Théophile Yvernault

Physical properties of the solvent mixtures triethylphosphate+hexamethylphosphoric triamide at 25C

Densities and viscosities have been determined, from 25 to 45°C, as well as the refractive indices and dielectric constants at 25°C, for mixtures of triethylphosphate (TEP) and hexamethylphosphoric triamide (HMPT), in the complete mole fraction interval. As far as steric considerations are concerned, comparison has been made with the properties of the two intermediate organophosphorus compounds, ethoxytetramethylphosphorodiamide (EtO)(Me2N)2PO and diethoxydimethylphosphoramide (EtO)2(Me2N)PO.

Enthalpies de complexation de quelques phosphoramides avec le chlorure d'antimoine(V). Influence de la structure sur le nombre donneur selon Gutmann

Abstract Complexation enthalpies for various compounds with SbCl 5 have been calorimetrically determined in dilute dichloro-1,2 ethane solution at 25°C. In the case of 22 organo-phosphorylated compounds OPX x ,Y 3- x , (X, Y = NMe 2 , Net 2 , NHEt, , OEt; x = 0, 1, 2, 3), our calorimetric results allow a characterization of Lewis basicity variations (as Gutmanns donor number DN) against the nature of substituents at the phosphorus atom. Within this scale, many compounds are more basic than HMPA OP(Nme 2 ) 3 whose DN is, according to our results, greater than currently admitted; if no systematic effects are noted, the influence of conformation may, however, explain the DN variations in each series (for X and Y given, x varying from 0 to 3). Moreover, thanks to conductometric measurements, an instantaneous reaction of triethylamine with the solvent is evidenced.

Gas Phase Basicity of Hexamethylphosphotriamide (HMPT) and Phosphinoxide Derivatives

Abstract Gas phase basicities are determined by Ion Cyclotron Resonance (ICR) mass spectrometry for the six organophosphorus compounds OP(NMe2)3-x Me x x=0 to 3, OP(nPr)3 and OP(OEt)3. All values are in the range 209–219.3 kcal · mol−1, and their variation with structure is examined. The site of protonation (O or N?) is briefly discussed, and arguments are presented which favour O-protonation.

Moments dipolaires et conformations de l'hexaméthyl-phosphotriamide (HMPT) et des dérivés aziridinylés correspondants

Abstract Some physical properties (density, refractive index, dielectric constant, dipole moment) have been determined for the phosphoramides Variations of dielectric constant and dipole moment as a function of the structure show a minimum for n = 2. In order to explain this minimum, the dipole moments are evaluated for various conformations, using both a rigid dipoles summation and quantum calculations (CNDO/2). The values adopted for the bond angles and for the interatomic distances are discussed. The conformation in which the three nitrogen lone pairs are essentially parallel to the PO axis (one in the same direction, two in the opposite direction) seems to be applicable to all the phosphoramides studied. In the case of HMPT ( n = 0), however, the arrangement in which the nitrogen lone pair is parallel to the PO axis in the opposite direction, and the two others in a plane perpendicular to PO, seems to be more reasonable. These structures are compared with those for some related compounds. Relationships between the basicity (deduced from proton NMR chemical shifts of hcci 3 ) and the orientation of dipole moment are discussed.

On the existence of the protonated hydronium dication H4O2+ in sulfolane solution

The enthalpy of solvation in sulfolane of the gaseous protonated hydronium dication is estimated as −628 kcalmol at 298 K. Using literature data, a value ΔHo = −212 kcal/mol is calculated for the reaction H3O+ + H+→ H4O2+ (in sulfolane), supporting the thermodynamic existence of H4O2+ in sulfolane solution, as characterized previously by potentiometric and conductometric titrations. Some aspects of these results are discussed.

Ionic solvation from conductivity data: Application and extension of the Chen-Adelman model

The most popular current theories representing the conductivity of a moving ion in an electric field are surveyed. The Chen-Adelman model of a partially solvated ion gives a good representation of literature data for alkaline and R4N+ cations in five dipolar aprotic solvents. For multivalent cations however, one must introduce an extension of the Chen-Adelman model to a two-shell solvation model. Most of these results may be interpreted in terms of hard and soft acid-base interactions.

Etude microcalorimetrique de l'inhibition de la cholinesterase par quelques phosphoramides aliphatiques

Abstract Flow microcalorimetry is applied to the determination of kinetic inhibition constants of cholinesterase by some organophosphorus compounds. Experimental data, treated with the integrated Michaelis-Menten equation, showed that the 9 aliphatic phosphoramides studied here (OPXYZ with X, Y, Z = NMe 2 ; NEt 2 ; ; or ) behave according to a competitive scheme; they are, however, weak inhibitors.

INHIBITION REVERSIBLE DE LA BUTYRYLCHOLINESTERASE PAR QUELQUES PHOSPHORAMIDES ALIPHATIQUES

Abstract The inhibition of horse serum butyrylcholinesterase by 16 aliphatic phosphoramides OPXYZ (with X,Y,Z = Me; NMe2; NHEt; NEt2; has been studied at 30°C and pH 7.4, with a spectrophotometric method using butyrylthiocholine as substrate. The inhibition was always reversible, although an apparent irreversible inhibition was sometimes observed with insufficiently purified inhibitors. Non-linear least-squares analysis of inhibition data showed 13 competitive inhibitors, 2 mixed and 1 non-competitive. The influence of the substituents borne by the phosphoramide molecule upon the competitive inhibition constant is approximately additive, allowing the attribution of a specific increment, δ, to each substituent. There is no correlation between this increment δ and Van der Waals volume Vw or the inductive parameters π and σΦ. However, there is a slight correlation between the competitive inhibition constant and the partition coefficient (octanol/water) of the phosphoramides, suggesting participation of hydro...

Structure and Basicities of Aliphatic Organophosphorus Compounds

Abstract As an extension of our previous works concerning the basicities of aliphatic phosphoric amides and phosphinoxides, the influence of structure is studied for some series of parent compounds, such as : XP(tBu)3 with X=lone pair; O; S; NH ˙ OP[N(CH2)X]3 with x=2; 3; 4; 5. The techniques used here are mainly: determination of gas phase basicities by ion cyclotron resonance mass spectrometry determination of Broensted basicities by titration in an non-aqueous solvent system dipole moment measurements