- One-pot Synthesis of 1,3-Butadiene and 1,6-Hexanediol Derivatives from Cyclopentadiene (CPD) via Tandem Olefin Metathesis Reactions
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A novel tandem reaction of cyclopentadiene leading to high value linear chemicals via ruthenium catalyzed ring opening cross metathesis (ROCM), followed by cross metathesis (CM) is reported. The ROCM of cyclopentadiene (CPD) with ethylene using commercially available 2nd gen. Grubbs metathesis catalysts (1-G2) gives 1,3-butadiene (BD) and 1,4-pentadiene (2) (and 1,4-cyclohexadiene (3)) with reasonable yields (up to 24 % (BD) and 67 % (2+3) at 73 % CPD conversion) at 1–5 mol % catalyst loading in toluene solution (5 V% CPD, 10 bar, RT) in an equilibrium reaction. The ROCM of CPD with cis-butene diol diacetate (4) using 1.00 - 0.05 mol % of 3rd gen. Grubbs (1-G3) or 2nd gen. Hoveyda-Grubbs (1-HG2) catalysts loading gives hexa-2,4-diene-1,6-diyl diacetate (5), which is a precursor of 1,6-hexanediol (an intermediate in polyurethane, polyester and polyol synthesis) and hepta-2,5-diene-1,7-diyl diacetate (6) in good yield (up to 68 % or TON: 1180). Thus, convenient and selective synthetic procedures are revealed by ROCM of CPD with ethylene and 4 leading to BD and 1,6-hexanediol precursor, respectively, as key components of commercial intermediates of high-performance materials.
- Turczel, Gábor,Kovács, Ervin,Csizmadia, Eszter,Nagy, Tibor,Tóth, Imre,Tuba, Robert
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p. 4884 - 4891
(2018/09/25)
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- Highly Efficient Photocatalytic Degradation of Dyes by a Copper–Triazolate Metal–Organic Framework
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A copper(I) 3,5-diphenyltriazolate metal–organic framework (CuTz-1) was synthesized and extensively characterized by using a multi-technique approach. The combined results provided solid evidence that CuTz-1 features an unprecedented Cu5tz6 cluster as the secondary building unit (SBU) with channels approximately 8.3 ? in diameter. This metal–organic framework (MOF) material, which is both thermally and chemically (basic and acidic) stable, exhibited semiconductivity and high photocatalytic activity towards the degradation of dyes in the presence of H2O2. Its catalytic performance was superior to that of reported MOFs and comparable to some composites, which has been attributed to its high efficiency in generating .OH, the most active species for the degradation of dyes. It is suggested that the photogenerated holes are trapped by CuI, which yields CuII, the latter of which behaves as a catalyst for a Fenton-like reaction to produce an excess amount of .OH in addition to that formed through the scavenging of photogenerated electrons by H2O2. Furthermore, it was shown that a dye mixture (methyl orange, methyl blue, methylene blue, and rhodamine B) could be totally decolorized by using CuTz-1 as a photocatalyst in the presence of H2O2 under the irradiation of a Xe lamp or natural sunlight.
- Liu, Chen-Xia,Zhang, Wen-Hua,Wang, Nan,Guo, Penghu,Muhler, Martin,Wang, Yuemin,Lin, Shiru,Chen, Zhongfang,Yang, Guang
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supporting information
p. 16804 - 16813
(2018/10/31)
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- A Cptt-Based Trioxo-Rhenium Catalyst for the Deoxydehydration of Diols and Polyols
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Trioxo-rhenium complexes are well known catalysts for the deoxydehydration (DODH) of vicinal diols (glycols). In this work, we report on the DODH of diols and biomass-derived polyols using CpttReO3 as a new catalyst (Cptt=1,3-di-tert-butylcyclopentadienyl). The DODH reaction was optimized using 2 mol % of CpttReO3 and 3-octanol as both reductant and solvent. The CpttReO3 catalyst exhibits an excellent activity for biomass-derived polyols. Specifically, glycerol is almost quantitatively converted to allyl alcohol and mucic acid gives 75 % of muconates at 91 % conversion. In addition, the loading of CpttReO3 can be reduced to 0.1 mol % to achieve a turn-over number as high as 900 per Re when using glycerol as substrate. Examination of DODH reaction profiles by NMR spectroscopy indicates that catalysis is related to Cp-ligand release, which raises questions on the nature of the actual catalyst.
- Li, Jing,Lutz, Martin,Otte, Matthias,Klein Gebbink, Robertus J. M.
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p. 4755 - 4760
(2018/10/02)
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- Chemical Synthesis and Self-Assembly of a Ladderane Phospholipid
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Ladderane lipids produced by anammox bacteria constitute some of the most structurally fascinating yet poorly studied molecules among biological membrane lipids. Slow growth of the producing organism and the inherent difficulty of purifying complex lipid mixtures have prohibited isolation of useful amounts of natural ladderane lipids. We have devised a highly selective total synthesis of ladderane lipid tails and a full phosphatidylcholine to enable biophysical studies on chemically homogeneous samples of these molecules. Additionally, we report the first proof of absolute configuration of a natural ladderane.
- Mercer, Jaron A. M.,Cohen, Carolyn M.,Shuken, Steven R.,Wagner, Anna M.,Smith, Myles W.,Moss, Frank R.,Smith, Matthew D.,Vahala, Riku,Gonzalez-Martinez, Alejandro,Boxer, Steven G.,Burns, Noah Z.
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supporting information
p. 15845 - 15848
(2016/12/23)
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- Pyrolysis of 3-carene: Experiment, Theory and Modeling
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Thermal decomposition studies of 3-carene, a bio-fuel, have been carried out behind the reflected shock wave in a single pulse shock tube for temperature ranging from 920 K to 1220 K. The observed products in thermal decomposition of 3-carene are acetylene, allene, butadiene, isoprene, cyclopentadiene, hexatriene, benzene, toluene and p-xylene. The overall rate constant for 3-carene decomposition was found to be k / s-1 = 10(9.95 ± 0.54) exp (- 40.88 ± 2.71 kcal mol-1/RT). Ab-initio theoretical calculations were carried out to find the minimum energy pathway that could explain the formation of the observed products in the thermal decomposition experiments. These calculations were carried out at B3LYP/6-311 + G(d,p) and G3 level of theories. A kinetic mechanism explaining the observed products in the thermal decomposition experiments has been derived. It is concluded that the linear hydrocarbons are the primary products in the pyrolysis of 3-carene.
- Sharath,Chakravarty,Reddy,Barhai,Arunan
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p. 2119 - 2135
(2016/01/12)
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- Dehydrogenation of 1,3-cyclohexadiene photocatalyzed by osmocene
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Osmocene acts as a photocatalyst for the dehydrogenation of 1,3-cyclohexadiene which yields benzene and hydrogen. It is suggested that the primary photochemical step is an electron transfer from the excited osmocene to the diene.
- Kunkely, Horst,Vogler, Arnd
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scheme or table
p. 134 - 136
(2010/06/12)
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- Methylene amine substituted arylindenopyrimidines as potent adenosine A2A/A1 antagonists
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A novel series of arylindenopyrimidines were identified as A2A and A1 receptor antagonists. The series was optimized for in vitro activity by substituting the 8- and 9-positions with methylene amine substituents. The compounds show excellent activity in mouse models of Parkinson's disease when dosed orally.
- Shook, Brian C.,Rassnick, Stefanie,Hall, Daniel,Rupert, Kenneth C.,Heintzelman, Geoffrey R.,Hansen, Kristen,Chakravarty, Devraj,Bullington, James L.,Scannevin, Robert H.,Magliaro, Brian,Westover, Lori,Carroll, Karen,Lampron, Lisa,Russell, Ronald,Branum, Shawn,Wells, Kenneth,Damon, Sandra,Youells, Scott,Li, Xun,Osbourne, Mel,Demarest, Keith,Tang, Yuting,Rhodes, Kenneth,Jackson, Paul F.
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scheme or table
p. 2864 - 2867
(2010/07/06)
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- SYNTHESIS OF SORBIC ALCOHOL (2E,4E-HEXADIEN-1-OL)
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The decomposition of 1-acetoxy-3-acetoxymethoxy-4-hexene by the action of acids leads to a 1:2 mixture of 1-acetoxy-2,4-hexadiene and 1-acetoxy-3,5-hexadiene.The same compounds are formed in a ratio of 1:1 during the pyrolysis of 1,3-diacetoxy-4-hexene.
- Vasil'ev, A. A.,Poddubnaya, S. S.,Cherkaev, G. V.,Cherkaev, V. G.
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p. 1457 - 1460
(2007/10/02)
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- Methyltriphenoxyphosphonium Iodide (MTPI); Induced Dehydration and Dehydrohalogenation in Aprotic Solvents
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Methyltriphenoxyphosphonium iodide (MTPI) is an effective dehydration and dehydrohalogenation reagent under mild conditions when 1,3-dimethylimidazolidin-2-one is used as an aprotic solvent in place of the more normally used hexamethylphosphoric triamide (HMPT).Since previosly suggested mechanisms had proposed alcohol-HMPT interaction as an important mechanistic step, this result coupled with comparative product geometric isomer distributions and the conjugated: non-conjugated triene product ratios leads to the conclusion that MTPI-alcohol interaction with displacement of phenoxide is the primary step in the reaction.In dimethyl sulphoxide (DMSO) alcohol dehydratation is hindered by DMSO-MTPI interaction yielding dimethyl sulphide.
- Spangler, Charles W.,Kjell, Douglas P.,Wellander, Lori L.,Kinsella, Mary A.
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p. 2287 - 2289
(2007/10/02)
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- Organic Photochemistry with 6.7-eV Photons: 1,4-Cyclohexadiene and 1,4-Cyclohexadiene-3,3,6,6-d4
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The photolysis of 1,4-cyclohexadiene has been investigated in solution at 185 and 214 nm, as well as by sensitization by benzene in solution at 254 nm or by mercury (3P1) atoms in the vapor phase.The reaction mechanisms under these conditions have been probed by the use of 1,4-cyclohexadiene-3,3,6,6-d4 (4).Both at 185 and 214 nm, the principal products are bicyclohex-2-ene (3), 1,3-cyclohexadiene, 1,3,5-hexatriene, and benzene.NMR analysis of the products formed in the photolysis of 4 at 185 nm shows that the formation of 3 is exclusively by a 1,2-hydrogen migration.The other two decomposition pathways at this wavelength correspond to 1,3- and 1,4-H migration.The relative importance of these reactions is sensitive to the wavelength in the range 185-214 nm.Triplet sensitization of 1,4-cyclohexadiene gives benzene (+H2) as a major product and 3 as a minor product.Deuterium labeling shows that in this instance 3 is formed by a di-?-methane rearrangement.Ab initio calculations on the ground state of 1,4-cyclohexadiene employing a STO-3G basis yield a dihedral angle of about 140 with a relatively flat minimum.The intermediate neglect of differential overlap (INDO-SCF-CI) method was used to calculate the energies of the low-lying singlet and triplet states in 1,4-cyclohexadiene for several values of the dihedral angle.At the experimental dihedral angle of 160, it was computed that there were two triplet states, 3A2 (3.7 eV) and 3B2 (3.8 eV), and three closely spaced singlet states, 1A2 (5.9 eV), 1B2 (6.3 eV), and 1B2 (6.4 eV).This is in reasonably good agreement with recent electron-impact data.The 3B2 state is deduced to undergo the di-?-methane rearrangement under triplet sensitization while all of the hydrogen migration reactions that are observed on direct irradiation are attributed to the higher 1B2 state.This state is derived from the excitation of an electron to the ?1* + ?2* orbital and contains significant C-H antibonding character.
- Srinivasan, R.,White, Lloyd S.,Rossi, Angelo R.,Epling, Gary A.
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p. 7299 - 7304
(2007/10/02)
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