58049-91-5Relevant articles and documents
MECHANISM OF SOLVOLYSIS OF 2,2-DIMETHYLCYCLOPENTYL P-BROMOBENZENESULFONATE
Shiner, V. J.,Imhoff, Michael A.
, p. 2121 - 2124 (1985)
Solvolysis of the title compound in ethanol-water, trifluoroethanol-water, and hexafluoroisopropyl alcohol-water mixtures yields > 90 percent products of methyl migration.The rate of solvolysis relative to the cyclopentyl analogue is 0.19 in 80 percent ethanol-water, 4.0 in 97 percent trifluoroethanol-water, and 10.0 in 90 percent hexafluoroisopropyl alcohol-water.The α-d and β-d2 rate effects in solvolysis range respectively from 1.19-1.20 to 1.26-1.30.The results are interpreted in terms of a mechanism which involves reversible formatin of the tight ion pair followed by rate-determining methyl migration.
Polyoxometalates as reduction catalysts: Deoxygenation and hydrogenation of carbonyl compounds
Kogan, Vladimir,Aizenshtat, Zeev,Neumann, Ronny
, p. 3331 - 3334 (2007/10/03)
Excellent deoxygenation of ketones and aldehydes is achieved with Keggin-type polyoxometalates in the presence of hydrogen (see Equation (1) for an example). The mixed addenda phosphovanadomolybdate [PV2Mo10O4]5- was found to be the best catalyst. X-ray diffraction and IR studies suggest that the polyoxometalates are structurally stable under the strongly reducing conditions.
Studies on the Thermal Conversion of Long-chain Alkynes at High Temperatures in the Gas Phase
Ondruschka, B.,Zimmermann, G.,Ziegler, U.,Kopinke, F.-D.,Teuber, M.
, p. 273 - 284 (2007/10/02)
In the gas phase pyrolysis of long-chain alkynes C5 to C9 at 773 to 873 K, a remarkable portion of molecular reaction (retro-ene analogous decompositions as well as cycloisomerizations of the parent alkynes to cyclopentenes alkylated in 3-position) takes place besides the thermal conversion of the starting compounds via radical chain processes.The different products were separated by GC and the main products identified by means of different methods.The mechanisms of formation of the major products are discussed.
On the Thermal Cycloisomerization of Long-Chain Alkylacetylenes in the Gas Phase
Ondruschka, Bernd,Zimmermann, Gerhard,Remmler, Matthias,Ziegler, Ulrich,Kopinke, Frank-Dieter,et.al.
, p. 715 - 720 (2007/10/02)
The thermal cycloisomerization of some alkylacetylenes was investigated in a tubular quartz reactor.At 570 deg C 1-hexyne (1) rearranges to 3-methyl-1-cyclopentene (5) with a selectivity of about 27 by a reaction sequence including an acetylene-vinylidene rearrangement and 1,5-C,H insertion of the intermediately formed alkylidenecarbene species. 5-methyl-1-hexyne (2) behaves analogously forming 3,3-dimethyl-1-cyclopentene (6), while 2-hexyne (3) provides 1-methyl-1-cyclopentene (7) indicating that the acetylene-vinylidene rearrangement is obviuosly not restricted to 1,2-H shifts.The mechanism of the cycloisomerization of alkylacetylenes is investigated by means of D-labeled parent alkynes.The results show that the unimolecular cycloisomerization via alkylidenecarbenes obviously can be an important channel despite the dominance of a radical chain course. - Keywords: Alkyne/ Carbene/ Cycloisomerization/ Pyrolysis
On 1.2-Shift Reactions and C-H-Insertions of Acyclic Alkylidene Carbenes
Ondruschka, Bernd,Remmler, Matthias,Zimmermann, Gerhard,Krueger, Christian
, p. 49 - 54 (2007/10/02)
Two series of acyclic terminal vinyl bromides (1...4 and 5...7) were tested in the reaction with potassium tert-butoxide as precursors of alkylidene carbenes.As expected 1 up to 4 only give 1-alkynes whereas the 2-methylated vinyl bromides 5, 6 and 7 yield 1-methylated cyclopentenes predominantly besides 2-alkynes.The formation of cyclopentenes indicates a reaction route via alkylidene carbenes and 1,5-C-H-insertion reactions, that of 2-alkynes is convincing evidence for 1,2-alkyl shift reactions in 2-methyl substituted alkylidene carbenes.The selectivity of 1,5-C-H-insertion depends on the degree of alkyl substitution of the C-5-atom.At 240 deg C the selectivity is 1deg:2deg:3deg ca. 1:54:240.
REACTIONS OF ALKANES AND CYCLOALKANES ON PLATINUM-GOLD ALLOY FILMS
Kane, Alan F.,Clarke, John K. A.
, p. 1640 - 1651 (2007/10/02)
The reactions of a series of cyclic and acyclic alkanes in excess hydrogen have been studied on evaporated films of Pt-Au.Film homogeneity was established by X-ray fluorescence spectroscopy and X-ray diffraction.The reactions which occur fall into two groups.First there are those whose rate is dramatically affected by Au incorporation in Pt, and these include the hydrogenolysis of ethane, neopentane, n-pentane, neohexane and n-hexane, the isomerization of neopentane and n-pentane and finally the ring opening and hydrocracking of the cyclopentane ring.Secondly, there are reactions whose rate is essentially unaffected by moderate Au incorporation in Pt, comprising the 1,5-cyclization of n-pentane, the 1,6-cyclization of n-hexane, the ring enlargement of methylcyclopentane and of 1,1-dimethylcyclopentane and finally dehyrogenation of saturated hydrocarbons to alkene and alkadiene.These results may be rationalized on either an electronic factor or by postulating that gold atoms locate preferentially at rough regions of the surface.
