No abstract

(+)‐1,2‐Diethoxypropane, a model diether for the repeating unit of poly(propylene oxide), was prepared, and its behavior in solutions regarding optical rotatory dispersion and proton magnetic resonance was compared with those of the polymer. It was found that the model compound and the poly(propylene oxide) show essentially the same optical properties in solutions. By using the Brewster model of optical activity, it was concluded that the solvation of the polymer may well modify the polarizability of the optically active species to cause changes in the order of the polarizabilities of four atoms directly attached to the asymmetric carbon atom. The explanation is shown to be applicable also to some of related polymers.

Optically active propylene sulfide was polymerized in the presence of potassium hydroxide as catalyst to give optically active poly(propylene sulfide). Rotatory dispersion curves of the polymer thus obtained were measured in benzene and chloroform media. In both cases, the curves were anomalous in shape with the same sign, having troughs at 290 and 275 mμ, respectively. (–)‐1,2‐Diethylthiopropane was prepared as an optically active model compound of poly(propylene sulfide) in optical rotatory properties. It was found that the model compound also shows anomalous rotatory dispersion both in benzene and chloroform with the same sign. Thus it may be concluded that the anomalous dispersion of poly(propylene sulfide) must be attributed to an additional Cotton effect caused by the absorption of sulfide bonds, which are generally admitted to have absorptions at 200 and 230 mμ (shoulder).

cis‐ and trans‐1‐Ethoxy‐1,3‐butadienes were polymerized by a variety of cationic agents in various solvents at −78°C. The trans ether, which is the more stable isomer, was found to have greater polymerizability than the cis ether. The trans monomer gave polymers predominantly of the trans‐1,4 type, whereas the cis monomer showed a tendency toward the formation of polymers having the microstructure of the 1,2 type. It was concluded that, in the cis ether, the carbon atom which is the most vulnerable to the attack of carbonium ions is the one at the 2‐position, whereas, in the case of the trans isomer, the terminal 4‐carbon is the most reactive center. The conclusion was confirmed from the results of acetal addition reaction catalyzed by boron trifluoride etherate. The marked contrast in the mode of reaction of the two isomeric ethers toward carbonium ions was interpreted in terms of the difference in the degree of bonding in the transition state.

Optically active polymers of methyl, ethyl, n-butyl, and tert-butyl P-vinylacrylates were synthesized b y using optically active catalyst systems such as n-Bulilsodium I-menthoxide and n-Bulilsodium d-bornoxide. The optically active alkoxides were found to be even more efficient cocatalysts for the asymmetric-induced polymerization than were the corresponding ethers.The polymers obtained were characterized from their optical rotatory dispersion curves and infrared absorption spectra. ZUSAMMENFASSUNG:Mit Hilfe von optisch aktiven Katalysatorsystemen wie z. B. mit n-Butyllithiumll-Mentholnatrium und n-Butyllithiumld-Borneolnatrium wurden die optisch aktiven polymeren Methyl-, Athyl-, n-Butyl-und tert-Butyl-P-vinylacrylsaureester hergestellt. Es wurde gefunden, da13 die optisch aktiven Alkoxide fiir die asymmetrisch induzierte Polymerisation wirksamere Cokatalysatoren sind als die entsprechenden Ather.Die dargestellten Polymeren wurden durch die optischen Rotationsdispersionskurven und die Infrarotabsorptionsspektra charakterisiert.