Studies on glyceryl esters II.The use of urea inclusion compounds for the fractionation of technical monoglycerides

Aylward, F.; Wood, Peter D.

doi:10.1002/jctb.5010080904

Cited by 3 publications

(1 citation statement)

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“…After this key historical event, synthetic urea has functioned in many roles. Urea inclusion compounds have served as separation media − and have provided an insight into the nature of hydrogen bonding for two-dimensional crystal engineering. − The ability of the urea molecule to participate in hydrogen-bonded α-networks via the carbonyl group of one unit and two hydrogen atoms of an adjacent unit (bifurcated hydrogen bonding) provides the supramolecular “cement”. Urea is a chaotropic agent and has progressed the understanding of hydrophobic interaction in aqueous solutions.…”

Section: Introductionmentioning

confidence: 99%

Nonionic Urea Surfactants: Influence of Hydrocarbon Chain Length and Positional Isomerism on the Thermotropic and Lyotropic Phase Behavior

et al. 2006

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The thermotropic and lyotropic phase behavior of 1- and 5-decyl urea, and 1-, 2-, 4-, and 6-dodecyl urea have been studied. This allowed the effect of positional isomerism to be examined. Intermolecular hydrogen bonding by the urea moiety is the dominant factor in determining the solid-state thermal behavior and crystal solubility boundary of these linear nonionic surfactants. The positional isomers where the urea moiety was not situated at the terminus of the hydrocarbon chain exhibited higher melting points than the 1-alkyl ureas. This has been rationalized by postulating interdigitated chains in the solid state. In the urea surfactant-water systems, three phases are observed, viz. crystalline solid, a dilute aqueous solution of the alkyl urea, and an isotropic liquid. The last two phases coexist in the low-surfactant, high-temperature region of the binary phase diagram. An overview of structure-property correlations for linear nonionic urea surfactants is presented in light of the new physicochemical data obtained for the decyl urea and dodecyl urea positional isomers.

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