Ether Epoxide Research Articles

Linear furocoumarins and other constituents from thamnosma texana

Eight linear furocoumarins and three coumarins were isolated and identified from Thamnosma texana. They were xanthotoxin, imperatorin, bergapten, alloimperatorin methyl ether epoxide, heraclenin, isopimpinellin, psoralen, oxypeucedanin, and the coumarins herniarin, osthol and thamnosmin. The linear furocoumarins appear to be agents that account for the known photosensitizing properties of Thamnosma texana, and consequently its colloquial name, ‘blisterweed.’ This is the first report on the occurrence of imperatorin, heraclenin, oxypeucedanin, herniarin or osthol in any Thamnosma species.

High‐resolution dark‐field imaging in epoxy and polyimide systems

AbstractThe feasibility of molecular imaging in polymers by electron microscopy is discussed. The tilted dark‐field method is specifically chosen for studying ultramicrotome thin sections. One system studied here is bisphenol‐A diglycidyl ether epoxide monomer (DGEBA) amine cured either by dicyandiamine or by diaminodiphenyl sulfone under various conditions. The second sample is a polyimide prepared from maleic anhydride and diaminophenyl methane. The distribution of the molecules is consistent with the random‐coil model when neither etching nor strains are applied. Bisphenol‐A groups distributed at random in the polymer are imaged in DGEBA as units 10 Å long and 5 Å wide, whereas larger isometric diffracting domains (10–15 Å) are imaged in polyimides.

Remote group derivatives: limitations on the effectiveness of pyrrolidide derivatives of oxygen-containing fatty acids.

The pyrrolidides of a number of fatty acids containing oxygen functions (ether linkage, epoxide ring and hydroxyl group) have been prepared and their mass spectra recorded. Detailed analyses of these, supported by accurate mass measurement, indicate that the presence of the oxygen atom has a profound effect on the normal, sequential, mode of pyrrolidide fragmentation. Cleavage adjacent to the oxygen is enhanced, this being most marked in the spectra of those compounds containing an ether linkage. However, further fragmentation of the carbon chain distal to the pyrrolidide group is minimal and prevents any structural information being obtained. These findings indicate that the usefulness of the pyrrolidide derivative for structural elucidation purposes is severely limited in some cases when an oxygen atom is present in the chain. However, for both the epoxy- and hydroxy-fatty acids, complementary derivatization methods are available.

Clarification of the mechanism of rearrangement of enol silyl ether epoxides

Clarification of the mechanism of rearrangement of enol silyl ether epoxides

The Synthesis of Tricyclo [4. 2. 2. 02, 5] Deca-3, 7, 9-Trienes and Related Derivatives Via the Kolbe Oxidation Route

Abstract The Koloe oxidation of cis-dicarboxylic acids is a convenient method for clafin synthesis 1,2,3. In an earlier communication 1 one of us reported the synthesis of Tryicyclo [4.2.2.02,5] deca-3,7,9-triane (Nenitzescu's hydrocarbon) by this method. In view of the interest in the (CH)10 energy surface, any entry at the C10H10 level immediately malcas & wide range of ring structure potentially available. 4 For this reason we have chosen to concentrate on the tricyclo[4.2.2.02,5] deca-3,5,7-triane system and now report the results of a series of compounds containing various functional groups which prove to be stable under the reaction conditions. These now include phosphine oxide35, cyclic ether 3g, nitrile1, ester1, vinyl bromide, vincinal dibromide, methoxy, ketone and epoxide group (See table).

Studies on constituents of Thamnosma montana Torr. and Frem. : The structure of thamnosmin, a novel coumarin epoxide

An intensive investigation on the natural products found in Thamnosma montana Torr. and Frem. is described and the identification of fifteen constituents is discussed. Of those compounds previously shown to occur in the plant, a number of coumarins were recognized for the first time. Two of these constituents were novel, alloimperatorin methyl ether epoxide ( 11) and thamnosmin ( 19), the latter possessing a unique system not previously encountered in nature.

Effect of certain hostile environments on adhesive joints

AbstractThe effects of water vapour on aluminium‐aluminium bonded joints, using a Bisphenol A diglycidyl ether epoxide resin cured with bis‐(4‐aminophenyl)‐methane as the adhesive, have been studied. A distinction has been drawn between the effect on joint strength and on polymer strength. The very significant fall in joint strength compared with the change in polymer strength is used to postulate that in adhesive joints of this type, water molecules rapidly enter the boundary region to interfere with the secondary valence forces responsible for adhesion between substrate and organic adhesive. The results are further interpreted as support for the view that the polymer adjacent to the metal substrate is likely to differ in structure and conformation from the main polymer mass, namely a boundary layer. Similar experiments using the less polar ethanol provide further evidence for the hypotheses.