- Formation of iron(III) meso-chloro-isoporphyrin as a reactive chlorinating agent from oxoiron(IV) porphyrin π-cation radical
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Iron(III) isoporphyrin, a tautomer of porphyrin with a saturated meso carbon, is one of the isoelectronic forms of oxoiron(IV) porphyrin π-cation radical, which is known as an important reactive intermediate of various heme enzymes. The isoporphyrin has been believed to be incapable of catalyzing oxygenation and oxidation reactions. Here, we report that an oxoiron(IV) porphyrin π-cation radical can be converted to iron(III) meso-chloro- isoporphyrin in the presence of trifluoroacetic acid and chloride ion. More importantly, this study shows the first evidence that iron(III) meso-chloro-isoporphyrin is an excellent reactive agent for chlorinating aromatic compounds and olefins. The results of this study suggest that the mechanism involves electrophilic chlorination of substrate with iron(III) meso-chloro-isoporphyrin.
- Cong, Zhiqi,Kurahashi, Takuya,Fujii, Hiroshi
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- Lipase catalysed oxidations in a sugar-derived natural deep eutectic solvent
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Chemoenzymatic oxidations involving the CAL-B/H2O2 system was developed in a sugar derived Natural Deep Eutectic Solvent (NaDES) composed by a mixture of glucose, fructose and sucrose. Good to excellent conversions of substrates like cyclooctene, limonene, oleic acid and stilbene to their corresponding epoxides, cyclohexanone to its corresponding lactone and 2-phenylacetophenone to its corresponding ester, demonstrate the viability of the sugar NaDES as a reaction medium for epoxidation and Baeyer-Villiger oxidation.
- Vagnoni, Martina,Samorì, Chiara,Pirini, Daniele,Vasquez De Paz, Maria Katrina,Gidey, Dawit Gebremichael,Galletti, Paola
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- Method for preparing o-chlorocyclohexanone by using cyclohexanone by-product lightweight oil
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The invention discloses a method for preparing o-chlorocyclohexanone through lightweight oil, wherein the lightweight oil is the by-product obtained from cyclohexanone preparation through oxidation ofcyclohexane, and the o-chlorocyclohexanone is prepared in the presence of an auxiliary agent and a catalyst by completely utilizing the cyclohexene oxide in the lightweight oil through ring opening,oxidation and other reactions. According to the present invention, with the method, the disadvantages of more impurities, harsh reaction condition or complex product purification and the like in the prior art are solved. The method comprises: in the presence of an auxiliary agent, carrying out a reaction on lightweight oil containing 1 mole of cyclohexene oxide and 1-2 moles of a hydrogen chloridesolution for 1-4 h at a temperature of 10-60 DEG C to generate 2-chlorocyclohexanol, distilling to remove the relatively low boiling point components to obtain high-purity 2-chlorocyclohexanol, carrying out a reaction on the high-purity 2-chlorocyclohexanol as a raw material and a certain amount of an oxidizing agent, washing, separating, rectifying, and collecting the distillate at a temperatureof 203-204 DEG C to obtain the o-chlorocyclohexanone with the purity of more than 99%, wherein the yield of the o-chlorocyclohexanone is more than 90%.
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Paragraph 0016; 0017; 0018; 0019; 0020
(2018/04/01)
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- Photoreduction of Thioether Gold(III) Complexes: Mechanistic Insight and Homogeneous Catalysis
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Complexes formed between AuCl3 and thioether ligands underwent a photoinduced reductive elimination under homogeneous conditions in dichloromethane and toluene solutions to afford the corresponding AuI complexes. All the gold(III) complexes were rapidly reduced to the gold(I) chloride complexes under 365 nm irradiation or ambient light while being thermally stable below 55 °C. The mechanism of photoreduction through Cl2 elimination is discussed based on a kinetic study and the chemical trapping of chlorine species: Cl2, radical Cl., and possibly Cl+. The catalytic activities of the gold(III) chloride complexes and the corresponding gold(I) complexes obtained by in situ reduction were evaluated in the cyclization of N-propargylic amides to oxazoles. The merits of such photoreducible complexes in homogeneous gold catalysis are illustrated by a cascade reaction catalyzed by thioether gold complexes that affords a 4H-quinolizin-4-one in high yields.
- Cao, Zhen,Bassani, Dario M.,Bibal, Brigitte
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supporting information
p. 18779 - 18787
(2018/11/23)
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- Highly selective halogenation of unactivated C(sp3)-H with NaX under co-catalysis of visible light and Ag@AgX
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The direct selective halogenation of unactivated C(sp3)-H bonds into C-halogen bonds was achieved using a nano Ag/AgCl catalyst at RT under visible light or LED irradiation in the presence of an aqueous solution of NaX/HX as a halide source, in air. The halogenation of hydrocarbons provided mono-halide substituted products with 95% selectivity and yields higher than 90%, with the chlorination of toluene being 81%, far higher than the 40% conversion using dichlorine. Mechanistic studies demonstrated that the reaction is a free radical process using blue light (450-500 nm), with visible light being the most effective light source. Irradiation is proposed to cause AgCl bonding electrons to become excited and electron transfer from chloride ions induces chlorine radical formation which drives the substitution reaction. The reaction provides a potentially valuable method for the direct chlorination of saturated hydrocarbons.
- Liu, Shouxin,Zhang, Qi,Tian, Xia,Fan, Shiming,Huang, Jing,Whiting, Andrew
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p. 4729 - 4737
(2018/10/23)
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- Chlorohydrination of allyl chloride with HCl and H2O2 catalyzed by hollow titanium silicate zeolite to produce dichloropropanol
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Overall, over 95% of epichlorohydrin is industrially manufactured via the chlorohydrination route with hazardous Cl2 as a reagent, which brings serious operation and pollution problems. Herein, we describe a novel Cl2-free process for the synthesis of dichloropropanols from allyl chloride with H2O2 and HCl catalyzed by hollow titanium silicate zeolite under mild conditions. A high conversion and overall dichloropropanol selectivity exceeding 95% are simultaneously achieved, and the heterogeneous catalyst is highly stable and amenable for reuse. Comprehensive experimental and spectroscopic data suggest that the Lewis acidity of the framework Ti species has a synergistic effect with the Br?nsted acidity of HCl that promotes the epoxidation of allyl chloride and the ring opening of the epoxy groups.
- Peng, Xinxin,Xia, Changjiu,Lin, Min,Yuan, Hui,Zhu, Bin,Zhang, Yao,Wang, Baorong,Shu, Xingtian
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supporting information
p. 1221 - 1225
(2017/08/15)
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- Photochemical oxygenation of cyclohexene with water sensitized by aluminium(III) porphyrins with visible light
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Aluminium(III)-tetramesitylporphyrin, with the Earth's the most abundant metal and the third most abundant element as the Al(III) ion, induces the photochemical oxygenation of cyclohexene in deaerated aqueous acetonitrile to form the corresponding epoxide and alcohol with water as both electron and oxygen atom donor upon visible light irradiation. The Al(III) should be the most available and meaningful element to be utilized in the artificial photosynthetic unit. The excited triplet state of the water-coordinated porphyrin is responsible for the photochemical oxygenation.
- Mathew, Siby,Kuttassery, Fazalurahman,Gomi, Yuki,Yamamoto, Daisuke,Kiyooka, Ryuichi,Onuki, Satomi,Nabetani, Yu,Tachibana, Hiroshi,Inoue, Haruo
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p. 137 - 142
(2015/10/28)
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- Visible light induced oxygenation of alkenes with water sensitized by silicon-porphyrins with the second most earth-abundant element
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Silicon as the second most abundant element on Earth was effectively utilized as the central atom in the porphyrin to induce photochemical oxygenation of alkenes as the first example of photocatalytic reaction through activation of water molecule in the presence of K2PtCl6 as an electron acceptor. Oxygen atom of water was confirmed to be incorporated in the oxygenated product by the photoreaction with H218O. The excited triplet state of silicon porphyrin was revealed to be responsible for the photochemical oxygenation. The one-electron oxidized silicon porphyrin was predicted by DFT calculation to have its spin population mostly on the axially ligated hydroxyl oxygen atom. The oxyl radical character of the axial ligand could rationalize the oxygenation reaction.
- Remello, Sebastian Nybin,Hirano, Takehiro,Kuttassery, Fazalurahman,Nabetani, Yu,Yamamoto, Daisuke,Onuki, Satomi,Tachibana, Hiroshi,Inoue, Haruo
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p. 176 - 183
(2015/10/28)
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- Enzymatic preparation of (1S,2R)- and (1R,2S)-stereoisomers of 2-halocycloalkanols
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The stereoisomers of cis-2-halocycloalkanols were resolved by a kinetically controlled transesterification with vinyl acetate in the presence of lipases in organic media. High enantioselectivities (ee >98%) and good isolated yields were obtained for all substrates using the appropriate lipase. Burkholderia cepacia lipase was the most efficient enzyme for the resolution of these substrates. The enantiomeric purities of the compounds were defined by derivatization with Mosher's acid and the absolute configurations were determined by chemical correlation.
- Kolodiazhna, Olga O.,Kolodiazhna, Anastasy O.,Kolodiazhnyi, Oleg I.
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- Preparation of ionic liquid-based vilsmier reagent from novel multi-purpose dimethyl formamide-like ionic liquid and its application
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In continuation of research to explore the applied potential of DMF-like ionic liquid, the ionic liquid version of N,N-dimethyliminiumchloride (Vilsmier reagent) has been synthesized from DMF-like ionic liquid and tested effectively for its capacity to achieve more useful organic transformations. The results show that DMF-like ionic liquid is world's first task specific ionic liquid which has catalyzed numerous diverse type of reaction and is multipurpose in its application. Thus a new term for this DMF-like ionic liquid has been coined that is DMF-like "multipurpose" ionic liquid. Copyright
- Hullio, Ahmed Ali,Mastoi
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scheme or table
p. 1647 - 1657
(2012/09/21)
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- Rate coefficients and products for gas-phase reactions of chlorine atoms with cyclic unsaturated hydrocarbons at 298 K
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Rate coefficients for the reaction of Cl atoms with cycloalkenes have been determined using the relative rate method, at 298 K and atmospheric pressure of N2. Reference molecule was n -hexane, and the concentrations of the organics were followed by gas chromatographic analysis. Cl atoms were prepared by photolysis of trichloroacetyl chloride at 254 nm. The relative rates of reactions of Cl atoms with cycloalkenes, with, respect to M-hexane, are measured as 1.12 ±0.38, 1.31 ±0.14, and 1.69±0.18forcyclopentene, cyclohexene, and cycloheptene, respectively. Considering the absolute value of the rate coefficient of the reaction of Cl atom with n-hexane as 3.03 ± 0.06 × 10-10 cm3 molecule-1 s -1, the rate coefficient values for cyclopentene, cyclohexene, and cycloheptene are calculated, to be (3.39 ± 1.08) × 10 -10, (3.97 ±0.43) × 10-10, and (5.12 ± 0.55) × 10-10 cm3 molecule-1 S -1', respectively. The experiments for each, molecule were repeated six to eight times, and the slopes and the rate coefficients given above are the average values of these measurements, and the quoted error includes 2σ as well as all other uncertainties in the measurement and calculations. The rate coefficient increases linearly with the number of carbon atoms, with an increment per additional CH2 group being (8.7 ± 1.6) × 11-12 cm3 molecule-1 s-1. Chloroketones and chloroalcohols, along with unsaturated, ketones and alcohols, were found to be the major products of Cl-atom-initiated oxidation of cycloalkenes in the presence of air. The atmospheric implications of these results are discussed, along with a comparison with the reported structure activity relationships.
- Sharma,Pushpa,Dhanya,Naik,Bajai
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body text
p. 98 - 105
(2011/06/21)
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- Enantioselective synthesis of vicinal halohydrins via dynamic kinetic resolution
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(Chemical Equation Presented) Expanding the scope of enantioselective catalysis via DKR, transfer hydrogenation of a variety of cyclic α-halo ketones was accomplished using the Noyori/Ikariya (R,R)- or (S,S)-I catalysts and either HCO2H/Et3N or HCO2Na/n-Bu 4NBr in H2O/CH2Cl2 as the hydrogen sources. Good yields of vicinal bromo-, chloro-, and fluorohydrins with excellent de and ee levels were achieved in most cases after a simple tuning of reaction conditions.
- Ros, Abel,Magriz, Antonio,Dietrich, Hansjoerg,Fernandez, Rosario,Alvarez, Eleuterio,Lassaletta, Jose M.
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p. 127 - 130
(2007/10/03)
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- 1,2-Ferrocenediylazaphosphinines 2: A new class of nucleophilic catalysts for ring-opening of epoxides
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1,2-Ferrocenediylazaphosphinines (1a-c) have been successfully employed as a new class of nucleophilic catalysts for ring-opening of a range of epoxides, their catalytic efficiency in terms of regioselectivity as well as chemical yield comparing well with the existing catalysts in the literature. In contrast, low enantiomeric excesses have been obtained from the reactions of meso-epoxides catalyzed by (R)-1.
- Paek, Seung Hwan,Shim, Sang Chul,Cho, Chan Sik,Kim, Tae-Jeong
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p. 849 - 851
(2007/10/03)
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- (Salen)chromium Complex Mediated Asymmetric Ring Opening of meso- And Racemic Epoxides with Different Fluoride Sources
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The asymmetric ring opening of five meso-and three racemic epoxides with different fluorinating reagents in the presence of stoichiometric or slightly sub-stoichiometric amounts of Jacobsen's enantiopure (salen)chromium chloride complex A gave the corresponding optically active vicinal fluorohydrins. Silver fluoride was used as one of the fluoride sources either in the presence of Bu4N+H2F3- in diethyl ether or in acetonitrile. The latter reactions starting from cyclohexene oxide (1) showed maximum 72% ee in the formed fluorohydrin 2 isolated in 90% yield. From other meso-epoxides such as cyclopentene oxide and cycloheptene oxide the corresponding fluorohydrins were isolated in 80% and 82% yield with 65% and 62% ee, respectively. In case of ring opening under similar conditions of the racemic styrene oxide or phenyl glycidyl ether 83% and 75% of the fluorohydrins with fluorine in the primary position were isolated with 74% ee and 65% ee, respectively. Tetrahydronaphthalene oxide yielded a 2:1 mixture of trans- (23% ee) and cis-2-fluoro-3,4-benzocyclohexenol (2% ee) suggesting competing SN2 and SN1 type ring openings. Other epoxides such as cyclooctene oxide, cis-stilbene oxide and α-methylstyrene oxide did not react or gave the fluorohydrins with very small enantiomeric excess.
- Haufe, Guenter,Bruns, Stefan
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p. 165 - 171
(2007/10/03)
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- Novel ring-opening of epoxides and oxetanes with POCl3 or PCl3 in the presence of DMAP
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Efficient synthesis of chlorohydrins by cleavage of oxiranes and oxetanes using POCl3 or PCl3 in the presence of DMAP (4-N,N-dimethylaminopyridine) has been studied.
- Sartillo-Piscil, Fernando,Quintero, Leticia,Villegas, Clarisa,Santacruz-Juárez, Ericka,Anaya De Parrodi, Cecilia
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- An efficient route to alkyl chlorides from alcohols using the complex TCT/DMF
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(formula presented) Efficient conversion of alcohols and β-amino alcohols to the corresponding chlorides (and bromides) can be carried out at room temperature in methylene chloride, using 2,4,6-trichloro[1,3,5]triazine and N,N-dimethyl formamide. This procedure can also be applied to optically active carbinols.
- De Luca, Lidia,Giacomelli, Giampaolo,Porcheddu, Andrea
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p. 553 - 555
(2007/10/03)
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- A mild preparation of α-halo-α,β-enones from cyclic enones
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A simple one pot procedure flor the selective transformation of cyclic enones into α-halo-α,β-enones is reported using dimethyldioxirane and metal halides/Amberlyst 15. The method appears particularly appealing for the preparation of labelled molecules for use with the CMIA technique.
- Righi, Giuliana,Bovicelli, Paolo,Sperandio, Anna
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p. 5889 - 5892
(2007/10/03)
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- Synthesis of Oxochromium(VI) Alkoxides via Epoxide Cleavage. Structure, Reactivity, and Mechanism
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In an NMR spectroscopic study the cleavage of epoxides [ethylene, propylene, and cis/trans-butylene oxide] by chromyl chloride giving access to oxochromium(VI) alkoxides was shown to proceed via a bimolecular rate-determining step where two molecules of a complex CrO2Cl2...epoxide collide. Subsequently one Cl ligand at the first Cr center attacks the backside of an epoxide molecule complexed at the Cr center of a second CrO2Cl2...epoxide molecule and vice versa. The trans-opening of the epoxides was proved by determining the configuration of the chlorohydrins resulting from hydrolysis of the corresponding alkoxide products in the cases of cis- and trans-butylene oxide. The NMR data provide evidence that each oxochromium(VI) alkoxide adopts one preferred conformation in solution although DFT calculations did not indicate any special stabilizing effects. The product formation was rationalized by DFT calculations concerning the thermodynamics of the reactions.
- Limberg, Christian,Wistuba, Tobias
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p. 6169 - 6176
(2007/10/03)
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- Indium(III) chloride-promoted rearrangement of epoxides: A selective synthesis of substituted benzylic aldehydes and ketones
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A simple and efficient procedure for the rearrangement of substituted epoxides catalyzed by InCl3 has been developed. Aryl-substituted epoxides isomerize with complete regioselectivity to form a single carbonyl compound via cleavage of the benzylic C-O bond. The reactions are simple, fast, and high yielding. This procedure is very mild compared to those catalyzed with BF3 and other Lewis acids and compatible with several acid-sensitive functionalities. This protocol provides a highly selective synthesis of substituted benzylic aldehydes and ketones. However, rearrangement of alkyl- substituted epoxides is not very selective.
- Ranu, Brindaban C.,Jana, Umasish
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p. 8212 - 8216
(2007/10/03)
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- Iron(II)-induced activation of 1:1 HOOH/HCl for the chlorohydroxylation of olefins and the chlorination of hydrocarbons: Chlorinated fenton chemistry
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Iron complexes [FeII(OPPh3)42+, FeII(bpy)2,2+, FeII(OH2)62+, and FeIIICl3] catalytically activate 1:1 HOOH/ HCl combinations for the efficient chlorohydroxylation of olefins. The reactive intermediate 7 is not HOCl, but appears to be formed via a Fenton process FeIILx2+ ? (B) [Lx+FeIIOOH(BH+)] (1) → (HCl) [LxFeIV(OH)Cl] (7) + H2O}. Although the major product from the reaction of 7 with olefin substrates (e.g., cyclohexene, C-C6H10) is the chlorohydroxo derivative [C-C6H10 + HOOH + HCl → (FeIILx) c-C6H10(OH)Cl + H2O], significant amounts of the dihydroxo [c-C6H10(OH)2] and traces of the dichloro [c-C6H10Cl2] derivatives are produced. The reaction efficiency with respect to HOOH/HC1 ranges from 51% for norbornene to 31% for cyclohexene to 10% for 1-hexene. The presence of dioxygen (O2) with c-C6H10 results in the production of some ketone [c-C6H8(O)] via oxygenated Fenton chemistry, but does not inhibit the chlorohydroxylation process. The catalyzed process is equally efficient and selective in a biphasic H2O/substrate solution as in acetonitrile. With cis-stilbene (cis-PhCH=CHPh) the major product is the epoxide (>80%); the reaction efficiency is 63% relative to HOOH/HCl. These systems chlorinate saturated hydrocarbons (c-C6H12 → c-C6H11Cl) and hydroxylate benzene (PhH → PhOH). Because 7 chlorohydroxylates olefins and chlorinates hydrocarbons in aqueous media much more efficiently than HOCl, its in-vivo analogue may be a reasonably reactive intermediate for "oxy-radical" damage in biological systems.
- Sawyer, Donald T.,Hage, John P.,Sobkowiak, Andrzej
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p. 106 - 109
(2007/10/02)
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- Preparation of chlorohydrins
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Described herein is a process for the preparation of chlorohydrins by reacting a concentrated, aqueous solution of hypochlorous acid with at least one unsaturated organic compound having from 2 to about 10 carbon atoms and selected from the group consisting of substituted or unsubstituted olefins and cyclic olefins.
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- sis- and trans-Dioxo complexes of chlororuthenium(VI)
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Dioxoruthenium(VI) complexes are prepared as the chloro derivatives O2RuCl42- and O2RuCl3- and isolated as the crystalline phosphonium and ammonium salts. Quantitative spectral studies (IR and UV-vis) establish the ready interconversion of the 6-coordinate O2RuCl42- to the 5-coordinate analogue with a dissociation constant K = 5.3 × 10-3 M for chloride loss in dichloromethane. The octahedral structure of O2RuCl42- is established by X-ray crystallography of the (Ph3P)2N+ salt to consist of trans-dioxo ligands with the asymmetric (A2u) stretching band at 830 cm-1 in the IR spectrum. [(Ph3P)2N+]2[O2RuCl 42-]: space group P1 (triclinic) with lattice constants a = 10.916 (2) A?, b = 12.378 (2) A?, c = 13.788 (2) A?, α = 105.65 (1)°, β = 93.16 (1)°, γ = 92.60 (1)°, and Z = 1. The coordinatively unsaturated trichloro derivative O2RuCl3- represents a rare example of a mononuclear dioxo complex whose solid-state structure is dependent on the counterion. Thus, the X-ray crystallography of the (Ph3P)2N+ salt establishes a trigonal-bipyramidal structure of O2RuCl3- with the cis-dioxo ligands absorbing as a single, strong IR band at 882 cm-1. [(Ph3P)2N+][O2RuCl3 -]: space group P21/n (monoclinic) with lattice constants a = 10.629 (4) A?, b = 15.636 (5) A?, c = 21.026 (7) A?, β = 99.60 (2)°, and Z = 4. The O2RuCl3- ion in the Ph4P+ salt is disordered between trigonal-bipyramidal and square-pyramidal geometries, which can be refined by using an occupancy ratio of 6:4 with R = 0.042 in the final refinement. The square-pyramidal component of O2RuCl3- is assigned with trans-dioxo ligands that account for the appearance of the unusual IR band at 891 cm-1 (together with the band at 878 cm-1) in crystalline [O2RuCl3-][Ph4P+] [tetragonal space group P4/n with lattice constants a = 12.672 (2) A?, c = 7.788 (2) A?, and Z = 2]. The (Ph3P)2N+, Ph4P+, Et4N+, and n-Bu4N+ salts of O2RuCl3- all show a single, sharp IR band at 885 cm-1 in solutions of dichloromethane or acetonitrile.
- Perrier,Kochi
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p. 4165 - 4173
(2008/10/08)
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- Facile Conversion of Epoxides to Chlorohydrins with Titanium(IV) Chloride/1,8-Diazabicycloundec-7-ene
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A series of epoxides has been converted to the analogous chlorohydrins by treatment with titanium(IV) chloride and 1,8-diazabicycloundec-7-ene.This procedure tolerates acetal protecting groups normally labile to aqueous acids, and when used in conjunction with the Sharpless epoxidation protocols, it allows the preparation of chiral chlorodiols selectively protected at one hydroxy group.
- Spawn, Carol-Lynn,Drtina, Gary J.,Wiemer, David F.
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p. 315 - 317
(2007/10/02)
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