Tetramethylethylene Research Articles

Investigation of chiral induction in photochemical oxetane formation

The formation of oxetanes from photochemical addition of tetramethylethylene (TME) or diethylketeneacetal with phenylglyoxylic acid esters in the “concave” position leads to high diastereomeric excess (d e).

Photolysis of gaseous tetramethylethylene between 185 and 230 nm

Photolysis of gaseous tetramethylethylene between 185 and 230 nm

ChemInform Abstract: BIS(TRIFLUOROMETHYL)CADMIUM.GLYME (GLYME = DIMETHOXYETHANE), A NEW, POWERFUL FLUOROALKYLATING AGENT AND LOW‐TEMPERATURE SOURCE OF DIFLUOROCARBENE

AbstractDas leicht zugängliche Reagens (III) alkyliert die Tetraiodide (IV) unter Bildung der Organo‐Metallverbindungen (V).

Bis(trifluoromethyl)cadmium·glyme (glyme = dimethoxyethane), a new, powerful fluoroalkylating agent and low-temperature source of difluorocarbene

The newly isolated reagent (CF3)2Cd·glyme [glyme =(MeOCH2)2] readily exchanges ligands with, e.g., GeI4, SnI4, or PI3 to form the fully substituted compounds (CF3)4Ge, (CF3)4Sn, or (CF3)3P, within minutes at ambient temperature; reactions with acyl halides, like MeC(O)Br, form the acyl fluorides, like MeC(O)F, in excellent yields, 95%, at –25 °C and extrusion of CF2 at –25 °C in this reaction in indicated by the formation of the expected difluorocyclopropane from tetramethyl ethylene in 53% yield.

Facile displacement of tetramethylethylene from thexylborane-triethylamine by treatment with olefins. a convenient synthesis of monoalkylborane derivatives

The reaction of thexylborane-triethylamine with representative olefins proceeds readily at 25° with the displacement of tetramethylethylene (TME) and the formation of the corresponding monoalkylborane-triethylamine adduct. This reaction provides a convenient synthesis in high yield of such monoalkylboranes and their derivatives.

Polymerization of ethylene by n-butyl lithium

The polymerization of ethylene with butyl lithium activated with tetramethyl ethylene diamine (TMEDA) has been investigated, and the mechanism proposed by McCabe et al. substantially vindicated. The active initiating species is considered to be free monomeric butyl lithium, unchelated to TMEDA, and the mechanism of propagation of olefin insertion between the metal-carbon bond, probably involving an intermediate π-complex between olefin and metal alkyl.

Energy Transfer in the Radiolysis of Neopentane-Alkane Mixture in the Solid Phase at 77 K

Abstract When neopentane containing a small amount of cyclohexane is γ-irradiated at 77 K, the cyclohexyl radical is mainly formed by the energy transfer from neopentane to cyclohexane. The addition of CCl4, which is an electron scavenger and an excitation acceptor, to the mixture suppresses the formation of the cyclohexyl radical. This fact indicates that the energy transfer is not due to an ion-molecule reaction. When CO2, which can capture an electron in the neopentane matrix to form CO2−, is added to the neopentane–cyclohexane mixture, scarcely any CO2 is formed by the irradiation. When ethyl chloride or nitrous oxide is added to the neopentane–cyclohexane mixture, the formation of the cyclohexyl radical is not suppressed, although these additives capture electrons effectively in the solid neopentane. The addition of tetramethylethylene (TME) to the neopentane–cyclohexane–carbon dioxide mixture does not affect the formation of the cyclohexyl radical, although an appreciable amount of TME+ is formed. These results show that the energy transfer is not due to the ionic process, but to a non-ionic process. The energy transfer is explained by two possible mechanisms, a selective abstraction reaction by the hydrogen atom and an excitation transfer via a highly-excited state.

Kinetics of reaction of metal alkyls with alkenes. Part 7.—n-Butyl lithium and N:N:N′:N′-tetramethyl ethylene diamine with butadiene

The polymerization of butadiene, initiated by the complexes of n-butyl lithium and tetramethyl ethylene diamine, has been studied in the range 230–280 K by dilatometry. Initial rates of polymerization were second order in monomer, and first in both amine and butyl lithium concentrations. Maximum rates were observed at molar ratios of lithium alkyl/amine below 1/2. Rates of polymerization decreased with conversion, consistent with first-order dependence on unconverted monomer. Molecular weights of the polymers increased with conversion, and at ratios below 1/2 in alkyl/amine compared exactly with moles of monomer consumer per mole of butyl lithium initially present. The micro-structure of the polymers varied with polymerization temperatures between 70–90 % of 1,2 addition product. All the polymers had narrow molecular weight distributions independent of the final degree of conversion.It was concluded that the polymerization of butadiene occurred by a “living” anionic addition mechanism, initiated by the 1/2 amine complex. The nature of the active polymerizing species was confirmed by a molecular weight study of the complexes present at various molar ratios, and their concentration dependence.

Common intermediates in the transfer of triplet excitation energy and molecular exchange reactions

Irradiation of acetone-d 6 and tetramethyl-ethylene (TME) yields acetone and TME-d 6 as the only products. The comparable behavior of this reaction and the transfer of triplet excitation energy from acetone to olefins points to a common molecular triplet oxetane intermediate for both processes.

A STUDY OF THE PRODUCTS OF THE REACTIONS OF OZONE WITH OLEFINS IN THE VAPOR PHASE AS DETERMINED BY GAS–LIQUID CHROMATOGRAPHY

A broad comparative survey has been made of the products of the vapor phase reactions of ozone with ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, isobutene, 2-methyl-1-butene, cis-2-butene, trans-2-butene, cis-2-pentene, trans-2-pentene, trimethyl ethylene, tetramethyl ethylene, cyclohexene, and 1,3-butadiene as determined by gas–liquid chromatography and, to a smaller extent, by other analytical methods.

MOLECULAR REARRANGEMENTS IN THE REACTIONS OF OXYGEN ATOMS WITH OLEFINS

Reactions of oxygen atoms with propylene, butene-1, iso-butene, cis-butene-2, trans-butene-2, cis-pentene-2, and tetramethyl ethylene have been studied at room temperature and at pressures between 50 and 600 mm. The following generalizations can be made. The oxygen atom adds predominantly to the "less-substituted" carbon atom of the olefinic double bond to form a short-lived biradical which rapidly rearranges into isomeric epoxy and carbonyl compounds. Rearrangements involve migration of radicals (including H atoms) from the carbon atom to which oxygen is attached to the other carbon atom of the original double bond. Partly inhibited rotation around the original double bond also takes place. Migration of H atoms is exclusively internal. Migration of larger radicals, such as CH3, is only partly internal: a large fraction of these radicals become completely detached from the rest of the molecule and the particular carbonyl compound is produced both by radical combination and by internal migration. The fragmentation resulting from the splitting off of a migrating radical is pressure independent. The final addition products formed are "hot" as a result of high heats of reaction and undergo decomposition if the excess energy is not removed by collisions. This second type of fragmentation is, therefore, pressure dependent. It is very extensive in the case of ethylene and appears to be completely suppressed in the investigated pressure range in the case of more complex olefins (possessing a greater number of degrees of freedom) such as butenes and higher homologues. Propylene exhibits an intermediate behavior. For orientation of addition of oxygen atoms a carbon atom of an olefinic double bond to which CH3 is attached is "less substituted" than a corresponding carbon atom to which C2H5 is attached.

テトラメチルエチレンの重合物

テトラメチルエチレンの重合物