Abstract: Water purification particles have porous particles and photocatalyst particles formed of titanium-based compound particles that are supported on the porous particles, have absorption at a wavelength of 500 nm in a visible absorption spectrum, and have an absorption peak at 2,700 cm?1 to 3,000 cm?1 in an infrared absorption spectrum, and a metal compound having a metal atom and a hydrocarbon group is bonded to the surface of each of the titanium-based compound particles through an oxygen atom.

Abstract: The present invention relates to a modification polymerization initiator and a method for preparing the same, and the modification polymerization initiator includes a derived unit from a compound represented by Formula 1 and may include various functional groups in a molecule, and thus, may initiate polymerization reaction and introduce a functional group into a polymer chain at the same time.

Abstract: Methods are described for the preparation of polymers using a lanthanide-based coordination catalyst and arresting polymerization using a reduced amount of a Lewis base while retaining the reactivity of the polymer chain ends toward functionalization agents. The Lewis base is a meso-enriched oxolanyl Lewis base. The resulting functionalized polymer has a higher level of purity and can be used in products such as tires.

Abstract: The present invention relates to a method for preparing a modified conjugated diene-based polymer, and more particularly, provides a method for preparing a modified conjugated diene-based polymer including a step of polymerizing a conjugated diene-based monomer in the presence of an organometal compound in a hydrocarbon solvent to prepare an active polymer which is coupled with an organometal (S1); and a step of reacting or coupling the active polymer prepared in step (S1) with a modifier (S2), wherein step (S1) is continuously performed in two or more polymerization reactors, and a polymerization conversion ratio in a first reactor among the polymerization reactors is 50% or less.

Abstract: The present invention relates to a method for preparing a modified conjugated diene-based polymer, and more particularly, provides a method for preparing a modified conjugated diene-based polymer including a step of polymerizing a conjugated diene-based monomer in the presence of an organometal compound in a hydrocarbon solvent to prepare an active polymer which is coupled with an organometal (S1); and a step of reacting or coupling the active polymer prepared in step (S1) with a modifier (S2), wherein step (S1) is continuously performed in two or more polymerization reactors, and a polymerization conversion ratio in a first reactor among the polymerization reactors is 50% or less.

Abstract: A stabilized initiator solution comprising a multi-valent lithiated containing initiator and an aliphatic or cycloaliphatic solvent.

Abstract: Catalyst compositions for use in forming polyurethane products include a gelling catalyst, a trimerization catalyst, and a cure accelerator. The gelling catalyst is a tertiary amine, mono(tertiary amino) urea, bis(tertiary amino) urea, or a combination of any of these. Any known trimerization catalyst may be used. The cure accelerator may be a diol having at least one primary hydroxyl group, and having from five to 17 chain backbone atoms chosen from carbon, oxygen, or both between the hydroxyl groups, provided that at least five of the backbone atoms are carbon. Alternatively or in addition, the cure accelerator may be a polyol having three or more hydroxyl groups, at least two of which are primary, and having molecular weights between 90 g/mole and 400 g/mole. Delayed initiation of the polyurethane-forming reaction and/or reduced demold time for producing the polyurethane part can be obtained by using these catalyst compositions.

Abstract: Sulfur chelated ruthenium compounds represented by the following formula: wherein M indicates the ruthenium metal bound to a benzylidene carbon; R represents C1-C7 alkyl group or optionally substituted aryl; X1 and X2 each independently represent halogen; Y1 and Y2 each independently denote unsubstituted or alkyl-substituted phenyl; and Z independently represents hydrogen, electron withdrawing or electron donating substituent, with m being an integer from 1 to 4, and processes and compositions related thereto.

Abstract: The invention provides: a polycondensation catalyst for polyester production, which contains titanium atoms, alkaline earth metal atoms and phosphorus atoms, has high reactivity and excellent long-term storage stability, can be easily produced industrially, and has an advantage in cost; a polyester resin obtained with the catalyst; and a molded article. These are: a polymerization catalyst for polyester production containing titanium atoms, alkaline earth metal atoms and phosphorus atoms and having a specific constitution; a polyester resin obtained with the catalyst; and a molded article.

Abstract: The present invention relates to a new hybrid catalyst system for the polymerization of olefins and to a polymerization process carried out in the presence of said catalyst. The new hybrid catalyst system comprises a tridendate iron compound and a zirconocene having a bridge of at least three carbon atoms connecting two indenyl ligands.

Abstract: Catalyst compositions for use in forming polyurethane products include a gelling catalyst, a trimerization catalyst, and a cure accelerator. The gelling catalyst is a tertiary amine, mono(tertiary amino) urea, bis(tertiary amino) urea, or a combination of any of these. Any known trimerization catalyst may be used. The cure accelerator may be a diol having at least one primary hydroxyl group, and having from five to 17 chain backbone atoms chosen from carbon, oxygen, or both between the hydroxyl groups, provided that at least five of the backbone atoms are carbon. Alternatively or in addition, the cure accelerator may be a polyol having three or more hydroxyl groups, at least two of which are primary, and having molecular weights between 90 g/mole and 400 g/mole. Delayed initiation of the polyurethane-forming reaction and/or reduced demold time for producing the polyurethane part can be obtained by using these catalyst compositions.

Abstract: A cationic polymerization process for isoolefins using a zinc halide initiator. The zinc halide initiator is added to a solution of the isoolefin in a suitable solvent, preferably a halocarbon solvent. Polymerization reactions are normally conducted at temperatures high enough to allow the zinc halide initiator to dissolve in the solution. An alkyl halide activator may optionally be used and is preferably added to the solution prior to the zinc halide initiator. A multiolefin may optionally be present in the solution. The process is particularly useful in the formation of isoolefin homopolymers and co-polymers of isoolefins and multiolefins, such as butyl rubber.

Abstract: The invention relates to soluble metal oxides and mixed metal oxides and to solutions comprising metal oxides and mixed metal oxides. The invention further relates to a process for preparing a soluble metal oxide and a soluble mixed metal oxide and additionally relates to a process for modifying the solubility of a soluble metal oxide. The metal oxides, mixed metal oxides and solutions thereof have a number of applications and in particular are suitable for use as catalysts and also as precursors for the formation of metal films.

Abstract: The present invention is directed to a catalyst system for synthesizing rubbery polymers, such as styrene-butadiene rubber, that can be utilized in tire tread rubbers. The catalyst system, in one embodiment, includes an organolithium compound and a potassium alkyl borohydride or potassium alkyl aluminum hydride defined by: (R)3A?(H)K+, wherein A is boron or aluminum, H is hydrogen, K is potassium, and R, which is the same or different, is either H, a C1-C10 alkyl, a C3-C10 cycloalkyl, phenyl, or phenyl substituted C1-C10 alkyl, or a C3-C10 cycloalkyl, with the proviso that at least one R is a C1-C10 alkyl, and further wherein any two R's may optionally be part of a carbocyclic ring. The rubbery polymers can have low to medium vinyl microstructure content, i.e., from about 10% to about 40%, and are useful in tire tread rubber compounds which can exhibit improved wear and tear characteristics.

Abstract: A catalytic system usable for the copolymerization of at least one conjugated diene and at least one monoolefin, a process for preparing this catalytic system, a process for preparing a copolymer of a conjugated diene and at least one monoolefin using said catalytic system, and said copolymer are described.

Abstract: The invention relates to a process for hydrogenating oligonitriles which have at least two nitrile groups in the presence of a catalyst which, before commencement of the hydrogenation, is pretreated by contacting with a compound A which is selected from alkali metal carbonates, alkaline earth metal carbonates, ammonium carbonate, alkali metal hydrogencarbonates, alkaline earth metal hydrogencarbonates, ammonium hydrogencarbonate, alkaline earth metal oxocarbonates, alkali metal carboxylates, alkaline earth metal carboxylates, ammonium carboxylates, alkali metal dihydrogenphosphates, alkaline earth metal dihydrogenphosphates, alkali metal hydrogenphosphates, alkaline earth metal hydrogenphosphates, alkali metal phosphates, alkaline earth metal phosphates and ammonium phosphate, alkali metal acetates, alkaline earth metal acetates, ammonium acetate, alkali metal formiates, alkaline earth metal formiates, ammonium formiate, alkali metal oxalates, alkaline earth metal oxalates and ammonium oxalate.

Abstract: Embodiments of the present invention are directed to a polymerization catalyst used to produce polyester. The catalyst comprises at least one metal-containing component, excluding antimony or germanium, and an organic compound component, containing at least one moiety of Ar—O— or Ar—N<, where Ar represents an aryl group.

Abstract: This invention discloses a process for synthesizing a hairy polymer particle which comprises the steps of (1) polymerizing a vinyl aromatic monomer by emulsion polymerization in an aqueous medium to produce core particles, (2) recovering the core particles from the aqueous medium, (3) dispersing the core particles in an organic solvent, (4) adding an organo-lithium compound to the dried core particles in the organic solvent to produce the hairless core initiator, and (5) utilizing the hairless core initiator to initiate the anionic polymerization of a conjugated diolefin monomer in an organic solvent to produce a solution of the hairy polymer particles. The hairy polymer nanoparticles can then be recovered from the organic solvent. These hairy polymer particles are comprised of (1) a core which is comprised of a polymer of a vinyl aromatic monomer and (2) hairs which are polymer chains of a conjugated diolefin monomer, wherein the hairs are covalently bonded to the core.

Abstract: Pulverulent solid which consists essentially of at least one metal alkyl compound bound chemically and/or physically to a finely divided, porous, mechanically stable and chemically inert support, has a proportion by weight of metal alkyl compound of at least 5% by weight, based on the support, and has an angle of repose, determined in accordance with ISO 4324, of up to 48°. The solid allows trouble-free metering as active component into a reactor.

Abstract: Rubbery polymers made by anionic polymerization can be coupled with tin halides or silicon halides to improve the characteristics of the rubber for use in some applications, such as fire treads. In cases where the rubbery polymer was synthesized utilizing a polar modifier it is difficult to attain a high level of coupling. This invention is based upon the unexpected finding that coupling efficiency can be significantly improved by conducting the coupling reaction in the presence of a lithium salt of a saturated aliphatic alcohol, such as lithium t-amylate. This invention discloses a process for coupling a living rubbery polymer that comprises reacting the living rubbery polymer with coupling agent selected from the group consisting of tin halides and silicon halides in the presence of a lithium salt of a saturated aliphatic alcohol.

Abstract: A process for preparing a functionalized polymerization initiator, the process comprising combining a functionalized styryl compound and an organolithium compound.

Abstract: The invention related to a process for the polymerization of at least one aliphatic or aromatic hydrocarbyl C2-20 mono- or multiolefin in the presence of a catalyst and a boron comprising co-catalyst, wherein the catalyst comprises a composition of a metal-organic reagent, a spectator ligand and optionally at least one equivalent of a hydrocarbylating agent. The invention further relates to a polymer obtainable by the process of the invention.

Abstract: A tethered ligand comprising the reaction product of an organofunctional silica and a ligand containing a functional group capable of reaction with said organofunctional silica, wherein the organofunctional silica is prepared from an alkyl silicate and an organofunctional silane is described. A supported catalyst is also described comprising additionally a source of catalytically-active metal. Methods for preparing the tethered ligand and supported catalyst are provided and uses of the supported catalyst for performing asymmetric reactions are claimed. The catalysts are readily separable from the reaction mixtures and may be re-used if desired.

Abstract: Catalyst for polymerization of an olefin is provided, which comprises (A) a transition metal compound having a carbon-metal bond structure and (B) an activating co-catalyst, or (A) a transition metal compound having a carbon-metal bond structure, (B) an activating cocatalyst and (C) an organometallic compound.

Abstract: This invention provides a novel polymerization catalyst other than antimony compounds, polyester produced by using the same and a process for producing polyester. The polycondensation catalyst of this invention is a polyester polymerization catalyst comprising an aluminum compound and a phosphorus compound having a specific structure. Further, this invention relates to polyester produced by using this polyester polymerization catalyst and a process for producing polyester. Further, this invention relates to fibers, films and hollow molded articles comprising the polyester.

Abstract: This invention reveals a catalyst system for use in isothermal polymerizations which consists essentially of (a) an organolithium compound, (b) a calcium alkoxide and (c) a lithium alkoxide. The subject invention further discloses a process for synthesizing a random styrene-butadiene rubber having a low vinyl content by a process which comprises copolymerizing styrene and 1,3-butadiene under isothermal conditions in an organic solvent in the presence of a catalyst system which consists essentially of (a) an organolithium compound, (b) a calcium alkoxide and (c) a lithium alkoxide. An amine can also be added to the catalyst system to increase the molecular weight (Mooney viscosity) of the rubber.

Abstract: Disclosed herein are compositions useful for introducing metal carboxylate salts as catalysts into systems useful for producing polyurethane and polyisocyanurate foams. The methods permit the introduction of such catalysts in the absence of substantial amounts of water which otherwise cause inferior foams to be produced. A method for producing foam employing the catalysts are also described.

Abstract: A catalyst for addition polymerization obtained by contacting (A) an organoaluminum compound, (B) a specific boron compound and (C) a solid inorganic compound, and a process for producing an addition polymer characterized by polymerizing an addition-polymerizable monomer in the presence of the catalyst.

Abstract: The present invention is directed to double metal cyanide catalysts (“DMC”) which are prepared by combining i) at least one metal salt; ii) at least one metal cyanide salt; iii) at least one organic complexing ligand; iv) at least one alkali metal salt; and, optionally, v) at least one functionalized polymer under conditions sufficient to form a catalyst; and adding a sufficient amount of the at least one alkali metal salt to the catalyst so formed in an amount such that the catalyst includes the at least one alkali metal salt in an amount of from about 0.4 to about 6 wt. % based on the total weight of the catalyst. The polyols produced in the presence of the catalysts of the present invention have reduced levels of high molecular weight tail.

Abstract: Methyllithium is prepared by reacting chloromethane with a dispersion lithium metal in an aromatic organic solvent with methyltetrahydrofuran.

Abstract: A process for the preparation of polycarbonate by the phase boundary process is disclosed. The process entails reacting at least one dihydroxydiarylalkane in the form of its alkali metal salts with phosgene in the heterogeneous phase in the presence of sodium hydroxide solution and an organic solvent. The process is characterized in that the feedstock have but low content of Fe, Cr, Ni, Zn, Ca, Mg, Al metals or homologues thereof, and in that the organic solvent is separated off, and in that the polycarbonate which is obtained is worked up. The resulting polycarbonate is particularly useful in producing transparent shaped articles.

Abstract: A shell impregnated catalyst of Pd-Au produced on a silica support to have a Pd loading of 1.8 g/L of catalyst to about 7.2 g/L and a Au to Pd weight ratio of 0.3 to 2.0 by impregnating the support with aqueous solutions of palladium and gold salts or acids and thereafter precipitating water insoluble compounds of Pd and Au on the with alkali metal silicate or hydroxide solutions, then dried, and the surface precipitated compounds of Pd and Au are then reduced by reaction with ethylene or hydrogen at a temperature of greater than 150° C. up to 310° C. or with hydrogen up to 299° C. until substantially all of the Pd and Au contents are reduced to a free metal state, after which the support is impregnated with potassium acetate to an extent of 6 to 7 weight percent of the weight of the total catalyst.

Abstract: The present invention provides protected functionalized polymerization initiators having less than one molar equivalent chain extension agent introduced therein to provide hydrocarbon solubility.

Abstract: The present invention provides a process for preparing amino functionalized diene polymers with 1,4-trans linkage content equal to or greater than 70%. The invention also concerns polymers of such type, a rubber composition and a tire casing containing those polymers. The process of preparation according to the invention comprises polymerizing at least one diene monomer by means of a lithium catalytic system, which comprises at least one hydrocarbon solvent, one compound A of a IIIA group metal, one compound B of an alkaline earth metal and one aminolithium initiator C. Amino functionalized diene polymers with high 1,4-trans linkage content according to the invention are such that the amino function, situated at the end of the polymer chain, is a tertiary amino function, the rate of functionalization of said polymers being equal to or greater than 50% and the 1,4-trans linkage content being equal to or greater than 70%.

Abstract: The present invention relates to a process for the production of a catalyst by reacting metal compounds with azo ligands, the catalyst, the use of this catalyst as a polymerization catalyst, a process for olefin (co)polymerization with the aid of these catalysts, reaction products of these catalysts with co-catalysts, the olefin (co)polymer, the use of this olefin (co)polymer for the production of molded parts and also molded parts produced from the olefin (co)catalyst.

Abstract: The present invention provides protected functionalized polymerization initiators having less than one molar equivalent chain extension agent introduced therein to provide hydrocarbon solubility.

Abstract: The present invention relates to a process for the polymerization and copolymerization of 1-olefins and to a catalyst to be used in said process wherein the catalyst comprises (1) a complex having formula (I) wherein M is Fe[II], Fe[III], Co[I], Co[II], Co[III], Mn[I], Mn[II], Mn[III], Mn[IV], Ru[II], Ru[III] or Ru[IV]; X represents an atom or group covalently or ionically bonded to the metal M; T is the oxidation state of the metal; b is the valency of the atom or group X; and R 1 to R 7 are each independently selected from hydrogen, halogen, hydrocarbyl, substituted hydrocarbyl, heterohydrocarbyl, substituted heterohydrocarbyl or SiR′ 3 where each R′ is independently selected from hydrogen, halogen, hydrocarbyl, substituted hydrocarbyl, heterohydrocarbyl, substituted heterohydrocarbyl; and when any two or more of R 1 to R 7 are hydrocarbyl, substituted hydrocarbyl, heterohydroc

Abstract: A block copolymer having narrow molecular weight distribution and excellent symmetrical property or a telechelic polymer having, equally at both terminals thereof, a functional group can be produced by using a polymerization initiator solution which comprises a dilithium polymerization initiator having an average number of functional groups of 1.8 to 2.0/molecule and a solvent selected from aliphatic hydrocarbon compounds and alicyclic compounds and is free of a polar substance.

Abstract: The present invention relates to a synthetic method in which one or more diaryl carbonates is reacted with one or more dihydroxy aromatic compounds in the presence of a transesterification catalyst under melt polymerization conditions to afford a product polycarbonate. The transesterifcation catalysts used according to the method of the present invention are alkali metal salts and alkaline earth metal salts of antimony oxides or germanium oxides in combination with tetraalkyl ammonium or tetraalkyl phosphonium compounds which serve as co-catalysts. The antimony oxide derivative “tartar emetic”, structure IV, was shown to possess excellent activity as a transesterifcation catalyst for the preparation of polycarbonate under melt polymerization conditions.

Abstract: The present invention relates to a synthetic method in which one or more diaryl carbonates is reacted with one or more dihydroxy aromatic compounds in the presence of a transesterification catalyst under melt polymerization conditions to afford a product polycarbonate. The transesterifcation catalysts used according to the method of the present invention are alkali metal salts and alkaline earth metal salts of heterocyclic diols in combination with tetraalkylammonium or tetraalkylphosphonium compounds which serve as co-catalysts. The furan diol derivative dimethyl 3,4-dihydroxy-2,5-furandiacarboxylate disodium salt, structure IV, was shown to possess excellent activity as a transesterifcation catalyst for the preparation of polycarbonate under melt polymerization conditions.

Abstract: The process and catalyst system of this invention can be utilized to synthesize polybutadiene rubber having a high trans content and a low melting point by solution polymerization. The trans-polybutadiene rubber made by the process of this invention can be utilized in tire tread rubbers that exhibit outstanding wear characteristics. More importantly, the trans-polybutadiene rubber of this invention can be easily processed because of its low level of crystallinity. In fact, the trans-polybutadiene made by the process of this invention does not need to be heated in a “hot-house” before being used in making rubber compounds. The process and catalyst system of this invention can also be used in the synthesis of trans-styrene-butadiene rubber (SBR).

Abstract: Compositions including one or more anionic polymerization initiators and one or more additives for improving functionalizing efficiency of living polymer anions are disclosed. The present invention also provides compositions including one or more electrophiles and one or more additives for improving functionalizing efficiency of living polymer anions. Novel electrophiles and processes for improving polymer anion functionalization efficiencies are also disclosed. The additives are generally alkali metal halides or alkoxides, and the initiators are generally organs alkali metal compounds, particularly alkyl lithium compounds.

Abstract: Metal salts of cyclic alcohols can be used as modifiers in lithium initiated solution polymerizations of diene monomers into rubbery polymers having a low vinyl content. For instance, such initiator systems can be used in the copolymerization of styrene and isoprene to produce low vinyl styrene-isoprene rubber having a random distribution of repeat units that are derived from styrene. It is important for such polymerizations to be conducted in the absence of polar modifiers, such as Lewis bases. The subject invention more specifically discloses an initiator system which is comprised of (a) a lithium initiator and (b) a metal salt of a cyclic alcohol, wherein said initiator system is void of polar modifiers. The present invention also discloses a process for preparing a rubbery polymer having a low vinyl content which comprises: polymerizing at least one diene monomer with a lithium initiator at a temperature which is within the range of about 5° C. to about 100° C.

Abstract: This invention is based upon the discovery that rubbery polymers having a high vinyl content and a low degree of branching can be synthesized with an initiator system that is comprised of (a) a lithium initiator selected from the group consisting of allylic lithium compounds and benzylic lithium compounds, (b) a Group I metal alkoxide, and (c) a polar modifier; wherein the molar ratio of the Group I metal alkoxide to the polar modifier is within the range of about 0.1:1 to about 10:1; and wherein the molar ratio of the Group I metal alkoxide to the lithium initiator is within the range of about 0.01:1 to about 20:1. These high vinyl polymers offer reduced levels of hysteresis and better functionalization efficiency.

Abstract: The present invention relates to a process for the preparation of a dilithiated initiator usable in anionic polymerization, a process for the preparation by anionic polymerization of a living diene elastomer which is provided with a carbon-lithium group at each of its chain ends, and a process for the preparation of a copolymer having three blocks starting from said living diene elastomer. The process for the preparation of a dilithiated initiator according to the invention involves of reacting a first reagent, a dialkenyl benzene, and a second reagent, secondary butyllithium, in the presence of a diamine, in an aliphatic or alicyclic hydrocarbon solvent, such that the ratio of the number of moles of first reagent to the number of moles of second reagent is substantially equal to 0.5, so that the initiator obtained is essentially a bi-adduct resulting from the addition of a molecule of secondary butyllithium to each of the two double bonds in the dialkenyl benzene.

Abstract: This invention discloses a process for making dilithium initiators in high purity. This process can be conducted in the absence of amines which is desirable since amines can act as modifiers for anionic polymerizations. The dilithium compounds made are highly desirable because they are soluble in aromatic solvents. The present invention more specifically discloses a process for synthesizing a dilithium initiator which comprises reacting disopropenylbenzene with a tertiary alkyl lithium compound in an aromatic solvent at a temperature which is within the range of about 0° C. to about 100° C. The present invention further discloses a process for synthesizing m-di-(1-methyl-3,3-dimethylbutyllithio)benzene which comprises reacting diisopropenylbenzene with tertiary-butyllithium in an aromatic solvent at a temperature which is within the range of about 0° C. to about 100° C.

Abstract: The present invention relates to an initiation system composed of the reaction product of at least one cyclic siloxane and at least one organometalic compound of sufficient reactivity to open the siloxane ring. Application of the present invention is to the preparation of homopolymers of (meth)acrylic, vinylaromatic or diene monomers, random or block copolymers of these monomers and, in particular, application to poly(methylmethacrylate) with a high content of isotactic triads.

Abstract: A process for the continuous anionic polymerization or copolymerization of styrene or diene monomers using an alkali metal alkyl compound as polymerization initiator is carried out in the presence of an alkyl- or arylmetal compound of an element which occurs in at least divalent form as rate regulator, preferably under non-isothermal conditions and without back-mixing in a tubular or tube-bundle reactor, preferably using an alkyl- or arylmetal compound A of the formula R1M1 and an alkyl- or arylmetal compound B of the formula R2nM2 in a molar ratio between B and A of from 0.1:1 to 500:1, where M1 is Li, Na or K; R1 is hydrogen, C1-C20-alkyl, C6-C20-aryl, or C7-C20-alkyl-substituted aryl; M2 is an n-valent element from group 2a, 2b or 3a of the Periodic Table; and R2 is hydrogen, halogen, C1-C20-alkyl or C6-C20-aryl; and a special anionic polymerization initiator containing no Lewis base.

Abstract: In a process for the homopolymerization of vinylaromatic monomers or the copolymerization of vinylaromatic monomers and dienes, the monomers are polymerized in the presence of at least one alkali metal organyl, at least one magnesium organyl and at least one aluminum organyl. The invention also provides an initiator composition for carrying out the process.

Abstract: A process for producing a vinyl polymer which comprises carrying out anionic polymerization under the condition that the polymerization temperature is not lower than 45° C. and not higher than 250° C. and the concentration of the vinyl monomer based on the polymerization solvent is 45-100% by weight, wherein the metal of the cation forming a counterpart to the carbonic anion at the polymerization propagating species consists essentially of Mg, or Mg and M1 wherein M1 is at least one alkali metal selected from the group consisting of Li, Na and K, and the molar concentrations of the metals of Mg and M1 satisfy the relation of [Mg]/[M1]≧4, the invention also relates to a vinyl monomer polymerization initiator comprising (R2)2Mg wherein R2 is a hydrocarbon group.