Nuclear magnetic resonance study of electrolytes in 1,3-dimethylethyleneurea

Abstract

JOSEPH ROSENFARB and JOSEPH A . CARUSO. Can. J. Chem. 54, 3492 (1976). A series of lithium, sotlium. potassium, and ammonium salts were investigated by proton magnetic resonance spectroscopy in 1,3-di1nethyIethylene~~rea. a relatively new non-aqueous solvent of high polarity and moderately high dielectric constant. The salts were found to shift the solvent proton peaks linearly as a function of salt concentration. Thiosulfate, perchlorate, and iodide salts shifted the solvent peaks downfield while tetraphenylborate salts uniquely shifted the peaks upfield indicating an ~~n u s u a l type of solvation behavior for the tetraphenyiborates in this solvent.JOSEPH ROSENFARB et JOSEPH A. CARUSO. Can. J. Chem. 54, 3192 (1976). On a CtudiC par rmil du proton dans la dimCt11y-1-1.3 ethylkne urke un solvant non aqueux relativement nouveau de haute polarit6 et de constante dieiectrique modCree, une sCrie de sels de lithium, de sodium, de potassium et d'ammonium. On a trouve que les sels dkplacent les signaux des protons du solvant d'une f a~o n lineaire en fonction de la concentration du sel. Les sels du thiosulfate. du perchlorate et de l'iodure deplacent les pics du solvant vers les bas champs alors que les sels du tCtraphinylborate sont les seuk B tiiplacer les pics vers les hauts champs; ces resultats indiquent un type particulier de colnportemene desolvatation des iCtraphenylborates dans ce solvant.[Traduit par le journal]Proton magnetic resonance which has been used to investigate the solvation behavior of ions in aqueous solutions (1-4) has bcen extended t o non-aqueous media as well (5). Recently 1,3-dimethylethyleneiirea (DMEU) has been investigated with regard t o somc of its fundamental properties (0) and to the behavior of electrolytes therein (7,8). It was found that DMEU is a solvent of high polarity (4.09 in dioxane) (9), moderately high dielectric constant (37.6 at 1 MHz) (6). and possesses good dissociative power towards electrolytes, comparable to that of hr-methyl-2-pyrrolidone and methanol. Particularl!~ interesting kvas the property that sodium and potassiu:~~ salts were isoconducting in DMEU (7). Therefore further study into the nature of solvation in DMEU was indicated.cipitates were thoroughly washed with deionized water, dried, and recrystallized from acetone with water portions. All salts were finely ground and dried in the appropriate manner (5, 7, 10).DMEU was freshly prepared as previously described (6) and had a specific conductance of about 5 X ohm-' ~111-1. MeasurenzetztsChemical shift data were obtained using a Varian A-60 nmr spectrometer. Tetramethylsilane ( 5 ' ; ) was used as an internal reference from which peak shifts were calculated. Since an internal reference was used. no bulk diamagnetic correctio~s were applied (11). Shift data were reproducible to t 0.3 Hz or 0.005 ppm.Results and Discussion A number of alkali halides, tetraalkylammonium salts, and multivalent salts have been investigated in aqueous solution (1,12). It was Experimentalobserved that a downfield (negative) shift of...

Alkali metal salt solvation study in 1,1,3,3-tetramethylurea using nuclear magnetic resonance spectroscopy

“…Chemical shift data from the present investigation for TMU are analogous to chemical shift data for DMEU (9). Studied in common were sodium and potassium tetraphenylborate, lithium and sodium perchlorate, and sodium iodide.…”

“…The oxygen site is more sterically accessible than the nitrogen sites. A solvated anion will interact with TMU solvents (7)(8)(9). The increase in electron density around solvent protons is probably associated with the proximity of the protons to the T electron system in tetraphenylborates.…”

“…Later papers described solution behavior of alkali metal salts in nonaqueous solvents (5)(6)(7)(8)(9)(10). Specific solvents included Nmethyl-2-pyrrolidone (5, 6), 3-methyl-2-oxazolidone (7, 8), 1,3-dimethyleneurea (9), and 1,1,3,3-tetramethylurea (10).…”

“…Proton NMR, used in the dimethyleneurea (DMEU) study, followed the chemical shifts of the solvent's methyl and ethylene protons. The salts, which included a variety of tetraphenylborates, perchlorates, and iodides, were dissociated until 0.75 molar (9).…”

Estudo cinético por TG e DSC da decomposição térmica de alguns adutos de haletos de cádmio

“…A dimetiletilenouréia (dmeu), diferentemente da etilenouréia da qual é derivada, é liquída à temperatura ambiente, chegando a ser utilizada como solvente em sínteses ou estudos espectroscópicos 2,3 . O estudo cinético da termodecomposição de sólidos pode ser efetuado utilizando-se dados de TG, DTA ou DSC 4 .…”