B-Propiolactone

SOS chromotest sfiA lacZ, alkaline phosphatase Benzofurans, naphtafurans, fungal toxins, MMC, NCS, MMS, EMS, DMS, DES, b-propiolactone, propane sultone, DMN, DEN, MNNG, B[a]P, 4NQO, DMSO, NaCI, Caffeine, Aspirin E. coli 50... 

Monomer conversion, as measured by the decrease in absorbance, A, of the lactone carbonyl group (ft ), as a function of reaction time for the polymerization of a-ethyl-a-butyl-B-propiolactone, EBPL, in DMSO at AO.A C. 

In anionic polymerization, B-propiolactone initiated with potassium alcoholate, gives,in initiation,both alco-holate and carboxylate anions. Alcoholate ions in every next step convert partially into carboxylate whereas carboxylate reproduce themselves quantitatively. Thus, after a few steps only carboxylate anions are left (14). Related situation was observed in the polymerization of styrene oxide (15). Here, however, it is only due to the structure of the initiator used. Thus, when in the initiation step both secondary and primary alcoholate anions are formed, due to the low steric requirements, in the next step apparently only the attack on the least substituted carbon atom takes place and already in the second step exclusively secondary alcoholate anions are present. 

In the anionic polymerization there are three monomers only that have been studied in more detail, namely ethylene oxide, propylene sulfide, and B-propiolactone. Some... 

Solvation by monomer itself was postulated by two of us in the polymerization of B-propiolactone. This is highly polar and powerfully solvating compound. It could be assumed that due to its dipolar feature 6-propiolacto-ne could solvate not only cation but also the growing anion. 

The anionic polymerization of B-propiolactone in CH2CI2 led to the dependence of the ratio of reactivities of macro ions and macroion pairs on the solvating power of the medium (53). For higher proportions in the mixture of the more powerfully ion solvating component (B-propiolactone) the ratio of kp/ki decreased (at 350C kp/ki= =210 and 150 for the systems with 1bPL o=1 and 3 mol l respecively). Moreover, k in this system practically does not depend on the composition of the mixture and the decrease of the ratio is due to the decrease of kp (33)). We found also that the ratio of kp/k decreases also when the temperature is lowered, e.g. in a system with bPL o= =3 mol l" from 150 at 35°C to 5.6 at -20OC. ... 

As a consequence of the a to P transition which accompanies orientation, fibre patterns of the a-form are difficult to obtain. Melt extruded fibres of poly(a,a-dimethyl-P-propiolactone), known as poly(pivalolactone) (PPL), do, however, crystallize in the a-form and retain their orientation upon high temperature annealing under tension . Furthermore, oriented samples of poly(a-methyl-a-n-propyl-B-propiolactone) (PMPPL) have been prepared which show x-ray layer lines corresponding to the two phases. The a-form of both PPL and PMPPL is characterized by a fibre repeat distance of about 6 A, which has been identified as the periodicity of a 2j helix. Although oriented samples of poly(a-methyl-a-ethyl-B-propiolactone) (PMEPL) in the a-phase have never been reported, x-ray powder data have been fitted with a monoclinic unit cell with c = 6.1 A. 

Equation (4) was used to prepare an optically active a-ethyl-a-phenyl-b-propiolactone starting from a substituted ethyl cyanoacetate. This compound was alkylated with ethyl bromide, hydrogenated to the amino ester, resolved in the form of an optically active isomer, and hydrolyzed to the amino acid ... 

The crystallization of racemic di-a-substituted poly(B-propiolactones) is not due to the formation of short isotactic sequences of R or S units since the polymer obeys Bernoullian statistics, as we have discussed above. Its crystallization necessarily involves the incorporation into the crystal of motifs of R and S configurations. 

In contrast to di-a-substituted poly(B-propiolactones), racemic (atactic) b-substituted poly(3-propiolactones do not crystallize. However, crystallization is found with the isotactic polymer chains, and those prepared from monomer of optical purities larger than 70-80%, depending upon the monomer considered. 

Table I. Properties of Poly-o-Phenyl-o-Ethyl-B-Propiolactone...

In the as-prepared form, after precipitation from solution, both types of polymers appeared to be highly crystalline by this method of analysis, and both were comparable in this property to polypivalolactone, which is known to be a very highly crystalline polyester. In addition, both the optically-active and racemic polymers had considerably higher degrees of crystallinity than those previously observed for racemic poly-o-methyl-o-propyl-B-propiolactone (1). Also of importance, in addition to the different x-ray diffraction patterns of the racemic and optically-active polymers, was that the racemic polymer did not readily crystallize from the melt in the DSC characterization while the optically-active polymer of high optical purity did. Hence, the higher stereoregularity also imparts a more favorable rate of crystallization to the polymer as would be expected. 

Films, fibers, and paper adhesives /S-Methylene-b-propiolactone United States 2,653,146 1953 DuPont... 

Specific features of the mechanism the reaction occurs in die absence of acid its rate is independent of pH in some interval of its change. Oxygen fiom water transits to alcohols (experiments in water enriched in 0). If the a-C atom of the alcohol residue is asymmetric, the inversion of the optical activity occurs during t drolysis. Steric effect also influences the reaction rate. This mechanism was established for lactone hydrolysis b-propiolactone, p-butyrolactone, and lactone of malic acid. 

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