576-23-8Relevant articles and documents
Regioselective Halogenation of Arenes and Heterocycles in Hexafluoroisopropanol
Tang, Ren-Jin,Milcent, Thierry,Crousse, Benoit
, p. 930 - 938 (2018/01/28)
Regioselective halogenation of arenes and heterocycles with N-halosuccinimides in fluorinated alcohols is disclosed. Under mild condition reactions, a wide diversity of halogenated arenes are obtained in good yields with high regioselectivity. Additionally, the versatility of the method is demonstrated by the development of one-pot sequential halogenation and halogenation-Suzuki cross-coupling reactions.
A NOVEL ROUTE FOR PREPARATION OF L,3:2,4-BIS-(3,4- D IM ETH YLB ENZYLIDENE)SO RB ITO L
-
Page/Page column 6, (2016/06/01)
A new route for preparation of 3:2,4-bis-(3,4- dimethylbenzylidene) sorbitol [DMDBS] has been disclosed which is comprising: bromination of o-xylene to obtain a mixture of 4-bromo- o-xylene as a major product and 3-bromo-o-xylene; conversion of bromo-o-xylenes into corresponding dimethylbenzaldehyde by Grignard reaction; and reaction of 3,4-dimethylbenzaldehyde with sorbitol in presence of catalyst and solvent to obtain DMDBS. The invented route is cost-effective and it obviates the need to separate 3,4-dimethylbenzaldehyde from its 2,3-isomer.
On the ionizing properties of supercritical carbon dioxide: Uncatalyzed electrophilic bromination of aromatics
Delgado-Abad, Thais,Martnez-Ferrer, Jaime,Reig-Lpez, Javier,Mello, Rossella,Acerete, Rafael,Asensio, Gregorio,Gonzlez-Nez, Mara Elena
, p. 51016 - 51021 (2015/01/16)
Supercritical carbon dioxide (scCO2), a solvent with a zero dipole moment, low dielectric constant, and no hydrogen bonding behavior, is a suitable medium to perform the uncatalyzed electrophilic bromination of weakly activated aromatics with no interference of radical pathways. The ability of scCO2 to promote these reactions matches those of strongly ionizing solvents such as aqueous acetic and trifluoroacetic acids. Conversely, carbon tetrachloride, with similar polarity parameters to scCO2, leads exclusively to side chain functionalization. The strong quadrupole moment, and the acidic, but non basic, Lewis character of carbon dioxide, are proposed as key factors for the singular performance of scCO2 in reactions involving highly polar and ionic intermediates.
Induced bromination of aromatic hydrocarbons with alkali metal bromides in the presence of oxidants
Sadygov,Alimardanov,Chalabiev
, p. 949 - 956 (2008/02/05)
The features of induced bromination of aromatic hydrocarbons in the NaBr(KBr)-HX-H2O2(NaOCl) system were studied. Pleiades Publishing, Inc., 2006.
Induced bromination of aromatic hydrocarbons by alkali metals bromides and sodium hypochlorite
Sadygov,Alimardanov,Chalabiev
, p. 1631 - 1636 (2007/10/03)
Induced bromination of aromatic compounds in a system MBr-acid-NaOCl was studied. Optimum conditions of the process were developed, kinetics of the reactions were investigated, and the process mechanism was suggested. The bromination occurs both with the bromine in statu nascendi and with the hypobromous acid by hydrogen substitution exclusively in the aromatic ring. 2005 Pleiades Publishing, Inc.
Regioselective bromination of aromatic compounds with Br 2/SO2Cl2 over microporous catalysts
Gnaim, Jallal M.,Sheldon, Roger A.
, p. 4465 - 4468 (2007/10/03)
A new selective brominating system Br2/SO2Cl 2/zeolite, has been discovered. Partially cation-exchanged Ca 2+-Y zeolite efficiently catalyzes the selective para-bromination of neat chlorobenzene (CB) by Br2/SO2Cl2 affording a CB conversion of ～89% and a para-selectivity of ～97%. During the bromination reaction, SO2Cl2 oxidizes HBr, prevents its accumulation within the zeolite pores and yields a more active brominating species. The Ca2+-Y catalyst was found to be stable under the bromination conditions, and can easily be regenerated by calcination. The Br2/SO2Cl2/Ca2+-Y brominating system could be applicable to other activated aromatic compounds such as o-xylene, toluene and fluorobenzene.
Ionic liquid promoted regioselective monobromination of aromatic substrates with N-bromosuccinimide
Rajagopal,Jarikote,Lahoti,Daniel, Thomas,Srinivasan
, p. 1815 - 1817 (2007/10/03)
Aromatic substrates were monobrominated regioselectively with NBS in the ionic liquid 1,3-di-n-butylimidazolium tetrafluoroborate [bbim]BF4 in 5 min at 28°C in excellent isolated yields (80-98%) in the absence of a catalyst.
Efficient method for the preparation of aromatic bromides and iodides by ferrocenium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate-catalyzed halogenation with bromine and iodine monochloride
Kitagawa, Hideo,Shibata, Tsuyoshi,Matsuo, Jun-Ichi,Mukaiyama, Teruaki
, p. 339 - 345 (2007/10/03)
Direct iodination and bromination of various aromatic compounds with 1.1-2.0 molar amounts of iodine monochloride (ICl) and 1.1-3.0 molar amounts of bromine proceeded smoothly to afford the corresponding aromatic iodides and bromides, respectively, in good to excellent yields by using 0.05 molar amount of ferrocenium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, Cp2FeB[3,5-(CF3)2C6H 3]4 (1), in the presence of ZnO. Iodination of toluene in the co-existence of 0.5 molar amount of DDQ also proceeded to give iodotoluenes in high yield.
Increasing the selectivity of bromination of aromatic compounds using Br2/SiO2
Ghiaci,Asghari
, p. 1151 - 1152 (2007/10/03)
Br2/SiO2 possessed considerable practical advantages over traditional reagents for the bromination of aromatic hydrocarbons, e.g., toluene, o-, m-, and p-xylene, anthracene and phenol. In the presence of SiO2, toluene reacted with bromine instantly. Compounds containing electron-donating substituents showed mainly bromination on the rings. The behavior of o-, m-, and p-xylene showed predominant substitution on the rings. The bromination of phenol to p-bromophenol showed good yield at 81%. Naphthalene was monobrominated to 1-bromonaphthalene with a yield of 84% in 2 has the potential to alter reaction selectivity. It may be able to switch a mechanism from radical to polar, or to influence the regioselectivity of the products formed. In the absence of SiO2, selectivity was lost and a mixture of products by substitution of bromine atom on the ring and on the side chain without any preferability was obtained. The nature of silica gel was important for the success of the reaction. Optimal results were obtained with silica gel dried at 250°C for 1 hr.
