- A Practical Procedure for Regioselective Bromination of Anilines
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A highly practical procedure for the preparation of bromoanilines by using copper-catalyzed oxidative bromination has been developed. Treatment of free anilines with readily available NaBr and Na 2S 2O 8in the presence of a catalytic amount of CuSO 4·5H 2O enabled regioselective bromination.
- Takahashi, Yusuke,Seki, Masahiko
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p. 1828 - 1832
(2021/04/15)
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- Non-photoisomerizable butterfly shaped tetrasubstituted azobenzenes: Synthesis and photophysical studies
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Thetrans-azobenzene (AB) substituted derivatives with bulky carbazole (1), phenothiazine (2), and phenyl (3) have been synthesized to understand the effect of steric crowding around the -NN- linkage on the photoisomerization process. The substituents maintain orthogonality to the azobenzene plane and the electronic properties exhibit a combination of individual chromophores. Irradiation of1and2with various light sources including a 365 nm pen-ray lamp, and a 150 W Xe-Hg lamp, and even exposure to sunlight for a week does not yield thecisisomer revealing the exceptional photostability of the synthesized azobenzene derivatives. These studies suggest that possessing steric crowding around the azo linkage would be a potential strategy to develop photostable azobenzene-based functional materials.
- Raman, Arunachalam,Neelambra, Afeefah U.,Karunakaran, Venugopal,Easwaramoorthi, Shanmugam
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supporting information
p. 8818 - 8822
(2020/06/08)
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- Method of catalytically synthesizing polybromo-aniline in water phase
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The invention discloses a method of catalytically synthesizing polybromo-aniline in a water phase. The method comprises following steps: adding a catalytic amount of a free radical initiator, aniline derivatives, cheap and low-toxic bromine salts, and water into a reactor; carrying out reactions in a photocatalytic reaction instrument under power of 5W at a room temperature; after a while, extracting the reaction product by ethyl acetate, and carrying out recrystallization to obtain polybromo-aniline; wherein the free radical initiator is eosin, sodium persulfate, or potassium persulfate. The power of the incandescent lamp of the photocatalytic reaction instrument is 5W. The free radical initiator and bromine salts are cheap and easily available. The method is an ideal synthesis method of polybromo-aniline. Cheap and low-toxic bromine salts are used to replace liquid bromine. The cheap and easily available free radical initiator is used to replace unstable and explosive hydrogen peroxide. After 4 to 10 hours of reactions under the power of 5W, polybromo-aniline can be synthesized, the yield and the reaction selectivity are high, the byproducts are few, and the post treatment is simple.
- -
-
Paragraph 0012; 0033
(2019/10/04)
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- Graphene Oxide Promoted Oxidative Bromination of Anilines and Phenols in Water
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The mildly acidic and oxidative nature of graphene oxide, with its large surface area available for catalytic activity, has been explored in aromatic nuclear bromination chemistry for the first time. The versatile catalytic activity of graphene oxide (GO) has been used to selectively and rapidly brominate anilines and phenols in water. The best results were obtained at ambient temperatures using molecular bromine in a protocol promoted by oxidative bromination catalyzed by GO; these transformations proceeded with 100% atom economy with respect to bromine and high selectivities for the tribromoanilines and -phenols. Reduced graphene oxide (r-GO) was observed to form after the second recycle (third use) of GO. This technique is also effective with N-bromosuccinimide (NBS) as the brominating reagent. In the case of NBS, reactions were instantaneous and the GO displayed excellent recyclability without any loss of activity over several cycles.
- Ghorpade, Prashant Vasantrao,Pethsangave, Dattatray Appasha,Some, Surajit,Shankarling, Ganapati Subray
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p. 7388 - 7397
(2018/07/29)
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- A Cu(II)-MOF capable of fixing CO2 from air and showing high capacity H2 and CO2 adsorption
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A porous Cu(ii)-MOF shows an adsorption of 6.6 wt% of H2 at 77 K and 62 bar and a very high 60 wt% of CO2 at 298 K and 32 bar. When air is bubbled into a suspension of the activated MOF in the presence of different epoxides at room temperature, the CO2 in air is readily converted into the corresponding cyclic carbonates.
- Sharma, Vivekanand,De, Dinesh,Saha, Ranajit,Das, Ranjita,Chattaraj, Pratim Kumar,Bharadwaj, Parimal K.
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supporting information
p. 13371 - 13374
(2017/12/26)
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- A Strategy towards the Multigram Synthesis of Uncommon Hexaarylbenzenes
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A novel rational synthetic pathway - the "functionalization of para-nitroaniline" (FpNA) - provides substituted hexaarylbenzenes (HABs) with uncommon symmetries that bear up to five different substituents, fully avoiding regioisomeric product distributions during the reactions. 4-Nitroaniline is functionalized by a cascade of electrophilic halogenations, Sandmeyer brominations, and Suzuki cross-coupling reactions, leading to 26 substitution geometries, of which 18 structures are not available by the current established techniques. Furthermore, we demonstrate that this method is applicable to the bulk production of such systems on a multigram scale. Regarding optoelectronic properties, we demonstrate how highly functionalized HABs can show strong luminescent behavior, making these molecules very attractive to organic electronic devices.
- Lungerich, Dominik,Reger, David,H?lzel, Helen,Riedel, René,Martin, Max M. J. C.,Hampel, Frank,Jux, Norbert
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supporting information
p. 5602 - 5605
(2016/05/09)
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- Green process development for the preparation of 2,6-dibromo-4-nitroaniline from 4-nitroaniline using bromide-bromate salts in an aqueous acidic medium
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An organic solvent-free process for the preparation of 2,6-dibromo-4-nitroaniline, (an important intermediate in the synthesis of azo disperse dyes) from 4-nitroaniline using 2:1 bromide-bromate salts under an aqueous acidic medium at ambient conditions has been developed. The 2:1 bromide-bromate couple could be obtained by mixing pure NaBr/NaBrO3 salts or by adjusting the 5:1 mole ratio of NaBr/NaBrO3 (obtained in an aqueous solution as an intermediate from the bromine manufacture industry by a cold process) to 2:1 by the addition of a suitable oxidant. After completion of the reaction the product was purified by simple filtration and washing with water. The aqueous acidic filtrate was recycled up to five times without loss of purity and yield of the product. The method was extended to other aromatic substrates.
- Pappula, Venkatanarayana,Adimurthy, Subbarayappa
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p. 90184 - 90187
(2016/10/07)
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- Rapid and total bromination of aromatic compounds using TsNBr2 without any catalyst
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N,N-Dibromo-p-toluenesulfonamide (TsNBr2) has been found to be a new reagent for bromination of aromatic compounds. The reaction is extremely fast and goes into completion instantaneously at ambient temperature to produce exclusively the corresponding polybrominated product. This procedure is applicable to various phenols, anisole, and anilines to give corresponding polybrominated compound as a single product in excellent yield.
- Saikia, Indranirekha,Chakraborty, Pranita,Sarma, Manas Jyoti,Goswami, Mridusmita,Phukan, Prodeep
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p. 211 - 217
(2015/10/29)
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- Polyphenylbenzene as a platform for deep-blue OLEDs: Aggregation enhanced emission and high external quantum efficiency of 3.98%
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Great efforts have been devoted to seek novel approaches for the construction of efficient deep-blue fluorescent materials, one of the most important prerequisites for the commercialization of OLEDs. Here, we report a new way to utilize polyphenylbenzene as a platform to yield a series of efficient deep-blue emitters. Nondoped multilayer electroluminescence (EL) devices using these new luminogens as emitting layers are fabricated. Maximum current efficiency (CE) of 2.0 cd A-1 is achieved and the Commission Internationale de lclairage (CIE) coordinates can stay at (0.15, 0.08), close to the saturated deep-blue (0.14, 0.08). Through rational design of the device structure, blue-violet emission with the CIE coordinates of (0.15, 0.06) can be realized. Furthermore, 10-based doped devices show deep-blue emission with improved CE as high as 4.51 cd A-1, and the external quantum efficiency (EQE) of 3.98%, which are among the best EL performance for deep-blue emission.
- Zhan, Xuejun,Sun, Ning,Wu, Zhongbin,Tu, Jin,Yuan, Lei,Tang, Xi,Xie, Yujun,Peng, Qian,Dong, Yongqiang,Li, Qianqian,Ma, Dongge,Li, Zhen
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p. 1847 - 1854
(2015/03/18)
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- Enantioposition-selective copper-catalyzed azide-alkyne cycloaddition for construction of chiral biaryl derivatives
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A highly enantioposition-selective copper-catalyzed azide-alkyne cycloaddition (CuAAC) of dialkynes bearing prochiral biaryls has been developed for the construction of 1,2,3-triazoles bearing axially chiral biaryl groups in up to 76% yield and up to 99% ee.
- Osako, Takao,Uozumi, Yasuhiro
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supporting information
p. 5866 - 5869
(2015/01/08)
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- Bromination of arenes using I2O5-KBr in water
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An efficient and environmentally benign bromination of various aromatic compounds using aN aqueous I2O5-KBr system at room temperature has been developed in this work. A series of aromatic compounds such as acetophenones, benzaldehydes, benzoic acids, anilines, amides, and aminopyridine have been successfully brominated in excellent regioselectivities and good yields under the typical reaction conditions. The features of KBr as brominating reagent, water as solvent, and mild conditions make this system an attractive synthetic procedure. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications for the following free supplemental resource(s): Full experimental and spectral details.]
- Hou, Jieping,Li, Zejiang,Jia, Xiao-Dong,Liu, Zhong-Quan
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supporting information
p. 181 - 187
(2013/12/04)
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- Polymer-anchored peroxo compounds of molybdenum and tungsten as efficient and versatile catalysts for mild oxidative bromination
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A polymer supported peroxomolybdate(VI) compound of the type [MoO 2(O2)(CN)2]-PAN [PAN = poly(acrylonitrile)] (PANMo) was obtained by reacting H2MoO4 with 30% H 2O2 and the macromolecular ligand, PAN at near neutral pH. The macrocomplex has been characterized by elemental analysis (CHN and EDX analysis), spectral (IR, UV-Vis and 13C NMR, 95Mo NMR), thermal (TGA-DTG) as well as SEM studies. The catalytic activity of PANMo and its previously reported tungsten containing analog PANW, in oxidative bromination of organic substrates has been explored. The supported complexes could serve as efficient heterogeneous catalysts for the oxidative bromination of a variety of structurally diverse aromatic compounds, with H 2O2 as terminal oxidant, to afford bromo organics in impressive yields under environmentally clean conditions. The catalysts afforded regeneration and could be reused for a minimum of six reaction cycles.
- Boruah, Jeena Jyoti,Das, Siva Prasad,Borah, Rupam,Gogoi, Sandhya Rani,Islam, Nashreen S.
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p. 246 - 254
(2013/05/23)
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- Fast and efficient bromination of aromatic compounds with ammonium bromide and Oxone
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A highly efficient, rapid and regioselective protocol was developed for the ring bromination of aromatic compounds under mild conditions with ammonium bromide as a source of bromine source and Oxone (potassium peroxysulfate) as an oxidant. No metal catalyst or acidic additive is required. A variety of aromatic compounds, including methoxy, hydroxy, amino, and alkyl arenes, reacted smoothly to give the corresponding monobrominated products in good to excellent yields in very short reaction times. Moreover, dibromination of deactivated anilines to give the corresponding dibromides proceeded in high yields. Interestingly, 1-(2-naphthyl)ethanone provided a ring-brominated product. Georg Thieme Verlag Stuttgart . New York.
- Naresh, Mameda,Arun Kumar, Macharla,Mahender Reddy, Marri,Swamy, Peraka,Nanubolu, Jagadeesh Babu,Narender, Nama
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p. 1497 - 1504
(2013/06/27)
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- An instant and facile bromination of industrially-important aromatic compounds in water using recyclable CaBr2-Br2 system
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Various industrially-important brominated intermediates have been instantly synthesized using aq. CaBr2-Br2 system as an efficient and recyclable brominating reagent under aqueous conditions at room temperature without the need for metal catalysts or acidic additives. Structurally-diverse phenol and aniline derivatives with strong electron-withdrawing groups such as carboxylic, nitro and formyl show remarkable reactivity to the brominating reagent and brominated in 92-98% yield with high purity (>99%) in a very short reaction time. Organic solvent-free conditions, a feature of the green chemistry, were successively used not only for the reactions but also for the isolation of products at the end of the reaction. The recycling of HBr by its neutralization, thereby generating additional amounts of industrially-important CaBr2 has been designed and developed. The brominating reagent has been recycled and regenerated, and the process was repeated up to 4 cycles after the fresh batch using the regenerated brominating reagent having almost identical selectivity and isolated yields, which seems to be the most promising methodology from the viewpoint of the green approach to organic synthesis.
- Kumar, Lalit,Mahajan, Tanu,Agarwal
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experimental part
p. 2187 - 2196
(2011/09/16)
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- Potent mGluR5 antagonists: Pyridyl and thiazolyl-ethynyl-3,5-disubstituted- phenyl series
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We report the synthesis of four series of 3,5-disubstituted-phenyl ligands targeting the metabotropic glutamate receptor subtype 5: (2-methylthiazol-4-yl) ethynyl (1a-j,), (6-methylpyridin-2-yl)ethynyl (2a-j), (5-methylpyridin-2-yl) ethynyl (3a-j,), and (pyridin-2-yl)ethynyl (4a-j,). The compounds were evaluated for antagonism of glutamate-mediated mobilization of internal calcium in an mGluR5 in vitro assay. All compounds were found to be full antagonists and exhibited low nanomolar to subnanomolar activity.
- Alagille, David,Dacosta, Herve,Chen, Yelin,Hemstapat, Kamondanai,Rodriguez, Alice,Baldwin, Ronald M.,Conn, Jeffrey P.,Tamagnan, Gilles D.
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supporting information; experimental part
p. 3243 - 3247
(2011/07/07)
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- Studies of one-pot double couplings on dibromoquinolines
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In a series of studies, the regioselectivity of Suzuki couplings of dibromoquinolines has been investigated. In general, it is much harder to achieve high levels of regioselectivity in these systems compared to many of the other dibromoheteroaromatics that have been studied. Useful levels of selectivity could be achieved for both a 5,7-dibromoquinoline as well as 3,4-dibromoquinoline. Double Suzuki couplings could also be achieved on these two compounds.
- Piala, Alexander,Mayi, Diyar,Handy, Scott T.
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scheme or table
p. 4147 - 4154
(2011/07/08)
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- Environmentally benign electrophilic and radical bromination 'on water': H2O2-HBr system versus N-bromosuccinimide
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A H2O2-HBr system and N-bromosuccinimide in an aqueous medium were used as a 'green' approach to electrophilic and radical bromination. Several activated and less activated aromatic molecules, phenylsubstituted ketones and styrene were efficiently brominated 'on water' using both systems at ambient temperature and without an added metal or acid catalyst, whereas various non-activated toluenes were functionalized at the benzyl position in the presence of visible light as a radical activator. A comparison of reactivity and selectivity of both brominating systems reveals the H2O2-HBr system to be more reactive than NBS for benzyl bromination and for the bromination of ketones, while for electrophilic aromatic substitution of methoxy-substituted tetralone it was higher for NBS. Also, higher yields of brominated aromatics were observed when using H2O2-HBr 'on water'. Bromination of styrene reveals that not just the structure of the brominating reagent but the reaction conditions: amount of water, organic solvent, stirring rate and interface structure, play a key role in defining the outcome of bromination (dibromination vs bromohydroxylation). In addition, mild reaction conditions, a straightforward isolation procedure, inexpensive reagents and a lower environment impact make aqueous brominating methods a possible alternative to other reported brominating protocols.
- Podgor?ek, Ajda,Stavber, Stojan,Zupan, Marko,Iskra, Jernej
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experimental part
p. 4429 - 4439
(2009/10/09)
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- Effect of structural factors and solvent nature in bromination of anilines
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Reaction of electrophilic bromination of aniline containing various ortho, meta, and para substituents in the aromatic ring was studied. The optimal conditions for synthesis of mono-, di-, tri-, and tetrabromo derivatives of aniline and brominated analog of Aniline Black were found.
- Bagmanov
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p. 1570 - 1576
(2011/06/20)
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- Oxidative bromination of aniline and its derivatives
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Oxidative bromination of aniline and its derivatives containing various substituents (CH3, Cl, NO2, COOH) in ortho, meta, and para positions with a brominating mixture of NaBr (KBr) and 20-22% hydrogen peroxide in 6-8% hydrochloric acid at the molar ratio aniline: NaBr (KBr): H 2O2: HCl = 1: 3.5: 3.2: 4.5 is described.
- Salakhov,Bagmanov,Umaeva,Bagmanova
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experimental part
p. 1479 - 1481
(2009/02/05)
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- An intriguing effect of lithium perchlorate dispersed on silica gel in the bromination of aromatic compounds by N-bromosuccinimide
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A convenient and efficient procedure for electrophilic aromatic bromination has been developed by mixing of N-bromosuccinimide and an aromatic compound at room temperature on the surface of silica gel mixed with solid anhydrous LiClO4. All of the substrates examined underwent clean electrophilic aromatic bromination in reaction times of a few minutes to afford the corresponding bromoarenes under neutral conditions in excellent yield. In the case of thiophenol, no substitution reaction occurred, and the corresponding disulfide was obtained in excellent yield.
- Bagheri, Mojtaba,Azizi, Najmedin,Saidi, Mohammad R.
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p. 146 - 149
(2007/10/03)
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- Facile and sensitive spectrophotometric determination of propoxur in formulations and environmental samples
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A facile, rapid, and sensitive spectrophotometric method for the determination of propoxur in insecticidal formulations, fortified water, vegetables, agricultural wastewater, and agricultural soil samples has been elaborated. The proposed method is based on the hydrolysis of propoxur under basic conditions, followed by instantaneous azo coupling of the resulting 2-isopropoxyphenol with the anilines 2a - c. This yielded the orange-red chromophore 3a (λmax = at 470 nm). the pale-red coupling product 3b (490 nm), or the red derivative 3c (478 nm), which are stable for 46 h, 38 h, and 24 h, respectively, and could be readily analyzed spectrophotometrically.
- Kumar, Kailasa Suresh,Suvardhan, Kanchi,Rekha, Dasari,Jayaraj,Chiranjeevi, Pattium
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p. 1022 - 1027
(2007/10/03)
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- Process for preparation of non-hazardous brominating agent
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A cost-effective process is described for the preparation of a stable and non-hazardous brominating reagent containing 2:1 stoichiometric ratio of alkali bromide to alkali bromate. The process comprises of reacting alkaline bromine intermediate mixture, obtained from bromine recovery plant, with chlorine gas in the presence of a strong alkali to oxidize the bromide ions to bromate ions. This brominating reagent is useful for the bromination of aromatic compounds by substitutions.
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- 1-Benzyl-4-aza-1-azoniabicyclo[2.2.2] octane tribromide as a highly reactive brominating agent for aniline derivatives
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Reaction of anilines with 1-benzyl-4-aza-1-azoniabicyclo[2.2.2]octane tribromide (3) in the presence of CaCO3 in small amounts of methanol gave brominated aromatic amines in good yields at room temperature. The isolation of products is straightforward.
- Hajipour,Imanieh,Pourmousavi
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p. 4597 - 4604
(2007/10/03)
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- Synthesis of Anthropomorphic Molecules: The NanoPutians
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Described here are the synthetic details en route to an array of 2-nm-tall anthropomorphic molecules in monomeric, dimeric, and polymeric form. These anthropomorphic figures are called, as a class, NanoPutians. Using tools of chemical synthesis, the ultimate in designed miniaturization can be attained while preparing the most widely recognized structures: those that resemble humans.
- Chanteau, Stephanie H.,Tour, James M.
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p. 8750 - 8766
(2007/10/03)
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- Environmentally benign chlorination and bromination of aromatic amines, hydrocarbons and naphthols
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A simple and efficient procedure for chlorination and bromination of aromatic amines, hydrocarbons and naphthols by the action of aqueous hydrohalic acid and hydrogen peroxide is described. This environmentally clean and safe procedure involves in situ generation of the active halogen and its uncatalyzed reaction with the substrates in this study.
- Vyas, Punita V.,Bhatt, Anjani K.,Ramachandraiah, Gadde,Bedekar, Ashutosh V.
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p. 4085 - 4088
(2007/10/03)
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- Pyridinium dichlorobromate: A new stable brominating agent for aromatic compounds
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Pyridinium dichlorobromate (PyHBrCl2, 1) is a new example of iminium-trihalide complexes. The compound is prepared from pyridine and chlorine in the presence of aqueous hydrogen bromide. The crystalline trihalide is quite stable and acts as a safe source of positive bromine. It shows a remarkable reactivity towards aromatic compounds compared with other bromine complexes. It is also considered as a potential source for bromine chloride BrCl.
- Muathen, Hussni A.
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p. 169 - 171
(2007/10/03)
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- Synthesis of polybrominated diphenyl ethers and their capacity to induce CYP1A by the Ah receptor mediated pathway
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Polybrominated diphenyl ethers (PBDEs) have become widely distributed as environmental contaminants due to their use as flame retardants. Their structural similarity to other halogenated aromatic pollutants has led to speculation that they might share toxicological properties such as hepatic enzyme induction. In this work we synthesized a number of PBDE congeners, studied their affinity for rat hepatic Ah receptor through competitive binding assays, and determined their ability to induce hepatic cytochrome P-450 enzymes by means of EROD (ethoxyre-sorufin-O-deethylase) assays in human, rat, chick, and rainbow trout cells. Both pure PBDE congeners and commercial PBDE mixtures had Ah receptor binding affinities 10-2-10-5 times that of 2,3,7,8-tetrachlorodibenzo-p-dioxin. In contrast with polychlorinated biphenyls, Ah receptor binding affinities of PBDEs could not be related to the planarity of the molecule, possibly because the large size of the bromine atoms expands the Ah receptor's binding site. EROD activities of the PBDE congeners followed a similar rank order in all cells. Some congeners, notably PBDE 85, did not follow the usual trend in which strength of Ah receptor binding affinity paralleled P-450 induction potency. Use of the gel retardation assay with a synthetic oligonucleotide indicated that in these cases the liganded Ah receptor failed to bind to the DNA recognition sequence.
- Chen,Konstantinov,Chittim,Joyce,Bols,Bunce
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p. 3749 - 3756
(2007/10/03)
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- A modified Sandmeyer methodology and the synthesis of (±)-convolutamydine A
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(±)-Convolutamydine A (5) has been prepared by it concise synthesis from 3,5-dibromoaniline using a modified Sandmeyer methodology. The modified Sandmeyer methodology has also been found to be beneficial for the synthesis of other α-isonitrosoacetanilides. The 4,6-dibromohydroxyoxindole nucleus was further confirmed by comparison with the isomeric 5,7-dibromohydroxyoxindole.
- Garden, Simon J.,Torres, Jose C.,Ferreira, Alexandre A.,Silva, Rosangela B.,Pinto, Angelo C.
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p. 1501 - 1504
(2007/10/03)
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- Multinuclear Magnetic Resonance Spectroscopic and Semiempirical Molecular Orbital (AM1) Studies of Substituted Anisoles
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13C, 15N, and 17O NMR spectra have been recorded for 4-nitroanisole (1), its 2-methyl-, 2-chloro-, 2-bromo-, 2-iodo-, 2,6-diamethyl-, 2,6-dichloro, 2,6-dibromo-, and 2,6-diiodo-derivatives 2-9, also nitrobenzene (1a), its 3-methyl-, 3-chloro-, 3-bromo-, and 3-iodo-derivatives 2a-5a and 3,5-dichloro- and 3,5-dibromo-derivatives 7a and 8a.Analysis of the chemical shifts of carbon bearing nitro group and nitro oxygens in these compounds suggests that presence of one substituent ortho- to the methoxyl group enhances its resonance interaction with the benzene ring whereas presence of two ortho-substituents inhibits this resonance.However, in no case the resonance is completely inhibited.The extent of enhancement or inhibition is almost independent of the nature of the ortho-substituent.This conclusion has also been arrived by analyzing the reported chemical shifts of the para-carbons in anisoles 1b-9b and the corresponding carbons in benzene derivatives 1c-9c.Though evidence could not be obtained for steric enhancement of resonance using methoxyl oxygen chemical shifts, analysis of these chemical shifts in di-ortho-substituted anisoles 6-9 and 6a furnishes evidence for steric inhibition of resonance.However, 15N chemical shifts are of no use in studying these phenomena.Semiempirical molecular orbital calculations using AM1 Hamiltonian suggest that the methoxyl group is coplanar with the benzene ring in anisole, 4-nitroanisole and 2-substituted-4-nitroanisoles but is perpendicular to the benzene ring in 2,6-disubstituted-4-nitroanisoles.Moreover, in 2-substituted-4-nitroanisoles the O-methyl group is anti to the 2-substituent.
- Pandiarajan, Karuppiah,Kabilan, Senthamaraikannan,Sankar, Punnaivanam,Kolehmainen,Erkki,Nevalainen, Tapio,Kauppinen, Reijo
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p. 2639 - 2646
(2007/10/02)
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- BROMINATION OF ANILINES BY BENZYLTRIPHENYLPHOSPHONIUM TRIBROMIDE
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Anilines and benzyltriphenylphosphonium tribromide in dichloromethane and methanol medium in the presence of sodium bicarbonate react within a few minutes at room temperature to give the corresponding polybromoanilines in good yields.
- Xin-teng, Ding,Guo-bin, Liu
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p. 1261 - 1266
(2007/10/02)
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- Magnetic susceptibilities of organic compounds: Part V - Influence of substituents on diamagnetic susceptibilities of disubstituted and trisubstituted benzenes
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The magnetic susceptibilities of a number of triads of isomeric disubstituted benzenes have been determined, choosing the compounds in such a way that the substituents are present in the following combinations: (i) two electron-releasing substituents, (ii) a halogeno and an electron-releasing substituent, (iii) a halogeno and an electron-attracting substituent, and (iv) two halogeno substituents.The data show that for types (i), (ii) and (iv), the ortho isomers have the highest magnetic susceptibilities, the susceptibilities decreasing in the order: ortho > meta > para; for type (iii), the meta-isomers have the highest susceptibilities, the susceptibilities decreasing in the order: meta > para > ortho.The diamagnetic susceptibilities of some isomeric trisubstituted benzenes have also been determined and the data reveal that the susceptibility is the highest where the crowding of substituents is the highest (1,2,3-isomer) and lowest where the substituents are staggered and least crowded (1,3,5-isomer).Another observation made in the case of trisubstituted benzene is the applicability of a principle of additivity of their diamagnetic susceptibilities.
- Baliah, V.,Jeyanthy, J. Judith Diana
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p. 472 - 476
(2007/10/02)
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- 15N Nuclear polarisation in rearrangement of 2,6-dichloro-N-nitroaniline and 2,6-dibromo-N-nitroaniline
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The acid-catalysed rearrangements of 2,6-dichloro-N-nitroaniline and 2,6-dibromo-N-nitroaniline to give the corresponding 4-nitro derivatives have been followed by 1H and 15N nmr spectroscopy in deuteriochloroform at 30 deg C.When 15NO2-labelled nitramines are used, the 15N nmr signals for both the substrate and product show enhanced absorption during reaction.When one labelled nitramine and one unlabelled nitramine rearranged together, isotopic exchange occurs and 15N nmr signals are seen for both substrates and both products.For the initially unlabelled nitramine and its product, these signals are in emission.The change in the enhancement of the signals during reaction shows that the nuclear polarization arises from the rearrangement, not from a preliminary equilibrium.
- Abu-Namous, Adel M. A.,Ridd, John H.,Sandall, John P. B.
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p. 1124 - 1129
(2007/10/02)
-