The results of an x‐ray and polarimetric study of a crystalline modification (form I) of isotactic poly‐(S)‐4‐methyl‐1‐hexene are reported and discussed. The x‐ray fiber spectra of this polymer are practically indistinguishable from those of isotactic poly‐(R)‐(S)‐4‐methyl‐1‐hexene. Although the crystal structure of the latter can be described on the basis of helices of different screw sense packed in a P4 space group, the crystal structure of poly‐(S)‐4‐methyl‐1‐hexene is better described on the basis of a P1 space group. The conclusion of the x‐ray investigation, that in the crystals of the optically active polymer an equal number of right‐handed and left‐handed helices must be present, is supported by the polarimetric measurements, which have shown that the polymer in the crystalline form I possesses a rather low rotatory power.
The general problems presented by the determination of the optical activity of polymers in the crystalline state are considered. The necessity of using unoriented samples, if the polarimetric data are to be compared with analogous data measured in solution, is emphasized. The optical activity in the crystalline state of a number of stereoregular vinyl polymers has been measured by employing either suspensions of fine powders or thin plates with no detectable orientation. The results of optical rotatory dispersion studies in the crystalline state suggest that, at least in the case of the poly‐α‐olefins investigated, the same chromophores are responsible for the optical activity in the crystalline state and in solution.
The thermal behaviour of isoracric poly[(S)-4-methyl-l-hexene], (P(S)4MH), isomtic poly[(R)-4-methyl-l-hexene], (P(R)4MH), of their equimolar mixture (r-P4MH) and of poly[(R)(S)-4-methyl-l-hexene], (P4MH). was investigated. The DSC curves obtained by melting P(S)4MH and P(R)4MH showed two endothermic peaks, while only one peak was found in the DSC curves obtained by melting r-P4MH or P4MH.For the optically active polymers the formation of a mesophase is proposed and the results are discussed on the basis of the conformation of these polymers in the crystalline and in the liquid state. ZUSAMMENFASSUNG: Das thermische Verhalten von isotaktischem Poly[(S)-4-methyl-l-hexen], (P(S)4 MH), Poly[(R)-4-methyl-l -hexen], (P(R)4MH), ihrer aquirnolaren Mischung (r-P4 MH) und von Poly[(R)(S)-4-methyl-l-hexen] (P4MH) wurde untersucht. Die DSC-Kurven von P(S)4MH und P(R)4MH ergdben beim Schmelzen zwei endotherme Peaks, wihrend nur ein Peak in den DSC-Kurven von r-P4MH und P4MH gefunden wurde. Fur die optisch aktiven Polymeren wird die Bildung einer Mesophase vorgeschlagen und die experimentellen Ergebnisse werden aufder Basis der Konformation dieser Polymeren im kristallinen und flussigen Zustand besprochen.
Das aus der Buttersäure (Ia) in bekannter Weise über den Alkohol (Ib) erhaltene Chlorid (Ic) wird nach Grignard in (II) übergeführt, das bei Behandlung mit Zn‐Pulver die Titelverbindung (III) [22% Ausbeute, bezogen auf (Ib)] ergibt.
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