295-17-0Relevant articles and documents
Mesomorphic State of Cyclotetradecane
Drotloff, H.,Rotter, H.,Emeis, D.,Moeller, M.
, p. 7797 - 7803 (1987)
Cyclotetradecane shows a thermal transition 7 K below the melting point.The high-temperature crystal phase is characterized by high molecular mobility and easy deformation.Thermal analysis, MAS 13C NMR with high-power proton decoupling, X-ray diffraction, and birefringence experiments have been performed and are discussed with respect to the onset of molecular motion and molecular disorder.The NMR experiments clearly show the onset of a conformational interconversion process well below the transition, while the positional, orientational, and conformational order are largly preserved.The same applies to some extent even within the high-temperature crystal phase.It is thus shown that molecular dynamics must be strictly differentiated from molecular and crystal disorder.Disordering of molecules with low symmetry such as cyclotetradecane is shown to result in rather large transition entropies, even when the molecular motins are jumplike and involve only minor disorder in the crystal.The concepts of liquid crystal, plastic crystal, and condis-crystal are discussed with regard to the classification of the mesomorphic character of the high-temperature crystal phase of cyclotetradecane.It is classified as a molecule that shows a mesophase with partial orientational disorder and high conformational mobility.
Flow Chemistry under Extreme Conditions: Synthesis of Macrocycles with Musklike Olfactoric Properties
Seemann, Alexandra,Panten, Johannes,Kirschning, Andreas
, p. 13924 - 13933 (2021/05/29)
Starting from small cyclic ketones, continuous flow synthesis is used to produce medium-sized rings and macrocycles that are relevant for the fragrance industry. Triperoxides are important intermediates in this process and are pyrolyzed at temperatures above 250 °C. The synthesis is carried out in two continuously operated flow reactors connected by a membrane-operated separator. The practicality of flow chemistry is impressively demonstrated in this work by the use of hazardous reagent mixtures (30% H2O2, 65% HNO3) and the pyrolysis of no less problematic peroxides. All new macrocycles were tested for their olfactory properties in relation to musk.
A Simple Synthesis of Macrocyclic Hydrocarbons by Metathesis of Cycloolefins
Warwel, Siegfried,Kaetker, Hans
, p. 935 - 937 (2007/10/02)
Metathesis of cycloolefins normally leads to unsaturated polymers.Using rheniumheptoxide on alumina, activated by tintetramethyl and working in dilution via soxhlet-similiar circulation system the metathesis reaction was directed to macrocyclic dienes, which are the dimers of the initial cyclolefins.Starting with C7-, C9- and C10-cycloolefins symmetric macrocyclic C14-, C18- and C20-dienes are obtained in yields of 58-74percent.The metathetic dimerization of cyclooctene leads to 1,9-cyclohexadecadiene in a yield of 30percent.By hydrogenation at room temperature and normalhydrogen-pressure all cyclodienes were converted quantitatively to cycloalkenes (catalyst: potassium on alumina) or to cycloalkanes (catalyst: palladium on carbon).
