- Gas-phase photocatalytic degradation and detoxification of o-toluidine: Degradation mechanism and Salmonella mutagenicity assessment of mixed gaseous intermediates
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The photocatalytic degradation of toluidine over titanium oxide (TiO 2) thin films under UV irradiation was investigated. The degradation efficiency of 98.7% was obtained for a toluidine concentration of about 4500 μg L-1 and illumination of 240 min. The degradation intermediates produced during photocatalytic oxidation were identified using Fourier transform-infrared spectrometry (FTIR) and gas chromatography-mass spectrometry (GC-MS). Only a small amount of intermediates, including phenol and toluene, were found in the gas phase. Many other trace amount intermediates, such as 2-hydroxybenzaldehyde, 2-nitrobenzaldehyde, 2-hydroxybenzenemethanol, 2-hydroxybenzoic acid, phenol etc., were detected on the TiO2 surface. An Ames assay of the Salmonella typhimurium strains TA98 and TA100 was employed to evaluate the mutagenicity of toluidine and its gaseous photocatalytic degradation intermediates. With or without rat liver microsomal fraction (S9 mix) activation, neither toluidine nor its gaseous intermediates presented mutagenic activity against strains TA98 (±S9) and TA100 (-S9) at all tested doses. Toluidine, however, can induce a weak positive response to the TA100 strain with an S9 mix at doses as high as 4000 μg plate -1. An increase of revertants per plate was obtained after 30 min photocatalysis in the TA100 strain with S9 mix. As reaction time further increased, photocatalytic technology exhibited the ability to completely and efficiently detoxify toluidine. Both our chemical analysis and toxic evaluation indicate that all mutagenic intermediates in the gas can be completely eliminated within 240 min, which further suggests that photocatalytic technology is an effective approach for degrading aromatic amines.
- An, Taicheng,Sun, Lei,Li, Guiying,Wan, Shungang
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- A Facile and efficient trimethylsilylation of hydroxyl groups using silica-supported zinc chloride and alumina-supported sodium hydrogensulfate as recyclable heterogeneous catalysts
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Silica-supported zinc chloride (SiO2-ZnCl2) and novel alumina-supported sodium hydrogensulfate (NaHSO4-Al 2O3) as recyclable heterogeneous catalysts have been used for the mild trimethylsilylation of hydroxyl groups under ambient conditions. This procedure also allows for the selective protection of primary and secondary alcohols in the presence of tertiary alcohols.
- Shaterian, Hamid Reza,Khorami, Fahimeh,Doostmohammadi, Razieh,Amirzadeh, Azita,Ghashang, Majid
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- An efficient method for the protection of alcohols and phenols by using hexamethyldisilazane in the presence of cupric sulfate pentahydrate under neutral reaction conditions
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Alcohols and phenols are protected with hexamethyldisilazane in the presence of cupric sulfate pentahydrate in good to excellent yields in acetonitrile. The method is highly selective for the conversion of primary alcohols in the presence of secondary and tertiary alcohols as well as phenols. Georg Thieme Verlag Stuttgart.
- Akhlaghinia, Batool,Tavakoli, Sedigheh
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- Novel and highly efficient protection of aliphatic alcohols and phenols with hexamethyldisilazane in the presence of La(NO3) 3·6H2O
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Aliphatic alcohols and phenols are protected with hexamethyldisilazane in the presence of lanthanum nitrate hexahydrate (La(NO3) 3·6H2O) in excellent yields at room temperature. Taylor & Francis Group, LLC.
- Akhlaghinia, Batool
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- Rapid and highly efficient trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS) catalyzed by reusable zirconyl triflate, [ZrO(OTf)2]
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In this paper, rapid and efficient trimethylsilylation of alcohols and phenols with hexamethyldisilazane in the presence of catalytic amounts of ZrO(OTf)2 is reported. Primary, secondary and tertiary alcohols as well as phenols were efficiently converted to their corresponding TMS ethers in short reaction times at room temperature. It is noteworthy that this method can be used for chemoselective silylation of primary alcohols in the presence of secondary and tertiary alcohols and phenols.
- Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Mohammadpoor-Baltork, Iraj,Chahardahcheric, Shahin,Tavakoli, Ziba
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- Activation of hexamethyldisilazane (HMDS) by TiO2 nanoparticles for protection of alcohols and phenols: the effect of the catalyst phase on catalytic activity
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Anatase TiO2 nanoparticles (TiO2 NPs) were synthesized by the sol–gel method using titanium tetra-isopropoxide (TTIP), isopropyl alcohol, and distilled water and then calcined at 400?°C for 3?h. X-ray diffraction and scanning electron microscopy methods, and Fourier transform infrared spectroscopy were used for characterization of the obtained TiO2 NPs. The obtained anatase TiO2 NPs were used as heterogeneous catalyst for trimethylsilation of various alcohols or phenols with hexamethyldisilazane (HMDS) in CH3CN at room temperature. High to quantitative yields of the products were obtained within short reaction times at room temperature using a very low loading of pure TiO2 NPs without any post-modification with Bronsted or Lewis acid species such as ClSO3H or HClO4. The catalyst can be recycled at least three times without significant loss of its activity. The results of this study provide evidence that the pure anatase phase of TiO2 exhibits higher catalytic activity in terms of catalyst loading and required reaction time compared to a mixture of anatase and rutile phases found in the commercial samples for trimethylsilation of various alcohols or phenols with HMDS.
- Azad, Alireza,Dekamin, Mohammad G.,Afshar, Shahrara,Tadjarodi, Azadeh,Mollahosseini, Afsaneh
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- A new and efficient method for the protection of alcohols and phenols by using hexamethyldisilazane in the presence of anhydrous ferric chloride under mild reaction conditions
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Alcohols and phenols are protected with hexamethyldisilazane in the presence of anhydrous ferric chloride in good to excellent yields in acetonitrile. This method is highly selective for the conversion of primary alcohols in the presence of secondary and
- Akhlaghinia, Batool
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- Electrophilic Hydroxylation with Bis(trimethylsilyl)peroxide. A Synthon for the Hydroxyl Cation
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The regiospecific introduction of an hydroxy group in aromatic and aliphatic compounds can be performed in good yields by electrophilic hydroxylation of their organometallic derivatives with bis(trimethylsilyl)peroxide.
- Taddei, Maurizio,Ricci, Alfredo
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- Differentiation of isomeric cresols by silylation in combination with gas chromatography/mass spectrometry analysis
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Rationale: m-Cresol is listed as a priority controlled contaminant in many countries, but it is very difficult to accurately determine isomeric cresols due to their incomplete chromatographic separation on commercially available chromatographic columns and their nearly identical mass spectra. Methods: Silylation of isomeric cresols was carried out by treatment with N-methyl-N-(trimethylsilyl)trifluoroacetamide. The formed trimethyl(tolyloxy)silanes were analyzed by gas chromatography/mass spectrometry (GC/MS). Theoretical calculations were carried out with the Gaussian 03 program using the density functional theory (DFT) method at the B3LYP/6-311 + G(2d,p) level. Results: The derivatives of three isomeric cresols and six isomeric xylenols have been completely separated on an HP-5MS capillary column within a GC run of only 10 minutes. In addition, the derivative o-cresol can be very easily differentiated from its isomers due to its characteristic base peak ion at m/z 91 in electron ionization (EI)-MS. DFT calculation results indicated that the formation of the abundant fragment ion at m/z 91 is attributed to a facile dissociation pathway involving the shift of a neighboring phenylmethyl hydrogen atom in EI-MS of trimethyl(o-tolyloxy)silane. Conclusions: Silylation provides a promising solution for simultaneous determination of isomeric cresols and isomeric xylenols.
- Xu, Jiaxiang,Zhu, Guohua,Zhang, Huarong,Liu, Jinsong,Jiang, Kezhi
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- Nanoporous Na+-montmorillonite perchloric acid as an efficient and recyclable catalyst for the chemoselective protection of hydroxyl groups
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Nanoporous Na+-montmorillonite perchloric acid as a novel heterogeneous reusable solid acid catalyst was easily prepared by treatment of Na+-montmorillonite as a cheap and commercially available support with perchloric acid. The catalyst was characterized using a variety of techniques including X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), energy dispersive X-ray spectroscopy (EDX), pH analysis and determination of the Hammett acidity function. The prepared reagent showed excellent catalytic activity for the chemoselective conversion of alcohols and phenols to their corresponding trimethylsilyl ethers with 1,1,1,3,3,3-hexamethyldisilazane (HMDS) at room temperature. Deprotection of the resulting trimethylsilyl ethers can also be carried out using the same catalyst in ethanol. All reactions were performed under mild and completely heterogeneous reaction conditions in good to excellent yields. The notable advantages of this protocol are: short reaction times, high yields, availability and low cost of the reagent, easy work-up procedure and the reusability of the catalyst during a simple filtration.
- Mashhadinezhad, Maryam,Shirini, Farhad,Mamaghani, Manouchehr
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p. 2099 - 2107
(2019/01/03)
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- Regioselectivity of Hydroxyl Radical Reactions with Arenes in Nonaqueous Solutions
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The regioselectivity of hydroxyl radical addition to arenes was studied using a novel analytical method capable of trapping radicals formed after the first elementary step of reaction, without alteration of the product distributions by secondary oxidation processes. Product analyses of these reactions indicate a preference for o- over p-substitution for electron donating groups, with both favored over m-addition. The observed distributions are qualitatively similar to those observed for the addition of other carbon-centered radicals, although the magnitude of the regioselectivity observed is greater for hydroxyl. The data, reproduced by high accuracy CBS-QB3 computational methods, indicate that both polar and radical stabilization effects play a role in the observed regioselectivities. The application and potential limitations of the analytical method used are discussed.
- Moores, Lee C.,Kaur, Devinder,Smith, Mathew D.,Poole, James S.
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p. 3260 - 3269
(2019/03/11)
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- Nanomagnetic zirconia-based sulfonic acid (Fe3O4@ZrO2-Pr-SO3H): A new, efficient and recyclable solid acid catalyst for the protection of alcohols: Via HMDS under solvent free conditions
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In the present work, sulfonic acid functionalized nanomagnetic zirconia is prepared by the reaction of (3-mercaptopropyl)trimethoxysilane and nanomagnetic zirconia. Then, nanomagnetic zirconia-based sulfonic acid (Fe3O4@ZrO2/su
- Tadjarodi, Azadeh,Khodikar, Rahim,Ghafuri, Hosssein
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p. 63480 - 63487
(2016/07/19)
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- Highly atom economical uncatalysed and I2-catalysed silylation of phenols, alcohols and carbohydrates, using HMDS under solvent-free reaction conditions (SFRC)
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An uncatalysed silylation of phenols, regardless on the aggregate state and nature of the substituents with 0.55 equiv of HMDS under solvent-free reaction conditions (SFRC) at room temperature is reported. Sterically hindered phenols, carbohydrates and most of the alcohols additionally required a catalytic amount (up to 2 mol %) of iodine. The reaction protocol is very simple; obtaining a pure product, particularly of uncatalysed reactions, was frequently a completely solvent-free process.
- Jereb, Marjan
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experimental part
p. 3861 - 3867
(2012/06/30)
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- Magnesium hydrogensulfate [Mg(HSO4)2] as an efficient catalyst for the preparation of silyl ethers, dibenzo[a,j]xanthenes, and octahydroxanthene derivatives
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Magnesium hydrogensulfate [Mg(HSO4)2], as a heterogeneous solid acid catalyst, has been used for the mild formation of trimethylsilyl (TMS) ethers from various primary, secondary, and tertiary aliphatic alcohols; aromatic alcohols; a
- Shaterian, Hamid Reza,Doostmohammadi, Razieh,Khorami, Fahimeh,Ghashang, Majid
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experimental part
p. 171 - 180
(2010/04/05)
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- Efficient and convenient procedure for protection of hydroxyl groups to the THP, THF and TMS ethers and oxidation of these ethers to their aldehydes or ketones in [BPy]FeCl4 as a low cost room temperature ionic liquid
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Alcohols were converted to the corresponding THP, THF or TMS ethers in high to excellent yields in 1-n-butylpyridinium chloroferrate media as a stable and low cost room temperature ionic liquid. In addition, oxidation of these ethers to their aldehydes or ketones without any overoxidation reactions in this ionic liquid was also performed.
- Khosropour, Ahmad R.,Khodaei, Mohammad M.,Ghaderi, Sattar
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p. 326 - 330
(2007/10/03)
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- Hexamethyldisilazane in the presence of n,n′,n″n?- tetramethyltetra-2,3-pyridinoporphyrazinato copper (II) is a new, mild and highly efficient reagent for silylation of alcohols and phenols
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Alcohols and phenols are protected with hexamethyldisilazane in the presence of N,N′,N″,N?-tetramethyletra-2,3- pyridinoporphyrazinato copper (II) in good-to-excellent yields at room temperature.
- Akhlaghinia, Batool,Asadi, Mozafar,Safaee, Elham,Heydarpoor, Mozhgan
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p. 2099 - 2104
(2007/10/03)
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- A Convenient Method for Protection and Deprotection of Alcohols and Phenols as Alkylsilyl Ethers Catalyzed by Iodine under Microwave Irradiation
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Irradiation of alcohols or phenols with tert-butyldimethylsilyl chloride (TBDMSCl) or trimethylsilyl chloride (TMSCl) in presence of catalytic amount (20 mol%) of iodine in a microwave oven for 2 min gives the corresponding silyl ethers in excellent yield. Iodine in methanol deprotects the silyl ether into its parent alcohol or phenol under similar reaction conditions.
- Saxena, Ira,Deka, Nabajyoti,Sarma, Jadab C.,Tsuboi, Sadao
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p. 4185 - 4191
(2007/10/03)
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- Silylation of hydroxy groups with HMDS under microwave irradiation and solvent-free conditions
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Phenols and alcohols are silylated with hexamethyldisilazane (HMDS) under microwave irradiation in solvent-free condition in good to excellent yields.
- Mojtahedi,Saidi,Bolourtchian,Heravi
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p. 289 - 292
(2007/10/03)
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- Synthesis of Trimethylsilyloxy and Hydroxy Compounds from Carbanions and Bis(trimethylsilyl)peroxide.
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The reactions of bis(trimethylsilyl)peroxide with alkyl, vinyl, alkynyl, aromatic and heteroaromatic anions are described.Depending on the reaction conditions, the trimethylsilyloxy derivatives can be obtained alone or together with the corresponding trimethylsilyl derivatives, which is sometimes the major product.Enolates, generated using magnesium diisopropylamide give the corresponding hydroxycarbonyl compounds in good yields.An attempt to rationalise the above results is given, emphasising the wide use of bis(trimethylsilyl)peroxide in organic synthesis as an electrophilic hydroxylation reagent.
- Camici, Lucia,Dembech, Pasquale,Ricci, Alfredo,Seconi, Giancarlo,Taddei, Maurizio
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p. 4197 - 4206
(2007/10/02)
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