The rules governing copolymerization of multicomponent systems are based on simple kinetic premises. From them can be calculated the composition of a copolymer and the distribution of sequences of the same monomer unit as affected by monomer concentration and degree of conversion. Copolymerization parameters (''r values") are normally used for characterizing the polymerization behavior, these parameters
SELECTED ABSTRACTSbeing valid for a given monomer pair; they are available in tabular form. The distribution of the sequences often have a great effect on the technological and physical properties of industrial copolymers, and this was discussed for two cases: 1. Ethylene-propane rubber. To repress the crystallization of the product as much as possible, it is desirable that there should be no long sequences (> 10-15) of the two components. The kinetic criterion for a suitable catalyst is as low a numerical value as possible for the product rethylene ;' 'propene.2. Styrene-butadiene copolymersthese are important as synthetic elastomers. On radical initiation, the copolymerization properties of styrene and butadiene present no problem in relation t o distribution of sequences (short styrene sequences are desirable). However, o n anionic initiation, the reactivities of the two monomers are generally so different that discontinuous copolymerization processes are excluded. Kinetiv calculations permit determination of suitable reaction conditions for a continuous process in a steady-state reactor 111. Radical copolymerization can be discussed from the general standpoint of the relation between structure and reactivity, as shown, for example, in the work of Bainfordand JenkinsI21.The cycloaddition of ck,cis,cis-l,3,5,7-~yclononatetraene to 4-phenyl-l,2,4-triazoline-3,5-dione has been studied by A . G . Anastassiou and R. P. Cellura. At -78 "C they obtained the adduct ( I ) (m.p. 181-183°C, yield about 60%) as sole $GH5 product. ( I ) could be distinguished from its conceivable isomers by N M R spectroscopy. / Tetrahedron Letters 1970, 911 /-Kr. [Rd 181 IE] Isomeric nickel complexes from tvans-2-(2-quinolyl)methylene-3-quinuclidone and its 6-methoxy derivative have been obtained by D. L. Coffen and T. E. McEntee jr. On admixture of transition metal dichlorides in ethanol with the ligands the complexes ( I ) , (21, (5), and (6) crystallize. On attempted recrystallization from methylene chloride/ethanol complex ( 2 ) was converted irreversibly into (3). The structures were assigned on the basis of the I R spectra and the fact that CoIII 4 c1 c1 ( J ) , M = Co, R = OCH3 ( 3 ) , M = Cu, R = OCH3 (21, M = Ni, R = OCH3 ( 4 ) , M = Ni, R = OCH3 (51, M = CO, R = H (7), M = CU, R = H ( 6 ) , M = Ni, R = H (S), M = Ni, R = H forms tetrahedral complexes and CuII planar ones. The magnetic moments for ( I ) , (61, (71, and (8) confirm the structures assigned and also indicate contamination of (8) with ( 6 ) . / J. Amer. chem. SOC. 92, 503 (1970) /-Kr. [Rd 183 IE]Addition of alkali metals to 1 ,l-diphenyl-2-cyclopropylethylene ( I ) ...
