Esterification of epoxy resins with fatty acids at 260° occurs in two stages (1) addition of one fatty acid molecule to an epoxy group to form a hydroxy‐ester, (2) esterification of the original and of the so‐formed hydroxy groups. The curing process of epoxy resins with amines has been studied by infra‐red spectroscopy, and by measurement of the material produced which is non‐extractable by solvents. The combined data provide some indication of the curing mechanism.
1,4-Bis(allyloxy)-2,3,5,6-tetrachlorobenzene (II). Tetrachlorohydroquinone (62.0 grams; 0.25 mole) was dissolved in absolute methanol (270 ml.) contained in a 1-liter, roundbottomed flask equipped with a reflux condenser, pressure equalizing addition funnel, thermometer, and a mechanical stirrer.To the vigorously stirred solution maintained at 30°C. under a nitrogen atmosphere was added dropwise over a 10-minute period a solution of sodium methoxide (14.5 grams assaying 95%; 0.255 mole) dissolved in methanol (105 ml.). Allyl chloride (23.0 grams; 0.3 mole) was added during 15 minutes, while the temperature was maintained at 30°to 35°C. After being refluxed for 20 hours, the reaction mixture was cooled to 30°C. and treated with a second portion of sodium methoxide (14.5 grams; 0.255 mole), followed by addition of allyl chloride (23.0 grams; 0.3 mole) in a manner similar to that described above. The reaction mixture, a brown-colored suspension, was cooled to +5°C. and filtered. The crystalline precipitate was stirred with two portions of 250 ml. of water and once with 250 ml. of 0.4% aqueous solution of sodium hydroxide. The crystals were washed with 250 ml. of water and sucked dry. Drying under reduced pressure at 50°to 60°C. gave 49.2 grams (60% yield) of l,4-bis(allyloxy)-2,3,5,6-tetrachlorobenzene (diallyl ether of tetrachlorohydroquinone), m.p. 124°-125°C.
A survey is made of the apylications of infra-red spectroscopy in the surface coatings field, especially in connexion with (1) the chemistry of drying oils, particularly with reference t o the geometrical isornerization of f a t t y acids, the autoxidation process and copolymerization of oils with unsaturated compounds; (2) the curing of epoxy resins, and (3) the identification of synthetic resins.The permeation of polychlorotrifluoroethylene by nitric acid has been found t o occur at a limited number of sites in the surface of the film. 1 hese sites have been detected using paper impregnated with a suitable indicator and also by microscopical examination ; they were found to be randomly distributed and were mainly macro-or visible cracks. Counts have been made of the numbers and size distribution of the cracks. Infra-red spectrometry was used t o investigate whether chemical reactions occurred between nitric acid and the fluorinated plastic film, but no evidence of chemical degradation products was found.
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