4900-62-3Relevant academic research and scientific papers
Regioselective Functionalization of 9,9-Dimethyl-9-silafluorenes by Borylation, Bromination, and Nitration
Murai, Masahito,Nishinaka, Naoki,Kimura, Mizuki,Takai, Kazuhiko
, p. 5667 - 5676 (2019/05/10)
Despite the utility of 9-silafluorenes as functional materials and as building blocks, methods for efficient functionalization of their backbone are rare, probably because of the presence of easily cleavable C-Si bonds. Although controlling the regioselectivity of iridium-catalyzed direct borylation of C-H bonds is difficult, we found that bromination and nitration of 2-methoxy-9-silafluorene under mild conditions occurred predominantly at the electron-rich position. The resulting product having methoxy and bromo groups can be utilized as a building block for the synthesis of unsymmetrically substituted 9-silafluorene-containing ?-conjugated molecules.
Regioselective Functionalization of 9,9-Dimethyl-9-silafluorenes by Borylation, Bromination, and Nitration
Murai, Masahito,Nishinaka, Naoki,Kimura, Mizuki,Takai, Kazuhiko
, (2019/05/08)
Despite the utility of 9-silafluorenes as functional materials and as building blocks, methods for efficient functionalization of their backbone are rare, probably because of the presence of easily cleavable C-Si bonds. Although controlling the regioselectivity of iridium-catalyzed direct borylation of C-H bonds is difficult, we found that bromination and nitration of 2-methoxy-9-silafluorene under mild conditions occurred predominantly at the electron-rich position. The resulting product having methoxy and bromo groups can be utilized as a building block for the synthesis of unsymmetrically substituted 9-silafluorene-containing π-conjugated molecules.
Aromatic nitration in liquid Ag0.51K0.42Na 0.07NO3
Mascal, Mark,Yin, Lunxiang,Edwards, Ross,Jarosh, Michael
, p. 6148 - 6151 (2008/12/22)
(Figure Presented) Aromatic molecules have a strong affinity for silver(I) and dissolve to a limited extent in Ag0.51K0.42Na 0.07NO3, a low-melting eutectic mixture of silver, potassium, and sodium nitrates. Aromatic nitration in this inorganic ionic liquid leads to products which arise from nonelectrophilic substitution pathways.
Improved nitrations using metal nitrate-sulfuric acid systems
Mellor, John M.,Mittoo, Stifun,Parkes, Rachel,Millar, Ross W.
, p. 8019 - 8024 (2007/10/03)
Procedures for efficient mono- and di-nitration of aromatic substrates have been developed using ceric ammonium nitrate suspended in dichloromethane in the presence of 2 equiv. of sulfuric acid. By suspending the sulfuric acid on silica gel following nitration, products are easily isolated by filtration and evaporation of solvent. In these nitrations ceric ammonium nitrate can be replaced by other metal nitrates, for example potassium- or tetrabutylammonium-nitrate. In contrast the nitration of naphthalene by ceric ammonium nitrate in the presence of methanol and sulfuric acid affords a mixture of 1,4- and 1,2-methoxynitronaphthalenes, but these nitrations cannot be achieved using potassium or tetrabutylammonium nitrate. The mechanism of this nitration/oxidation is discussed. (C) 2000 Elsevier Science Ltd.
Synthesis of 1-alkoxy-4-nitronaphthalenes in a novel nitration of naphthalene
Mellor, John M.,Parkes, Rachel,Millar, Ross W.
, p. 8739 - 8742 (2007/10/03)
A new nitration of naphthalene affords as major products 1,4-disubstituted naphthalenes and as minor products 12-disubstituted naphthalenes. By use of eerie ammonium nitrate suspended on silica gel, or in homogeneous solution, nitration of naphthalene in the presence of alcohols, sodium- or tetrabutyl ammonium- nitrite and acid gives alkoxynitronaphthalenes. A preparation of 1-nitroaaphthalene is described under heterogeneous conditions.
Thermal and photochemical decomposition pathways of trinitromethylarenes. part II. The effects of ethanol on the photolysis reactions of some alkoxy- and dialkoxyarenes in the presence of tetranitromethane. enhancement of adduct and trinitromethyl substitution product formation
Butts, Craig P.,Eberson, Lennart,Hartshorn, Michael P.,Persson, Ola
, p. 718 - 732 (2007/10/03)
The photolysis of the charge transfer (CT) complex of tetranitromethane with 1-methoxynaphthalene, 1,4-dimethoxybenzene, 1,2-dimethoxybenzene, 1,2-methylenedioxybenzene or 2-methylanisole is reported for dichloromethane, acetonitrile, dichloromethane-ethanol and acetonitrile-ethanol solvent systems. The effects of adding ethanol (8% v/v ? 1.4 mol dm-3) to dichloromethane or acetonitrile as reaction solvents include: (i) the stabilization of alkoxytrinitro-methylarenes, thus reducing their normal tendency for decomposition according to ArC (NO2)3→ArCOOH→ArNO2, (ii) a reduction in the nucleophilicity of trinitromethanide ion, and (iii) changes in the regioselectivity of trinitromethanide ion attack on the radical cations of alkoxyaromatic compounds away from attack ipso to the alkoxy substituent. Adducts are also stabilized, as shown by the photolysis of the CT complex of 1,4-dimethoxybenzene-tetranitromethane in dichloromethane-ethanol (8% v/v) which gives the epimeric 1,4-dimethoxy-3-nitro-6-trinitromethylcyclohexa-1,4-dienes and 1,4-dimethoxy-2-trinitromethylbenzene, in addition to 1,4-dimethoxy-2-nitrobenzene. The adducts are detected also among the products of photolysis reactions in neat dichloromethane or acetonitrile. Acta Chemica Scandinavica 1997.
Photochemical Nitration by Tetranitromethane. Part XXII. Adducts as Precursors of Nitro Substitution Products from the Photolysis of 1-Methoxynaphthalene-Tetranitromethane, Dehydrodimer Formation and the Regiochemistry of Trinitromethanide Ion Attack on the Radical Cation of ...
Butts, Craig P.,Eberson, Lennart,Hartshorn, Michael P.,Persson, Ola,Robinson, Ward T.
, p. 253 - 264 (2007/10/02)
The photolysis of 1-methoxynaphthalene with tetranitromethane in dichloromethane at 20 deg C gives mainly 1-methoxy-4-nitronaphthalene (2) and 1-methoxy-4-trinitromethylnaphthalene (5), together with smaller amounts of 1-methoxy-2-nitronaphthalene (1) and the two adducts, 4-methoxy-r-1-nitro-t-2-trinitromethyl-1,2-dihydronaphthalene (6) and 4-methoxy-r-2-nitro-t-1-trinitromethyl-1,2-dihydronaphthalene (7).Photolysis in the presence of trifluoroacetic acid under otherwise identical conditions gives initially exclusively 4,4'-dimethoxy-1,1'-binaphthalene (10) as the product, trinitromethanide ion being eliminated as a reactant by protonation to give nitroform.EPR spectral and cyclic voltammetric data indicate that the radical cation 10 is present in this reaction.Evidence is presented that, in the absence of trifluoroacetic acid, the reaction products 1, 2 and 5 all arise by decomposition of highly labile nitro-trinitromethyl or nitrito-trinitromethyl adducts 11, 12 and 14.The regiochemistry of attack of trinitromethanide ion on the radical cation of 1-methoxynaphthalene is discussed, and it is proposed that this step is reversible, the regiochemistry of attack being determined by the relative energies of the carbon radicals formed in the process.X-Ray crystal structures are reported for 1-methoxy-4-trinitromethylnaphthalene (5) and 4,4'-dimethoxy-1,1'-binaphthalene (10).
Light-initiated and thermal nitration reactions during photolysis of naphthalene/tetranitromethane or 1-methoxynaphthalene/tetranitromethane in dichloromethane
Eberson, Lennart,Radner, Finn
, p. 5825 - 5834 (2007/10/02)
The photolysis of naphthalene or 1-methoxynaphthalene together with tetranitromethane in dichloromethane, using light with a cutoff at λ 2-promoted nitration (α/β ratio ca. 20). The adducts are formed by photochemical excitation of the CT complex between naphthalene and tetranitromethane, resulting in formation of the triad [ArH?+ NO2 (NO2)3C-] from which the observed chemistry develops by attack of trinitromethanide upon the radical cation. For 1-methoxynaphthalene, a representative of more highly reactive aromatics, the reaction is again photochemically initiated and again adducts seem to be responsible for the further development of thermal nitration reactions, apart from the NO2-induced reaction. Elimination of HNO2 from one of the 1,4-adducts induces a novel HNO2/tetranitromethane-dependent nitration process, shown separately to operate in the dark on reactive substrates. The aryltrinitromethane formed in this step is "hydrolyzed" to the corresponding carboxylic acid, 4-methoxy-1-naphthoic acid, under the anhydrous conditions prevailing during photolysis. Nitrous acid is a likely candidate as the proton source for this reaction. With an alcohol present, moderate yields (up to ≈50%) of alkyl 4-methoxy-1-naphthoates are obtained. From other adducts, nitro compounds are formed by elimination of nitroform. Trinitromethanide ion was shown to possess greatly differing reactivity (ratio >103) toward a model radical cation, tris(4-bromophenyl)aminium ion, in dichloromethane and acetonitrile, respectively.
