Polymerization of allyl(vinyl phenyl) ethers and reactions of the resulting polymers

Solution polymerizations of allyl(o-vinyl phenyl)ether and allyl(p-vinyl phenyl)ether with cationic and radical initiators were investigated. Soluble polymers were formed in polymerizations with boron trifluoride etherate and with benzoyl peroxide. In polymerization with azobisisobutyronitrile the polymerization in dilute solution gave a soluble polymer, whereas that in concentrated solution gave a crosslinked, insoluble one. For informationon the polymerization behavior some infrared and ultraviolet spectroscopic investigations of the soluble polymers were made. From these results it appears that polymers with pendant allyl groups are formed in polymerization with boron trifluoride etherate at low temperature, and polymers containing pendant vinyl groups and allyl groups are obtained with the two types of radical initiator. Copolymerizations of these monomers with ethyl vinyl ether and styrene with the use of boron trifluoride etherate were sucessfully effected. Such reactions as Claisen rearrangement, crosslinking induced with radical initiators, and epoxidation with perbenzoic acid were examined for the polymers prepared in the polymerization with boron trifluoride etherate. Good results were obtained for the former two reactions. However, the latter was unsuccessful.     

Radical polymerization behavior of hydroxystyrenes

Homopolymerizations of m- and p-hydroxystyrene and their copolymerizations with styrene and methyl methacrylate by use of azobisisobutyronitrile as initiator were investigated, and the results were compared with those obtained previously o-hydroxystyrene. Intrinsic viscosities of m- and p-hydroxystyrene polymers obtained by bulk and solution polymerizations were ca. 2 to 3 times larger than those of o-hydroxystyrene polymers obtained by the similar conditions. The structures of the polymers thus produced were investigated by infrared and ultraviolet spectroscopy. These studies suggested that all of the homopolymers consisted mainly of structures of normal vinyl type polymer. R_p was proportional to [I]^0.52 for m-hydroxystyrene and to [I]^0.50 for p-hydroxystyrene, for o-hydroxystyrene R_p was proportional to [I]^0.72. A reasonable chain transfer mechanism for these monomers was postulated. The apparent activation energies of polymerization for m- and p-hydroxystyrene were found to be 20.1, and 18.0 kcal/mole, respectively, compared to the value of 21.5 kcal/mole for o-hydroxystyrene. Monomer reactivity ratios and Q ? e values for m- and p-hydroxystyrene were determined, and the results were also compared with the case of o-hydroxystyrene. Copolymerization generally gave a polymer with relatively high intrinsic viscosity, even in the case of o-hydroxystyrene.     

Polymerization of 2,2,2-trifluoroethyl vinyl ether

The polymerization of 2,2,2-trifluoroethyl vinyl ether by six different catalyst systems was examined. Low-temperature studies (?78°C) with boron trifluoride etherate catalyst in hydrocarbon and chlorinated solvents slowly yielded low molecular weight polymers which were amorphous and noncrystallizable upon cold drawing. Under similar conditions, polymerizations with boron trifluoride gas were spontaneous, quantitative, and gave relatively high molecular weight, form-stable, amorphous polymer. Heterogeneous polymerizations with chromium trioxide crystals in toluene at 68°C and bulk reactions with ethylmagnesium bromide–carbon tetrachloride catalyst at 40°C failed to produce polymer. Room temperature runs with triisobutylaluminum–titanium tetrachloride catalyst gave amorphous, tacky material. Aluminum hexahydrosulfate heptahydrate (AHS) initiated polymerizations conducted at 25 and 60°C gave low yields of mixtures of amorphous and crystalline polymers, the ratio depending upon the polymerization solvent employed. The infrared spectra and x-ray diffraction intensity curves of crystalline and amorphous poly(trifluoroethyl vinyl ether) are reported and compared herein for the first time.     

Cationic oligomerization and polymerization of some propenylbenzene derivatives

A comparative study was undertaken of the cationic oligomerization/polymerization of the natural propenylbenzene derivatives, anethole, isoeugenol, and isosafrole, together with synthetic o-methoxypropenylbenzene and N,N-dimethyl-p-propenylaniline using boron trifluoride diethyletherate as catalyst. Two (optimum) reaction temperatures were employed, ?12 and ?45°C, and only the (E) isomers of the monomers were studied. The order of reactivity of the monomers was found to be anethole > isoeugenol > isosafrole > o-methoxypronylbenzene as measured by following the rate of loss of monomer by proton magnetic resonance spectrometry at ?12°C. N,N-dimethyl-p-propenylaniline only appeared to form a complex with the catalyst. Low-molecularweight polymeric materials were prepared from anethole, isosafrole, and isoeugenol at ?45°C using the same catalyst while o-methoxypropenylbenzene formed oligomers. Isosafrole was recovered unchanged when treated with the boron trifluoride diethyl etherate initiator system at ?78°C in an attempt to increase the molecular weight of the polyisosafrole.     

Syntheses of vinyl polymers containing the N-phenothiazinyl group in the side chain

Four kinds of vinyl polymers containing N-substituted phenothiazinyl groups in side chains were obtained by syntheses of the respective monomers and subsequent polymerizations. Thus, N-acrylamidomethylphenothiazine, N-(N-acrylamidomethyl)carbamoylethyl phenothiazine, β-(N-phenothiazinyl)ethyl acrylate and methacrylate, and β-(N-phenothiazinyl)ethyl vinyl ether were synthesized. It was found that all monomers except the last monomer can be polymerized with typical free-radical initiators such as α,α′-azobisisobutyronitrile to afford stable soluble polymers with electron-donating characteristics, presumably due to the absence of a hydrogen atom at the site of the nitrogen atom of the phenothiazinyl group. The last monomer was found to be susceptible to typical cationic initiators such as boron trifluoride etherate to afford a stable soluble polymer also with the electron-donating characteristic.     

Studies on polymers containing functional groups. II. Polymerization behavior of o-hydroxystyrene

The polymerization behavior of o-hydroxystyrene with free-radical and cationic initiators and without an initiator was examined. The structures thus obtained were estimated. Although polymerization behavior of o-hydroxystyrene was rather complicated, according to the results, it appeared that each polymerization more or less might simultaneously follow the two types of mechanisms: normal vinyl polymerization and polymerization through the addition to benzene nuclei. The proportion of addition to benzene nuclei was considered to be highest in the polymerization with BF₃·(OEt)₂ and lowest in that with azobisisobutyronitrile. Degrees of polymerization of these polymers were low in all cases (42–82). Some brief experiments on copolymerization of o-hydroxystyrene were carried out.     

Cationic polymerization of vinyl compounds in the presence of tetra-n-butylammonium salts

The effects of salts were examined in cationic polymerization of vinyl compounds. Cationic polymerization of styrene was carried out at 0°C, with acetyl perchlorate, stannic chloride, stannic chloride–trichloroacetic acid and boron trifluoride etherate as catalysts. Tetra-n-butylammonium perchlorate, fluoroborate and iodide were used as salts. The presence of small amounts of the salts changed both the polymerization rate and the molecular weight of polymer considerably. The consideration of various effects led to the conclusion that the results are explicable principally on the basis of counterion exchange. To confirm this, the copolymerization of 2-chloroethyl vinyl ether with γ-methylstyrene was investigated at ?78°C. The copolymer composition curve when stannic chloride was used as catalyst was changed and coincided with that of polymer obtained with acetyl perchlorate catalysis when the perchlorate salt was added. This supports the concept of counterion exchange.     

A pronounced ortho effect in the polymerization of o-substituted β-nitrostyrenes

It was shown in a previous paper that a number of m - and p-substituted β-nitrostyrenes would readily undergo polymerization via anionic initiation with alkoxide ions to yield high polymers, whereas, in all cases, the corresponding o-substituted isomers could not be induced to produce polymers under any conditions tried. This article reports a systematic study of this unexpected “ortho effect” based on the initial postulate that the effect was the result of steric inhibition of the propagation step that would ordinarily lead to polymer. Since the fluorine atom is only slightly larger than the hydrogen atom, the series o-, m-, and p-fluoro-β-nitrostyrenes was synthesized and its alkoxide ion-initiated polymerization studied. Although it was shown in all cases of o-substituted β-nitrostyrenes studied that initiation was rapid, only in the case of o-fluoro-β-nitrostyrene was a substantial amount of polymer obtained. With up to 3 mole % initiator a maximum of 26% polymer was obtained, whereas polymerization was rapid in cases of the meta and para isomers. The values of the propagation rate constants k_p were found to be 1.1 liters/mole-sec for the para isomer as compared with 4.8 × 10^?2 liter/mole-sec for the ortho isomer for a ratio k_p(p)/k_p(o) = 23, the magnitude of this ortho effect for the fluorine atom.     

Syntheses of optically active polymers by condensation polymerization of d-tartaric acid with some diamines

In order to synthesize optically active polymers which have asymmetric carbon atoms in the polymer main chain, polyamides were synthesized at high temperatures by the condensation of the salt prepared from d-tartaric acid with diamines, such as hexamethylenediamine, o-, m-, and p-phenylenediamine. Effects of the solvent, polymerization time, intrinsic viscosity, and pH on the degree of the specific rotation of polyhexamethylene-d-tartaramide, were investigated. From the results of hydrolyses of the polymers, it was found that d-tartaric acid is not racemized during condensation polymerization.     

Cationic-Initiated Ring-Opening Polymerization of Cyclopropenone Ketals. II. Novel Polymers via Bromine as Polymerization Initiator

Cyclopropenone ketals are functionally capable of undergoing both vinyl and ring-opening polymerization. In a previous paper we reported ring-opening polymerization via boron trifluoride etherate initiation to yield a polymer of complicated structure. However, this previous study showed that conventional cationic initiators yield an exceptionally stable carbocation intermediate which is essentially incapable of further propagation. This paper reports the effective use of the unconventional cationic initiator, elemental bromine, to yield polymer, proposed to be formed by a sequence of steps which involve initial addition of bromine to the cyclopropene double bond, followed by electrophilic ring opening of the brominated cyclopropane ring and propagation via the carbocation intermediate formed. At least three different and simultaneous pathways are believed to be involved. The resulting polymers have [Mbar]_n values in the range of 10,000.     

Polymerization of butadiene sulfone

Polymerization of butadiene sulfone (BdSO₂) by various catalysts was studied. Azobisisobutyronitrile (AIBN), butyllithium, tri-n-butylborn (n-Bu)₃B, boron trifluoride etherate, Ziegler catalyst, and γ-radiation were used as catalysts. Butadiene sulfone did not polymerize with these catalysts at low temperatures (below 60°C.), but polymers were obtained at high temperature with AIBN or (n-Bu)₃B. The polymerization of BdSO₂ initiated by AIBN in benzene at 80–140°C. was studied in detail. The obtained polymers were white, rubberlike materials and insoluble in organic solvents. The polymer composition was independent of monomer and initiator concentrations and reaction time. The sulfur content in polymer decreased with increasing polymerization temperature. The polymers prepared at 80 and 140°C. have the compositions (C₄H₆)_1.55- (SO₂) and (C₄H₆)_3.14(SO₂), respectively, and have double bonds. These polymers were not alternating copolymers of butadiene with sulfur dioxide. The polymerization mechanism was discussed from polymerization rate, polymer composition, and decomposition rate of BdSO₂. From these results, the polymerization was thought to be “decomposition polymerization,” i.e., butadiene and sulfur dioxide, formed by the thermal decomposition of BdSO₂, copolymerized.     

Structure and reactivity in cationic polymerization of butadiene derivatives. IV. 1-alkoxybutadienes

The reactivity of trans-1-alkoxybutadienes in cationic homopolymerization and copolymerizations and structure of the polymers produced were investigated. 1-Ethoxybutadiene is polymerized easily at ?78°C by various acidic catalysis. The reactivity of 1-ethoxybutadiene was similar to that of ethyl vinyl ether. The polymers produced possessed molecular weights of several thousands, and were composed of 70–95% 1,4 structure and 5–30% 3,4 structure. In the copolymerization of ethyl vinyl ether (M₁) with 1-ethoxybutadiene at ?78°C in toluene by boron trifluoride diethyl etherate, r₁ = 1.15, r₂ = 2.62. From the Hammett plot of the relative reactivities of alkoxybutadienes (alkoxy: CH₃O, C₂H₅O, i-C₃H₇O), the reaction constant _p^* was determined to be ?2.9. Results of the present study were compared with those of various butadiene derivatives.     

Synthesis of Boron-containing Complexes of 1-(2-hydroxyphenyl)-3-phenyl-2-propen-1-one

Condensation of o-hydroxyacetophenone with benzaldehyde in alcohol in the presence of a triple excess of a sodium hydroxide solution leads to 2'-hydroxychalcone sodium salt. The latter was heated with boron trifluoride etherate in toluene to a 2'-hydroxychalcone boron fluoride complex in which the boron atom is coordinated to the carbonyl oxygen atom. The same complex was obtained by boiling of the o-hydroxyacetophenone boron fluoride complex with benzaldehyde in acetic anhydride.     

Oxonium ions as initiators for vinyl polymerizations. A reappraisal

Triethyl oxonium fluoroborate either preformed or preparedin situ by the reaction of boron trifluoride etherate with epichlorohydrin does not initiate the homo or copolymerization of vinyl monomers. Small conversions to copolymers by use of these initiators with low methyl methacrylate incorporation is ascribed to conventional vinyl copolymerizations, initiated by free boron trifluoride and/or protonic impurities in the system.     

Selective initiation of nonconjugated dienes containing electron donor–electron acceptor systems. IV. Polymerization of vinyl ether–styrene monomers

Three isomeric nonconjugated dienes, o-, m- and p-(2-vinyloxyethoxy)styrenes, were selectively polymerized by anionic or radical initiators through the styryl double bond while leaving the vinyl ether moiety intact. The anionic-initiated polymeric products are of high molecular weight and narrow molecular weight distribution as characterized by membrane osmometry and gel-permeation chromatography, respectively. These polymers were subsequently crosslinked by cationic initiators via the vinyl ether moiety on the polymer side chains. Acid-catalyzed hydrolysis of the poly(2-vinyloxyethoxy)styrenes yielded their respective hydroxy-containing polymers, polyvinylphenoxyethanols. The latter were physically and spectroscopically identical to authentic samples prepared by radical polymerization of the corresponding vinylphenoxyethanols, which, in turn, were synthesized by hydrolysis of the (2-vinyloxyethoxy)styrenes. The polyvinylphenoxyethanols were shown to undergo many chemical transformations, such as esterification with 3,5-dinitrobenzoyl chloride, cyanoethylation, and urethane formation.     

Structural characterization of hydroxyl terminated polyepichlorohydrin obtained using boron trifluoride etherate and stannic chloride as initiators

Epichlorohydrin was polymerized using boron trifluoride etherate or stannic chloride as initiators in presence of diols. The molecular weight of the polymer increased with increase in the ratio of epichlorohydrin to the diol in the reaction mixture. The polymers were characterized by IR, proton NMR and ¹³C NMR analysis. The terminal hydroxyl groups of the polymers were characterized by derivatizing them using trifluoro acetic anhydride and analyzing the resulting ester by NMR. Both primary and secondary hydroxyls were present in the polymer. The primary hydroxyl terminals of the polyepichlorohydrin (PECH) prepared using stannic chloride initiator were twice the amount of that present in the polymer prepared using BF₃ etherate initiator. The ¹³C NMR spectrum of PECH prepared using BF₃ etherate indicates that the polymer backbone is rich in H-T diad. Both cationic and co-ordination mechanisms operate during the polymerization in the presence of SnCl₄ and the ¹³C NMR spectrum of the polymer showed more of T-T and H-H sequences.     

Cationic ring-opening polymerization of 1,4-anhydro-2,3-di-O-benzyl-α-L-arabinopyranose and synthesis of L-arabinofuranan

1,4-Anhydro-2,3-di-O-benzyl-α-L -arabinopyranose (=1,5-anhydro-2,3-di-O-benzyl-β-L -arabinofuranose) (ABAP) was synthesized and underwent cationic ring-opening polymerization with several kinds of Lewis acids. All the polylmers prepared by Lewis acids as catalyst were found to consist of two different structural units, α-furanosidic and β-furanosidic units, and the structure of the polymers greatly depended on the polymerization conditions. Polymerization of ABAP with antimony pentachloride catalyst at 0°C for 42 h gave a polymer with the highest α content of 93%, and that at ?20°C for 3 h gave a polymer with the lowest (25%) α content. The other catalysts such as phosphorus pentafluoride, boron trifluoride etherate, niobium pentafluoride, and tantalum pentafluoride also afforded polymers with mixed structure of α-and β-furanosides. After debenzylation of poly(ABAP), a new polysaccharide, L -arabinofuranan was obtained.     

Studies on polymers containing functional groups. VI. Kinetics of the polymerization and copolymerization behaviors of o-hydroxystyrene

Some kinetic studies were made of the homopolymerization of o-hydroxystyrene and its copolymerization behavior with styrene and methyl methacrylate in tetrahydrofuran using azobisisobutyronitrile as initiator were done. The rate of polymerization experimentally obtained is given by R_p = K[M][I]^0.72. Accordingly, it is likely that the growing chain radicals are terminated not only by mutual termination but also by a chain-transfer mechanism, the latter occupying a considerable portion. The latter is mostly attributed to the transfer to monomer, i.e., C_m for o-hydroxystyrene was 1.3 × 10^?2. Some transfer mechanisms were assumed, although it is difficult to elucidate the mechanism in detail, owing to its complexity. Effects of solvent on the rate of polymerization were examined, dioxane, methyl ethyl ketone, ethanol, and tetrahydrofuran being used. However, no differences were found among the solvents. The apparent activation energy of polymerization was found to be 21.5 kcal./mole. Monomer reactivity ratios and Alfrey-Price Q–e values for o-hydroxystyrene were determined. The Q–e values (Q = 1.41, e = ?1.13) are rather similar to those of p-methoxystyrene. Thus, the e value for o-hydroxystyrene is more negative than that for styrene.     

Low-temperature polymerization of isobutyl vinyl ether

Isobutyl vinyl ether has been polymerized under conditions well known to yield isotactic polymer, viz., with boron trifluoride etherate at 78°C. in a nonpolar hydrocarbon diluent. A particular mixed solvent ratio and previous dissolution of catalyst enabled the polymerization to proceed homogeneously at the beginning. By following the temperature rise in an initially thermostatted system, we showed that the progress of the reaction eventually proceeded via a homogeneous phase to a gellike phase. Isotactic polymer is shown to be produced in both steps by a mechanism of slow chain propagation.     

Living ring-opening polymerization of cyclic thiocarbonate

This work deals with the cationic ring-opening polymerization of a cyclic thiocarbonate, 5,5-dimethyl-1,3-dioxane-2-thione (1). The polymerization was carried out with 2 mol% of trifluoromethanesulfonic acid, methyl trifluoromethanesulfonate, boron trifluoride etherate, or triethyloxonium tetrafluoroborate as an initiator to afford the polythiocarbonate with the narrow molecular weight distribution (M_n = 11200-31000, M_w/M_n = 1.04-1.15). The molecular weight of the obtained polymer could be controlled by the feed ratio of the monomer to the initiator and increased when the second monomer was added to the polymerization mixture after quantitative consumption of 1 in the first stage, supporting that the cationic ring-opening polymerization of 1 proceeded via a living process.