190,087 research outputs found
Carbonyl ylide from 3-chloro-3-p-nitrophenylcarbene and acetone
No full textPT: J; CR: BEKHAZI M, 1983, J AM CHEM SOC, V105, P1289 DEMARCH P, 1982, J AM CHEM SOC, V104, P4952 DEMARCH P, 1982, J AM CHEM SOC, V104, P4953 GRAHAM WH, 1965, J AM CHEM SOC, V87, P4396 GRILLER D, UNPUB HUAN Z, 1983, TETRAHEDRON LETT, V24, P2829 LIU MTH, 1972, CAN J CHEM, V50, P3009 LIU MTH, 1982, CHEM SOC REV, V11, P127 MARTIN CW, 1983, J ORG CHEM, V48, P1898 TAKEBAYASHI M, 1970, B CHEM SOC JPN, V43, P1500 UEDA K, 1972, B CHEM SOC JPN, V45, P2779; NR: 11; TC: 22; J9: TETRAHEDRON LETT; PG: 4; GA: D9916Source type: Electronic(1
Behavior of carbonyl ylide generated from 3-chloro-3-(p-nitrophenyl)diazirine and acetone 1,3-dipolar cycloaddition to benzaldehyde and epoxide formation
No full textPT: J; CR: DEMARCH P, 1982, J AM CHEM SOC, V104, P4952 DEMARCH P, 1982, J AM CHEM SOC, V104, P4953 GILL HS, 1983, J ORG CHEM, V48, P1051 HOUK KN, 1973, J AM CHEM SOC, V95, P7302 HUISGEN R, 1977, ANGEW CHEM INT EDIT, V16, P572 IBATA T, 1986, TETRAHEDRON LETT, V27, P4383 LIU MTH, 1974, TETRAHEDRON LETT, P1329 LIU MTH, 1987, TETRAHEDRON LETT, V28, P1011 MARTIN CW, 1971, J CHEM SOC CHEM COMM, P1438 MARTIN CW, 1971, J CHEM SOC CHEM COMM, P15 MARTIN CW, 1985, J ORG CHEM, V50, P2050 PADWA A, 1969, J ORG CHEM, V34, P2728 SEYFERTH D, 1974, J ORGANOMET CHEM, V67, P341 UEDA K, 1972, B CHEM SOC JPN, V45, P2779; NR: 14; TC: 8; J9: CHEM LETT; PG: 4; GA: L0892Source type: Electronic(1
Transformation of phenylchlorodiazirines to 1,3-dioxolanes and a 1,3-dithiolane
No full textPT: J; CR: FREIDRICH K, 1985, TETRAHEDRON LETT, V26, P193 GRAHAM WH, 1965, J AM CHEM SOC, V87, P4396 GRILLER D, 1982, J AM CHEM SOC, V104, P5549 GRILLER D, 1983, J ORG CHEM, V48, P1359 INDICTOR N, 1969, J CHEM ENG DATA, V14, P76 KIRMSE W, 1971, CARBENE CHEM KIRMSE W, 1981, J AM CHEM SOC, V103, P5935 LIU MTH, 1972, CAN J CHEM, V50, P3009 LIU MTH, 1984, J CHEM SOC CHEM COMM, P1062 LIU MTH, 1984, TETRAHEDRON, V40, P887 MOSS RA, 1973, CARBENES, V1 MOSS RA, 1975, CARBENES, V2 MOSS RA, 1984, TETRAHEDRON LETT, V25, P1023 STEINBECK K, 1979, CHEM BER, V112, P2402 WARNER P, 1984, J ORG CHEM, V49, P3666; NR: 15; TC: 0; J9: HETEROCYCLES; PG: 5; GA: AVW79Source type: Electronic(1
Self quenching reaction of (Phenoxymethyl) chlorocarbene with diazirine
No full textThe combination of laser flash photolysis and product analysis demonstrates that even though (phenoxymethyl)chlorocarbene reacts with its diazirine precursor with a substantial rate constant of 3.5 x 10(8) M(-1)s(-1), the predicted azine product is not formed. These results indicate either carbene/diazirine reversibility or subsequent hydrogen migration of the carbene/diazirine adduct. Also, a rate constant of 2.0 x 10(7) s(-1) for the 12-hydrogen atom migration in (p-nitrophenoxymethyl)chlorocarbene has been determined using the pyridinium ylide technique.PT: J; CR: CHATEAUNEUF JE, 1991, J ORG CHEM, V56, P5942 GRAHAM WH, 1965, J AM CHEM SOC, V87, P4396 LIU MTH, 1992, J AM CHEM SOC, V114, P3604 LIU MTH, 1992, J PHOTOCH PHOTOBIO A, V63, P115 MORGAN S, 1991, J AM CHEM SOC, V113, P2782 MOSS RA, 1990, J AM CHEM SOC, V112, P5642 MOSS RA, 1990, KINETICS SPECTROSCOP; NR: 7; TC: 6; J9: RES CHEM INTERMEDIATES; PG: 5; GA: ND525Source type: Electronic(1
Spectroscopic detection of an arylchlorocarbene-ethyl acetate carbonyl ylide and subsequent oxirane formation
No full textLaser flash photolysis of 3-chloro-3-(p-nitrophenyl)diazirine (1) generates the corresponding ground-state singlet carbene (lambda-max = 310 nm), which reacts with ethyl acetate to form a carbonyl ylide of the ester (lambda-max = 490 nm). The absolute rate constant for ylide formation in CH2Cl2 is k = (2.85 +/- 0.17) X 10(6) M-1 s-1. Subsequent cyclization of the ylide to the corresponding oxirane (lambda-max = 350 nm) occurs with a rate constant of 1.26 x 10(6) S-1 (21-degrees-C) in ethyl acetate with Arrhenius activation parameters for oxirane formation of E(act) = 6.68 +/- 0.19 kcal/mol and log A (s-1) = 11.08 +/- 0.15. The carbonyl ylide is also intercepted with the dipolarophile, diethyl fumarate, with a rate constant of (1.04 +/- 0.07) x 10(7) M-1 s-1. Additionally, solvent polarity effects on (p-nitrophenyl)chlorocarbene reactivity and spectroscopic evidence of oxirane formation (lambda-max = 350 nm) from the related acetone ylide of (p-nitrophenyl)chlorocarbene are presented.PT: J; CR: BONNEAU R, 1989, J CHEM SOC CHEM COMM, P510 BONNEAU R, 1990, J AM CHEM SOC, V112, P744 IBATA T, 1987, CHEM LETT, V28, P2135 LIU MTH, 1972, CAN J CHEM, V50, P3009 LIU MTH, 1987, TETRAHEDRON LETT, V28, P1011 LIU MTH, 1990, J CHEM SOC CHEM COMM, P1482 NAGARAJAN V, 1985, J PHYS CHEM-US, V89, P2330 PAUL H, 1978, J AM CHEM SOC, V100, P4520 PLATZ MS, COMMUNICATION REICHARDT C, 1988, SOLVENTS SOLVENT EFF, P352 SOUNDARARAJAN N, 1988, J AM CHEM SOC, V110, P7143 SOUNDARARAJAN N, 1988, TETRAHEDRON LETT, V29, P3419; NR: 12; TC: 14; J9: J AMER CHEM SOC; PG: 4; GA: GB298Source type: Electronic(1
Kinetic studies of chloro-p-nitrophenylcarbene with acetone and diethyl fumarate
No full textPT: J; CR: BEKHAZI M, 1983, J AM CHEM SOC, V105, P1289 DEMARCH P, 1982, J AM CHEM SOC, V104, P4952 DEMARCH P, 1982, J AM CHEM SOC, V104, P4953 GRAHAM WH, 1965, J AM CHEM SOC, V87, P4396 GRILLER D, IN PRESS HUAN Z, 1983, TETRAHEDRON LETT, V24, P2829 IBATA T, 1986, TETRAHEDRON LETT, V27, P4383 LIU MTH, 1972, CAN J CHEM, V50, P3009 MARTIN CW, 1983, J ORG CHEM, V48, P1898 TAKEBAYASHI M, 1970, B CHEM SOC JPN, V43, P1500 UEDA K, 1972, B CHEM SOC JPN, V45, P2779; NR: 11; TC: 14; J9: TETRAHEDRON LETT; PG: 4; GA: G4363Source type: Electronic(1
The thermal decomposition of diazirines: 3-(3-methyldiazirin-3-yl)propan-1-ol and 3-(3-methyldiazirin-3-yl)propanoic acid
No full textPT: J; CR: BIGOT B, 1978, J AM CHEM SOC, V100, P6575 BRIDGE MR, 1969, J CHEM SOC A, P91 CHURCH RFR, 1970, J ORG CHEM, V35, P2465 CLOSS GL, 1965, J AM CHEM SOC, V87, P4270 EFFIO A, 1980, J AM CHEM SOC, V102, P1734 FIGUERA JM, 1976, AN QUIM, V72, P737 FIGUERA JM, 1978, J CHEM SOC F1, V74, P809 FIGUERA JM, 1979, J PHOTOCHEM, V10, P473 FREY HM, 1963, J CHEM SOC, P3514 FREY HM, 1964, J CHEM SOC, P4700 FREY HM, 1965, J CHEM SOC, P1700 FREY HM, 1965, J CHEM SOC, P3101 FREY HM, 1966, J CHEM SOC A, P968 FREY HM, 1977, J CHEM SOC F1, V73, P2010 FREY HM, 1979, J CHEM SOC A, P1916 GANZER GA, 1986, J AM CHEM SOC, V108, P1517 GRILLER D, 1982, J AM CHEM SOC, V104, P5549 LAL D, 1974, J AM CHEM SOC, V96, P6355 LIU MTH, 1972, INT J CHEM KINET, V4, P229 LIU MTH, 1972, J PHYS CHEM-US, V76, P797 LIU MTH, 1973, CAN J CHEM, V51, P2393 LIU MTH, 1974, J CHEM SOC P2, P937 LIU MTH, 1977, CAN J CHEM, V55, P3596 LIU MTH, 1982, CHEM SOC REV, V11, P127 LIU MTH, 1984, J CHEM SOC CHEM COMM, P1062 LIU MTH, 1984, TETRAHEDRON, V40, P887 LIU MTH, 1985, J CHEM SOC CHEM COMM, P982 LIU MTH, 1986, J CHEM SOC PERK T 2, P211 LIU MTH, 1987, CHEM DIAZIRINES, V1, P111 MANSOOR AM, 1966, TETRAHEDRON LETT, P1753 MANSOOR M, 1967, THESIS U SOUTHAMPTON MOSS RA, 1984, TETRAHEDRON LETT, V25, P1023 NEUVARAND EW, 1967, J PHYS CHEM-US, V71, P1229 SCHMID P, 1979, INT J CHEM KINET, V11, P333 SHERIDAN RS, 1984, J AM CHEM SOC, V106, P436 SKELL PS, 1972, TETRAHEDRON, V28, P3571 SMITH NP, 1979, J CHEM SOC P2, P213 SMITH RAG, 1975, J CHEM SOC P2, P686 VOIGT E, 1975, CHEM BER, V108, P3326; NR: 39; TC: 8; J9: J CHEM SOC PERKIN TRANS 2; PG: 7; GA: DD960Source type: Electronic(1
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
Skyrmion-skyrmion and skyrmion-edge repulsions in skyrmion-based racetrack memory
No full textMagnetic skyrmions are promising for building next-generation magnetic memories and spintronic devices due to their stability, small size and the extremely low currents needed to move them. In particular, skyrmion-based racetrack memory is attractive for information technology, where skyrmions are used to store information as data bits instead of traditional domain walls. Here we numerically demonstrate the impacts of skyrmion-skyrmion and skyrmion-edge repulsions on the feasibility of skyrmion-based racetrack memory. The reliable and practicable spacing between consecutive skyrmionic bits on the racetrack as well as the ability to adjust it are investigated. Clogging of skyrmionic bits is found at the end of the racetrack, leading to the reduction of skyrmion size. Further, we demonstrate an effective and simple method to avoid the clogging of skyrmionic bits, which ensures the elimination of skyrmionic bits beyond the reading element. Our results give guidance for the design and development of future skyrmion-based racetrack memory
Laser flash photolysis study of substituent effects on the rate of 1, 2-H migration in a series of benzylchlorocarbenes
No full textLaser flash photolysis of para-substituted 3-chloro-3-benzyldiazirines in isooctane produces the corresponding carbenes, which react with pyridine to form ylides or undergo 1,2-H migration to form the (Z)- and (E)-beta-chlorostyrenes. The rate for the 1,2-H migration is determined by plotting the pseudo-first-order rate constants for the growth of the ylide vs [pyridine] and extrapolating to zero pyridine concentration. In the case of (p-chlorobenzyl)chlorocarbene, the carbene decay can be monitored directly at 310 nm, whereas in [p-(trifluoromethyl)benzyl]chlorocarbene, the 285-nm trace may bc analyzed as the sum of the absorption of the carbene and of the product beta-chlorostyrenes. A Hammett plot of the logarithms of the rate constants for 1,2-H migration vs sigma(p) values gave a rho-value of -1.0, consistent with a hydride-like 1,2-H shift to the carbene center. The rate constants for the cyclopropanation of carbenes with tetramethylethylene (TME) were determined. In particular, the cyclopropanation of (p-chlorobenzyl)chlorocarbene with TME gave a negative activation energy of -4.7 kcal mol-1.PT: J; CR: BONNEAU R, 1989, J AM CHEM SOC, V111, P5973 BONNEAU R, 1989, J PHYS CHEM-US, V93, P4802 CARMICHAEL I, 1986, J PHYS CHEM REF DATA, V15, P1 DOYLE MP, 1987, J ORG CHEM, V52, P1619 EVANSECK JD, 1990, J PHYS CHEM-US, V94, P5518 GOULD IR, 1985, TETRAHEDRON, V41, P1987 GRAHAM WH, 1965, J AM CHEM SOC, V87, P4396 HO GJ, 1989, J AM CHEM SOC, V111, P6875 HOUK KN, 1984, J AM CHEM SOC, V106, P4291 JACKSON JE, 1989, J AM CHEM SOC, V111, P6874 JONES M, 1980, REACTIVE INTERMEDIAT, V2 JONES WM, 1980, REARRANGEMENTS GROUN KIRMSE W, 1971, CARBENE CHEM LAVILLA JA, 1989, J AM CHEM SOC, V111, P6877 LIU MTH, 1908, J ORG CHEM, V52, P4223 LIU MTH, 1985, J CHEM SOC CHEM COMM, P982 LIU MTH, 1987, CHEM DIAZIRINES, CH5 LIU MTH, 1989, J AM CHEM SOC, V111, P6873 LIU MTH, 1989, J CHEM SOC CHEM COMM, V12 LIU MTH, 1990, J AM CHEM SOC, V112, P3915 LIU MTH, 1992, J PHOTOCH PHOTOBIO A, V63, P115 MORGAN S, 1991, J AM CHEM SOC, V113, P2782 MOSS RA, 1986, J AM CHEM SOC, V108, P7028 MOSS RA, 1990, J AM CHEM SOC, V112, P5642 SCHAEFER HF, 1979, ACCOUNTS CHEM RES, V12, P288; NR: 25; TC: 27; J9: J AMER CHEM SOC; PG: 4; GA: HT801Source type: Electronic(1
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