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1.
《Tetrahedron》1988,44(12):3645-3652
The bromination of 3-bromo-6,7-benzobicyclo [3.2.1] octa-2,6-diene at -50°C has been found to give only one product, the tribromide 8 produced via Wagner-Meerwein rearrangement with accompanying aryl migration. The bromination at 0°C produced nonrearranged tribromides beside the rearranged tribromide and the ketone 12. The structures of the products were determined by 1H-, 13C-NMR data and single X-ray structural analysis. The addition mechanism is discussed in terms of exo- and endo-attack. 相似文献
2.
The electrophilic addition of Br to ‘endo‐benzocyclobutanorbornene' 5 at −50° led in high yield to the formation of the rearranged dibromides 6 and 7 . However, high‐temperature bromination of 5 in decalin at 150° gave exclusively nonrearranged product 8 in 98% yield. From the elimination of nonrearranged product 8 , ‘endo‐bromobenzocyclobutanorbornene' 9 and ‘endo‐benzocyclobutanorbornene' 5 were obtained. Similarly, bromination of monobromide 9 at 77° yielded the nonrearranged tribromide 12 in quantitative yield. The dehydrobromination of 12 provided the ‘endo 11,12‐dibromobenzocyclobutanorbornene' 3 in high yield, which is a synthon for the trimerization reactions. 相似文献
3.
Sylvain Rault Michel Cugnon De Svricourt Paulette Touzot Max Robba Hussein El-Kashef 《Journal of heterocyclic chemistry》1980,17(7):1399-1404
The nitration and bromination of both [1]benzothieno[3,2-d]pyrimidin-4(3H)one ( 1 ) and [1]benzothieno-[3,2-d]pyrimidine ( 2 ) has been studied. Nitration of 1 at ?30° afforded a mixture of 8-nitro[1]benzothieno-[3,2-d]pyrimidin-4(3H)one ( 7b ) (70%) and 6-nitro[1]benzothieno[3,2-d]pyrimidin-4(3H)one ( 7a ) (30%). However when the nitration was carried out at 60°, the 6,8-dinitro derivative 8 was the result. On the contrary, the nitration of 2 at ?30° gave a single nitration product, 8-nitro[1]benzothieno[3,2-d]pyrimidine ( 11 ). The bromination of both 1 and 2 gave the corresponding 8-bromo derivatives 10 and 13 . Assignment of structure of all the products was based on ir and nmr spectral studies and on unequivocal syntheses. 相似文献
4.
The electrochemical bromination of 4-methoxy toluene by two-phase electrolysis yields 3-bromo 4-methoxy toluene at first, which subsequently undergoes side-chain bromination to give 3-bromo 4-methoxy benzyl bromide as a final product in 86% yield. The two-phase electrolysis consists of 25–50% NaBr as aqueous electrolyte and CHCl3 containing aromatic compound as organic phase. The reaction temperature is maintained at 10–25 °C. The probable orientation of bromine atom in an alkyl aromatic compound (nuclear versus side chain) is explained from the experimental result. 相似文献
5.
The sorption of bromine from bromine water on cis-1,4-polyisoprene film and the initial stages of bromination are studied at concentrations of 0.002–0.1 mol/l and temperatures of 15–35°C. The diffusion coefficient of bromine into natural rubber (NR) is 1.3–2.0 × 10?6 cm2/sec for the total sorption and 5–13 × 10?7 cm2/sec for the irreversible sorption. The partition coefficient of bromine between water and rubber increased from 17.3 at 15°C to 37.1 l/kg at 35°C. The chemical potential, enthalpy and change in entropy of partition are, at 25°C, respectively: ?1.9 kcal/mol, 6.6 kcal/mol and 28.4 cal/mol. K. The irreversible sorption is due to a charge-transfer complex between bromine molecules and double bonds of the rubber. The complex is the first stage of the addition reaction, which becomes noticeable at concentrations above 0.012 mol/l. With increasing bromine concentration the concentration of the complex decreases and the added bromine increases. The charge transfer complex appears to change the conformation of the cis-NR chains so that the bromine addition occurs in the trans-conformation, as shown by FT–IR spectra. The bromination is accompanied by a marked crystallization effect as illustrated by thermal analysis and WAXS measurements. 相似文献
6.
The photobromination of 5‐methoxyindane and 5‐methoxyindanone was studied at both high and low temperatures. 1,2,3‐Tribromo‐6‐methoxyindene was easily synthesized by photolytic bromination of 5‐methoxyindane at low temperature. 1,1,2,3‐Tetrabromo‐6‐methoxyindene was obtained from the photobromination of 5‐methoxyindan at 77 °C, which could then be easily converted to the 2,3‐dibromo‐6‐methoxyindene by silver‐supported hydrolysis. Photochemical bromination of 5‐methoxy‐1‐indanone with N‐bromosuccinimide (NBS) gave 3‐bromo‐6‐methoxyindene, which upon thermolysis gave a benzo[c]fluorenone derivative. 相似文献
7.
Isobutyric acid in the presence of cyanuric chloride and N‐methylmorpholine was converted into active ester 3 at 0–5 °C, and it was subsequently treated with 3‐aminobenzotrifluoride 4 at 25 °C to furnish corresponding amide 5. This amide finally, on nitration, produced the desired product flutamide, 2‐methyl‐N‐[4‐nitro‐3‐(trifluoromethyl)phenyl]propionamide 6 in good yield. By‐product 2,4,6‐trihydroxy‐1,3,5‐triazine 7 was converted into the useful starting material cyanuric chloride 1 by refluxing with N,N‐diethylamine and POCl3. 相似文献
8.
The bromination reaction of p-benzoquinone-fused norbornadiene was studied at various temperatures (?78, ?50, 0, 25, and 77 °C). At room temperature, the double bonds of the p-benzoquinone units were mainly brominated. The double bond of the norbornene unit also underwent a bromination reaction in a yield of only 2%. However, the reaction at ?78 °C resulted in the formation of products derived from the attack of bromine on the norbornene double bond with higher charge density. In contrast to the bromination reaction, the epoxidation reaction of the same compound with m-chloroperbenzoic acid and dimethyldioxirane exclusively resulted in the formation of products derived from the addition to the double bond of norbornadiene. The regioselectivity observed was investigated and the results were supported by theoretical calculations. 相似文献
9.
10.
Sodium cyclo-octaphosphate heptahydrate, (NaPO3)8 · 7H2O, has been made by heating lead cyclo-tetraphosphate at 340°C, dissolving the thermal product in a 3% aqueous solution of tetrasodium ethylene-diaminetetraacetate, and then crystallizing it by addition of sodium chloride and acetone to the solution. When the cyclo-octaphosphate was heated up to 400°C, it decomposed to produce phosphates with both shorter and longer chain lengths. A main product at 300° to 350°C was sodium cyclo-triphosphate, and the thermal product melted at about 630°C. 相似文献
11.
Phenyl‐modified natural rubber was prepared in latex stage by bromination of deproteinized natural rubber followed by Suzuki‐Miyaura cross‐coupling reaction. First, the bromination of natural rubber was carried out using N‐bromosuccinimide in latex stage. The bromine atom content increased as amount of N‐bromosuccinimide increased. Second, the allylic bromine atom was replaced with a phenyl group using phenyl boronic acid in the presence of a palladium catalyst, according to the Suzuki‐Miyaura cross‐coupling reaction in latex stage. The resulting products were characterized by nuclear magnetic resonance (NMR) spectroscopy. Signal at 7.13 ppm was assigned to the phenyl group of the product, while signals at 3.98, 4.14, and 4.44 ppm were assigned to the remaining allylic brominated cis‐1,4‐isoprene units. The estimated phenyl group content and the conversion of the Suzuki‐Miyaura cross‐coupling reaction were 1.32 and 23.7 mol%, respectively. Glass transition temperature (Tg) of deproteinized natural rubber increased from ?62°C to ?46.7°C, when the phenyl group was introduced into the rubber. 相似文献
12.
Weihong Liu Frantiek Mike Yinzhong Guo Yasuhiro Koike Yoshi Okamoto 《Journal of polymer science. Part A, Polymer chemistry》2004,42(20):5180-5188
Partially fluorinated and perfluorinated dioxolane and dioxane derivatives have been prepared to investigate the effect of fluorine substituents on their free‐radical polymerization products. The partially fluorinated monomer 2‐difluoromethylene‐1,3‐dioxolane (I) was readily polymerized with free‐radical initiators azobisisobutyronitrile or tri(n‐butyl)borane–air and yielded a vinyl addition product. However, the hydrocarbon analogue, 2‐methylene‐1,3‐dioxolane (II), produced as much as 50% ring opening product at 60 °C by free‐radical polymerization. 2‐Difluoromethylene‐4‐methyl‐1,3‐dioxolane (III) was synthesized and its free‐radical polymerization yielded ring opening products: 28% at 60 °C, decreasing to 7 and 4% at 0 °C and −78 °C, respectively. All the fluorine‐substituted, perfluoro‐2‐methylene‐4‐methyl‐1,3‐dioxolane (IV) produced only a vinyl addition product with perfluorobenzoylperoxide as an initiator. The six‐membered ring monomer, 2‐methylene‐1,3‐dioxane (V), caused more than 50% ring opening during free‐radical polymerization. However, the partially fluorinated analogue, 2‐difluoromethylene‐1,3‐dioxane (VI), produced only 22% ring opening product with free‐radical polymerization and the perfluorinated compound, perfluoro‐2‐methylene‐1,3‐dioxane (VII), yielded only the vinyl addition polymer. The ring opening reaction and the vinyl addition steps during the free‐radical polymerization of these monomers are competitive reactions. We discuss the reaction mechanism of the ring opening and vinyl addition polymerizations of these partially fluorinated and perfluorinated dioxolane and dioxane derivatives. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5180–5188, 2004 相似文献
13.
A gas-phase electron-diffraction study of the product of rearrangement of N,N-dichloro-perfluoroaniline has assisted in establishing it to be the N-chloroimine, I, rather than the azepine, II. The molecule is found to be planar apart from atoms Cl13 and F14. The detailed dimensions shown in Fig. 2 were obtained by least-squares refinements in which several structural constraints were applied to reduce the total number of independent parameters. Of particular interest is the evidence for overcrowding around the CN bond: ∠N7C1C2 = 128°, ∠C18N7C1 = 126°, ∠N7C1C6 = 118° ; the distance C18 β F9 is 2.73 Å. 相似文献
14.
《Tetrahedron: Asymmetry》2000,11(7):1513-1516
The addition of cyanomethyl lithium to (−)-menthone at −78°C followed by 1.5 h stirring at room temperature and acidic workup produced exclusively the axial addition product, being the first example of preferred axial attack of an organometallic reagent to menthone. In the case of hydrolysis at −78°C after 0.5 h reaction time the equatorial addition product was isolated as the preferably formed isomer. The axial and equatorial cyanomethyl substituted menthol and neomenthol, respectively, were isolated in high yields. 相似文献
15.
Dong Wook Chae Seong Geun Oh Byoung Chul Kim 《Journal of Polymer Science.Polymer Physics》2004,42(5):790-799
The effect of introducing silver nanoparticles on the rheological properties and dynamic crystallization behavior of nylon‐6 was investigated. The nanocomposites showed slightly higher viscosity than pure nylon‐6 in the low‐frequency range even at an extremely low loading level of the silver particles (0.5–1.0 wt %). The nanoparticles had a more noticeable effect on the storage modulus than on the loss modulus of a nylon‐6 melt and reduced its loss tangent. They increased the crystallization temperature of nylon‐6 by about 14 °C and produced a sharper crystalline peak. The silver nanoparticles promoted the crystallization of nylon‐6, and their effect on the dynamic crystallization of nylon‐6 at 200 °C was more notable at a lower shear rate and at 190 °C at a higher frequency. Nylon‐6 produced large spherulitic crystals, but the nanocomposites showed a grainy structure. In addition, the silver nanoparticles reduced the fraction of the α‐form crystal but increased that of the γ‐form crystal. The nanocomposites crystallized at 190 °C showed a lower melting temperature than nylon‐6 by about 3 °C, whereas the nanocomposites crystallized at 200 °C showed almost the same melting temperature. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 790–799, 2004 相似文献
16.
Treatment of vinylcyclopropane (6) with lithium in liquid ammonia at 0° or 25° slowly effects reductive cleavage to afford a mixture of cis-2-pentene (7), trans-2-pentene (8), and 1-pentene (9). The major product is 7 and the ratio 7:8 is greater at 0° (4·25) than at 25° (3·2). Control experiments have established that the products are stable in lithium amide-liquid ammonia at 25°. In contrast, product ratios for cleavage of 6 with sodium in liquid ammonia at 0° or 25° are somewhat variable due to equilibration under the reaction conditions, and 8 is the major product at longer reaction times at 25°. It is suggested that the predominant cis-stereoselectivity is greatest in solvent-separated ion pair transition states. 相似文献
17.
Addition of hydrochloric or hydrobromic acid to a solution of potassium permanganate in acetonitrile produced a homogeneous mixture, which is suitable for laboratory chlorination or bromination, respectively. Aromatic compounds more reactive than alkylbenzenes can be chlorinated or brominated without additional catalyst. Alkenes and alkynes give the corresponding vicinal dihaloalkanes and vinyl halides. All reactions complete within two hours under mild condition (25-60 °C) with excellent to moderate yields. 相似文献
18.
Kozo Tsuji 《Journal of polymer science. Part A, Polymer chemistry》1973,11(8):2069-2075
When ethylene–acrolein copolymer was irradiated at ?196°C with ultraviolet light, a sharp singlet spectrum with a g value of about 2.001 was predominant. This spectrum is attributed to acyl radicals, which are produced by dissociation of a hydrogen atom from an aldehyde group. At the same time it is supposed that dissociation of formyl groups also took place to give alkyl radicals, CO, and H2. The alkyl radicals reacted with CO molecules to give acyl radicals at ?78°C under vacuum. Peroxy radicals were produced when the sample irradiated at ?196°C in the presence of air was treated at ?78°C. The sample irradiated at ?196°C was warmed to near 0°C and an apparent singlet spectrum with a g value of about 2.004 was observed. This spectrum was tentatively assigned as due to free radicals of the type 相似文献
19.
V. I. Potkin S. K. Petkevich R. V. Kaberdin P. V. Kurman 《Russian Journal of Organic Chemistry》2007,43(11):1617-1621
Bromination of 3,4,4-trichlorobut-3-enoic acid in boiling carbon tetrachloride led to the formation of 2-bromo-3,4,4-trichlorobut-3-enoic acid as a result of replacement of hydrogen in the CH2 group. The reaction at 40°C involved the double C=C bond to give 3,4-dibromo-3,4,4-trichlorobutanoic acid. The brominated acids were converted into the corresponding chlorides which were used to acylate benzene, toluene, and bromobenzene according to Friedel-Crafts. The acylation was not selective, and only the reaction of 3,4-dibromo-3,4,4-trichlorobutanoyl chloride with benzene gave 3,4-dibromo-3,4,4-trichloro-1-phenylbutan-1-one as the only product. 1-Aryl-2-bromo-3,4,4-trichlorobut-3-en-1-ones were synthesized by bromination of the corresponding 1-aryl-3,4,4-trichlorobut-3-en-1-ones which were prepared previously by Friedel-Crafts acylation of substituted benzenes with 3,4,4-trichlorobut-3-enoyl chloride. 相似文献
20.
《Journal of Inorganic and Nuclear Chemistry》1978,40(7):1347-1349
The reaction 2CuO + V2O5 → Cu2V2O7 has been studied at 500–730°C by X-ray diffraction and DTA and a number of literature errors are rectified. At < 550°C the product is β-Cu2V2O7, previously reported as the “high-temperature” polymorph. At 560–680°C the product is α-Cu2V2O7, previously reported as the “low-temperature” polymorph. At > 680°C the product is γ-Cu2V2O7, a new polymorph which on cooling transforms at 600°C to β-Cu2V2O7. The previously reported α-Cu2V2O7 → β-Cu2V2O7 transformation at about 710°C is due to α-Cu2V2O7 → γ-Cu2V2O7. β-Cu2V2O7 transforms to α-Cu2V2O7 at 605°C. 相似文献