Terminal Ethyl Group Research Articles

Crystal and molecular structure of O-ethyl-N-phenylthiocarbamate

Abstract The crystal structure of the title compound O-ethyl-N-phenylthiocarbamate, [EtOC(=S)N(H)Ph], has been determined at room temperature. The colorless crystals are triclinic, space group P[unk] with unit cell dimensions a = 11.972(4), b = 12.114(1), c = 9.607(2) Å, α = 95.52(1), β = 94,80(3), γ = 89.34(2)°, Z = 6 and Dx = 1.307 Mg m−3. The structure was solved by direct-methods and refined by a full-matrix least-squares procedure to final R = 0.054 using 3499 reflections. There are three molecules in the crystallographic asymmetric unit which differ by minor variations in the orientations of the terminal ethyl and phenyl groups. The –OC(=S)N(H) chromophore is essentially planar in each molecule and the average C=S, C–O and C–N bond distances of 1.650(3), 1.302(4) and 1.323(4) Å, respectively indicate substantial delocalization of π-electron density over this moiety.

Enthalpies of hydrogenation of the octenes and the methylheptenes

Enthalpies of hydrogenation are given for the octenes and methylheptenes. Results follow the same general pattern that was found for alkenes and methyl alkenes of lower molar mass. Terminal double bonds not adjacent to a methyl group have ΔhydHom = −(125.6 ± 0.7) kJ·mol−1. Unbranched cis-octenes have ΔhydHom = −(118.5 ± 0.8) kJ·mol−1, and the trans-isomers have ΔhydHom = −(115.4 ± 0.4) kJ·mol−1. The terminal methyl, ethyl, or propyl groups of the trans-octenes stabilize the double bond about as much as the methyl group of 2-methylhept-1-ene: ΔhydHom = −(115.1 ± 0.7) kJ·mol−1.

Synthesis and X-ray crystal structure of the [Ti 2(OC 2H 5) 8Cl] 2Mg 2(μ-Cl) 2 complex

The reaction between Ti(OC 2H 5) 4 and MgCl 2 in the 2:1 stoichiometric ratio yields the title bimetallic complex from which single crystals were obtained after recrystallization from n-heptane solution. The molecular structure was determined by X-ray diffraction. The molecule crystallizes in the monoclinic, space group P2 1/ n system, with two molecules per unit cell and a=13.900(9), b=14.624(8), c=13.982(8) Å and β=95.05(4)·, V=2831(3) Å 3, D calc= 1.292 g/cm 3. A high degree of position disorder affecting some ethyl groups limits the accuracy of the refinement and causes a rather high final discrepancy factor R of 0.076. The molecule is centrosymmetric and lies on a crystallographic centre of symmetry. The asymmetric unit in the cell, i.e. half molecule, is built up by three face-shared pseudooctahedra centered on the two Ti and Mg atoms and is surrounded by the eight terminal ethyl groups. The two asymmetric parts of the molecule are bonded to each other by a double chlorine bridge between the two Mg atoms. Some speculations on a possible way to form the complex are presented.

Fragmentation reactions of the enolate ions of 2‐pentanone

AbstractThe reaction of [OH]− with 2‐pentanone produces two enolate ions, [CH3CH2CH2COCH2]− and [CH3COCHCH2CH3]−, by proton abstraction from C(1) and C(3), respectively. Using deuterium isotopic labelling the fragmentation reactions of each enolate have been delineated for collisional activation at both high (8 keV) and low (5–100 eV) collisional energies. The primary enolate ion fragments mainly by elimination of ethene. Two mechanisms operate: elimination of C(4) and C(5) with hydrogen migration from C(5), and elimination of C(3) and C(4) with migration of the C(5) methyl group. Minor fragmentation of the primary enolate also occurs by elimination of propane and elimination of C2H5; the latter reaction involves specifically the terminal ethyl group. The secondary enolate ion fragments mainly by loss of H2 and by elimination of CH4; for the latter reaction four different pathways are operative. Minor elimination of ethene also is observed involving migration of a C(5) hydrogen to C(3) and elimination of C(4) and C(5) as ethene.

27Al NMR spectroscopy of triethylaluminium. A direct method to the determination of the proportion of monomer in solution

The sole 27Al NMR signal of triethylaluminum (TEA) is shifted significantly to lower field with: (1) decreasing concentration; (2) increasing temperature; and (3) increasing polarity of the solvent; that is, in each case with an increase in the amount of the monomeric form. 27Al NMR chemical shifts of Al 2Et 6 and AlEt 3 are estimated as 153 ± 2 and 265 ± 10 ppm, respectively. By use of these and observed values, thermodynamic data K d, Δ H d and Δ S d were calculated for the dissociation of Al 2Et 6. The dependence of the monomer—dimer equilibria on the concentration of TEA in the solvents used indicated the participation of an “intermolecular” process in the exchange of bridging and terminal ethyl groups not only in aromatic solvents but also, in contrast to previous reports, in aliphatic hydrocarbons.

Isomerization of molecular ions of alkenes and cycloalkanes studied by photodissociation in an ICR spectrometer

Photodissociation spectra and ion—molecule reaction kinetics of the molecular ions of all C 4-, C 5- and some of the C 6-alkenes and cyclopropane, cyclobutane and cyclohexane are discussed. From the spectra it is deduced that cyclobutane molecular ions ring open directly upon ionization, whereas for the molecular ions of cyclopropane and cyclohexene a mixture of cyclic and acyclic ions is formed. The fraction of C 3 H 6- + ions from cyclopropane that isomerize to the propene structure appears to be strongly dependent on the energy of the ionizing electrons. The three linear butene ions cannot be distinguished by the photodissociation spectra alone; isobutene molecular ions retain their original structure upon ionization. For some of the C 5- and C 6-alkenes studied it follows from both the photodissociation spectra and the kinetics of ion—molecule reactions, that upon ionization two isomeric molecular ions with strongly different reactivity and photodissociation spectra are formed. In all cases, the reactivity ions have a larger photodissociation rate in the visible region than the less reactive ions. Some possibilities in relation to the nature of these two ions are discussed. No straightforward explanation can be given for the observed phenomena. An explanation in terms of differences both in the position of the double bond and the sterical structure (non-planarity of the double bond as well as rotation of single bonds in the terminal ethyl-group) must presumably be taken into consideration.

13C NMR-spektroskopische Untersuchungen an Äthylaluminiumverbindungen / 13C NMR Spectroscopic Investigations of Ethylaluminium Compounds

The 13C NMR spectra of the ethylaluminium compounds [Al(C2H5)xCl3_x]2 x = 1, 1,5, 2 and 3 are presented and factors governing the temperature dependence of the line shape are discussed. The exchange reaction of terminal ethyl groups for chlorine ligands and ethyl ligands, resp., in ethylaluminium-sesquichloride was investigated by fitting the calculated line shapes to the observed spectra. The energy of activation of this exchange process was determined as to be 12,3 ‡ 1,5 kcal/mole. The synthesis of 13C2-[Al(C2H5)Cl2]2 is described.

Plaquenil sulfate in treatment of lupus erythematosus and light-sensitivity eruptions.

The value of antimalarials in the treatment of lupus erythematosus has been well established since Page's article on the use of quinacrine (mepacrine). 1 A recent article by Leeper and Allende 2 compared the use of quinacrine, chloroquine, and amodiaquin for this condition and indicated that the latter two were preferable. Also, light-sensitivity eruptions have been successfully treated and recurrences prevented with quinacrine and chloroquine. 3,4 Another antimalarial preparation under investigation is Plaquenil sulfate (7-chloro-4-[4-N-ethyl-N-β-hydroxyethylamino-1-methylbutylamino]-quinoline). This drug has also been referred to as Win 1258 and is a synthesized stable colorless crystalline solid. It is supplied in tablets of 0.2 and 0.4 gm. It is a 4-aminoquinoline, differing from chloroquine diphosphate in that one of the terminal ethyl groups on the tertiary amino nitrogen is replaced by a hydroxyethyl group. Plaquenil sulfate has been mentioned by several investigators. Goldman 5 felt it was ``certainly less toxic