Thane D. Rounsefell

The preparation, polymerization and copolymerization of (η5-vinylcyclopentadienyl)dicarbonylnitrosylchromium, (η5-C5H4CHCH2)Cr(CO)2NO

Abstract The first report on the preparation, polymerization, and copolymerization of a nitrosyl-containing vinylcyclopentadienylmetal monomer, (η5-C5H4CHCH2)-Cr(CO)2NO, is described. (η5-Vinylcyclopentadienyl)-dicarbonylnitrosylchromium (A) was prepared in good yield by the acylation of η5-cyclopentadienyl-carbonylnitrosylchromium followed by sodium borohydride reduction of the keto function and acid-catalyzed dehydration. Monomer A homopolymerizes and copolymerizes with styrene, N-vinylpyrrolidone, and vinyl cymantrene in the presence of azo initiators. Reactivity ratios in the copolymerization of A with styrene were r1 = 0.30 and r2 = 0.82 from which the value of e for A was found to be −1.98. Thus, A is an exceptionally electron-rich monomer.

Search for a Steric Penultimate Effect: Copolymerization of 2,3,4-Trimethyl-3-pentyl Methacrylate with Styrene

Abstract The hindered monomer, 2,3,4-trimethyl-3-pentyl methacrylate (I), was synthesized for penultimate effect studies. Since it readily homopoiymerized (km111≠ 0) and readily copolymerized with styrene, copolymerizations of I with styrene were carried out at 60°C in benzene with AIBN as initiator. The conversion to copolymer and the copolymer composition were determined by using GLC techniques. Composition-conversion data was analyzed by performing a computerized nonlinear least-squares fitting to the integrated form of the penultimate model equation. The experimental design included the use of optimized M1°/M2° ratios. The penultimate reactivity ratios calculated from these data were r1′ = 0.23, r1′= 0.59, r2 = 0.59, r2′ = 1.34. Thus, when I is the penultimate unit, a terminal styryl radical prefers to add styrene, whereas when styrene is the penultimate unit, terminal styryl radicals prefer to add I. These results constitute the best evidence for a steric penultimate effect yet available in the liter...

The Preparation, Polymerization and Copolymerization of Substituted Derivatives of Cynichrodene (eta5-C5H5)Cr(CO)2NO.

Abstract : The novel vinyl organometallic monomer (vinyl-cyclopentadienyl)-dicarbonylnitrosylchromium (hereafter called vinylcynichrodene), was prepared and homopolymerized and copolymerized in solution and neat using azo initiators. Reactivity ratios were obtained in radical initiated copolymerizations with styrene and N-vinyl-2-pyrrolidone. When M2 was styrene, r1 = 0.30 and r2 = 0.82. The value of the Alfrey-Price parameter e for vinylcynichrodene was -1.98 and the resonance interaction parameter Q was 3.1. copolymerizations with N-vinyl-2-pyrrolidone (M2) gave r1 = 5.3, r2 = 0.079 and e = -2.07. Thus, vinylcynichrodene is an exceptionally electron-rich vinyl monomer resembling vinyl-ferrocene and vinylcymantrene. Vinylcynichrodene readily copolymerized with vinylcymantrene. (Author)