Rapid synthesis of biodegradable poly(epsilon-caprolactone-co-p-dioxanone) random copolymers under microwave irradiation

<正>Biodegradable poly(epsilon-caprolactone-co-p-dioxanone)(PCDO) random copolymers have been synthesized by ring-opening polymerization of epsilon-caprolactone(CL) and p-dioxanone(PDO) under microwave irradiation.The effects of irradiation time and different CL/PDO molar feed ratios on the microwave-assisted ring-opening polymerization(MROP) of PCDO have been discussed.The resultant products were characterized by ~1H NMR,GPC and DSC.It was found that the polymerization was completed within 20 min at 140℃.In the presence of different CL/PDO molar feed ratios,the conversions of both monomers were kept relatively constant.DSC sturdy suggested that with increasing the content of PDO in the copolymers,the crystalline degree of the copolymers decreased gradually.It is believed to be a promising biodegradable material.     

Different crystallinity of poly(d,l-lactide-co-p-dioxanone) copolymers acquired by control of chain microstructure

Poly(d,l-lactide-co-p-dioxanone)(P(LA-co-PDO)) copolymers with different chain microstructures were synthesized by one-step or two-step bulk ring-opening polymerizations of d,l-lactide(LA) and p-dioxanone(PDO) monomers using stannous octoate [Sn(Oct)_2]/n-dodecanol as the initiating system.The average sequence lengths of the lactidyl(L_(LA)) and dioxanyl(L_(PDO)) units were calculated from the ~1H NMR spectra.It was found that both L_(LA) and L_(PDO) values from the two-step syntheses were significantly ...     

SYNTHESIS AND POLYMERIZATION OF 2-OXO-3-METHYLENE-1,4-DIOXANES

A new kind of monomers was successfully synthesized by the reaction between 2-chloro methyl cycloketal and trimethylsilyl cyanide, followed by ring closure and dehaiogenation. Polymerizations of the monomers were carried out in benzene solution at 80℃with benzoyl peroxide as initiator. Both the structures of monomers and polymers were characterized by IR, ~1H NMR, ~(13)C NMR and elemental analysis.     

FREE RADICAL RING OPENING POLYMERIZATION OF CYCLIC ACRYLATES

Cyclic acrylates, 2,2- dimethyl-5-methylene-1 , 3-dioxolan-4 -one and 2- phenyl-5-methylene-1,3-dioxolan-4-one, were synthesized successfully. The monomers were characterized by ~1H NMR, ~(13)C NMR, IR and elemental analysis or HRMS. Polymerization of the monomers were carried out at 120℃with di-t-butylperoxide as initiator. The polymers were studied by ~1H NMR, ~(13)C NMR, UV and hydrolysis. The molecular weights of the resulting polymers were estimated by viscosity measurement and the extent of ring opening was estimated also by ~1H NMR and hydrolysis of the polymers and further confirmed by UV spectra.     

STUDIES ON THE POLYSILANE CONSISTING CYCLODISILAZANE UNITS IN THE MAIN CHAIN

Since the reactivity of Me_2SiCl_2(Ⅰ) and ■(Ⅱ) are very different. it is difficult to cocondensate the above two monomers with sodium in general Wurtz reaction. We have proposed a modified method to prepare copolymer containing permethylpolysilane segments and cyclodisilazane units by reaction of (Ⅱ)with Na at first, then adding (Ⅰ) into the mixture to proceed with further reaction.The obtained copolysilanes are pale yellow elastic substance and soluble in common solvents. The amounts of N in the copolymers are influenced by the operating conditions of the synthetic method. The resultant products were characterized by IR, UV, NMR, and elementary analysis. The highest molecular weight determined by gel permeation chromatography is 60000.     

Syntheses, Confirmation and Properties of Porphyrin Oligomers with Alkoxyl Linkages

A new and general synthesis of a porphyrinK( Ⅰ ) with two alkoxyl linkages is described. The synthesis involves the reaction of dibromopropane with phenolic porphyrin to form ω-bromopropylporphyrin ether. This ether then reacts with another phenolic porphyrin to give the target compounds. The properties of the target compounds were confirmed by means of elemental analysis, UV-Vis, IR, and ^1H NMR spectroscopies. Their spectral properties and thermal stability were also studied.     

Synthesis, Structural Characterization of Ferrocenyl Iminophosphines and Amidophosphines as Well as Their Application in the Suzuki Reaction

Ferrocenyliminophosphine 1 and 1,1'-bisferrocenyliminophosphine 2 were easily prepared from the condensation of formylferrocene or 1,1'-diformylferrocene with 2-(diphenylphosphino)aniline.The following reduction of imine group by LiAlH4 led to the formation of the corresponding ferrocenyl amidophosphines 3 and 4.The new ligands 2-4 were well characterized by IR,1H NMR,31P NMR spectra,elemental analysis,and ESI-MS.The catalytic activity of all the ligands with palladium compounds in the Suzuki reaction was evaluated.Ligand 1,in combination with Pd(OAc)2,was found to be the most effective for the Suzuki reaction of aryl bromides with phenylboronic acid.Typically,the use of 0.1%(molar fraction)of Pd(OAc)2/ligand 1 in the presence of two equivalents of K2CO3 as base in toluene at 110 ℃ provided good to excellent yields of the coupled products.     

Synthesis,Crystal Structure and Anion Recognition Property of a Flexible Urea-functionalized Receptor

A flexible urea-functionalized receptor bearing two p-nitrobenzene units was designed and synthesized from the reaction of precursors 4-nitrophenyl isocyanate and 1,2-bis(2?-aminophenoxy) benzene. The receptor was characterized by ~1 H NMR, MS, FTIR and elemental analysis, and the crystal structure of the receptor was determined by X-ray diffraction analysis. The crystal belongs to the orthorhombic system, space group Pca21 with a = 12.740(2), b =14.133(3), c = 15.842(3) ?, V = 2852.4(9) ?~3, Z = 4, M_r = 620.57, D_c = 1.445 g/cm~3, F(000) = 1288,= 0.0585 and wR = 0.1032 for 3177 observed reflections(Ⅰ 2σ(Ⅰ)), and R = 0.1304 and wR =for all data. The results show that the receptor displays selective recognition ability for H_2PO_4~– in DMSO with a series of anions using UV-Vis absorption spectra technique. Furthermore, the coordination reaction of the receptor with H_2PO_4~– was investigated via UV-Vis spectra and ~1 H NMR.The stoichiometric ratio and the association constant(Ka) of the coordination reaction were obtained as well.     

Partial Oxidation of Methane to Syngas Using LatticeOxygen of La_(1-x)Sr_xFeO_3 Perovskite OxideCatalysts Instead of Molecular Oxygen

Catalytic partial oxidation of methane to syngas using the lattice oxygen of La1-xSrxFeO3 perovskite oxide catalysts in place of molecular oxygen was studied. La1-xSrxFeO3 (x=0, 0.1, 0.2, 0.5) perovskite oxides were prepared by the "auto-combustion method". XRD analysis showed that all La1-xSrxFeO3 samples have a single-phase perovskite-type oxide. The redox properties of the catalysts were investigated by temperature programmed reduction with hydrogen (H2-TPR). Reducibility of the catalysts increase with the increasing of the Sr2+ content. The oxygen species of the catalysts and their reaction with CH4 were studied by the temperature programmed surface reaction (CH4-TPSR). In the absence of gas phase oxygen, there exist two kinds of oxygen species on the catalysts. One kind of the oxygen species with strong oxidative ability is produced first, which can oxidize CH4 completely to CO2 and H2O. Then, the second oxygen species with weak oxidative ability is formed, which can oxidize CH4 partially to CO and     

A novel efficient synthetic method for 2,2′,3,3′-biphenyltetracarboxylic dianhydride

A novel approach to the synthesis of 2,2′,3,3′-biphenyltetracarboxylic dianhydride is described.The target compound was prepared by a nickel-catalyzed coupling reaction of dimethy 3-chlorophthalate(3-DMCP) for 4 h at 70-80℃,followed by subsequent hydrolysis of tetra-ester in acid solution and dehydration of tetra-acid,with overall yield of 68%.The structures of the products were characterized by IR,~1H NMR and ~(13)C NMR respectively.     

Synthesis,UV-curing Behavior and Surface Properties of New Fluorine-containing Aromatic Oxetane Monomers

In this paper,we combined high-end cationic UV-curable material with fluorinated chain obtaining a series of new fluorine-containing aromatic oxetane monomers via a mild nucleophilic substitution reaction.The structures and properties of monomers were characterized using 1H-NMR,19F-NMR,dynamic viscosity tests and differential scanning calorimetry (DSC).It was determined that all of the fluorinated monomers obtained had much lower viscosity and higher thermostability after the introduction of hexafluorobenzene.Then,UV-curable coatings were prepared using four fluorine-containing aromatic oxetane monomers (FOX1-4);the UV-curing kinetics,with three kinds of initiators,and properties of the cured films were evaluated using real-time Fourier transform infrared (FTIR) spectroscopy,water and diiodomethane contact angle tests,surface energy calculations and scanning electron microscopy (SEM).The FTIR spectroscopy results showed that the coatings possessed excellent conversion rate (＞ 99％ with liquid initiator PAG-201 in 150 s),and as the fluorine content increased,the monomers exhibited decreased mobility with the increasing viscosity and worse solubility with fluorinated monomers,resulting in a lower conversion rate.Moreover,the coatings possessed favorable hydrophobic and oleophobic properties and low surface energies owing to the fluoride chains floating to the membrane-air interface,which was also confirmed by discrete concave structures in SEM images.These new kinds of monomers can replace traditional fluorinated cationic monomers applied to the fingerprint resistant,fouling resistant,scratch resistant and anti-aging coatings,adhesives or printing ink materials.     

ONE''''POT REACTION OF TRIVALENTPHOSPHORUS COMPOUNDS (Ⅰ)——A NOVEL ONE-STEP REACTION OF ADDITION,REDUCTION AND CYCLIZATION OF SUBSTITUTED β-NITROSTYRENE WITH O,O-DIALKYL PHOSPHITES

In this paper the reaction of substituted β-nitrostyrene with O,O-dialkyl phosphite under cocatalysis of trimethylsilyl chloride (TMS-C1) and triethylamine (or other acidbinding agent) has been first studied and the new cyclization reaction leading to the formation of product Ⅱ, as a new class of derivatives of 1-hydroxyindoles, difficultly accessible or inaccessible with usual methods has been observed. In the related reaction it is surprising that when the Arbuzov rearrangement occurs under mild conditions, the addition, reduction and cyclization as a one-pot reaction take place simultaneously with the formation of products Ⅰ, Ⅱ, Ⅲ. By controlling the reaction conditions the products were formed almost in specificity, and thus the most interesting cyclic products Ⅱ_(a-h) containing phosphorus-carbon bond were obtained. Their structures were confirmed by elemental analysis, IR, ~1H or ~(31)p NMR and MS spectra. The crystal structure of representative compound Ⅱ_h was determined by X-ray diffract     

Synthesis and crystal structure of polyaryl substituted diene derivatives based on the reduction of diphenylacetylene with lithium naphthalenide

The reduction of diphenylacetylene with lithium naphthalenide produced two kinds of intermediates,1 or 2,depending on the ratio of diphenylacetylene to lithium naphthalenide.A series of polyaryl substituted ethylene/diene derivatives were synthesized by reaction of electrophⅡes with the corresponding intermediates produced in situ.All new compounds were fully characterized,and their single crystal structures were determined.     

Chemical inequivalence behavior of the protons attached to the same carbon in ethylene-propylene copolymer（EPC）

Six ethylene-propylene copolymer samples with different structural parameters were analyzed by ^1H NMR,^13C NMR and ^1H-^13C COSY in this paper.With the aid of the ^1H-^13C COSY spectra of ethylene-propylene copolymer,the chemical inequivalence behavior of the protons attached to the same carbon in the ethylene-propylene copolymer could be observed. Four basic types of chemical bonds were divided,and two kinds of main conformations were proposed to explain this phenomenon. Based on the calculation of conformation distribution,it can be proved that the explanation of this phenomenon was reasonable.     

A New Solution—phase Parallel Synthesis of 2—Alkyamino—3—aryl—5—phenylmethylene—3,5—dihydro—4H—imidazol—4—ones

Thirteen new 2-alkylaminoimidazolones(4) wre rapidly synthesized by a new solution-phase parallel synthetic method,which includes aza-Wittig reaction of iminophosphorane(1) with aromatic isocyanate to give carbodi-imide(2) and subsequent reaction of 2 with various aliphatic primary amine in a parallel fashion.The products were confirmed by ^1H NMR,MS,IR and X-ray crystallographic analysis.The unusual selectivity of the cyclization was probably due to the deometry of the guanidine intermediate.     

Synthesis of 1,3,4-Diazaphospholidin-2-One-4-Oxides by Mannich-Type Reaction and Structure Analysis of Products

The Mannich-type reaction of phenylurea with phenyl dichlorophosphine and aldehydes (or ketones) is studied in this paper. It is found that straight chain and cyclic products are obtained respectively, when different solvents are used.The ways of cyclization are affected by the substituents of ketones.There exist two geometrical isomers for each of the title compounds which are proved by their ~1H NMR and ~(31)P NMR spectra, and the configuration of each isomer is confirmed by means of X-ray diffraction and ~1H NMR spectra. Besides, it is found that the five-membered phosphorus heterocycle is of a plane conformation with a dπ-pπ bond between P and N.     

Acyclic diene metathesis polymerization of tailor-made monomers towards sequence-regulated vinyl copolymers

 Acyclic diene metathesis polymerization (ADMET) enables convenient transfer of sequential information of the designed monomers to the corresponding sequence-regulated copolymers. In this study, two structurally symmetric monomers, M1 and M2, were synthesized via atom transfer radical addition (ATRA) of diethyl meso-2,5-dibromohexanedioate with 1,5-hexadiene and 1,7-octadiene, respectively. Thus, sequenced segment of VB-EA-EA-VB (VB and EA represent vinyl bromide and ethyl acrylate, respectively) was incorporated into the ADMET diene monomers. ADMET polymerization of these two monomers with Grubbs first generation catalyst (Grubbs-I) was performed in CH₂Cl₂ at 40℃ for 5 days under nitrogen purge. Effects of catalyst amount, monomer concentration and methanol precipitation on the M_p and PDI of polymers were investigated by GPC, and the structures of the formed polymers were characterized by NMR. Our results indicate that using 3.0 mol% of Grubbs-I to monomer can afford polymers with high M_p. Moreover, selective precipitation in methanol enables complete removal of low molecular weight components from the crude products. Meanwhile, M2 exhibits higher ADMET polymerization reactivity than M1 due to its capability of suppressing negative neighboring group effect.     

Suzuki reaction of bromoallenes with arylboronic acids using an air-stable palladium complex Pd(Ph_2PCH_2CO_2)_2 as a precatalyst

<正>Suzuki reaction of bromoallenes with arylboronic acids was successfully performed by using an air-stable hemilabile P-O coordinated cyclopalladated complex Pd(Ph_2PCH_2CO_2)_2 as a precatalyst,and the corresponding coupling products were obtained in satisfactory to excellent yields.All products are unknown compounds which were characterized by ~1H NMR,~(13)C NMR,IR,and HRMS.     

Chiral separation by （S）-naproxen imprinted monolithic column with mixed functional monomers

Molecularly imprinted polymers (MIPs), using (S)-naproxen as template and the combination of butyl methacrylate (BMA) and MAA (1:1 molar ratio) as functional monomers were synthesized by an in situ polymerization reaction. The rendered monolithic column was evaluated in HPLC mode. The result showed that the monolithic MIPs with the combination of two monomers produced better chiral resolution of rac-naproxen (Rs=1.55) and column efficiencies of imprinted molecules (N=2860 plates/m)than that with pure MAA.     

Synthesis of 4″-benzyloxyimino-4″-deoxyavermectin Bla derivatives

Six new 4″-benzyloxyimino-4″-deoxyavermectin Bla derivatives were synthesized from avermectin Bla by the selective protection of C-5-hydroxy group,oxidation of C-4″-hydroxy group,and deprotection followed by reaction with O-substituted hydroxylamine hydrochlorides.Their structures were confirmed by IR,~1H NMR,~(13)C NMR and MS.Insecticidal activities of the derivatives against Phopalosiphum pseudobrassicae,Spodoptera exigua and Pluteua xylosteua were evaluated.