Polymers derived from alkylaluminum

Polymers Derived from Alkylaluminum Hydrides. All of the above synthetic routes utilize ammonia or an amine as the nitrogen source for the polymers. Significantly less effort has been spent on the study of the interaction of aluminum reagents with other nitrogen donor molecules. For example, addition of AIH3-NR3 adducts to acetonitrile or aziridine solutions yields polymeric products with imine end groups according to equation 11 (35,36), The product is soluble in benzene and has a... 

The use of C-labeled triethylaluminum allowed us to demonstrate that the quantity of —C2HB groups [deriving from A1(C2Hb)3] which is bound to the non-atactic polymer at the end of the polymerization, when operating with a constant amount of titanium trichloride, is a linear function of the square root of the alkylaluminum concentration (Fig. 22), in the considered range of experimental conditions (4 ). Similar results have been obtained by analyzing the fraction of amorphous polymer (Fig. 23) (38). 

Determinations of aluminum have been carried out on fractions of polymeric product containing isotactic chains deriving from the polymerization. These measurements were performed in an attempt to establish whether the chain transfer process, depending on the alkylaluminum concentration, leads to the formation of macromolecules which remain bound to the aluminum. The polymer has been therefore purified by physical methods from the unreacted ethylaluminum and from the heterogeneous catalyst. 

The results obtained are plotted in Table III. In the same table, for purposes of comparison, are recorded the amounts of ethyl groups derived from the Al(C2H6)a, as found in certain fractions of the polymer by the radiochemical methods. The amount of aluminum bound in the polymer is higher in the test performed with higher triethylaluminum concentrations. A comparison with the tests performed with the same alkylaluminum concentrations, but with different amount of a-TiCU, shows, on the contrary, that the amount of aluminum bound to the polymer decreases remarkably... 

The method employed to calculate the total number of active centers relies upon the determination of the variation occurring in the ratio between ethyl groups (deriving from the alkylaluminum) which are present in the polymer and the whole amount of polymerized propylene, on increasing the time of polymerization. 

In the following cases, only those reactions in which there is no chain growth, or at most dimerization, are considered (see Olefin polymers). Alkyl titanium halides can be prepared from alkylaluminum derivatives. The ring structure imparts regiospecificity to the ensuing carbometalation (216) ... 

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