P-Aroyl-a-(ar y1methylen)propionsaurenKondensation der P-Aroylpropionsauren 2a -d mit Furfural (1) fiihrt zu (E,Z)-Gemischen der Enollactone 3a-d. Die Zuordnung zur (E)-oder (2)-Reihe und das Isomerenverhaltnis wurden durch hochaufgeloste 'H-NMR-Spektren bestimmt.Condensation of aromatic aldehydes with P-aroylpropionic acids gives the en01 lactones of P-aroyl-a-(arylmethy1ene)propionic acids' -3). These enol lactones purified by recrystallization, were assigned to be (E)-configurated without a crucial evidence. We were interested to investigate whether the reaction leads also to the (Z)-enol lactones which were probably lost during thc purification steps described in former publications.We therefore treated furfural(1) with p-substituted P-benzoylpropionic acids 2a -d in the presence of acetic anhydridelsodium acetate (Perkin conditions) and we obtained isomeric
Heterocyclic aldehydes such as 2-thiophenecarbaldehyde (1) condense with 3-aroylpropionic acids 2 or their sodium salts to give the enol lactones 3a-d of 3-aroyl-2-(2-thienylmethy1ene)propionic acids. Isomerization of 3 a -d leads to the corresponding 4-arylbenzo[b]-thiophene-6-carboxylic acids 4a-d. The structure of the latter is confirmed by an independent synthesis. Recently I ) we described the reaction of furfural with p-substituted 3-benzoylpropionic acids 2a-d to afford the enol lactones 3a-d (Scheme 1, furan instead of thiophene). These lactones could not be isomerized by treatment with acid because the furan ring was cleaved.
Synthese von Enol-LactonenTherefore, we were interested in the analogous reaction of the more stable
This study investigates the effects of fluorinated or non-fluorinated water-repelling finishes on woven cotton fabric properties of ring and compact plain cotton fabrics made from Egyptian cotton variety (Giza 92). Spray rating test, stiffness, flexural rigidity, tensile strength and Elongation were done to assess the effect of water-repellent finishes on treated cotton fabric properties. The relationships between cotton fabric spinning type and fabric stiffness were measured. The results showed that the water repellent finishing has a great influence on fabric properties according to the cotton fabric spinning type and finishing concentration, The fabric stiffness (Flexural Rigidity) is increased by increasing of water repellent concentrations, as well as the weight of fabric increases in all finished fabrics at all concentrations, all treated fabrics showed a high level of water repellency.
ChemInform Abstract Acid (IIIa) cannot be isomerized to the corresponding benzofuran since the furan ring is cleaved under the reaction conditions shown.
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