Alfin reagent

This paper will put together facts and ideas in Alfin polymerization which are related to the surface effects. The specific components of the reagent, their proportions, and their probable arrangement will be described. Polymerization will be interpreted as a phenomenon which occurs only on the surface and actually only on certain areas of that surface. Once started, chain growth does not spread to other areas or into solution, but remains on that particular area. In line with other catalysts, the Alfin reagent can be spread upon certain noncatalytic surfaces and can be poisoned by various salts or ions. The special features are further exemplified by the fact that the action is specific for extremely few monomers. Finally, a manner by which polymerization actually occurs on such a surface will be suggested. 

All of the above features show the specific character of the components of the Alfin reagent or catalyst. The method of preparing the reagent may be varied, but all three components must be present. These are as a rule an alkenylsodium compound, a secondary alkoxide, and a sodium halide. Of the first two salts the most effective have the shortest unbranched carbon chain. 

The above collection of ions from three different salts functions as a solid surface upon which polymerization begins, continues, and finishes. Several facts justify this view. In pentane the solubility of allylsodium from the Alfin reagent is not noticeable by any ordinary measurement, but the amount of poljmerization can nevertheless be doubled or tripled as the quantity of reagent is correspondingly increased. A poljmerization caused only by a saturated solution should be unaffected by such means. 

A third fact is that a near-colloidal suspension of the reagent freshly formed has little activity, whereas the large particles several weeks later are very active. Alfin reagents made with mixtures of isopropoxide and... 

Naphthylmethylsodium does not itself induce Alfin polymerization but can act as a support or extender for an Alfin reagent. When mixed in equal quantities (1 mole of allylsodium to 1 mole of naphthylmethylso-dium), the capacity of the reagent is doubled or tripled (9). Polymerization does not spread to the naphthylmethylsodium but remains the same as for the Alfin catalyst alone. That is to say, the viscosity and the ratio of trans-... 

H. E. Diem B. F. Goodrich Co., BrecksviUe, Ohio) I should like to point out that the highly specific character of the alfin reagent for the polymerization of butadiene, which Dr. Morton s many papers have demonstrated (Lecture 75), suggest that the monomer is adsorbed in a specific oriented fashion on the catalyst surface. If this is true, it seems unlikely that the structure of the poljuner (% 1,4- vs. % 1,2- addition) can serve to distinguish the mechanism of the reaction. That is, the fact that the structure of the polymer butadiene from the alfin catalyst is very similar to that obtained from free radical catalysts is only a coincidence. 

Acrylonit e is one of the most reactive monomers toward anionic catalysts. A wide range of initiators of this type has been used and include the alfin catalysts, alkoxides, butyUithium, metal ketyls, and solutions of alkali metals in ethers. In a number of anionic polymerizations, there is no termination reaction if pure reagents are used, and so-called living polymers are formed. Sudi living" systems are more difficult to observe in the case of acrylonitrile owing to the insolubility of the polymer in most of the usual solvents. It is possible to produce block co-polymers with acrylonitrile from other living" polymeric anions. 

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