Sample records for dimethyl ether

Sample records 1 - 2 shown.


Dependência das vias de dissociação unimolecular com a energia interna da molécula de éter dimetílico/ Internal energy dependence of the unimolecular dissociation channels of dimethyl ether

Peres, Rodrigo; Linnert, Harrald Victor

Resumo em inglês Internal energy dependence of the competitive unimolecular dissociation channels of dimethyl ether were studied with the statistical RRKM formalism. The C-O and C-H fission reactions and the 1,2-H and 1,3-H shifts, and 1,1-H2 and 1,3-H2 molecular eliminations are discussed as a function of energy dependence of k a(E*), the microcanonical rate constant for production of transition states. C-O fission is the dominant process while reaction channels involving C-H fission, 1, (mais) 1-H2 and 1,3-H2 elimination and production of MeOH should be competitive at energies around 400 kJ mol-1. The less favorable process is the channel of CH4 formation.

Scientific Electronic Library Online (Portuguese)


Constituintes químicos de Vernonia chalybaea mart./ Chemical constituents of Vernonia chalybaea mart.

Costa, Francisco José da; Bandeira, Paulo N.; Albuquerque, Maria Rose Jane R.; Pessoa, Otília Deusdênia L.; Silveira, Edilberto R.; Braz-Filho, Raimundo

Resumo em inglês The chemical investigation of the hexane and ethanol extracts from aerial parts of Vernonia chalybaea conducted to the isolation and characterization of a new aliphatic tetrahydroxyl ether, along with a series of known compounds such as 4 α,10 α-epoxyaromadendrane, friedelin, taraxasteryl acetate, pseudotaraxasteryl acetate, lupeyl acetate, lupeol, α-amiryn, β-amiryn, β-sitosterol, stigmasterol, 2,3-dimethyl-1,2,3-tri-hydroxybuthanol, angophorol, (mais) angophorol-7-O-glucoside, angophorol-7-O-rutinoside, 3,7-dimethoxy-5,3',4'-trihydroxyflavone and acacetin. The structures of all compounds were determined by spectroscopic analysis and comparison with published spectral data.

Scientific Electronic Library Online (Portuguese)