Dicarboxylic acid-urea complexes

Abstract

A study of the reaction of several acids with urea resulted in a series of compounds of varying stoichiometry and structure. The acids having the structure H02C(CH2)"C02H produced saltlike compounds with urea when n -0 and 1 and H-bonded complexes for = 2-5. The stoichiometry of all the complexes was 2H2NCONH2-HOOC(CH2)"COOH, except for -1 which had a 1:1 ratio of urea to acid. None of the products was an inclusion compound. From our general observations, we concluded that urea and the dicarboxylic acids are unlikely to form inclusion compounds, and reports of such molecular compounds should be verified by X-ray powder diffraction measurement as well as analysis.2-urea-oxalic acid-2-water. Ljubawin6 in 1872 de-(1) Reprint requests should be addressed to this author at the Pitman-Dunn Research Laboratories.(2) (a) W. Schlenk, Jr., Ann., 565, 204 (1949); (b) L.

Super water-absorbing new material from chitosan, EDTA and urea

“…However, the crosslinking of chitosan through the interaction of its amino groups with EDTA is possible, since EDTA is a tetra functional acid. The protonation of urea by organic acids resulting in compounds of varying stoichiometry and structure has also been reported (Paleckiene, Sviklas, & Slinksiene, 2005;Radell, Brodman, & Domanski, 1967). Thus, the reaction between urea and citric acid is reported to result in the formation of urea citrate (with a molar ratio 1:1).…”

The utility of a ternary phase diagram in the discovery of new co-crystal forms

“…(2 : 1 co-crystal -monoclinic, C 2 /c, a ¼ 11.954, b ¼ 10.932, c ¼ 9.078, a ¼ 90, b ¼ 97.86, g ¼ 90). The melting point of this form has been determined to be between 120 and 130 C. 18 In addition, there is one report by Videnova 19 of the crystal structure of a 1 : 1 co-crystal. (1…”

Harnstoffkomplexe mit Dicarbonsäuren. 1. Mitteilung: die Struktur von Bernsteinsäure–Harnstoff

“…Modellverbindungen hierfiir sind Harnstoff-Komplexe mit Dicarbons/iuren. Die Existenz dieser Addukte wurde bereits mehrfach erwiihnt (Radell, Brodman & Domanski, 1967;Molodkin, Ellert, Ivanova & Skotnikova, 1967;Siemons, 1970). Die Kristallstrukturen von Oxals/iure-Hamstoff 1/2 und 1/1 wurden bereits beschrieben (Harkema, Bats, Weyenberg & Feil, 1972;Harkema & Ter Brake, 1979 (7) 8668 (4) 41 (2)* Ol 4331 (8) 2106 (5) 5447 (3) 49 (2)* 02 2621 (7) 1419 (5) 3788 (3) 46 (1)* 05 7534 (7) 1310 (5) 9640 (3) 48 (2) (Johnson, 1976).…”