295-65-8Relevant articles and documents
Conformation of the Cycloalkanes C14H28, C16H32, and C22H44 in the Liquid and High-Temperature Crystalline Phases by Vibrational Spectroscopy
Shannon, V. L.,Strauss, H. L.,Snyder, R. G.,Elliger, C. A.,Mattice, W. L.
, p. 1947 - 1958 (1989)
This paper reports a conformational analysis, by means of vibrational red spectroscopy, of the conformationally disorded phases of c-C14H28, c-C16H32, and c-C22H44.From the observed spectra, the concentration of the lowest energy conformer in the liquid state has been estimated along with the concentration ratios of certain short sequences of trans and gauche bonds.The experimentally derived values of the concentrations are compared with calculated values derived from various sets of conformers whose calculated strain energies have been previously reported in the literature.Good agreement was found for c-C14H28.However, for c-C16H32, the calculated concentration of the lowest energy conformer is significantly higher than is found experimentally and, in addition, there are some serious differences between the observed and calculated values of the concentrations of the conformational sequences.The most important factor contributing to the discrepanciens between the measured and calculated conformational statistics is probably the force field used in the strain energy calculations.For c-C22H44, a relatively flexible ring, the experimentally measured concentrations are in reasonable agreement with values derived from a set of diamond-lattice conformers.The distribution of conformers in the high-temperature crystalline phase of all three cycloalkanes is similar to, but somewhat narrower than, that found for the liquid.In the case of c-C14H28, for which a measurement is possible, the concentration of the lowest energy (rectangular) conformer in the high-temperature crystalline phase is estimated to be about 70 +/- percent, a value somewhat higher than the 60 +/- 10percent estimated for the liquid.For c-C22H44, the concentration of gauche bonds is used to characterize the liquid and the high-temperature crystalline phases.In terms of the average number of gauche bonds per ring, the high-temperature phase of c-C22H44 is found to lie closer to the liquid than to the low-temperature phase.
Wideman
, p. 4541 (1968)
Cyclooctane metathesis catalyzed by silica-supported tungsten pentamethyl [(ΞSiO)W(Me)5]: Distribution of macrocyclic alkanes
Riache, Nassima,Callens, Emmanuel,Samantaray, Manoja K.,Kharbatia, Najeh M.,Atiqullah, Muhammad,Basset, Jean-Marie
supporting information, p. 15089 - 15094 (2015/02/19)
Metathesis of cyclic alkanes catalyzed by the new surface complex [(ΞSiO)W(Me)5] affords a wide distribution of cyclic and macrocyclic alkanes. The major products with the formula CnH2n are the result of either a ring contraction or ring expans
1,x-Elimination reactions: Extending the limits of a classical organic reaction
Werner, Christian,Hopf, Henning,Dix, Ina,Bubenitschek, Peter,Jones, Peter G.
, p. 9462 - 9477 (2008/12/22)
α,ω)-Dibromo derivatives in ich the two terminal carbon atom are separated by an unsaturated spacer unit (ππ spacer") undergo 1,x-elimination reactions (with x = 6, 8, 10, and 14), using Mori's reagent (nBu3SnSiMe3/CsF). The resulting cumulenic intermediates cyclodimerize in a subsequent step yielding novel macrocyclic acetylenic and bridged aromatic compounds (cyclophanes). Thus 1,6-eliminations were carried out with dibromide 17 to yield 1,3,7,9-cyclododecatetrayne (20) and with benzylbromide 24 to provide cyclophanes 26 and 27. By 1,8-eliminations the 16-membered macrocycle 33 could be prepared from enediyne 31, the benzannelated 1,5-cyclooctadiyne 41 from dibromide 38, and a mixture of cyclophanes 45 and 46 from the precursor 43. 1,10-Eliminations were carried out successfully with dibromides 47, 50, and 53 yielding the corresponding unsaturated cyclophanes ("cyclophynes") 49, 52, and 55. The influence of the solvent on the cyclodimerization 47→49 was investigated, with acetonitrile providing the highest yields. The heterophanes 59a and b were obtained by 1,10-elimination of the precursor dibromides 57 a and b, and in an elimination experiment involving a 1:1 mixture of the dibromides 50 and 57 b the "mixed dimer" 60 was isolated, besides the homodimers 52 and 59 b. The method reached its limits with the 1,14-elimination of 68, 70, and 74 providing the cyclophanes 69, 71, and 75 in varying amounts. Two final debrominations with 76 and 77, which in principle could undergo 1,16- and 1,20-eliminations reactions, respectively, failed. The structures of the new cyclophanes 49, 50, 59 a, and 59 b were established by X-ray structural analysis; all other structure assignments rest on the usual spectroscopic and analytical data.
