Isotopic exchange reactions of the tertiary hydrogen in polyacrylonitrile accompanied by acid and base hydrolyses

Rhodes, J. H.; Chiang, Ruei‐Tang; Randall, Jack

doi:10.1002/pol.1966.110040605

J. Polym. Sci. B Polym. Lett.

1966

DOI: 10.1002/pol.1966.110040605

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Isotopic exchange reactions of the tertiary hydrogen in polyacrylonitrile accompanied by acid and base hydrolyses

J. H. Rhodes¹,

Ruei‐Tang Chiang²,

Jack Randall³

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1967

1976

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Cited by 14 publications

References 8 publications

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The chemical modification of polymers for analytical purposes

Harwood

1968

Angew. Makromol. Chem.

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When it is possible to convert one polymer quantitatively into another, the derived polymer can sometimes be studied to obtain information about the original polymer. In other instances, the derived polymer can serve as a reference material for use in the development of polymer characterization procedures. This paper reviews the use of such techniques in studies on branching and stereoregularity in homopolymers and in studies on sequence distribution in copolymers. The reactions covered include hydrolysis, ammonolysis, alcoholysis, esterification, transesterification and the hydrogenation of polyhalocarbons and unsaturated polyhydrocarbons. In addition, recent studies on cyclization reactions in polymers are surveyed. Such studies can provide information about sequence distribution in copolymers. ZUSAMMENFASSUNG :Derivate von Polymeren, die durch quantitative Umwandlung entstanden sind, konnen in gewissen Fallen dazu benutzt werden, die Eigenschaften des Ausgangspolymeren zu untersuchen. Das Polymerderivat kann auch als Bezugssubstanz bei der Entwicklung von Methoden zur Charakterisierung von Polymeren dienen. I n dieser Arbeit wird uber die Anwendung derartiger Methoden fur Untersuchungen uber die Verzweigung und Stereoregularitiit von Homopolymeren und die Sequenzverteilung von Copolymeren berichtet. Es werden verschiedene Reaktionen beschrieben, darunter Hydrolyse, Ammonolyse, Alkoholpse, Veresterung, Umesterung und die Hydrierung von Polyhalogenkohlenwasserstoffen und ungesatt,igten Polykohlenwasserstoffen. Weiterhin wird ein uberblick uber neuere Ringschlufireaktionen an Polymeren gegeben. Derartige Reaktionen konnen fur Untersuchungen der Sequenzverteilung von Copolymeren von Wichtigkeit sein.

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The chemical modification of polymers for analytical purposes

Harwood

1968

Angew. Makromol. Chem.

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Racemization of isotactic polyacrylonitrile during hydrolysis

1970

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a-Hydrogen of polyacrylonitrile (PAN) is known to be reactive. Previ-ously132) we have attempted t o determine the stereoregularity of PAN by converting i t into poly(acry1ic acid) (PAA) by acid or alkali hydrolysis, followed by esterification to poly(methy1 acrylate) (PMA). J t was observed, however, that in the hydrolysis of polyacrylonitrile-cr-d (PAN-a-d), D-H exchange reaction of a-hydrogen took place and NMR spectra of the converted PMA's were identical with those of PMA's derived from the PAN'S not deuterated. So, we concluded that racemization had occurred in the course of conversion, that is, during hydrolysis. This conclusion was confirmed by RHODES et a1.3). HUNTER investigated the exchange reaction of a-proton in detail4). We succeeded in determining the stereoregularity of PAN in 1966 and reported that PAN prepared by radical and anionic processes had random configuration independent of polymerization temperature, but an isotactic-rich PAN was obtained by y-ray irradiation of urea canal complex of acrylonitrile5>6). Considering that the samples of PAN used for the hydrolysis had random configuration and PMA's derived from the PAN also had random configuration, a question remains whether racemization of the configuration of a-carbon took place during hydrolysis or not, since hydrolysis of random PAN would give random PMA regardless of racemization of a-carbon. We now studied this problem by analyzing the PMA converted from an isotactic PAN.The isotactic PAN was obtained by y-ray irradiation of urea canal complex of acrylonitrile a t -78OC. The irradiation dose was 2.0 Mrad and the successive operation was the same as before6). Hydrolysis of PAN was carried out with 50% sulfuric acid for 69 hrs a t 8OoC and subsequent operations were the same as beforel.2). The yield of PMA was 82 % based on PAN. Methylation is almost quantitative. The intrinsic viscosity of polymers was determined from viscosity measurement in a dilute dimethylformamide solution for PAN and in a benzene solution for PMA both a t 3OoC by means of an UBBELOHDE viscometer. The viscosity-av. mol. wt. of isotactic PAN was calculated from the equation7), [q] = 3.35 * l o 4 @v.72, and that of PMA from the equations), [q] = 4.5 .lop5 e7'. The mol. wt. of the isotactic PAN was 1.59.105 and that of PMA converted by acid hydrolysis was 9.3 .lO4. 295

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Vinyl polymerisation of acrylonitrile by the vanadium(V)‐glycerol redox system

1976

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A kinetic study of the thermal polymerisation of acrylonitrile initiated by the redox system V5+-glycerol in sulfuric acid and perchloric acid was made in the temperature range 3545°C. The rates of polymerisation and of V5+ disappearance were measured with respect to their dependence on time, monomer, metal ion, glycerol, acid, and ionic strength. Experimental evidences provide support to a mechanism involving initiation by a free radical produced by the decomposition of the acyclic complex between V5+ and glycerol. The kinetics are consistent with a linear termination of polymerisation (1st order in respect of growing radicals) at higher concentration of V5+. The various rate and activation parameters were evaluated and an appropriate reaction scheme is proposed. The induction period and the polymerisation rate of the V5 +-glycerol system were compared with those involving polyhydroxy alcohol systems such as sorbitol and mannitol. ZUSAMMENFASSUNG :Gegenstand dieser Arbeit ist die Untersuchung der Kinetik der durch das Redoxsystem V5 +-Glyzerin angeregten thermischen Polymerisation von Acrylnitril in Gegenwart von Schwefel-oder Perchlorsaure im Temperaturbereich von 35-45 "C. Polymerisationsgeschwindigkeit und die Geschwindigkeit des V5 +-Verbrauchs wurden hinsichtlich ihrer Abhangigkeit von der Zeit, der Monomer-, Metallion-, Glyzerin-und Saurekonzentration sowie der Ionenstarke untersucht. Die experimentellen Ergebnisse stiitzen einen Mechanismus, der einen Start uber freie Radikale vorsieht, die aus dem Zerfall eines acyclischen V5 +-Glycerin-Komplexes resultieren. Die kinetischen Befunde sind mit der Annahme eines linearen Abbruchs (1. Ordnung bezuglich der Radikalketten) bei hoheren V5 +-Kenzentrationen vereinbar. Die verschiedenen Geschwindigkeits-und Aktivierungsparameter wurden ermittelt und ein geeignetes Reaktionsschema vorgeschlagen. Die in diesem System auftretenden Induktionsperioden und Polymerisationsgeschwindigkeiten wurden mit den entsprechenden fur andere Polyhydroxy-Systeme (Mannit, Sorbit) registrierten GroDen vergleichen.

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Isotopic exchange reactions of the tertiary hydrogen in polyacrylonitrile accompanied by acid and base hydrolyses

Cited by 14 publications

References 8 publications

The chemical modification of polymers for analytical purposes

The chemical modification of polymers for analytical purposes

Racemization of isotactic polyacrylonitrile during hydrolysis

Vinyl polymerisation of acrylonitrile by the vanadium(V)‐glycerol redox system

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