Organometallic compounds containing a metal belonging to the second column of the periodic table, and method for preparing same

#The present invention relates to a novel organometallic compound based on a divalent metal belonging to the 2nd column of the Periodic Table that can be used as an alkylating co-catalyst in a catalytic system for polymerization based on a rare earth. The present invention also relates to a process for preparing said novel organometallic compound.

#Now that savings in fuel and the need to protect the environment have become a priority, it is desirable to produce mixtures having good mechanical properties and a hysteresis which is as low as possible in order to be able to employ them in the form of rubber compositions which can be used in the manufacture of various semi-finished products incorporated into the composition of tyres, such as, for example, underlayers, sidewalls or treads, and in order to obtain tyres having an increasingly reduced rolling resistance. In order to achieve such an objective, it has been proposed to modify the structure of the diene polymers and copolymers at the end of polymerization by means of functionalizing, coupling or star-branching agents in order to introduce into the elastomer an interactive function with respect to the filler (or fillers) used in the rubber composition.

#A very large majority of these solutions firstly concentrated on the use of functionalized polymers that are active with respect to carbon black, for the purpose of obtaining a good interaction between the polymer thus modified and the carbon black.

#All of the organometallic syntheses were carried out under an inert argon atmosphere using either Schlenk techniques or a glovebox. All the solvents used during these syntheses are dried according to conventional techniques (distillation over sodium or over a molecular sieve) and are kept under an inert atmosphere. For example, the pentane and the THF are freshly distilled over sodium/benzophenone. All of the reactants come from Sigma-Aldrich, Strem and Fluka.

#Nd(BH4)3(THF)3 was prepared according to a procedure described in the literature: S. Cendrowski-Guillaume, M. Nierlich, M. Lance, M. Ephritikhine, Organometallics, 1998, 17, 786.

#13.4 g of ortho-dimethylaminotoluene (or N,N-dimethyl-o-toluidine) (M=135 g.mol−1; 99 mmol) are diluted in a mixture of 40 ml of hexanes and 20 ml of diethyl ether. At ambient temperature, under nitrogen and with stirring, 40 ml of a solution of butyllithium (2.5M in hexane) are added. After 3 h, 1 equivalent of tBuOK is added in fractions, under argon. The solution is heated and a yellow precipitate appears. The stirring is maintained overnight. The solution is filtered and the yellow precipitate is washed three times with a mixture of hexanes (3×40 ml). After drying under vacuum, the solid is milled and dried again under vacuum overnight. 14.9 g of yellow powder of ortho-dimethylaminobenzyl potassium are obtained (yield=80%). 1H NMR (THF-d8, 22° C.): δ=2.03 and 2.57 (2×1H, s, KCH2—), 2.67 (s, 6H, —NMe2), 5.11 (t, 1H, JH-H=7 Hz, aromatic CH), 6.04 (d, 1H, JH-H=7 Hz, aromatic CH), 6.16 (t, 1H, JH-H=7 Hz, aromatic CH), 6.26 (t, 1H, JH-H=7 Hz, aromatic CH).