM, wherein R"' and M are defined as above, to form an α-formyl sulfide of the formula EQU5 and oximating the α-formyl sulfide to form a 2-hydrocarbylthioaldoxime of the formula EQU6
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