Abstract
The influence of some typical oxygen‐, sulfur‐, and nitrogen‐containing impurties on the polymerization of propylene in a hydrocarbon medium under the catalytic action of titanium trichloride and triethylaluminum was studied. Both these catalyst components used in polar‐coordinated polymerizations of α‐olefins are very reactive toward substances having atoms with a free electron pair. Triethyl aluminum forms complex compounds with these substances. Some of the complexes are so stable as to allow distillation; attempts to isolate the original components often lead to the destruction of the whole molecule. Donor‐type compounds do not attack triethylaluminum only; they also attack titanium trichloride which displays the properties of a strong sorbent. The transitional metal (Ti) with incompletely occupied d‐orbits and a lone electron gives ample opportunities for chemisorbing molecules of olefins as well as molecules containing atoms of the fifth and sixth groups of the periodic table. Donor‐type substances were studied on the one hand from the viewpoint of the interaction with the separate catalyst components (the influence of the so modified catalyst on the polymerization being studied) and on the other hand from the viewpoint of the influence of the donor‐type substance during the course of polymerization, i.e., the effect on both unmodified catalyst components (including the active complex) simultaneously. Changes of the principal characteristics of the polymerization process (viz., the overall rate of reaction, the molecular weight, and the percentage of amorphous matter) have been followed. It became evident that the interaction between the donors and the solid phase of the catalyst is governed by rules of adsorption (excluding cases involving deeper changes of the solid phase during the reaction, e.g., its dissolution). Compounds which are sorbed influence the polymerization process in a significant manner. They come into play more intensely than the products of the interaction of donor‐type substances with triethylaluminum which generally result in the formation of complex compounds not influencing the course of polymerization so strongly. It has been found that from among the characteristics studied the overall rate of polymerization is the one which is most affected by the presence of substances with free electron pairs. With minor exceptions the molecular weight was found to increase through the agency of the admixtures. A similar relationship has been found to hold for the percentage of amorphous matter as well.