S. Brunel

Polyoxyethylene di-phosphonates as efficient dispersing polymers for aqueous suspensions

Polyoxyethylenes having a di-phosphonate functional group at one of their chain ends strongly adsorb on calcium carbonate particles in aqueous colloidal suspensions. An enhanced colloidal stability of such suspensions results with a concomitant drastic reduction of the viscosity of concentrated aqueous suspensions. The viscosity of a 20 wt % CaCO3 colloidal suspension in water could be lowered to 2 mPa · s with low concentrations of polymer. The adsorption and viscosity reduction were studied as a function of the chemical nature of the end chain group and the polymer molecular weight. The di-phosphonate group was found the most efficient anionic group when associated with a polyoxyethylene of polymerization degree larger than 20. The main features of this di-block architecture of the polymer are discussed.

Synthesis of new zwitterionic surfactants with improved solubility in water

Abstract New neutral zwitterionic surfactants of the sulfobetaine series have been synthesized in a preparative scale in a two steps procedure. Ring opening of propane or butane sultone is obtained by a 2-methyl-1,3-cycloiminoether in a first stage, and the resulting inner cycloiminium sulfonate salt is ring-opened by a fatty tertiary amine. The introduction of an acetamide group between the two charged groups of the zwitterion enhances the solubility in water and then allows the use of octadecyl chained surfactants in water at room temperature. This synthesis provides pure compounds, free of inorganic ions, in good yield addition reactions from commercially available starting materials.

A new alkylamidation reaction

Abstract Cyclo 1,3-oximminium salts are found to react regiospecifically with functional carbanions. Steric effects induced at the C-2 site on salts or at the carbanionioc centers promote the condensation at the C-5 or C-6 opposite sites. A bulky substituent such as 2-mesityl group is a powerful auxiliary which not only modifies the steric environment at the reactive C-2 site but also contributes to enhance the reactivity of the cyclo oxoimminium ring.

Alkylamidation d'organometalliques par les sels d'oxoimminium-1,3 cycliques

Abstract Dialkylcuprolithium reagents are efficiently condensed at low temperature onto N-Methyl 2-(2,4,6-trimethyl) cyclo 1,3-oxoimminium salts giving rise specifically to the corresponding alkylamides.