排序方式: 共有27条查询结果,搜索用时 15 毫秒
1.
The electronic effect on the regioselectivity in the alkynylation of phenyloxiranes was investigated using three kinds of metal acetylides. BF3 mediated lithium acetylide provided either the α- or β-alkynylated products by controlling the effect of the para-substituents of the phenyloxiranes. LiClO4 mediated lithium acetylide and titanium acetylide, on the other hand, afforded predominantly the β- and α-products, respectively. 相似文献
2.
Ali Reza Kiasat Foad Kazemi Mehdi Fallah Mehr Jardi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(9):1841-1844
A simple and efficient method for the conversion of various oxiranes to the corresponding thiiranes using thiourea under solvent free conditions is described. 相似文献
3.
Liqiang Wu Limin Yang Lizhen Fang Chunguang Yang Fulin Yan 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):2159-2164
A mild, simple, and efficient method for the synthesis of thiiranes from epoxides using a catalytic amount of silica chloride under solvent-free conditions has been developed. Experimental simplicity, simple work-up procedure, and solvent-free reaction conditions are important features of the present protocol. 相似文献
4.
Foad Kazemi Ali Reza Kiasat 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6):1333-1337
Epoxids are efficiently converted to the corresponding thiiranes by ammonium thiocyanate (NH 4 SCN) in the presence of catalytic amounts of oxalic acid with excellent isolated yields under mild and nonaqueous reaction conditions. This conversion performed under both conventional heating and microwave conditions. Distinct rate enhancement is observed under microwave irradiation. 相似文献
5.
Takuma Tsubusaki 《Tetrahedron》2009,65(18):3745-9961
The manganese(III)-based aerobic oxidation of arylacetylenes with 2,4-pentanedione at ambient temperature unexpectedly gave the 1,2-dioxolane derivatives in moderate yields together with a small amount of the oxiranes. The 1,2-dioxolanes underwent silica gel-assisted contraction to quantitatively give the oxiranes. The reaction pathway for the formation of the 1,2-dioxolanes and the by-product was discussed. 相似文献
6.
An efficient synthesis of alkyl bis(dimethylamino)methylenecarbamodithioates via a one-pot reaction between 1,1,3,3- tetramethylguanidine,carbon disulfide and substituted oxiranes,in good yields,is described. 相似文献
7.
亲水性含环氧基磁性聚合物微球的制备与性能表征 总被引:9,自引:0,他引:9
选择甲酰胺作磁性Fe3O4微晶的分散剂,通过设计反相悬浮聚合体系,合成了粒径分布窄、球状亲水性含环氧基磁性聚合物(MGM).利用扫描电子显微镜(SEM)、红外光谱(FT-IR)、X射线粉末衍射仪(XRD)、振动样品磁强计(VSM)和低温N2吸附以及化学分析方法对聚合物进行了性能表征.结果表明,合成的MGM呈球形,且粒度分布较窄,粒径为0.13~0.28 mm的粒子占91%;甲酰胺分散Fe3O4,微晶表面的亲水性进一步增强,单体甲基丙烯酸缩水甘油酯和N,N′-亚甲基双丙烯酰胺交联共聚生成的胶粒能够包埋Fe3O4微晶形成胶核,胶核聚集形成均匀、稳定的MGM微球.MGM中Fe3O4含量为6.17%时,比饱和磁化强度σs达6.5 emu/g;其比表面积、平均孔径和孔容分别为117.6 m2/g,15.6 nm和0.46 cm3/g,表面环氧基团含量为0.53 mmol/g.MGM借助自身的活性环氧基团在十分温和的条件下共价偶联青霉素酰化酶(penicillin G acylase EC 3.5.1.11,简称PGA),制备的固定化酶在37℃下催化水解青霉素G钾生成6-氨基青霉烷酸(6-APA)的表观活性达502IU/g,并且在使用过程中没有出现磁聚集现象. 相似文献
8.
Symmetric and non-symmetric 2,6-disubstituted morpholines were synthesized through regioselective nucleophilic ring opening of oxiranes with tosylamide under solid-liquid phase transfer catalysis (SL-PTC) conditions followed by cyclization of the tosylamido diols thus obtained and final deprotection of the corresponding N-tosyl morpholines. The morpholines prepared are interesting building blocks in the synthesis of pharmaceuticals and agrochemicals. 相似文献
9.
The nature of the bonding in the three-membered ring molecules cyclopropane, thiirane, oxirane, and aziridine has been investigated
throughab initio FSGO calculations. The direct correspondence between floating spherical Gaussian orbitals and specific chemical bonds has
been used to study the degree of “bond bending”. In accord with chemical intuition, it is demonstrated that the C-C ring bond
becomes progressively more bent as the bond length is reduced. C-C bonds are found to be more flexible than C-N (O, S) bonds.
The sizes and locations of carbon-heteroatom bond orbitals and C-H bond orbitals are also discussed. 相似文献
10.
Zhen Wang Jian WenQing-Wei Bi Xiao-Qi XuZhu-Qing Shen Xiao-Xiao LiZili Chen 《Tetrahedron letters》2014
A new method was developed to synthesize oxirane products from the reaction of diazocarbonyl substrates with aryl aldehydes by using Ag(I) N-heterocyclic carbene complex as the catalyst. A combination of N-heterocyclic carbene silver complex (IPrAgCl) with another silver salt (AgOTf) generated the catalytic active IPr-Ag+ intermediate, which then catalyzed the epoxidation reaction. 相似文献