Acceleration effects of 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene with 2‐methylimidazole‐intercalated α‐zirconium phosphate as a latent thermal initiator in the reaction of glycidyl phenyl ether and hexahydro‐4‐methylphthalic anhydride

The catalytic effects of 1,5,7‐Triazabicyclo[4.4.0]dec‐5‐ene (TBD) with 2‐methylimidazole‐intercalated α‐zirconium phosphate (α‐ZrP?2MIm) in the reaction of glycidyl phenyl ether (GPE) and hexahydro‐4‐methylphthalic anhydride (MHHPA) were investigated. The reaction did not proceed within 1 h at 60 °C. On increasing the temperature to 100 °C, the conversion reached 93% for 1 h. Without the addition of TBD, the conversion was 67% at 100 °C for 1 h. Under storage conditions at 25 °C for 7 days, the conversion of GPE was only 18%. The curing behavior of 2,2‐bis(4‐glycidyloxyphenyl)propane (DGEBA) and MHHPA in the presence of TBD with α‐ZrP?2MIm was evaluated by differential scanning calorimetry. The addition of TBD with α‐ZrP?2MIm as a latent thermal initiator, the storage stability was maintained and the reaction proceeded rapidly under heating conditions. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 2557–2561     

Application of S‐alkylsulfonium salts of aromatic sulfides as new thermal latent cationic initiators

The cationic initiation activity of derivatives of S‐methylsulfonium salts of dibenzothiophene ( 3a ), diphenyl sulfide ( 4a ), thioanisole ( 4d ), and tetrahydrothiophene ( 5 ) was evaluated in the polymerization of glycidyl phenyl ether ( 1 ). These initiators were soluble in 1 and capable of initiating the cationic polymerization of 1 on heating, with the exception of methyltetrahydrothiophenium tetrafluoroborate ( 5 ; in the range of room temperature to 160 °C). Among them, methyldiphenylsulfonium tetrafluoroborate ( 4a ) showed a moderate thermal latency that brought about the polymerization of 1 efficiently at 160 °C but not below 80 °C. S‐Alkylsulfonium salts of aromatic sulfides such as phenoxathiin ( 6a ) and thianthrene ( 6b ) also were evaluated for their activity in the cationic polymerization of 1 , from which the thermal latent behavior of these salts also was confirmed (i.e., there was no reaction at 60 °C for 3 h, but there was a high enough conversion at 140 °C). Furthermore, the catalytic activity of S‐alkylsulfonium derivatives was controllable by both the property of the substituents on the aromatic rings and the character of the alkyl groups on the sulfur atom. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 18–27, 2000     

Application of novel polymers with S‐alkylsulfonium salt moieties as alkylating agents and thermal latent cationic initiators

Sulfonium‐containing polymers prepared from dibenzothiophene and diphenyl sulfide were applied as both alkylating agents and latent initiators for the cationic polymerization of glycidyl phenyl ether. The alkylation of acetonitrile proceeded smoothly with poly(S‐n‐octyl‐2‐vinyldibenzothiophenium tetrafluoroborate) ( 4 ; 64 mol % octyldibenzothiophenium tetrafluoroborate unit) to give N‐(n‐octyl)acetamide in an excellent yield on the basis of the starting octyldibenzothiophenium tetrafluoroborate unit in 4 . The cationic polymerization of glycidyl phenyl ether was also carried out in the presence of poly(S‐methyl‐2‐vinyldibenzothiophenium tetrafluoroborate) or poly(S‐n‐octyl‐4‐vinyldiphenylsulfonium tetrafluoroborate) to confirm their moderate thermal latent activity. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3928–3933, 2001     

Synthesis of phosphate‐pendant polymers and their application to thermally latent polymeric initiators

A novel phosphate monomer, O‐p‐(methacryloyloxymethyl)benzyl O,O‐diethyl phosphate (MDP) was synthesized by the reaction of diethyl phosphorochloridate with 1,4‐benzenedimethanol, followed by the reaction with methacryloyl chloride in the presence of triethylamine. The radical polymerization of MDP and copolymerization with methyl methacrylate were carried out in the presence of 2,2′‐azobisisobutyronitrile (3 mol %) in dimethylacetamide at 60 °C for 20 h to afford phosphate‐pendant polymers. The polymerization of glycidyl phenyl ether (GPE) was carried out with the phosphate‐pendant polymer as an initiator in the presence of ZnCl₂. The polymerization did not proceed below 90 °C but rapidly proceeded above 90 °C to afford polyGPE. The phosphate‐pendant polymer served as a good thermally latent polymeric initiator. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3365–3370, 2001     

Synthesis and properties of α-substituted benzylpyridinium salts as cationic initiators

α-Methylbenzylpyridinium SbF₆ (1a) and α,α-dimethylbenzylpyridinium SbF₆ (1b) were prepared and the effect of α-methyl groups on the active species and the activity of 1a, 1b during the cationic polymerization of glycidyl phenyl ether (GPE) was evaluated. 1b was prepared by the reaction of α,α-dimethylbenzyl alcohol with pyridinium hexafluoroantimonate (2) in several solvents, and the yield depended on the dipole moment of the solvents, although it was poor for the reaction of α,α-dimethylbenzyl chloride with pyridine for the steric hindrance of the α-methyl groups followed by exchange with NaSbF₆. Both 1a and 1b acted as a latent thermal initiator during the cationic polymerization of GPE and 1b showed higher activity during cationic polymerization with the higher steric effect of the α-methyl groups than 1a. The ¹H-NMR analysis of the obtained poly GPE indicated that the active species of 1b changed from the benzyl cation to H⁺, depending on the reaction temperature, although 1a released benzyl cations as active species in the cationic polymerization of GPE. © 1996 John Wiley & Sons, Inc.     

Synthesis of phosphate end‐functional polymers and application to thermally latent polymeric initiators

Novel phosphates, O‐p‐(hydroxymethyl)benzyl O,O‐diethyl phosphate ( 1 ) and O‐(2‐bromoisobutyryloxymethyl)benzyl O,O‐diethyl phosphate ( 2 ) were synthesized by the reaction of diethyl phosphorochloridate with 1,4‐benzenedimethanol and the successive reaction with 2‐bromoisobutyryl bromide in the presence of triethylamine and submitted to the polymerization of ?‐caprolactone and methyl methacrylate as the initiators. They afforded phosphate end‐functional poly(?‐caprolactone) and poly(methyl methacrylate) with controlled molecular weights and polydispersity ratios by living ring‐opening polymerization and samarium‐induced polymerization. The polymerization of glycidyl phenyl ether (GPE) was carried out with the phosphate end‐functional polymers as the latent polymeric initiators in the presence of ZnCl₂. The polymerization of GPE did not proceed below 90 °C, but it rapidly proceeded to afford poly(GPE) above the temperature. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3832–3840, 2001     

Cationic polymerization behavior of isobutyl vinyl ether with arenesulfonates as non‐salt‐type latent thermal initiators

Substituted and unsubstituted benzenesulfonic acid cyclohexyl esters (1–7) were synthesized, and their possibility as latent thermal initiators in the cationic polymerization of isobutyl vinyl ether (IBVE) was examined to develop novel non‐salt type latent cationic initiators. Thermal decomposition of cyclohexyl p‐nitrobenzenesulfonate (2) in C₆D₆ at 80°C proceeded to exclusively afford cyclohexene as well as p‐nitrobenzenesulfonic acid. Cationic polymerization of IBVE with 1 mol % of an arenesulfonate (1–6) in bulk was carried out at 40–100°C for 12 h. No polymerization took place below 50°C, while the consumption of IBVE depending on both the polymerization temperature and the structure of the arenesulfonates was observed above 60°C. The obtained polyIBVEs showed bimodal GPC curves in several cases, revealing the intervention of two independent propagation species in the polymerization. The cationic polymerization of IBVE with cyclohexyl 2,4,6‐triisopropylbenzenesulfonate (7) at 80°C confirmed the acceleration effect of bulkiness on the polymerization rate. It was concluded that the polymerization was largely dependent on both electronic and steric factors of the aryl groups of the initiators which were directly related to the stability of the sulfonate anions. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 293–301, 1999     

A convenient synthesis of α,α′‐ homo‐ and α,α′‐hetero‐bifunctionalized poly(ε‐caprolactone)s by ring opening polymerization: The potentially valuable precursors for miktoarm star copolymers

Two new ring opening polymerization (ROP) initiators, namely, (3‐allyl‐2‐(allyloxy)phenyl)methanol and (3‐allyl‐2‐(prop‐2‐yn‐1‐yloxy)phenyl)methanol each containing two reactive functionalities viz. allyl, allyloxy and allyl, propargyloxy, respectively, were synthesized from 3‐allylsalicyaldehyde as a starting material. Well defined α‐allyl, α′‐allyloxy and α‐allyl, α′‐propargyloxy bifunctionalized poly(ε‐caprolactone)s with molecular weights in the range 4200–9500 and 3600–10,900 g/mol and molecular weight distributions in the range 1.16–1.18 and 1.15–1.16, respectively, were synthesized by ROP of ε‐caprolactone employing these initiators. The presence of α‐allyl, α′‐allyloxy and α‐allyl, α′‐propargyloxy functionalities on poly(ε‐caprolactone)s was confirmed by FT‐IR, ¹H, ¹³C NMR spectroscopy, and MALDI‐TOF analysis. The kinetic study of ROP of ε‐caprolactone with both the initiators revealed the pseudo first order kinetics with respect to ε‐caprolactone consumption and controlled behavior of polymerization reactions. The usefulness of α‐allyl, α′‐allyloxy functionalities on poly(ε‐caprolactone) was demonstrated by performing the thiol‐ene reaction with poly(ethylene glycol) thiol to obtain (mPEG)₂‐PCL miktoarm star copolymer. α‐Allyl, α′‐propargyloxy functionalities on poly(ε‐caprolactone) were utilized in orthogonal reactions i.e copper catalyzed alkyne‐azide click (CuAAC) with azido functionalized poly(N‐isopropylacrylamide) followed by thiol‐ene reaction with poly(ethylene glycol) thiol to synthesize PCL‐PNIPAAm‐mPEG miktoarm star terpolymer. The preliminary characterization of A₂B and ABC miktoarm star copolymers was carried out by ¹H NMR spectroscopy and gel permeation chromatography (GPC). © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 844–860     

Synthesis of new optically active α,α′,β‐trisubstituted‐β‐lactones as monomers for stereoregular biopolyesters

Various optically active (4R)‐alkyloxycarbonyl‐3,3‐dialkyl‐2‐oxetanones as monomers were synthesized from L‐(S)‐malic acid in six steps to prepare a new family of stereopolyesters for biomedical applications. The synthesis began with an esterification followed of a dialkylation in the aim to introduce hydrophobic groups as methyl or reactive group as allyl. Then, a saponification has permitted to obtain the corresponding diacids that reacted with appropriate alcohols to furnish different monoesters. The last and most important step was activation of hydroxyl group of monoesters with the asymmetric carbon configuration inversion according to the Mitsunobu reaction. Thus, this reaction has provided lactones from monoesters with 100% enantiomeric excess which was confirmed by ¹H NMR and by the synthesis of corresponding isotactic and semicrystalline homopolyesters. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2586–2597     

Radical‐initiated polymerization of β‐methyl‐α‐methylene‐γ‐butyrolactone

β‐Methyl‐α‐methylene‐γ‐butyrolactone (MMBL) was synthesized and then was polymerized in an N,N‐dimethylformamide (DMF) solution with 2,2‐azobisisobutyronitrile (AIBN) initiation. The homopolymer of MMBL was soluble in DMF and acetonitrile. MMBL was homopolymerized without competing depolymerization from 50 to 70 °C. The rate of polymerization (R_p) for MMBL followed the kinetic expression R_p = [AIBN]^0.54[MMBL]^1.04. The overall activation energy was calculated to be 86.9 kJ/mol, k_p/k_t^1/2 was equal to 0.050 (where k_p is the rate constant for propagation and k_t is the rate constant for termination), and the rate of initiation was 2.17 × 10^?8 mol L^?1 s^?1. The free energy of activation, the activation enthalpy, and the activation entropy were 106.0, 84.1, and 0.0658 kJ mol^?1, respectively, for homopolymerization. The initiation efficiency was approximately 1. Styrene and MMBL were copolymerized in DMF solutions at 60 °C with AIBN as the initiator. The reactivity ratios (r₁ = 0.22 and r₂ = 0.73) for this copolymerization were calculated with the Kelen–Tudos method. The general reactivity parameter Q and the polarity parameter e for MMBL were calculated to be 1.54 and 0.55, respectively. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1759–1777, 2003     

The Renaissance of α‐Methylene‐γ‐butyrolactones: New Synthetic Approaches

The amount of research activity concerning α‐methylene‐γ‐butyrolactones and α‐alkylidene‐γ‐butyrolactones has increased dramatically in recent years. This Review summarizes the structural types, biological activities, and biosynthesis of these compounds, concentrating on publications from the past 10 years. Traditional approaches to α‐methylene‐γ‐butyrolactones and α‐alkylidene‐γ‐butyrolactones are then reviewed together with novel approaches, including those from our own research group, reported more recently.     

Studies on the Mass Spectra of N‐Aryl α,β‐Unsaturated γ‐Lactams

The mass spectra of a series of N‐aryl α,β‐unsaturated γ‐lactams were studied. Besides the molecular ion, the three characteristic fragments such as [M⁺‐29], [M⁺‐55], and [M⁺‐82] were commonly found in a series of N‐Aryl α,β‐unsaturated γ‐lactams in EI/MS. Further more the mechanism for the interpretation of these fragments is also de scribed.     

Preparation of novel poly(ethylene oxide‐co‐glycidol)‐graft‐poly(ε‐caprolactone) copolymers and inclusion complexation of the grafted chains with α‐cyclodextrin

A well‐defined comblike copolymer of poly(ethylene oxide‐co‐glycidol) [(poly(EO‐co‐Gly)] as the main chain and poly(ε‐caprolactone) (PCL) as the side chain was successfully prepared by the combination of anionic polymerization and ring‐opening polymerization. The glycidol was protected by ethyl vinyl ether to form 2,3‐epoxypropyl‐1‐ethoxyethyl ether (EPEE) first, and then ethylene oxide was copolymerized with EPEE by an anionic mechanism. The EPEE segments of the copolymer were deprotected by formic acid, and the glycidol segments of the copolymers were recovered after saponification. Poly(EO‐co‐Gly) with multihydroxyls was used further to initiate the ring‐opening polymerization of ε‐caprolactone in the presence of stannous octoate. When the grafted copolymer was mixed with α‐cyclodextrin, crystalline inclusion complexes (ICs) were formed, and the intermediate and final products, poly(ethylene oxide‐co‐glycidol)‐graft‐poly(ε‐caprolactone) and ICs, were characterized with gel permeation chromatography, NMR, differential scanning calorimetry, X‐ray diffraction, and thermogravimetric analysis in detail. The obtained ICs had a channel‐type crystalline structure, and the ratio of ε‐caprolactone units to α‐cyclodextrin for the ICs was higher than 1:1. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3684–3691, 2006     

Synthesis of Phenanthrene Derivatives through the Reaction of an α,α‐Dicyanoolefin with α,β‐Unsaturated Carbonyl Compounds

Phenanthrene derivatives were prepared by reacting an α,α‐dicyanoolefin with different α,β‐unsaturated carbonyl compounds resulting from Wittig reaction of ninhydrin and phosphanylidene or condensation of barbituric acid and an aldehyde. The easy procedure, mild and metal‐catalyst free, reaction conditions, good yields, and no need for chromatographic purifications are important features of this protocol. The structures of the product of type 3 and 5 were corroborated spectroscopically (IR, ¹H‐ and ¹³C‐NMR, and EI‐MS). A plausible mechanism for this type of reaction is proposed (Scheme 1).     

Comparison of Methionine α,γ‐Lyase and Homocysteine α,γ‐Lyase for Electrochemical Determination of Homocysteine

Recently, a novel enzymatic method was developed for determination of homocysteine. This method utilizes the electrochemical hydrogen sulfide sensor along with methionine α,γ‐lyase to accomplish the fast, accurate, sensitive and selective measurements. As a continuation of this work, another enzyme, homocysteine α,γ‐lyase, was used and the parallel experiments of using both enzymes were carried out against the effect of pH, sensitivity, linearity, and interferences, in an intended comparison between these two enzymes. The excellent linearity of amperometric currents against homocysteine concentrations, high sensitivities and low detection limits for both enzymes reconfirmed that the electrochemical method is superior over other analytical means. The high enzymatic activity of methionine α,γ‐lyase surpassing homocysteine α,γ‐lyase endowed the former higher sensitivity, lower detection limit and faster response than the latter, suggesting methionine α,γ‐lyase a better candidate for homocysteine measurement by electrochemical method. The differences between these two enzymes on the trends of response time and sensitivity at different pH environments, reactivity toward several forms of homocysteine as well as on the interference from several agents were also addressed and discussed.     

Helical Poly(α,β‐unsaturated ketone) with Bulky Pendant of Binaphthyl from Anionic Polymerization of ((−)‐Menthyl (S)‐6′‐Acrylyl‐2′‐methyloxy‐1,1′‐binaphthalene‐2‐carboxylate

((?)‐Menthyl (S)‐6′‐acrylyl‐2′‐methyloxy‐1,1′‐binaphthalene‐2‐carboxylate ( 3 ) was synthesized and anionically polymerized using n‐BuLi as an initiator in toluene. The monomer 3 was levorotatory and had an [α]_D²⁵ value of ?72.4, but its corresponding polymer poly‐ 3 was dextrorotatory and showed an [α]_D²⁵ value of +162.0. Poly‐ 3 was confirmed to exist in the form of one‐handed helical structure in solution by means of comparing the specific optical rotation and the CD spectra with that of 3 and the model compounds such as (?)‐menthyl (S)‐6′‐propionyl‐2′‐methyloxy‐1,1′‐binaphthalene‐2‐carboxylate 2b and (?)‐menthyl (S)‐6′‐heptanoyl‐2′‐methyloxy‐1,1′‐binaphthalene‐2‐carboxylate 2c . This conclusion was also confirmed by the fact that the g‐value of poly‐ 3 is about 11 times of that of monomer 3 .     

Synthesis of Halogenated α,β‐Unsaturated γ‐Butyrolactone Derivatives by Triphenylphosphine‐Catalyzed Cyclization of α‐Halogeno Ketones with Dialkyl Acetylenedicarboxylates (=Dialkyl But‐2‐ynedioates)

A Ph₃P‐catalyzed cyclization of α‐halogeno ketones 2 with dialkyl acetylenedicarboxylates (=dialkyl but‐2‐ynedioates) 3 produced halogenated α,β‐unsaturated γ‐butyrolactone derivatives 4 in good yields (Scheme 1, Table). The presence of electron‐withdrawing groups such as halogen atoms at the α‐position of the ketones was necessary in this reaction. Cyclization of α‐chloro ketones resulted in higher yields than that of the corresponding α‐bromo ketones. Dihalogeno ketones similarly afforded the expected γ‐butyrolactone derivatives in high yields.     

A Mild Isomerization Reaction for β,γ‐Unsaturated Ketone to α,β‐Unsaturated Ketone

A series of β,γ‐unsaturated ketones were isomerized to their corresponding α,β‐unsaturated ketones by the introduction of DABCO in iPrOH at room temperature. The endo‐cyclic double bond (β,γ‐position) on ketone was rearranged to exo‐cyclic double bond (α,β‐position) under the reaction conditions.