69,042 research outputs found
Greener synthesis of Tadalafil using dimethylcarbonate and ionic liquids
No full textIntroduction
Tadalafil (commercially named Cialis™), a drug for the treatment of male erectile dysfunction, is commonly prepared from L-tryptophan through four steps in which different solvents and reagents are used. As it often happens in drug preparation the overall mass index of the preparation is quite low, causing a great amount of waste to be produced.
Results
Each step of the published synthesis of Tadalafil was investigated in view of the design of a greener and more afficient process by focussing on solvents and on integrating synthetic steps .
Dimethylcarbonate proved to be a good greener alternative to traditional solvents (i.e. nitromethane or ethanenitrile) for the diastereoselective Pictet-Spengler reaction (i.e. the second step of the synthesis). Both its lower toxicity and the water immiscibility contribute to the greenness of the procedure. In addition the last two steps of the preparation could be carried out stepwise in the same reactor by using [C4dmim][NTf2] (an ionic liquid) as the solvent.
These findings allowed us to propose two alternative processes named A and B. The principal improvements of processes A and B compared to the published synthesis is that they both do without solvents such as CH3CN, toluene, CH2Cl2, DMF and DMSO, and both combine the final two steps of by using an ionic liquid as solvent.
Conclusions
In summary processes A and B are high-yielding methods for the preparation of Tadalafil using only [C4dmim][NTf2] (an ionic liquid) and dimethylcarbonate as reaction media. Both have a better mass index than the published process, particularly if the the ionic liquid is recycled
Evidence for the decay B0→J/ψω and measurement of the relative branching fractions of meson decays to J/ψη and J/ψη′
No full textFirst evidence of the B 0 → J / ψ ω decay is found and the B s 0 → J / ψ η and B s 0 → J / ψ η ′ decays are studied using a dataset corresponding to an integrated luminosity of 1.0 fb -1 collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV. The branching fractions of these decays are measured relative to that of the B 0 → J / ψ ρ 0 decay:frac(B (B 0 → J / ψ ω), B (B 0 → J / ψ ρ 0)) = 0.89 ± 0.19 (stat) - 0.13 + 0.07 (syst),frac(B (B s 0 → J / ψ η), B (B 0 → J / ψ ρ 0)) = 14.0 ± 1.2 (stat) - 1.5 + 1.1 (syst) - 1.0 + 1.1 (frac(f d, f s)),frac(B (B s 0 → J / ψ η ′), B (B 0 → J / ψ ρ 0)) = 12.7 ± 1.1 (stat) - 1.3 + 0.5 (syst) - 0.9 + 1.0 (frac(f d, f s)), where the last uncertainty is due to the knowledge of f d / f s, the ratio of b-quark hadronization factors that accounts for the different production rate of B 0 and B s 0 mesons. The ratio of the branching fractions of B s 0 → J / ψ η ′ and B s 0 → J / ψ η decays is measured to befrac(B (B s 0 → J / ψ η ′), B (B s 0 → J / ψ η)) = 0.90 ± 0.09 (stat) - 0.02 + 0.06 (syst)
Letter from Carl Hayden to M. J. Riordan
No full textLetter from Carl Hayden to M. J. Riordan expressing his support for Coconino County in turning over the Bright Angel Trail to the federal government
Letter from M. J. Riordan, Arizona Lumber and Timber Company, to Carl Hayden
No full textLetter from M. J. Riordan to Carl Hayden expressing his opposition to the federal government's takeover of Bright Angel Trail
Measurement of the time-dependent CP asymmetry in B0 -> J/ψ KS0 decays
No full textThis Letter reports a measurement of the CP violation observables SJ/ψK0S and CJ/ψK0S in the decay channel B0→J/ψK0S performed with 1.0 fb−1 of pp collisions at s√=7 TeV collected by the LHCb experiment. The fit to the data yields SJ/ψK0S=0.73±0.07(stat)±0.04(syst) and CJ/ψK0S=0.03±0.09(stat)±0.01(syst). Both values are consistent with the current world averages and within
expectations from the Standard Model
Author Correction: Establishment and equilibrium levels of deleterious mutations in large populations (Scientific Reports, (2019), 9, 1, (10384), 10.1038/s41598-019-46803-7)
No full textThe original version of this Article contained errors. Affiliations 1 and 2 were reversed. Secondly, Affiliation 7 was incorrectly given as ‘Institute for Cellular and Molecular Medicine, Department of Immunology, and SAMRC Extramural Unit for Stem Cell Research and Therapy, Faculty of Health Sciences, University of Pretoria, Pretoria, 0084, South Africa’. Thirdly, an affiliation was omitted for the author Michael S. Pepper, which is now listed as Affiliation 8. Fourthly, Affiliation 1 was omitted for the author Johan W. Viljoen. Finally, Augustinus J. van Zyl was incorrectly affiliated with ‘Institute for Maternal and Child Health, IRCCS ‘Burlo Garofolo’, Trieste, Italy.’ The correct author affiliations are listed below: Affiliation 1: Department of Electrical, Electronic and Computer Engineering, EBIT, University of Pretoria, Pretoria 0028, South Africa Johan W. Viljoen and J. Pieter de Villiers Affiliation 2: Development, Research and Technology Department, Hensoldt Optronics, Centu..
Measurement of the ratio of prompt χ c to J / ψ production in pp collisions at √s = 7 TeV
No full textThe prompt production of charmonium χ c and J / ψ states is studied in proton-proton collisions at a centre-of-mass energy of √s = 7 TeV at the Large Hadron Collider. The χ c and J / ψ mesons are identified through their decays χ c → J / ψ γ and J / ψ → μ + μ - using 36 pb - 1 of data collected by the LHCb detector in 2010. The ratio of the prompt production cross-sections for χ c and J / ψ, σ (χ c → J / ψ γ) / σ (J / ψ), is determined as a function of the J / ψ transverse momentum in the range 2 < p T J / ψ < 15 GeV / c. The results are in excellent agreement with next-to-leading order non-relativistic expectations and show a significant discrepancy compared with the colour singlet model prediction at leading order, especially in the low p T J / ψ region
Dimethyl carbonate as a green solvent for the synthesis of platform chemicals from renewable lignin feedstocks
No full textDimethyl carbonate was evaluated as a green methylating and transesterification reagent and solvent for the chemical-valorisation of renewable platform chemicals from lignin model compounds using a range of catalysts. Of the major components of lignocellulosic biomass (namely cellulose, hemicellulose, and lignin), chemical technologies for the conversion of lignin into higher value-added compounds are the least studied.[1] With a view to developing new chemical products from lignin, it is desirable to first study lignin model compounds. Thus, cinnamyl alcohol, 3-(4-hydroxypropyl)phenol, vanillyl alcohol, and syringic acid were chosen as representative of the p-coumaryl alcohol, coniferyl alcohol, and sinapyl alcohol building blocks of lignin. Moreover, dimethyl carbonate was chosen because it is cheap, readily available, and has low toxicity, making it a good alternative to traditional methylating agents such as dimethyl sulfate and methyl halides.[2] In the present work, a range of catalysts, including K2CO3, CsF/αAl2O3, NaX, NaY and [P8881][CH3OCOO], are investigated for the methylation and transesterification of the model compounds. One approach is to form the methyl carbonate product in a first step, followed by the methylation reaction in a second step.
References
[1] J. Zakzeski, P. C. A. Bruijnincx, A. L. Jongerius, B. M. Weckhuysen, Chem. Rev. (Washington, DC, U. S.) 2010, 110, 3552-3599.
[2] M. Selva, A. Perosa, Green Chem. 2008, 10, 457-464
J. M. Coetzee in Context and Theory
No full textNobel Laureate and the first author to win the Booker Prize twice, J.M. Coetzee is perhaps the world's leading living novelist writing in English. Including an international roster of world leading critics and novelists, and drawing on new research, this innovative book analyses the whole range of Coetzee's work, from his most recent novels through his memoirs and critical writing. It offers a range of perspectives on his relationship with the historical, political, cultural and social context of South Africa. It also contextualises Coetzee's work in relation to his literary influences, colonial and post-colonial history, the Holocaust and colonial genocides, the 'politics' and meaning of the Nobel prize in South Africa and Coetzee's very public move from South Africa to Australia. Including a major unpublished essay by leading South African novelist André Brink, this book offers the most up-to-date study of Coetzee's work currently available.Intro -- Contents -- Acknowledgements -- Biographies -- Introduction -- Part I: Context -- 1. Post-Apartheid Literature: A Personal View -- 2. Elizabeth Costello as Post-Apartheid Text -- 3. Coetzee and Gordimer -- 4. Wordsworth and the Recollection of South Africa -- 5. Border Crossings: Self and Text -- 6. Sex, Comedy and Influence: Coetzee's Beckett -- Part II: Theory -- 7. Writing Desire Responsibly -- 8. Literature, History and Folly -- 9. Queer Bodies -- 10. Eating (Dis)Order: From Metaphoric Cannibalism to Cannibalistic Metaphors -- 11. Acts of Mourning -- 12. Sublime Abjection -- 13. Authenticity: Diaries, Chronicles, Records as Index-Simulations -- 14. Disrupting Inauthentic Readings: Coetzee's Strategies -- Index -- A -- B -- C -- D -- E -- F -- G -- H -- I -- J -- K -- L -- M -- N -- O -- P -- Q -- R -- S -- T -- U -- V -- W -- X -- YNobel Laureate and the first author to win the Booker Prize twice, J.M. Coetzee is perhaps the world's leading living novelist writing in English. Including an international roster of world leading critics and novelists, and drawing on new research, this innovative book analyses the whole range of Coetzee's work, from his most recent novels through his memoirs and critical writing. It offers a range of perspectives on his relationship with the historical, political, cultural and social context of South Africa. It also contextualises Coetzee's work in relation to his literary influences, colonial and post-colonial history, the Holocaust and colonial genocides, the 'politics' and meaning of the Nobel prize in South Africa and Coetzee's very public move from South Africa to Australia. Including a major unpublished essay by leading South African novelist André Brink, this book offers the most up-to-date study of Coetzee's work currently available.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
Measurement of the CP-violating phase \phi s in Bs->J/\psi\pi+\pi- decays
No full textMeasurement of the mixing-induced CP-violating phase phi_s in Bs decays is of prime importance in probing new physics. Here 7421 +/- 105 signal events from the dominantly CP-odd final state J/\psi pi+ pi- are selected in 1/fb of pp collision data collected at sqrt{s} = 7 TeV with the LHCb detector. A time-dependent fit to the data yields a value of phi_s=-0.019^{+0.173+0.004}_{-0.174-0.003} rad, consistent with the Standard Model expectation. No evidence of direct CP violation is found
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