608-26-4Relevant academic research and scientific papers
NEW PROCESS FOR THE SYNTHESIS OF PIPERAZINYL-ETHOXY-BROMOPHENYL DERIVATES AND THEIR APPLICATION IN THE PRODUCTION OF COMPOUNDS CONTAINING THEM
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Page/Page column 23-26, (2020/05/21)
Process for the industrial synthesis of the compound of formula (I).
para-Selective chlorination of cresols and m-xylenol using sulfuryl chloride in the presence of poly(alkylene sulfide)s
Smith, Keith,Hegazy, Amany S.,El-Hiti, Gamal A.
, p. 345 - 356 (2020/03/23)
Chlorination of o-cresol, m-cresol, and m-xylenol using sulfuryl chloride in the presence of a range of poly(alkylene sulfide)s and a Lewis acid (aluminum or ferric chloride) has been studied. The sulfur containing catalysts used led to the production of para-chlorophenols in high yields and higher para/ortho ratios than for reactions in the absence of such poly(alkylene sulfide)s. The effectiveness of the polymers was found to be dependent on the length of the spacer groups between the sulfur atoms. For example, polymers with shorter spacers provided high yields of 4-chloro-o-cresol (ca. 97%), while polymers with at least one longer spacer provided high yields of both 4-chloro-m-cresol (up to 94.6%) and 4-chloro-m-xylenol (up to 97.6%).
Regioselective chlorination of phenols in the presence of tetrahydrothiopyran derivatives
Smith, Keith,Williams, Des,El-Hiti, Gamal A.
, p. 529 - 538 (2019/06/13)
Four six-membered cyclic sulfides, namely tetrahydrothiopyran, 3-methyltetrahydrothiopyran, 4-methyltetrahydrothiopyran and 4,4-dimethyltetrahyrdrothiopyran have been used as moderators in chlorination reactions of various phenols with sulfuryl chloride in the presence of aluminum or ferric chloride. On chlorination of phenol, ortho-cresol and meta-cresol the para/ortho chlorination ratios and yields of the para-chloro isomers are higher than when no cyclic sulfide is used for all of the cyclic sulfides, but chlorination of meta-xylenol is less consistent, with some cyclic sulfides producing higher p/o ratios and others producing lower ratios than reactions having no sulfide present.
Examination of Selectivity in the Oxidation of ortho- and meta-Disubstituted Benzenes by CYP102A1 (P450 Bm3) Variants
Munday, Samuel D.,Dezvarei, Shaghayegh,Lau, Ian C.-K.,Bell, Stephen G.
, p. 2512 - 2522 (2017/07/12)
Cytochrome P450 CYP102A1 (P450 Bm3) variants were used to investigate the products arising from the P450 catalysed oxidation of a range of disubstituted benzenes. The variants used all generated increased levels of metabolites compared to the wild-type enzyme. With ortho-halotoluenes up to six different metabolites could be identified whereas the oxidation of 2-methoxytoluene generated only two aromatic oxidation products. Addition of an ethyl group markedly shifted the selectivity for oxidation to the more reactive benzylic position. Epoxidation of an alkene was also preferred to aromatic oxidation in 2-methylstyrene. Significant minor products arising from the migration of one substituent to a different position on the benzene ring were formed during certain P450-catalysed substrate turnovers. For example, 2-bromo-6-methylphenol was formed from the turnover of 2-bromotoluene and the dearomatisation product 6-ethyl-6-methylcyclohex-2,4-dienone was generated from the oxidation of 2-ethyltoluene. The RLYF/A330P variant altered the product distribution enabling the generation of certain metabolites in higher quantities. Using this variant produced 4-methyl-2-ethylphenol from 3-ethyltoluene with ≥90 % selectivity and with a biocatalytic activity suitable for scale-up of the reaction.
Comparison of cyclic and polymeric disulfides as catalysts for the regioselective chlorination of phenols
Smith, Keith,Al-Zuhairi, Ali J.,El-Hiti, Gamal A.,Alshammari, Mohammed B.
, p. 74 - 85 (2015/10/20)
Two cyclic and two polymeric disulfides have been synthesized and established to be useful catalysts for the chlorination of m-xylenol, o-cresol, m-cresol and phenol using freshly distilled sulfuryl chloride in the presence of aluminum or ferric chloride as a co-catalyst at room temperature. The yields of p-isomers and para/ortho ratios were higher compared to cases where no catalyst was used with most catalysts for most phenols even when a very low concentration of disulfide was used.
Investigations of the reactions of monochloramine and dichloramine with selected phenols: Examination of humic acid models and water contaminants
Heasley, Victor L.,Fisher, Audra M.,Herman, Erica E.,Jacobsen, Faith E.,Miller, Evan W.,Ramirez, Ashley M.,Royer, Nicole R.,Whisenand, Josh M.,Zoetewey, David L.,Shellhamer, Dale F.
, p. 5022 - 5029 (2008/04/18)
The phenols are an important area of investigation because they are substituents in the humic acids and are common contaminants in water. The reactivities and orientations of two common phenols (phenol and m-cresol), and some of their chlorinated intermediates with aqueous monochloroamine and dichloroamine were presented. m-Cresol was more reactive than phenol with both chlorinating agents. NH2Cl and NHCl2 showed extensive reactivity toward the phenols, even the partially chlorinated less reactive intermediates would be expected to fully chlorinate the activated positions in phenolic substituents in the humic acids.
A simple, efficient and regioselective oxychlorination of aromatic compounds using ammonium chloride and oxone
Narender,Mohan, K.V.V. Krishna,Srinivasu,Kulkarni,Raghavan
, p. 1335 - 1338 (2007/10/03)
A simple, efficient, mild and regioselective method for oxychlorination of aromatic compounds is reported. The electrophilic substitution of chlorine generated in situ from NH4Cl as a chlorine source and oxone as an oxidant is reported for the first time.
Kinetics of chlorination of phenol and monosubstituted phenols by t-butyl hypochlorite in aqueous alkaline medium
Moodithaya,Gowda, B. Thimme
, p. 420 - 425 (2007/10/03)
The kinetics of chlorination of the parent and sixteen monosubstituted phenols (2-chloro, 2-methyl, 2-carboxy, 2-nitro, 3-chloro, 3-methyl, 3-carboxy, 4-fluoro, 4-chloro, 4-bromo, 4-methyl, 4-ethyl, 4-methoxy, 4-carboxy, 4-acetyl and 4-nitro) by t-BuOCl have been studied in aqueous alkaline medium. The rates of reactions show first order kinetics each in |t-BuOCl| and |XC 6H4OH| and inverse first order in |OH-|. Variation in either ionic strength or addition of reaction product has no significant effect on the rates of reactions, while lowering of the dielectric constant of the medium increases the rate. The rates are measured at different temperatures and the activation parameters for all the phenols computed. A mechanism involving the electrophilic attack of phenoxide ions by HOCl in the rate determining step is suggested. The rates decrease in the order: 3-CH 3 > 2-CH3 > 4-OCH3 > 4-CH3 > 4-C2H5 > H > 3-Cl > 3-COO- > 4-F > 2-COO- > 4-Br > 2-Cl > 4-Cl > 4-COO- > 4-COCH3 > 2-NO2 > 4-NO2. Hammett equation of the type, log k = -3.44 - 2.35 ρ is found to be valid for substituent effects. The enthalpy and entropy of activation are correlated.
Kinetics and mechanism of chlorination of phenol and substituted phenols by sodium hypochlorite in aqueous alkaline medium
Gowda,Mary
, p. 1196 - 1202 (2007/10/03)
The kinetics of chlorination of the parent and thirteen substituted phenols (2-methyl, 2-chloro, 2-carboxy, 3-methyl, 3-chloro, 3-carboxy, 4-methyl, 4-ethyl, 4-chloro, 4-bromo, 4-carboxy, 4-acetyl and 4-nitro phenols) by NaOCl have been studied in aqueous alkaline medium under varying conditions. The rates show first order kinetics each in [NaOCl] and [(X)C6H4(OH)] and inverse first order in [OH-]. Variation in ionic strength of the medium and addition of Cl have no significant effect on the rates of reactions. The rates of the reactions are measured at different temperatures and the activation parameters for all the phenols computed. A mechanism involving the electrophilic attack of the phenoxide ions by NaOCl in the rate determining step has been considered. The values of the pre-equilibrium and the rate determining steps have been calculated for all the phenols. The rates decrease in the order: 3-CH3 >2-CH3 >4-C2H5 = 4-CH3 >phenol >3-COO = 3-Cl > 2-COO >4-COO >2-Cl ? 4-Cl ? 4-Br > 4-COCH3 >4-NO2. Hammett plot of the type, log kobs = -2.88 -3.2980σ is found to be valid. The correlation between the enthalpies and the free energies of activations is reasonably linear with an isokinetic temperature of 300 K. Further, the energies of activation of all the phenols are optimised corresponding to the log A of the parent phenol through the equation, Ea = 2.303 RT (log A - log kobs). Similarly log A values of all the phenols are optimised corresponding to the Ea of PhOH through the equation, log A = log kobs + Ea/2.303RT. Ea increases with the introduction of electron-withdrawing groups into the benzene ring, while the introduction of the electron-releasing groups lowers Ea for the reaction. Similarly log A decreases with the substitution of electron-withdrawing groups, while log A increases on substitution with the electron-releasing groups.
Reactions of OH and SO4.- with Some Halobenzenes and Halotoluenes: A Radiation Chemical Study
Merga, Getahun,Rao, B. S. M.,Mohan, H.,Mittal, J. P.
, p. 9158 - 9164 (2007/10/02)
The optical absorption and kinetic characteristics of the transients formed in the reactions of OH and SO4.- with bromobenzene, ortho and meta-isomers of chloro- and bromobenzenes, and monobromotoluenes have been studied by pulse radiolysis technique.The rates for OH reaction are generally higher (k = (1.7-4.4)X109 M-1s-1) than those found for the SO4.- reaction (k = (0.4-2.3)x109 M-1s-1). ρ+ values of -0.4 for OH and -1.2 for SO4.- reactions were obtained from the Hammett analysis.The formation of substituted hydroxycyclohexadienyl radicals (λmax = 315-330 nm) is the major reaction channel, and the phenoxyl type radical (λ >/=400 nm) formation is an additional minor process in the SO4.- reaction.Abstraction of H by SO4.- from the -CH3 group is only significant with the para-isomers of bromo- and chlorotoluenes.This result is in accord with the observed yields (70 percent of SO4.-) of the products resulting from the oxidation of the 4-chlorobenzyl radical in the presence of K3Fe(CN)6 under steady-state conditions.The total yields of the phenolic products accounting for >90 percent of OH and SO4.- suggest that the attack at the ipso positions is considerably small.The rate constants for OH reactions relative to benzene at positions 3 and 6 of 2-chlorotoluene and positions 2 and 3 of 4-chlorotoluene are between 1.18 and 1.39, indicating that the directing effects of -CH3 and -Cl groups are comparable.This is also reflected in the additive effects of activation of the ortho and para-positions and deactivation of meta-positions by these substituents in 3-chlorotoluene.
