Télomérisation de l'isobutylène

The telomerization of isobutene was investigated using redox catalysis, free radical, and particularly cationic initiation. The influence of the initiator on the degree of polymerization and the structure of the telomers was studied. Redox and free radical telomerization with CCl₄ and CCl₃Br were found to permit synthesis and identification of the monoadduct structure. Cationic telomerization gives regular structure compounds and the molecular weights are higher than those obtained by other methods of telomerization.     

Synthèse de macromères à base de chlorures de vinyle et de vinylidène au moyen de télomères

New macromers 4, 8, and 10, containing ester, alcohol, or acid functions, were prepared starting with vinyl chloride (CV) or vinylidene dichloride (CV₂). The telomer 1, resulting from CV₂ and CCI₄ was telomerized with allyl acetate and the product was transformed into the acrylate 4 by hydrolysis of the reaction product and subsequent esterification. Macromers 8 and 10 were prepared from CV by radical telomerization with thioglycolic acid (7) and 2-mercaptoethanol (9), respectively. Reactive double bonds were introduced into these macromers by reaction with acrylic acid, Vinyl chloroformate, methacryloyl chloride, or 2,3 -epoxypropyle methacrylate, leading to new macromers 12, 13, 14, and 15, respectively.     

Cinétique de télomérisation, 3. Détermination des constantes de tranfert en catalyse rédox

Three methods were used for the determination of transfer constants to the metallic complex in the telomerization reaction with redox catalysis. The first one consists in the determination of DP _n as a function of the mole ratio of telogen to monomer at the beginning of the reaction. The second one is based on the variation of the conversion degree of telogen to monomer. The last one requires the knowledge of the cumulated DP _n and the conversion degree of monomer samples during the reaction. The proposed laws were checked following the methyl acrylate telomerisation with CCl₄ as a telogen and CuCl₂ as a catalyst at 120°C. The transfer constant to CuCl₂ was found to be about 600 according to the three methods.     

Cinétiques de télomérisation, 7. Calcul de k/kTe en polymérisation radicalaire de divers monomères

In contrast to the usual method of determination of the principle ratio in radical polymerization, k/k_Te, which is based on the comparison of the rate of polymerization with the concentration of initiator, a method was used consisting in the representation of log_e([M]₀/[M]) versus (1 ? e^?kd^t/2). The results obtained with styrene, vinyl acetate, acrylic acid, methacrylic acid, and 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl acrylate ( 1 ) were found to be in good agreement with those already obtained by the other method.     

Synthèse et transformations chimiques des télomères de l'undécène-10 oate de méthyle, 1

Redox of radical telomerizations of methyl 10-undecenoate (1) with different telogens such as CCl₄, CCl₃Br, CCl₃CF₃, HPO (OEt)P₂ or different adducts of CCI₄, on vinylidene chloride and chlorotrifluoroethylene, were studied. Chemical transformation of the end of the chains led to the corresponding difunctional compounds. Starting with these last compounds, polycondensation reactions were carried out.     

Télomères monofonctionnels du chlorure de vinyle, 2. Cinétique par amorçage radicalaire

Radical telomerizations of vinyl chloride with telogens R? CCl₃, containing alcohol and acid functions in the R group, were carried out. The molecular weights of the obtained products are between 1000 and 10 000. Transfer constants (C_T) were calculated for each case by studying the DP_n (10 to 50) variation as a function of the mole ratio (R) of telogen to monomer. In addition, the functionality of the resulting poly(vinyl chloride) was evaluated from the values of C_T and R.     

Télomères monofonctionnels du chlorure de vinyle, 3. Cinétique par catalyse rédox

A kinetic study of the redox telomerization of vinyl chloride with carbon tetrachloride was carried out. Transfer constants of PVC to the metallic ion (C_Feⁿ), initiation rate (k_i), and functionnality of the resulting telomers were measured. Instantaneous and cumulated polymerization degrees, (DP_n )_i and (DP_n )_cum were determined with the help of a theoretical study. These constants provide a rigorous control of the telomerization of vinyl chloride with RCCl₃, (R containing an alcohol or ester group).     

Polymérisation et copolymérisation de l'acétoxy-1 butadiène

1-Acetoxybutadiene ( 1a, b ) can be polymerized under radical conditions as well in bulk, in benzene solution or in an aqueous emulsion. Polymers consist of ca. 80% 1, 4-units ( 4 ) and 20% 3,4-units ( 5 ), as determined by use of model compounds ( 2 and 3 ). Important chain transfer reactions to monomer, which have been measured, account for low number-average molecular weights (M?_n ≈ 5000). Radical copolymerisations with acrylic, vinyl, and diene monomers indicate 1a, b to be quite similar to isoprene in these reactions. Copolymers with M?_n ≈ 20 000 are readily obtained. 1-Acetoxybutadiene polymers prepared via cationic catalysts are unstable unless careful purified. Anionic reagents are destroyed by this monomer even at ?80°C.     

Etude de la diaddition de l'acétate d'allyle sur les télogènes chlorofluorés possédant deux groupements CCl3 en extrémité de chaîne

The redox catalyzed addition of compounds such as Cl₃C? CF₂? CCl₃ and Cl₃C? CF₂? CCl₂? CH₂? CHCl? CH₂? OCOCH₃ to allyl acetate was studied with the purpose of obtaining telechelic products. RuCl₂[P(C₆H₅)₃]₃ was used as catalyst, and its action was compared to that of cooper- or iron-based catalysts. The products were isolated and their structures studied by means of ¹³C, ¹⁹F and ¹H NMR spectroscopy. The reaction mechanism was studied to improve the yield of the diaddition product for its utilisation as monomer in polycondensation reactions. It was found that the low reactivity for a second addition is not due to the presence of a chlorine atom in β-position of the acetate function. When allyl acetate was replaced by allyl bromide or chloride in the first addition, the second addition to allyl acetate occurred normally.     

Cinétiques de télomérisation, 4. Nouvelle méthode de détermination des constantes de transfert en catalyse radicalaire

For the determination of transfer constants C_T to the telogen in telomerization reactions started with free radicals we used three methods. The first one is the method of Mayo, the second one is based on the variation of the conversion degree of telogen to monomer and the last method requires the knowledge of the cumulated number-average degree of polymerization DP _n and monomer conversion α_M of the samples during the reaction. Verifications of the proposed laws are made for methacrylic acid telomerization with CCl₃Br and methyl methacrylate telomerization with benzenethiol as a telogen and 2,2′-azoisobutyronitrile as the initiator at 70°C. The transfer constant to CCl₃Br is ca. 0,03 and that to C₆H₅SH ca. 1,5.     

Synthèse de compoisés photoréticulables, 4. Estérification de l'acide acrylique sur les télomères de l'acrylate d'hydroxy-2 éthyle

Several telomers were prepared by redox catalysis from 2-hydroxyethyl acrylate ( 1 ) and telogens such as carbon tetrachloride, methyl trichloroacetate, 1, 1, 1-trichlorotrifluoroethane, and 2,4,4,4-tetrachloro-2-methylbutyric acid ( 2d ), as well as block-cotelomers from 1 and a telomer 4 prepared from chlorotrifluoroethylene and carbon tetrachloride. Polyols ( 3a–d and 5 ) with two to twenty primary hydroxyl groups were obtained. They were esterified with acrylic acid, to obtain new photosensitive compositions. ( 6a–d ).     

Synthèse de monoalcools et de monoacides chlorofluorés par télomérisation avec des telogènes chlorofluorés

Telomerizations of chlorofluorinated telogens CF₃CCl₃ and \documentclass{article}\pagestyle{empty}\begin{document}$${\rm Cl\rlap{--} (CFCl \hbox{---} CF}_{\rm 2} {\rm \rlap{--} )}_{\rm n} {\rm CCl}_{\rm 3}$$\end{document} (1 ≤ n ≤ 4) with acrylic, allylic, and vinylic monomers were studied. With allyl alcohol and 2-hydroxyethyl acrylate the corresponding fluorinated adducts 1 and 2 were obtained directly. Vinyl and allyl acetates led to the adducts 4a , b and 5a , b , respectively, which could be transformed into the corresponding acetals and alcohols. Telomerizations of methyl acrylate and methacrylate led to the fluorinated adducts 12a and b in the presence of copper chloride as catalyst or also with iron trichloride in the case of methyl methacrylate. By intramolecular elimination the methacrylate adducts were transformed into the lactons 13 and 14 and the acrylate adducts by reduction into the alcohols 1 and 2 . The same reduction of the methacrylate adduct led to the 2,4,4-trichloro-5,5,5-trifluoro-2-methyl-1-pentanol ( 15 ). Independent on the applied catalyst the telomerization of vinylacetic acid led to the monoaddition product, whereas in the case of methacrylic or acrylic acid the formation of monoadducts or higher addition products was found to depend on the catalyst.     

Synthèse et copolymérisation avec l'acrylamide de macromonomères d'acrylate de dodécyle

Graft copolymers of well-defined structure and composition were prepared by radical copolymerization of acrylamide and poly(dodecyl acrylate) macromonomers. The macromonomers were prepared by telomerization of dodecyl acrylate in the presence of 2-mercaptoethanol as a transfer agent, followed by reaction with acryloyl chloride. Poly(dodecyl acrylate) macromonomers with M _n = 1100, 1100, 2200 and 4600 were synthesized. The kinetics of the radical telomerization of dodecyl acrylate with 2-mercaptoethanol and AIBN was studied at 66°C in THF. Under these conditions we obtained the transfer constant C_T = 0,9. The graft copolymerization of acrylamide with the poly(dodecyl acrylate) macromonomer was carried out in the presence of the transfer agent C₆F₁₃C₂H₄SH. If C₀ = [AIBN]/[Acrylamide] = 0,01 and R₀ = [C₆F₁₃C₂H₄SH]/[Acrylamide] = 0,01, for acrylamide a DP _n = 160 was obtained in all cases, for the macromonomer of M _n = 1100 a DP _n = 2,5, and for the macromonomer of M _n > 1100 a DP_n = 1.     

Synthèse de composées photoréticulables, 7. Télomères des acides acrylique et méthacrylique gréffés par méthacrylate d'époxy-2,3 propyle

Telomers were prepared from acrylic or methacrylic acid and CCl₃Br, C₁₂H₂₅SH, C₁₈H₃₇SH or C₈F₁₇C₂H₄SH by initiation with 2,2'-azoisobutyronitrile. The transfer constant of CCl₃Br and the thiols, which are about 0,03 and 0,5, respectively, were determined. These telomers were used as supports of photopolymerizable functions, which were introduced by grafting of 2,3-epoxypropyl methacrylate, catalysed with dodecyldimethylamine. The reactions were followed by ¹H NMR, elemental analyses, tonometrie, and especially by GPC and titration of the acid functions. The grafting telomers, holding many acrylic functions which react upon UV and electron irradiation, give photoreticulated varnish coatings with very interesting properties.     

Recherche de télomères à activité pharmacologique potentielle, 4. Réactions sur les télomères de l'alcool vinylique

Chlorides of carboxylic acids were grafted on telomers of vinyl alcohol. The yields of grafting were improved by increasing the temperature and the concentration of the reactants. In the range investigated, they do not depend on the DP_n of the telomers, nor on the stoichiometric rates of the reactants. Therefore, the grafting rates are directly related to the initial conditions of the reaction. Modification of the telomers by treatment with ethylene oxide provides more soluble substances, but it does not affect the behaviour of the telomers in grafting reactions. Grafting of 1-(p-chlorobenzoyl)-5-methoxy-2-methyl-3-indolacetic acid ( 9 ) (indomethacin), an antiinflammatory drug, leads to potentially pharmacologically active telomers.     

Télomères monofonctionnels du chlorure de vinyle, 4. Synthèse et caractérisation par catalyse rédox

Monofunctional telomers of vinyl chloride ( 1 ) were synthesized by two ways. In the first one, the telomers resulting from the reaction of 1 with carbon tetrachloride were used as telogenic agents to react with allyl acetate leading to a monoadduct. In the second one, monofunctional telogens were used in a redox catalyzed reaction with 1 . Trichloroacetic acid and its esters ( 2b–d ) were applied as telogens. The theoretical maximum yields and the number average degrees of polymerization at these yields were calculated and compared with the experimental results.     

Caractérisation de réactions primaires de dégradation oxydante au cours de l'autoxydation des polyoxyéthylènes à 25°C: Étude en solution aqueuse avee amorçage par radiolyse du solvant. II. Arguments pour un mécanisme monomoléculaire de décomposition des radicaux peroxyles

Cationic copolymerizations of furfural were carried out with several vinyl monomers. No copolymers were obtained with some hydrocarbon comonomers. At low temperatures furfural copolymerized with vinyl ethers selectively through the aldehyde group. On the other hand, deeply-colored copolymers of complex structures were formed at higher temperatures (ca. 0°C). Three typical vinyl ethers (p-tolyl vinyl ether, dihydropyran, and divinyl ether) were selected as comonomers, and their copolymerization behaviour studied in detail. The monomer reactivity ratios for furfural (M₁) and p-tolyl vinyl ether (M₂) were r₁ = 0,15 ± 0,15, r₂ = 0,25 ± 0,05. The furfural (FF) contents were fairly independent of the monomer feeds when dihydropyran (DHP) and divinyl ether (DVE) were used as comonomers: 37–47% for FF-DHP copolymers and 40–50% for FF-DVE copolymers. More than half of the second vinyl groups were consumed in the FF-DVE copolymers indicating the formation of 1,3-dioxane rings as in the case of benzaldehyde-DVE copolymers.     

Radical telomerization of vinyl acetate with chloroform. Application to the synthesis of poly(vinyl acetate)‐block‐polystyrene copolymers by consecutive telomerization and atom transfer radical polymerization

This paper demonstrates that radical telomerization and atom transfer radical polymerization (ATRP) can be combined in a two‐step procedure to prepare poly‐(vinyl acetate)‐block‐polystyrene (PVOAc‐b‐PSt) diblock copolymers. The first step consists in telomerizing VOAc with chloroform, leading to trichloromethyl‐terminated VOAc telomers CCl₃(VOAc)_nH. A detailed ¹H NMR analysis shows that nearly pure telomer structures are obtained over a broad range of DP_n values (up to at least 60 units). When ATRP of styrene is initiated with a model telomer adduct (CCl₃CH₂CH₂OAc), molecular weights increase linearly with monomer conversion and match theoretical values. Moreover, polydispersities are consistently low (1.22 < M_w/M_n < 1.38) throughout polymerization. Similarly, VOAc telomers (DP_n = 9 and 62) are good ATRP macroinitiators. The high purity of the resulting diblock copolymers is confirmed by GPC using RI/UV dual detection.     

Recherche de télomères à activité pharmacologique potentielle, 3. Préparation et toxicologie de supports télomères à fonctions hydroxyles

Several telomers of vinyl alcohol with chloroform and diethyl phosphonate were prepared. Their DP _n were measured by several analytical methods (elemental analysis, NMR spectroscopy, viscosimetry). Their small molecular size, their good water-solubility, and their very low acute toxicity allow to use them as drug-carriers in pharmacological applications.     

Radical Copolymerization Behavior of 2,2‐Dimethyl‐5‐methylene‐1,3‐dioxolan‐4‐one with Common Monomers

Radical copolymerization of 2,2‐dimethyl‐1,3‐dioxolan‐4‐one (DMDO) consisting of a hybrid structure of acrylate and vinyl ether moieties with styrene, methyl methacrylate, and vinyl acetate was examined. The radical copolymerization was carried out without a solvent or in chlorobenzene in the presence of 3 mol‐% of 2,2′‐azoisobutyronitrile at 60°C for 20 h to obtain the copolymers with number‐average molecular weights of 1 400‐700 000 in 27–86% yields. No ring‐opening occurred but vinyl polymerization of DMDO selectively proceeded in the copolymerization. The monomer reactivity ratios were evaluated as r₁ = 6.42, r₂ = 0.08 (M₁, DMDO; M₂, styrene) by the Fineman‐Ross method. The Alfrey‐Price Q‐ and e‐values of DMDO were calculated as 5.97 and –0.13, respectively. Ab initio molecular orbital calculations were carried out to compare the reactivity of DMDO with methyl α‐methoxyacrylate and vinyl ether.