zum 60. Geburtstag gewidmet Lineare Polyurethane, wefche in groJeren Abstanden ionische Zentren enthalten, sind Heteropolymere mit ausgepragter Segmentstruktur, d. h. Ionomere. Durch interchenare Wechselwirkung (Coulomb-Krajle und Wasserstoffbriicken) haben sie ahnliche Eigenschaften wie vernetzte Elastomere. Sowohl in organischer afs auch in wajriger Losung sind sie stark assoziiert. In polaren organischen Losungsmitteln vorliegende Polyurethan-Ionomere bilden bei Wasserzusatz spontan stabile wajrige Dispersionen rnit dem Ionomeren als disperser Phase. Die Teilchendurchmesser konnen zwischen 20 nm und I mm variiert werden.
It has already been reported 111 that phenyl o-phenoxybenzoate can be prepared in high yields by heating a melt of diphenyl carbonate in the presence of small amounts of KzC03 a t 23&270 "C. We have now found that the diphenyl ethers (2) can be prepared from 0-and/or p-substituted diphenyl carbonates ( I ) when subjected to similar reaction conditions. ' R3 (1)The oxidation product first prepared by H . v. Pechmann and W. Bauer by reaction of 2,3-butanedione bis(benzoy1hydrazone) ( I ) [11 with potassium hexacyanoferratefrrr) wasformulated [21 as 2,3-dibenzoyl-5,6-dimethyl-2,3-diliydrotetraazine (2). Catalyst wt.-% calc. w. r. t. ( I ) 1 K2CO3 0.5 KOCOCH, 1 KOCOCH, 1 KOCOCHi 1 K2C03 1 KzCO, 1 K2CO3 1 K2C03 Temp. f "C) 210-250 180-205 190-220 156-1 86 186-226 200-242 240-260 200-2 14 17 > 90 41 89 31 65 66 22 [ a ] Not optimized.A prerequisite for this reaction is that a t least one of the groups R1-R" is a second order substituent; preparatively useful yields, however, are obtainable only from symmetrically substituted, particularly p,p'-disubstituted, diphenyl carbonates. Numerous other alkali metal compounds may be used as catalysts (in amounts of 0.5-2 wt.-%) instead of potassium carbonate. (2), Rl=R2=N02, R3=R4=H [21 4,4'-Dinitrodiphenyl carbonate (1 000 g) (crude phosgenation product, m.p. 140 "C) [3J is melted (silicone oil bath) in a 2 1 three-necked flask fitted with stirrer, internal thermometer, and a delivery tube connected via a bubble counter. Potassium acetate (5 g) is added slowly, with stirring, to the melt a t a temperature of 150 'C. Decarboxylation ( 18@-205 'C, bath temperature 190-215 "C) is complete after 4-5 hours. The temperature of the mixture is then allowed to drop to 150 'C, and, after the apparatus has been fitted with a reflux condenser, toluene (580 g) is added slowly. The solution is filtered hot from insoluble residue (ca. 8 g). The filtrate is then cooled and the 4,4'-dinitrodiphenyl ether which crystallizes out is recovered by filtration, washed with a little methanol, and finally dried in a vacuum (yield 749 g (88 %), H3C ,N-NH-CO-C,H, H3C x N-NH-CO-CBH, H3C 4,4'-Dinitrodiphenyl etherThe 1H-NMR spectra (in CDC13) of the oxidation product at 60 and 220 MHz 131 show that the compound does not have a symmetrical structure. Two methyl-group signals appear in the 60 MHz spectrum at 2.23 ppm and 2.36 ppm in addition to a multiplet (signal width ca. 20 Hz) centered at 8.1 ppm which is due to the protons of both aromatic rings that are ortho to the carbonyl groups. i n the 220 MHz spectrum the multiplet is resolved into two pseudo doublets at 8.116 ppm and 8.236 ppm ( J = 7.8 to 8.0 Hz). The remaining six aromatic protons absorb between 7.4 and 7.8 ppm. On the basis of these findings, therefore, we suggest that the oxidation product has the structure of a mesoionic triazole (3),which is in agreement with the chemical properties of this compound. The ready hydrolytic and thermal loss of a benzoyl group is now understandable since the compound is being considered as an azolider41. As i...
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