首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.

Equimolar alternating copolymers of vinyl acetate and electrophilic trisubstituted ethylene monomers, ring‐substituted methyl (E)‐2‐cyano‐3‐phenyl‐2‐propenoates, RC6H4CH?C(CN)CO2CH3 (where R=4‐acetamido, 2‐cyano, 3‐cyano, 4‐cyano, 4‐diethylamino) were prepared via copolymerization in solution with radical initiation (ABCN) at 70°C. The compositions of the copolymers were calculated from nitrogen analysis and the structures were analyzed by IR, 1H‐ and 13C‐NMR. High glass transition temperatures of the copolymers in comparison with that of polyvinyl acetate indicate a decrease in chain mobility of the copolymers due to the high dipolar character of the trisubstituted ethylene monomer unit. The gravimetric analysis indicated that the decomposition of the copolymers occurs in two steps. The first step is relatively fast weight loss in 257–370°C range followed by very slow decomposition of the formed residue in 370–950°C range.  相似文献   

2.

Electrophilic trisubstituted ethylene monomers, some ring‐substituted 2‐phenyl‐1,1‐dicyanoethylenes, RC6H4CH?C(CN)2 (where R is 3‐Br, 4‐CH3O; 5‐Br, 2‐CH3O; 4‐Cl, 3‐NO2; 5‐Cl, 2‐NO2; 2‐CN, 3‐CN, 4‐CN, and 4‐(CH3)2N), were synthesized by piperidine catalyzed Knoevenagel condensation of ring‐substituted benzaldehydes and malononitrile, and characterized by CHN elemental analysis, IR, 1H‐ and 13C‐NMR. Novel copolymers of the ethylenes and vinyl acetate were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator (ABCN) at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, 1H and 13C‐NMR, GPC, DSC, and TGA. High T g of the copolymers, in comparison with that of polyvinyl acetate, indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. The gravimetric analysis indicated that the copolymers decompose in the 190–800°C range.  相似文献   

3.
A general method for the preparation of 2‐(N‐Substituted)‐2‐imidazolines and 2‐(N‐Substituted)‐1,4,5,6‐tetrahydropyrimidines is described. These heterocycles can be synthesized from their respective anilines with 2‐chloro‐2‐imidazoline or 2‐chloro‐1,4,5,6‐tetrahydropyrimidine, generated in situ from imidazolidin‐2‐one and tetrahydropyrimidin‐2(1H)‐one activated by dimethyl chlorophosphate, in good to excellent yields.  相似文献   

4.

In this article, the graft copolymerization of 4‐vinyl pyridine (4VP) onto nylon‐6 (PA6) using potassium diperiodacuprate (III) (DPC)–PA6 redox system as initiator is investigated in an alkaline medium. The structure and the properties of graft copolymer are confirmed by Fourier transfer infrared spectroscopy (IR), X‐ray diffraction and thermogravimetric analysis (TGA). The mechanism is proposed to explain the generation of radicals and the initiation. The effects of reaction variables, such as the initiator concentration, ratio of 4VP to PA6, pH, as well as reaction temperature and time are investigated. Graft copolymers with high grafting efficiency (>95%) were obtained, which indicated that the DPC–PA6 redox system was an efficient initiator for this graft copolymerization. The quaternized PA6‐g‐P4VP (QPAVP) is proven to be an excellent adsorbent to heavy metal ions.  相似文献   

5.
(E)‐ and (Z)‐5‐(bromomethylene)furan‐2(5H)‐one have been prepared starting from the commercially available adduct between furan and maleic anhydride. A bromodecarboxylation reaction is a key step in the synthesis. The reaction gives the (E)‐ or (Z)‐5‐(bromomethylene)furan‐2(5H)‐one as the major product, dependent on the method used in the bromodecarboxylation.  相似文献   

6.

Electrophilic trisubstituted ethylene monomers, alkyl ring‐substituted 2‐phenyl‐1,1‐dicyanoethylenes, RC6H4CH?C(CN)2 (where R is 2‐methyl, 3‐methyl,4‐methyl, 4‐ethyl, 4‐isopropyl, 4‐butyl, and 4‐t‐butyl), were synthesized by piperidine catalyzed Knoevenagel condensation of ring‐substituted benzaldehydes and malononitrile, and characterized by CHN elemental analysis, IR, 1H‐ and 13C‐NMR. Novel copolymers of the ethylenes and vinyl acetate were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator (ABCN) at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, 1H and 13C‐NMR, GPC, DSC, and TGA. High Tg of the copolymers, in comparison with that of polyvinyl acetate, indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. The gravimetric analysis indicated that the copolymers decompose in the 190–700°C range.  相似文献   

7.
Electrophilic trisubstituted ethylene monomers, some ring‐substituted 2‐phenyl‐1,1‐dicyanoethylenes, RC6H4CH?C(CN)2 (where R is 3‐C6H5O, 4‐C6H5O, 3‐C6H5CH2O, 4‐C6H5CH2O, 4‐CH3CO2, 4‐CH3CONH, 4‐(C2H5)2N) were synthesized by piperidine catalyzed Knoevenagel condensation of ring‐substituted benzaldehydes and malononitrile, and characterized by CHN elemental analysis, IR, 1H‐ and 13C‐NMR. Novel copolymers of the ethylenes and vinyl acetate were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator (ABCN) at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, 1H and 13C‐NMR, GPC, DSC, and TGA. High T g of the copolymers, in comparison with that of polyvinyl acetate, indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. The gravimetric analysis indicated that the copolymers decompose in the 190–700°C range.  相似文献   

8.
Electrophilic trisubstituted ethylene monomers, halogen ring‐disubstituted 2‐phenyl‐1,1‐dicyanoethylenes, RC6H3CH?C(CN)2 (where R is 2,3‐diCl, 2,4‐diCl, 2,6‐diCl, 3,4‐diCl, 3,5‐diCl, 2,4‐diF, 2,5‐diF, 2,6‐diF, 3,4‐diF, 3,5‐diF, 2‐Cl, 6‐F) were synthesized by piperidine catalyzed Knoevenagel condensation of ring‐substituted benzaldehydes and malononitrile, and characterized by CHN elemental analysis, IR, 1H‐and 13C‐NMR. Novel copolymers of the ethylenes and vinyl acetate were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator (ABCN) at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, 1H and 13C‐NMR, GPC, DSC, and TGA. High Tg of the copolymers, in comparison with that of polyvinyl acetate, indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. The gravimetric analysis indicated that the copolymers decompose in the 220–800°C range.  相似文献   

9.
Enantiomerically pure (S)‐RO363 was synthesized by using (R,R) Salen Co(III) complex for the resolution of terminal epoxide. The hydrolytic kinetic resolution process was carried out at room temperature in excellent enantioselectivity. The method can be applied for large‐scale preparation of (S) RO363.  相似文献   

10.
Vinyl ethers were prepared with good yields in a one‐pot, two‐step transformation by O‐alkylation reaction of phenyl 2‐hydroxyalkyl selenides with primary or secondary organic halides followed by oxidation elimination with 30% hydrogen peroxide.  相似文献   

11.

Electrophilic trisubstituted ethylene monomers, alkyl and alkoxy ring‐disubstituted 2‐phenyl‐1,1‐dicyanoethylenes, RC6H3CH?C(CN)2 (where R is 2,4‐(CH3)2, 2,5‐(CH3)2, 2,3‐(CH3O)2, 2,4‐(CH3O)2, 2,5‐(CH3O)2, 3,4‐(CH3O)2, 3‐C2H5O‐4‐CH3O, 4‐CH3O‐3‐CH3), were synthesized by piperidine catalyzed Knoevenagel condensation of ring‐disubstituted benzaldehydes and malononitrile, and characterized by CHN elemental analysis, IR, 1H‐ and 13C‐NMR. Novel copolymers of the ethylenes and vinyl acetate were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator (ABCN) at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, 1H and 13C‐NMR, GPC, DSC, and TGA. High T g of the copolymers, in comparison with that of polyvinyl acetate, indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. The gravimetric analysis indicated that the copolymers decompose in the 190–700°C range.  相似文献   

12.
The preparation of the title compound has been revisited and improved. Starting from inexpensive cuminonitrile, 4‐(2‐hydroxy‐2‐methyl)‐ethyl‐benzylamine is obtained in a scalable two‐step process with an overall yield of 55%.  相似文献   

13.
A. K. El‐Ziaty 《合成通讯》2013,43(22):4043-4057
(E) 2‐Cyano‐3‐(3′,4′‐dimethoxyphenyl)‐2‐propenoyl chloride (2) underwent mono‐ and binucleophilic displacement with hydrazines, amines, ureas, and aromatic bifunction amines to give new 2‐propenoyl hydrazines (4 and 5), 2‐propenoylamide (6, 7, 12, 13, 15, 17, 19, 21), and 2‐thiol propenoate (2224). Some of these products were cyclized to give novel heterocyclic derivatives (8, 10, 14, 16, and 20).  相似文献   

14.
Different substituted 2‐chloromethylpyridyl derivatives (6ad) were oxidized with mCPBA to give the respective 2‐chloromethylpyridine‐N‐oxide derivatives (7ad) at low temperature, which on condensation with 2‐mercapto‐1H‐benzimidazole (8ac) in the presence of aprotic solvents give the 2‐[[(pyridin‐2‐yl‐1‐oxide)methyl]sulfanyl]‐1H‐benzimidazole (9ad) in good yield. Finally, 9ad oxidized with mCPBA in chlorinated solvent gives a mixture of 2‐[[(pyridin‐2‐yl‐1‐oxide)methyl]sulfonyl]‐1H‐benzimidazole (3ad, 10%) and 2‐[[(pyridin‐2‐yl‐1‐oxide) methyl]sulfinyl]‐1H‐benzimidazole (4ad, 90%) derivatives.  相似文献   

15.
16.
《Analytical letters》2012,45(6):1075-1086
Abstract

A novel plasticized membrane sensor for Ho(III) ions based on N‐(1‐thien‐2‐ylmethylene)‐1,3‐benzothiazol‐2‐amine (TBA) as a neutral carrier was prepared. The best performance was obtained with a membrane composition of 31% PVC, 61% benzyle acetate, 2% sodium tetra phenyl borate and 6% carrier. The electrode exhibits a Nernstian response for Ho(III) ions over a particular concentration range (1.0×10?5?1.0×10?2 M) with a slope of 19.7±0.2 mV decade?1. The limit of the detection is 7.0×10?6 M. The sensor has a response time of <15 s and a useful working pH range of 4.0–9.5. The proposed sensor discriminates relatively well towards Ho(III) ions with regard to common alkali, alkaline earth, and specially lanthanide ions. It was successfully applied as an indicator electrode in a potentiometric titration of Ho(III) ions with EDTA. It was also applied in determination of fluoride ions in a mouth wash preparation. The proposed sensor was applied for the determination of Ho(III) ion concentration in binary mixtures.  相似文献   

17.
《合成通讯》2013,43(12):1641-1647
Abstract

Interaction of 2‐imino‐2H‐pyrano[2,3‐c]pyridin‐3‐carboxamide with substituted 2‐aminobenzophenones proceeds via recyclization mechanism leading to substituted 3‐(4‐arylquinazolyn‐2‐yl)‐2H‐pyrano[2,3‐c]pyridin‐2‐ones. Their reaction with acetic anhydride affords the O‐acylation products.  相似文献   

18.
Shinsei Sayama 《合成通讯》2013,43(18):3067-3075
2‐Alkoxy‐1,3,4‐triphenylfurans were oxidized to 3‐alkoxy‐2,4,5‐triphenyl‐ 2‐butene‐1,4‐diones with 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ) in t‐BuOH. In contrast, various 3‐alkoxy‐2,4,5‐triphenylfurans were directly converted to 2‐hydroxy‐3(2H)‐furanone with phenyltrimethylammonium tribromide (PTAB) in t‐BuOH. The oxidative ring opening of 3‐alkoxy‐2,5‐diphenylfurans to cis‐2‐hydroxy‐2‐butene‐1,4‐dione was also accomplished with PTAB in t‐BuOH under the same reaction conditions.  相似文献   

19.

The new acrylamide monomer, N‐(4‐Bromophenyl)‐2‐methacrylamide (BrPMAAm) has been synthesized by reacting 4‐Bromoaniline with methacryloyl chloride in the presence of triethylamine(NR3) at 0–5°C. The radical‐initiated copolymerization of (BrPMAAm), with 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid (AMPS) has been carried out in dimethylformamide (DMF) solution at 70±1°C using 2,2′‐azobisisobutyronitrile (AIBN) as an initiator with different monomer‐to‐monomer ratios in the feed. The copolymers were characterized by FTIR, 1H‐ and 13C‐NMR spectroscopy. The copolymer composition was evaluated by nitrogen content (N for AMPS‐units) in polymers led to the determination of reactivity ratios. The monomer reactivity ratios for BrPMAAm (M1)‐AMPS (M2) pair were computed using the Fineman‐Ross (F‐R), Kelen‐Tüdös (KT) and Extended Kelen‐Tüdös (EKT) methods. These parameters were also estimated using a non‐linear computational fitting procedure, known as reactivity ratios error in variable model (RREVM). The mean sequence lengths determination indicated that the copolymer was statistically in nature. By TGA and DSC analyses, the thermal properties of the polymers have been studied. The antimicrobial effects of polymers were also tested on various bacteria, and yeast.  相似文献   

20.
The reaction of dialkyl acetylenedicarboxylates with alkyl 2‐[3‐oxo‐3,4‐dihydro‐2(1H)‐quinoxadinylidene]ethanoates in the presence of triphenylphosphine leads to trialkyl (E)‐3‐{3‐oxo‐2‐3,4‐dihydro‐2‐(1H)‐quinoxalinylidene}‐prop‐1‐ene‐1,2,3‐tricarboxylates in good yields.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号