Salt effect in the base-catalyzed polymerization of unsaturated amide compounds. III. Nature of the polymerization system

Coordination complexes of lithium chloride with polar solvents and monomers were isolated, and their physical properties were studied. The parallel between stabilities of isolated complexes and coordination function in the polymerization system is discussed. The increase of the Q and e values of p-vinylbenzamide (VBA) supports the mechanism of vinyl-type polymerization of VBA in the presence of the salt. The specific solvent effect of dimethyl sulfoxide was determined by measurement of electrical conductivity of a model system.     

Salt effect in the base-catalyzed polymerization of unsaturated amide compounds. IV. Polymerization of p-vinylbenzamide in the presence of LiCl/N,N,N′,N′-tetramethylethylenediamine

In the presence of lithium chloride and N,N,N′,N′-tetramethylethylenediamine, p-vinylbenzamide was polymerized in basic media to form a polymer with structure consisting of units due to both proton transfer and vinyl type polymerization, whereas in the presence of the salt alone the monomer underwent exclusively vinyl type of polymerization to give a polystyrene derivative:      

Salt effects and the mechanism of electrophilic mercuration of unsaturated compounds

The kinetics of the addition of Hg(OAc)₂ to strained and unstrained alkenes was studied in MeOH solution in the presence of NaOAc. Based on salt effects, the HgOAc ion was shown to be the actual reagent in the reaction of the unstrained alkenes, whereas Hg(OAc)₂ was the reagent in the case of the strained alkenes. The mechanisms of the solvomercuration of alkenes of various structures were proposed.For the previous report seeIzv. Akad. Nauk, Ser. Khim., 1994, 819 [Russ. Chem. Bull., 1994,43, 760 (Engl. Transl.)].Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 344–352, February, 1995.     

Salt effects and the mechanism of electrophilic mercuration of unsaturated compounds

The reaction of Hg(OAc)₂ with bornylene in THF-H₂O and CH₃CN-H₂O mixed solvents (75 25, v/v) was studied. The effects of the addition of NaOAc on the reaction rate and the composition of products were investigated. In the CH₃CN-H₂O mixture, the addition of NaOAc decreases the amount of the rearranged product, fundamentally changes the ratio between the regioisomeric solvoadducts, and promotes the formation of products of Hg(OAc)₂ addition. The reaction proceedsvia an ion pair and free mercurinium ion; the cation of the ion pair and the free mercurinium ion have dissimilar structures.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 544–548, March, 1995.     

Ring-opening polymerization of unsaturated alicyclic compounds

The ring-opening polymerizations of cyclooctene, cyclododecene, 1,5-cyclooctadiene, 1,5,9-cyclododecatriene, 3-methylcyclooctene, and 3-phenylcyclooctene have been carried out by using a two-component catalyst system composed of ethylaluminum dichloride and tungsten hexachloride. NMR and infrared analyses of the respective polymers indicate structures which are consistent with a ring-cleavage mode of propagation. No evidence for double-bond shifts or transannular reactions during the polymerizations of 1,5-cyclooctadiene, 1,5,9-cyclododecatriene, 3-methylcyclooctene, and 3-phenylcyclooctene was found. The polymerizability of substituted, unsaturated, mediumsized alicyclic monomers suggests a convenient method for synthesis of certain perfectly alternating terpolymers. Since polymerizations occurred rapidly with little evolution of heat, it was concluded that entropy is a substantial contributor to the free energy of the ring-opening polymerization of medium-sized, unsaturated alicyclic monomers.     

Polymerization of cyclic monomers, 1. Radical polymerization of unsaturated spiro orthocarbonates

7-Methyl-2-methylene- ( 1 ) and 7-methyl-2,3-dimethylene-1,4,6,9-tetraoxaspiro[4.4]nonane (2) were synthesized and characterized by elemental analysis, IR, ¹H NMR and ¹³C NMR spectroscopy. Radical polymerization of the spiro orthocarbonates (SOC) 1 and 2 show that they undergo primarily vinyl polymerization with a low degree of ring-opening reaction. Homopolymerization of 2 at 120°C with di-tert-butyl peroxide gives a transparent crosslinked polymer and the polymerization generates a 12,5% shrinkage in volume.     

Salt effects in the mercuration of unsaturated compounds. Kinetic evidence for the formation of ion pairs and a solvated ion

The kinetics of mercuration of bornylene and cyclohexene in different solvents in the presence of NaOAc and LiClO₄ has been investigated. Addition of NaOAc sharply decreases the rate of addition reactions of mercuric acetate to bornylene and cyclohexene in alcohols; the main direction of the mercuration of bornylene is the formation of acetoxy-adducts, and the yield of solvo-adducts decreases from 76 % in the absence of NaOAc, to 19 % in the presence of the salt (4·10^–3 mol L^–1). A reaction scheme involving the participation of intermediate ion pairs and a solvated mercurinium ion is suggested and confirmed by a steady-state concentration method. The influence of NaOAc on the rate of the reaction and on product formation is realized through the common ion effect.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 819–826, May, 1994.     

Studies of the polymerization of diallyl compounds. XI. Polymerization of styrene in the presence of diallyl compounds

Radical polymerization of styrene in the presence of various diallyl compounds was carried out at 60°C, with the use of 2,2′-azobisisobutyronitrile as an initiator. The chain transfer constant C_s of the styryl radical to diallyl compounds was determined graphically by solving the Mayo equation. The C_s values of diallyl esters are quite small compared to those of diallyl acetals. The polymerization mechanism of styrene in the presence of diallyl compounds was also discussed in connection with the results obtained previously.     

Tributylborine: A catalyst for the polymerization of unsaturated compounds

Summary It was found that tributylborine is a catalyst for the polymerization of styrene and methyl methacrylate.     

Anionic polymerization of N-substituted maleimide. II. Polymerization of N-ethylmaleimide

Anionic polymerization of N-ethylmaleimide (N-EMI) was carried out with potassium t-butoxide, lithium t-butoxide, n-butyllithium, and ethylmagnesium bromide as initiators in THF and in toluene. An almost quantitative yield of poly(N-EMI) was obtained with potassium t-butoxide as initiator in THF in a wide range of polymerization temperatures. Initiators possessing lithium as counter cation produced poly(N-EMI) in slightly lower yields and ethylmagnesium bromide gave the polymer only in less than 35% yield in THF. As a polymerization reaction solvent, THF was preferable for the polymerization of N-EMI compared with toluene with respect to polymer yields. Poly(N-EMI) obtained with anionic initiators exerted unimodal molecular weight distribution. From ¹H- and ¹³C-NMR spectra of poly(N-EMI) anionic polymerization of N-EMI with potassium t-butoxide was revealed to proceed at carbon–carbon double bond. t-Butoxide system was found to have a “living” polymerization character, i.e., the observed average degree of polymerization was in good agreement with the one calculated from the initial molar ratio of N-EMI/initiator and the yield of polymer.     

Solid-state polymerization of acrylamide and its derivatives complexed with some lewis acids. II. Radiation-induced in-source polymerization

Radiation-induced solid-state polymerizations of complexes of N-tert-butylacrylamide, N-tert-amylacrylamide, and N-tert-hexylacrylamide with zinc chloride and zinc bromide have been studied. An accelerating effect of temperature and an inhibiting effect of oxygen on the polymerization process were observed. The activation energies have been established. The influence of monomer structure as well as the halide used on the polymerization rate have been discussed and some regularities have been pointed out. The polymers obtained show good solubilities in common solvents, which proves that they are not crosslinked.     

Polymerization in nonuniform latex particles. II. Kinetics of two-phase emulsion polymerization

A new theory, based on the concept of nonuniform distribution of free radicals in polymerizing latex particles, has been developed for the kinetics of two-phase emulsion polymerization reactions. This theory also takes into account the diffusion controlled termination and propagation reactions to describe the gel effect and limiting conversion. The kinetic model permits prediction of the distribution of free radicals in the two polymer phases and rate of polymerization as a function of reaction conditions. Experimental data for polystyrene/polymethyl methacrylate and polymethyl methacrylate/polystyrene (postformed polymer/preformed polymer) in the literature have been used to assess the proposed idea of nonuniform distribution of free radicals in the latex particle.     

Polymerization of hexamethylcyclotrisiloxane with a biscatecholsiliconate. II. Kinetics of polymerization

The kinetics of polymerization were investigated for the polymerization of hexamethylcyclotrisiloxane (D₃) in toluene with methanol or water as an initiator, benzyltrimethylammonium bis(o-phenylenedioxy)phenylsiliconate as a catalyst, and dimethyl sulfoxide (DMSO) as a promoter. The rate of initiation was found to be comparable with both water and methanol. Addition of catechol drastically reduces the rate of initiation. The rate of propagation was found to be dependent upon the catalyst, DMSO, catechol and the aging of the catalyst solution. Two types of functional groups were postulated to be present during the propagation reaction, i.e., ?SiOH (dormant form) and ?SiONR₄ (living form). The former can be converted to the latter by R₄NOH derived from hydrolysis of catalyst. A postulated mechanism of polymerization with biscatecholsiliconate is presented.     

Electrochemical cyclization of unsaturated hydroxy compounds. Part II. Phenylselenolactonization

Phenylselenolactonization was performed, in one step, by electrolysis of Δ4- and Δ5 -unsaturated carboxylic acids and diphenyl diselenide in methanol containing ammonium bromide.     

Crystallization during polymerization of poly-p-xylylene. II. Polymerization at low temperature

The polymerization of p-xylylene was followed with a newly designed differential thermal analysis system at temperatures between ?196°C and ?20°C. It was found that at the lower temperatures the monomer condenses first to the crystalline monomer before simultaneous polymerization and crystallization. At the higher temperatures, polymerization and crystallization are successive. The data are in agreement with the morphology and crystal structure data derived in Part I of this series of papers on crystallization during polymerization of poly-p-xylylene.     

High-pressure reactions. II. γ-Ray polymerization of acrylamide

The post-irradiation effect of high pressure on the γ-ray-initiated solid-state polymerization of acrylamide has been described. Polymer conversion was found to increase significantly with applied pressure. The molecular weight of polymer increases with pressure.     

脲对丙烯酰胺聚合及产物结构的影响

本文研究了添加脲（添加量为丙烯酞胺的０．０６３到０．２００质量比）对丙烯酰胺聚合的影响。脲的加入能取代丙烯酞胺的双分于氢键缔合，使聚丙烯酰胺的水溶性速度提高，玻璃化温度下降。用红外光谱分析和差热分析的结构分析证实了上述机理。     

Polymerization photoinitiated by carbonyl compounds. XI. Styrene polymerization photoinitiated by cyclododecanones

To establish their potential as source of biradicals to initiate free-radical polymerization, 2-methyl- and 2,2,12-trimethylcyclododecanones were photolyzed in the presence of styrene. The initiation efficiency of both ketones is low—0.03. The molecular weight of the obtained polymer is ca. 25% higher than that obtained employing photoinitiators that produce monoradicals. This difference is explained in terms of a mixed polymerization mechanism comprising mono- and biradicals. © 1996 John Wiley & Sons, Inc.