Catalytic synthesis of 1,6‐dicarbamate hexane over MgO/ZrO2

MgO/ZrO₂ catalyst was prepared for the synthesis of 1,6‐dicarbamate hexane (HDC) using dimethyl carbonate (DMC) and 1,6‐diamine hexane (HDA) as raw materials. When the catalyst is calcined at 600 °C and MgO load is 6 wt%, the catalyst exhibits better activity. When the concentration of catalyst is 2 g (100 mL)^?1 DMC, n(HDA):n(DMC) = 1:10, reaction time is 6 h under reflux temperature, and the yield of 1,6‐dicarbamate hexane is 53.1%. HDC yield decreases from 53.1% to 35.3% after MgO/ZrO₂ being used for three times. The decrease in specific surface area may be attributed to deactivation of MgO/ZrO₂. Copyright © 2007 Society of Chemical Industry     

High activity of rare earth tetrahydroborates for ring‐opening polymerization of ω‐pentadecalactone

Ring‐opening polymerization of ω‐pentadecalactone (PDL) by tetrahydroborate complexes of rare earth metals, Ln(BH₄)₃(THF)₃ (Ln = La ( 1 ), Nd ( 2 ), Y ( 3 )), was studied. These complexes showed high activity for PDL polymerization in THF at 60°C. Among the complexes 1 – 3 , the neodymium complex 2 was most active. The obtained poly(PDL) was demonstrated to be hydroxy‐telechelic by ¹H‐NMR and MALDI‐TOF MS spectroscopy. Biodegradation of the poly(PDL) in compost at 60°C was investigated, where 18% weight loss of the samples was observed after 280 days. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Catalytic synthesis of toluene‐2,4‐diisocyanate from dimethyl carbonate

The process for catalytic synthesis of toluene‐2,4‐diisocyanate (TDI) from dimethyl carbonate (DMC) consists of two steps. Starting from the catalytic reaction between toluene‐2,4‐diamine (TDA) and DMC, dimethyl toluene‐2,4‐dicarbamate (TDC) is formed, and then decomposed to TDI. For the first step, the yield of TDC is 53.5% at a temperature of 250 °C, over Zn(OAc)₂/α–Al₂O₃ catalyst. For the second step, the yield of TDI is 92.6% at temperatures of 250–270 °C and under pressure of 2.7 kPa, over uranyl zinc acetate catalyst, when di‐n‐octyl sebacate(DOS) is used as heat‐carrier, and a mixture of tetrahydrofuran (THF) and nitrobenzene is used as solvent. © 2001 Society of Chemical Industry     

Synthesis of poly(vinyl alcohol)‐graft‐poly(ε‐caprolactone) and poly(vinyl alcohol)‐graft‐poly(lactide) in melt with magnesium hydride as catalyst

Grafting of poly(ε‐caprolactone) (PCL) and poly(lactide) (PLA) chains on poly(vinyl alcohol) backbone (PVA degree of hydrolysis 99%) was investigated using MgH₂ environmental catalyst and melt‐grown ring‐opening polymerization (ROP) of ε‐caprolactone (CL) and L ‐lactide (LA), that avoiding undesirable toxic catalyst and solvent. The ability of MgH₂ as catalyst as well as yield of reaction were discussed according to various PVA/CL/MgH₂ and PVA/LA/MgH₂ ratio. PVA‐g‐PCL and PVA‐g‐PLA were characterized by ¹H‐ and ¹³C‐NMR, DSC, SEC, IR. For graft copolymers easily soluble in tetrahydrofuran (THF) or chloroform, wettability and surface energy of cast film varied in relation with the length and number of hydrophobic chains. Aqueous solution of micelle‐like particles was realized by dissolution in THF then addition of water. Critical micelle concentration (CMC) decreased with hydrophobic chains. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis of well‐defined polystyrene by radical polymerization using 1,1,2,2‐tetraphenyl‐1,2‐ethanediol/feCl3/PPh3 initiation system

Well‐defined polystyrenes with an α‐hydrogen atom and an ω‐chlorine atom end groups and narrow polydispersity (M_n = 2500–4200, M_w/M_n = 1.29–1.48) have been synthesized by a free radical polymerization process using a 1,1,2,2‐tetraphenyl‐1,2‐ethanediol (TPED)/FeCl₃/PPh₃ initiation system. The end groups were monitored by ¹H nuclear magnetic resonance spectroscopy. When the polymerization of styrenes in bulk carried out at 120°C and the ratio of [St]₀ : [TPED]₀ : [FeCl₃]₀ : [PPh₃]₀ was 200 : 1 : 4 : 12, the polymerization exhibited some living/controlled radical polymerization characteristics. The polymerization mechanism was proposed proceeding via a reverse atom transfer radical polymerization (ATRP). Because the polymers obtained were end‐functionalized by chlorine atoms, they were used as macroinitiators to proceed chain extension polymerization in the presence of CuCl/2,2′‐bipyridine catalyst system via a conventional ATRP process. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1607–1613, 2000     

Ring‐opening polymerization of D,L‐lactide by rare earth 2,6‐dimethylaryloxide

Ring‐opening polymerization of D,L ‐lactide (LA) has been successfully carried out by using rare earth 2,6‐dimethylaryloxide (Ln(ODMP)₃) as single component catalyst or initiator for the first time. The effects of different rare earth elements, solvents, monomers and catalyst concentration as well as polymerization temperature and time on the polymerization were investigated. The results show that La(ODMP)₃ exhibits higher activity to prepare poly(D,L ‐lactide) (PLA) with a viscosity molecular weight of 4.5 × 10⁴ g mol^?1 and the conversion of 97 % at 100 °C in 45 min. The catalytic activity of Ln(ODMP)₃ has following sequence: La > Nd > Sm > Gd > Er > Y. A kinetic study has indicated that the polymerization is first order with respect to both monomer and catalyst concentration. The apparent activation energy of the polymerization of LA with La(ODMP)₃ is 69.6 kJ mol^?1. The analyses of polymer ends indicate that the LA polymerization proceeds according to ‘coordination–insertion’ mechanism with selective cleavage of the acyl–oxygen bond of the monomer. Copyright © 2004 Society of Chemical Industry     

Efficient enzymatic regioselective benzoylation of 5‐fluorouridine catalysed by Novozym 435

BACKGROUND: This work focuses on developing a mild, efficient and regioselective enzymatic procedure to synthesise 5′‐O‐benzoyl‐5‐fluorouridine, a more powerful antitumour drug than 5‐fluorouridine itself, and examining the influences of several key variables on the reaction. RESULTS: The enzymatic regioselective benzoylation of 5‐fluorouridine can be successfully conducted with Novozym 435. The end‐product was confirmed to be 5′‐O‐benzoyl‐5‐fluorouridine by ¹³C nuclear magnetic resonance analysis. A co‐solvent mixture of hexane and tetrahydrofuran (THF) (50:50 v/v) was found to be the best reaction medium. The optimal initial water activity, molar ratio of vinyl benzoate to 5‐fluorouridine and reaction temperature were 0.07, 25:1 and 70 °C respectively. Under the optimised conditions the initial reaction rate, substrate conversion and regioselectivity were found to be 32.8 mmol L^?1 h^?1, 98.9% and > 99% respectively. In addition, Novozym 435 still maintained 88.2% of its original activity even after being reused for ten batches at 70 °C, indicating excellent thermal and operational stability of the enzyme in the co‐solvent mixture of hexane and THF. CONCLUSION: The results clearly show that the Novozym 435‐catalysed regioselective benzoylation of 5‐fluorouridine is a novel and facile route for efficient preparation of 5′‐O‐benzoyl‐5‐fluorouridine with potential antitumour activity. Copyright © 2008 Society of Chemical Industry     

Zinc‐based catalyst for the ring‐opening polymerization of cyclic esters

A zinc‐based catalyst zinc bis[bis(trimethylsilyl)amide] was used for the polymerization of cyclic esters including L ‐lactide (L ‐LA) and 2‐methyl‐2‐carboxyl‐propylene carbonate (MBC). The polymerization of L ‐lactide in THF could be carried out successfully under mild conditions in very short time by using the zinc catalyst and alcohols as the initiators. Kinetic study in solution polymerization prooved the polymerization has high monomer conversion degree close to 100% and the molecular weight of the resulting polyester has linear increase with the increase of [M]₀ /[I] (molar ratio of monomer to initiator). Sequential polymerization of L ‐LA and MBC in THF also showed high MBC conversion of 94% with a narrow molecualr weight maintained, indicating a living nature of this polymerization. The zinc catalyst system has also been used for the L ‐LA bulk polymerization with a high monomer conversion. ¹³C NMR indicated the polymer possesses high regioregularity and the minor regioirregular component was owing to the D ‐LA in the monomer inserted into the polymer mainchain during the transesterifcation. Interaction between monomer and zinc catalyst has been found to be a key factor to sustain a homogenous solution during the initiating procedure. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Poly(1‐octene) synthesis using high performance supported titanium catalysts

Poly(1‐octene) was synthesized by polymerization of 1‐octene using high performance MgCl₂‐supported TiCl₄ in combination with triethyl aluminum (TEAl) as cocatalyst in n‐hexane for 2 h. Two catalysts, C₁ (diester catalyst) having di‐isobutyl phthalate as internal donor and C₂ (monoester catalyst) having ethyl benzoate as internal donor were utilized for the atmospheric polymerizations to evaluate the influence of structurally different internal donors on the productivity, rate of polymerization and molecular weight profiles. The kinetic profile assessed in terms of variation of reaction parameters like temperature, cocatalyst to catalyst molar ratio and monomer concentration was found to be dependent on them. From these kinetic analyses, optimize conditions for polymerizations of 1‐octene using diester as well as monoester catalyst were elucidated. The difference in the performance of diester and monoester catalyst system can be explained in terms of stability of active titanium species and chain transfer process. NMR spectroscopy of synthesized poly(1‐octene) indicate predominantly isotactic nature. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Polymerization of 4‐(4′‐N‐1,8‐naphthalimidophenyl)‐1,2,4‐triazolidine‐3,5‐dione with diisocyanates

4‐(4′‐Aminophenyl)‐1,2,4‐triazolidine‐3,5‐dione ( 1 ) was reacted with 1,8‐naphthalic anhydride ( 2 ) in a mixture of acetic acid and pyridine (3 : 2) under refluxing temperature and gave 4‐(4′‐N‐1,8‐naphthalimidophenyl)‐1,2,4‐triazolidine‐3,5‐dione ( NIPTD ) ( 3 ) in high yield and purity. The compound NIPTD was reacted with excess n‐propylisocyanate in N,N‐dimethylacetamide solution and gave 1‐(n‐propylamidocarbonyl)‐4‐[4′‐(1,8‐naphthalimidophenyl)]‐1,2,4‐triazolidine‐3,5‐dione ( 4 ) and 1,2‐bis(n‐propylamidocarbonyl)‐4‐[4′‐(1,8‐naphthalimidophenyl)]‐1,2,4‐ triazolidine‐3,5‐dione ( 5 ) as model compounds. Solution polycondensation reactions of monomer 3 with hexamethylene diisocyanate ( HMDI ), isophorone diisocyanate ( IPDI ), and tolylene‐2,4‐diisocyanate ( TDI ) were performed under microwave irradiation and conventional solution polymerization techniques in different solvents and in the presence of different catalysts, which led to the formation of novel aliphatic‐aromatic polyureas. The polycondensation proceeded rapidly, compared with conventional solution polycondensation, and was almost completed within 8 min. These novel polyureas have inherent viscosities in a range of 0.06–0.20 dL g^?1 in conc. H₂SO₄ or DMF at 25°C. Some structural characterization and physical properties of these novel polymers are reported. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2861–2869, 2003     

Microwave‐assisted rapid polycondensation reaction of 4‐(4′‐acetamidophenyl)‐1,2,4‐triazolidine‐3,5‐dione with diisocyanates

4‐(4′‐Aminophenyl)‐1,2,4‐triazolidine‐3,5‐dione was reacted with 1 mol of acetyl chloride in dry N,N‐dimethylacetamide (DMAc) at ?15°C and 4‐(4′‐acetamidophenyl)‐1,2,4‐triazolidine‐3,5‐dione [4‐(4′‐acetanilido)‐1,2,4‐triazolidine‐3,5‐dione] (APTD) was obtained in high yield. The reaction of the APTD monomer with excess n‐isopropylisocyanate was performed at room temperature in DMAc solution. The resulting bis‐urea derivative was obtained in high yield and was finally used as a model for the polymerization reaction. The step‐growth polymerization reactions of monomer APTD with hexamethylene diisocyanate, isophorone diisocyanate, and tolylene‐2,4‐diisocyanate were performed under microwave irradiation and solution polymerization in the presence of pyridine, triethylamine, or dibutyltin dilaurate as a catalyst. Polycondensation proceeded rapidly, compared with conventional solution polycondensation; it was almost completed within 8 min. The resulting novel polyureas had an inherent viscosity in the range of 0.07–0.17 dL/g in dimethylformamide or sulfuric acid at 25°C. These polyureas were characterized by IR, ¹H‐NMR, elemental analysis, and thermogravimetric analysis. The physical properties and structural characterization of these novel polyureas are reported. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2103–2113, 2004     

Polymerization of styrene using bis(β‐ketoamino)nickel(II)/methylaluminoxane catalytic systems

Styrene (St) was polymerized in toluene solution by using bis(β‐ketoamino)nickel(II) complex as the catalyst precursor and methylaluminoxane (MAO) as the cocatalyst. The polymerization conditions, such as Al : Ni ratio, monomer concentration, reaction temperature, and polymerization time, were studied in detail. Both of the bis(β‐ketoamino)nickel(II)/MAO catalytic systems exhibited higher activity for polymerization of styrene, and polymerization gave moderate molecular weight of polystyrene with relatively narrow molecular weight distribution (M_w/M_n < 1.6). The obtained polymer was confirmed to be atactic polystyrene by analyzing the stereo‐triad distributions mm, mr, and rr of aromatic carbon C¹ in NMR spectrum of the polymer. The mechanism of the polymerization was also discussed and a metal–carbon coordination mechanism was proposed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Copolymerization of phenylisocyanate and ϵ‐caprolactone with rare earth chloride systems

A copolymer of phenylisocyanate (PhNCO) and ε‐caprolactone (CL) was synthesized by the rare earth chloride systems lanthanide chloride isopropanol complex (LnCl₃·3iPrOH) and propylene epoxide (PO). Polymerization conditions were investigated, such as lanthanides, reaction temperature, monomer feed ratio, La/PO molar ratio, and aging time of catalyst. The optimum conditions were: LaCl₃ preferable, [PhNCO]/[CL] in feed = 1 : 1 (molar ratio), 30°C, [monomer]/[La] = 200, [PO]/[La] = 20, aging 15 min, polymerization in bulk for 6 h. Under such conditions the copolymer obtained had 39 mol % PhNCO with a 78.2% yield, M_n = 20.3 × 10³, and M_w/M_n = 1.60. The copolymers were characterized by GPC, TGA, ¹H‐NMR, and ¹³C‐NMR, and the results showed that the copolymer obtained had a blocky structure with long sequences of each monomer unit. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2135–2140, 2007     

Synthesis of PMMA‐PTHF‐PMMA and PMMA‐PTHF‐PST linear and star block copolymers

Combination of cationic, redox free radical, and thermal free radical polymerizations was performed to obtain linear and star polytetramethylene oxide (poly‐THF)‐polymethyl methacrylate (PMMA)/polystyrene (PSt) multiblock copolymers. Cationic polymerization of THF was initiated by the mixture of AgSbF₆ and bis(4,4′ bromo‐methyl benzoyl) peroxide (BBP) or bis (3,5,3′,5′ dibromomethyl benzoyl) peroxide (BDBP) at 20°C to obtain linear and star poly‐THF initiators with M_w varying from 7,500 to 59,000 Da. Poly‐THF samples with hydroxyl ends were used in the methyl methacrylate (MMA) polymerization in the presence of Ce(IV) salt at 40°C to obtain poly(THF‐b‐MMA) block copolymers containing the peroxide group in the middle. Poly(MMA‐b‐THF) linear and star block copolymers having the peroxide group in the chain were used in the polymerization of methyl methacrylate (MMA) and styrene (St) at 80°C to obtain PMMA‐b‐PTHF‐b‐PMMA and PMMA‐b‐PTHF‐b‐PSt linear and star multiblock copolymers. Polymers obtained were characterizated by GPC, FT‐IR, DSC, TGA, ¹H‐NMR, and ¹³C‐NMR techniques and the fractional precipitation method. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 219–226, 2004     

Synthesis and characterization of new polyureas derived from 4‐(4′‐Methoxyphenyl)urazole

4‐(4′‐Methoxyphenyl)urazole (MPU) was prepared from 4‐methoxybenzoic acid in five steps. The reaction of monomer MPU with n‐isopropylisocyanate was performed at room temperature in N,N‐dimethylformamide solution, and the resulting bis‐urea derivative was obtained in high yield and was finally used as a model for polymerization reaction. The step‐growth polymerization reactions of monomer MPU with hexamethylene diioscyanate, isophorone diioscyanate, and toluene‐2,4‐diioscyanate were performed in N,N‐dimethylacetamide solution in the presence of pyridine as a catalyst. The resulting novel polyureas have an inherent viscosity (η_inh) in a range of 0.07–0.21 dL/g in DMF and sulfuric acid at 25°C. These polyureas were characterized by IR, ¹H‐NMR, elemental analysis, and TGA. Some physical properties and structural characterization of these novel polyureas are reported. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1141–1146, 2002     

Controlled ring‐opening polymerization of ε‐caprolactone initiated by in situ formed yttrium trisalicylaldimine complexes,and their study by density functional theory

A series of yttrium trisalicylaldimine complexes formed in situ by the reaction of trialkyl complex [Y(CH₂SiMe₃)₃(THF)₂] (THF is tetrahydrofuran) with three equivalent salicylaldimines were used as initiators for the ring‐opening polymerization of ε‐caprolactone. Electronic and steric effects of the salicylaldimine ligand played important roles on the catalytic properties of the yttrium complexes. The yttrium trisalicylaldimine complex Y( L7 )₃ ( L7 = (S)‐2,4‐di‐tert‐butyl‐6‐[(1‐phenylethylimino)methyl]phenol) most effectively initiated controlled ring‐opening polymerization of ε‐caprolactone to prepare poly(ε‐caprolactone)s with high molecular weights and moderate molecular weight distributions. Obtained by density functional theory calculations, the optimized geometries of the four different active centers with four salicylaldimine ligands explained the experimental results. Copyright © 2011 Society of Chemical Industry     

The investigation of novel non‐metallocene catalysts with phenoxy‐imine ligands for ethylene (co‐)polymerization

Phthaldialdehyde and phthaldiketone were treated with substituted phenols of 2‐amino‐4‐methylphenol, 2‐amino‐5‐methylphenol and 2‐amino‐4‐t‐butylphenol, respectively, and then treated with transition metal halides of TiCl₄, ZrCl₄ and YCl₃. A series of novel non‐metallocene catalysts (1–12) with phenoxy‐imine ligands was obtained. The structures and properties of the catalysts were characterized by ¹H NMR and elemental analysis. The catalysts (1–12) were used to promote ethylene (co‐)polymerization after activation by methylaluminoxane. The effects of the structures and center atoms (Ti, Zr and Y) of these catalysts, polymerization temperature, Al/M (M = Ti, Zr and Y) molar ratio, concentration of the catalysts and solvents on the polymerization performance were investigated. The results showed that the catalysts were favorable for ethylene homopolymerization and copolymerization of ethylene with 1‐hexene. Catalyst 10 is most favorable for catalyzing ethylene homopolymerization and copolymerization of ethylene with 1‐hexene, with catalytic activity up to 2.93 × 10⁶ gPE (mol Y)^?1 h^?1 for polyethylene (PE) and 2.96 × 10⁶ gPE (mol Y)^?1 h^?1 for copolymerization of ethylene with 1‐hexene under the following conditions: polymerization temperature 50 °C, Al/Y molar ratio 300, concentration of catalyst 1.0 × 10^?4 L^?1 and toluene as solvent. The structures and properties of the polymers obtained were characterized by Fourier transform infrared spectroscopy, ¹³C NMR, wide‐angle X‐ray diffraction, gel permeation chromatography and DSC. The results indicated that the obtained PE catalyzed by 4 had the highest melting point of 134.8 °C and the highest weight‐average molecular weight of 7.48 × 10⁵ g mol^?1. The copolymer catalyzed by 4 had the highest incorporation of 1‐hexene, up to 5.26 mol%, into the copolymer chain. © 2012 Society of Chemical Industry     

Synthesis and characterization of alternate copolymers constructed by 1,3‐bis(diphenylsilyl)‐2,2,4,4‐tetraphenylcyclodisilazane units with oligo‐dimethylsiloxane segments

1,3‐Dichloro‐1,1,3,3‐tetraphenyldisilazane (DCTPS) with 71.6% yield was synthesized by the reaction of hexaphenylcyclotrisilazane (HPCT) with Ph₂SiCl₂ catalyzed by dibutyltin dilaurate. A ring‐closure reaction of DCTPS was carried out with BuLi in xylene–hexane mixture solvent; 1,3‐bis(chlorodiphenylsilyl)‐2,2,4,4‐tetraphenyl‐cyclodisilazane (BcPTPC) with 73.2% yield was obtained. Hydrolysis of BcPTPC in ether–triethylamine solvent resulted in 71.9% yield of 1,3‐bis(diphenylhydroxysilyl)‐2,2,4,4‐tetraphenylcyclodisilazane (B_HPTPC). By condensation polymerization of B_HPTPC with α,ω‐bis(diethylamino)‐oligo‐dimethylsiloxane, a kind of alternate copolymer constructed by 1,3‐bis(diphenylsilyl)‐2,2,4,4‐tetraphenylcyclodisilazane units with oligo‐dimethylsiloxane segments [P(BPTPC‐alt‐ODMS)] was synthesized. BcPTPC, B_HPTPC as well as P(BPTPC‐alt‐ODMS) were characterized by ²⁹Si‐NMR spectra, FT‐IR spectra, and elemental analysis. DGA study shows that P(BPTPC‐alt‐ODMS)s are thermally stable. The thermal decomposition onsets of P(BPTPC‐alt‐ODMS)s are all above 520°C. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1484–1490, 2005     

Synthesis of poly(1‐hexene)s end‐functionalized with phenols

Electrophilic alkylations of phenol/2,6‐dimethylphenol were performed with vinylidene‐terminated poly(1‐hexene)s using BF₃·OEt₂ catalyst. Vinylidene‐terminated poly(1‐hexene)s with M_n varying from 400 to 10000 were prepared by bulk polymerization of 1‐hexene at 50 to ?20 °C using Cp₂ZrCl₂/MAO catalysts. The phenol/2,6‐dimethylphenol‐terminated poly(1‐hexene)s was characterized by NMR (¹H, ¹³C), UV, IR and vapor phase osmometer (VPO). The isomer distribution (ortho, para and ortho/para) was determined by ¹³P NMR using a phosphitylating reagent, namely 2‐chloro‐1,3,2‐dioxaphospholane. The number‐average degree of functionality (F_n) >0.9 with >95% para selectivity could be achieved using low‐molecular‐weight oligomers of poly(1‐hexene)s. Copyright © 2005 Society of Chemical Industry     

Ring‐opening polymerization of trimethylenecarbonate and its copolymerization with ϵ‐caprolactone by lanthanide (II) aryloxide complexes

Lanthanide metal (II) 2,6‐di‐tert‐butylphenoxide complexes (ArO)₂Ln(THF)₃ (Ln = Sm 1 , Yb 2 ) alone have been developed to catalyze the ring‐opening polymerization of trimethylenecarbonate (TMC) and random copolymerization of TMC and ε‐caprolactone (ε‐CL) for the first time. The influence of reaction conditions, such as initiator, initiator concentration, polymerization temperature, and polymerization time, on monomer conversion, molecular weight, and molecular weight distribution of the resulting PTMC was investigated. It was found that the divalent complex 1 showed higher activity for the polymerization of TMC than complex 2 . The random structure and thermal behavior of the copolymers P(TMC‐co‐CL) have been characterized by ¹H NMR, ¹³C NMR, GPC, and DSC analysis. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007