Ureas as Solvents for Chemical Investigations

Abstract

N-Alkylated ureas, including cyclic derivatives. are readily obtained pure. These stable compounds are already used as industrial solvents owing to their considerable solvent power, their wide liquid range, and their favorable dielectric constants and dipole moments. They are being increasingly employed as reaction media for electrochemical and analytical studies.

Substitution of HMPT by the cyclic urea DMPU as a cosolvent for highly reactive nucleophiles and bases

“…-20" (m.p. of HMPT: 7") has been reported [6]; we find that a (1 : 2)-mixture with THF is clear and homogeneous down to -9O", and during reactions, we have not experienced solvent precipitations at temperatures of -78" or above.…”

“…3, For a review on tetramethylurea, see [5]; for a more recent survey of tetrasubstituted ureas as solvents see [6]. A few other solvents, cosolvents, and/or complexing agents have also been studied; for example tetraalkylsulfamides [7] and N, N, N', N'-tetramethylethylenediamine (TMEDA) 181.…”

“…We were particularly interested in a cosolvent which a) would be compatible with highly nucleophilic and basic reagents3), and b) could be employed at dry-ice temperature or below. We reportFor a review on tetramethylurea, see [5]; for a more recent survey of tetrasubstituted ureas as solvents see [6]. A few other solvents, cosolvents, and/or complexing agents have also been studied; for example tetraalkylsulfamides [7] and N, N, N', N'-tetramethylethylenediamine (TMEDA) 181.Other solvents such as dimethyl sulfoxide (acidic) or 1-methyl-2-pyrrolidinone (both acidic and electrophilic) were thus not suitable.…”

Excess molar volumes of binary mixtures of 1,3-dimethylimidazolidin-2-one with an alkan-1-ol at the temperatures 283.15K, 298.15K, and 313.15K

“…Limited studies on physical properties of pure DMI have been carried out and only two reviews on the properties are available in the literature [3,4]. Since DMI is completely miscible with water, we have so far reported not only the excess molar volumes V E m from density measurements under atmospheric pressure at 298.15 K and 308.15 K [5] but also the static relative permittivities under pressures up to 300 MPa at 298.15 K [6] over the entire composition range for binary aqueous DMI mixtures.…”

D2O–H2O solvent isotope effects on the volumetric properties of aqueous 1,3-dimethyl-2-imidazolidinone between (278.15 and 318.15)K

“…DMI, known earlier as N,N'-dimethylethyleneurea, being a molecular cyclic analogue of 1,1,3,3-tetramethylurea (TMU) in the individual liquid state is a versatile dipolar aprotic solvent whose physicochemical and thermodynamic properties are rather well studied [18][19][20][21][22][23][24][25]. Herewith, having hydrophobic ÀCH 3 and ÀCH 2 ÀCH 2 À groups (attached to two various N atoms) in the molecular five-membered ring and acting only as a H-bond acceptor via a hydrophilic C@O group, DMI can be regarded as a simplified model cyclic compound for studying the complex interaction with the aqueous surroundings [14,26].…”