591-35-5Relevant academic research and scientific papers
C-H nickellation of phenol-derived phosphinites: Regioselectivity and structures of cyclonickellated complexes
Mangin, Lo?c P.,Zargarian, Davit
, p. 16159 - 16170 (2017)
This report describes the results of a study on the ortho-C-H nickellation of the aryl phosphinites i-Pr2P(OAr) derived from the following four groups of substituted phenols: 3-R-C6H4OH (R = F (b), Me (c), MeO (d), Cl (e)); 3,5-R2-C6H3OH (R = F (f), Me (g), Cl (h), OMe (i)); 2-R-C6H4OH (R = Me (j), Ph(k)); and 2,6-R2-C6H3OH (R = Me (l), Ph (m)). No nickellation was observed with the phosphinites derived from the 3,5-disubstituted phenols g and h, and the 2,6-disubstituted phenols l and m; in all other cases nickellation occurred at an ortho-C-H to generate either the Br-bridged dimers [{κP,κC-(i-Pr)2POAr}Ni(μ-Br)]2 (1b-1f, 1j, and 1k) or the monomeric acetonitrile adduct {κP,κC-ArOP(i-Pr)2}Ni(Br)(NCMe) (1i-NCMe). Analysis of C-H nickellation regioselectivity with 3-R-C6H4OH pointed to the importance of substituent sterics, not electronics: nickellation occurred at the least hindered position either exclusively (for R = Me (c), MeO(d), and Cl (e)) or predominantly (for R = F (b); 6:1). This conclusion is also consistent with the observation that C-H nickellation is possible with the 3,5-disubstituted aryl phosphinites bearing F and OMe, but not with the more bulky substituents Me or Cl. For the 2-substituted aryl phosphinites, C-H nickellation occurs at the unsubstituted ortho-C-H and not on the R substituent, regardless of whether the alternative C-H moiety of the substituent is sp3 (R = Me (j)) or sp2 (R = Ph (k)). The system thus reveals a strong preference for formation of 5-membered metallacycles. Consistent with this reactivity, no nickellation occurs with (2,6-R2-C6H3O)P(i-Pr)2. Tests with the parent dimer derived from i-Pr2P(OPh) showed that conversion to the monomeric acetonitrile adduct is highly favored, going to completion with only a small excess of MeCN. All new cyclonickellated complexes reported in this study were fully characterized, including by single crystal X-ray diffraction studies. The solid state structures of the dimers 1b and 1d showed an unexpected feature: two halves of the dimers displayed non-coplanar conformations that place the two Ni(ii) centers at shortened distances from each other (2.94-3.16 ?). Geometry optimization studies using DFT have shown that such non-coplanar conformations stabilize the complex, implying that the "bending" observed in these complexes is not caused by packing forces. Indeed, it appears that the occurrence of coplanar conformations in the solid state structures of these dimers is a simple consequence of packing forces rather than an intrinsic property of the compound.
Highly efficient heterogeneous V2O5@TiO2 catalyzed the rapid transformation of boronic acids to phenols
Upadhyay, Rahul,Singh, Deepak,Maurya, Sushil K.
supporting information, p. 3925 - 3931 (2021/08/24)
A V2O5@TiO2 catalyzed green and efficient protocol for the hydroxylation of boronic acid into phenol has been developed utilizing environmentally benign oxidant hydrogen peroxide. A wide range of electron-donating and the electron-withdrawing group-containing (hetero)aryl boronic acids were transformed into their corresponding phenol. The methodology was also applied successfully to transform various natural and bioactive molecules like tocopherol, amino acids, cinchonidine, vasicinone, menthol, and pharmaceuticals such as ciprofloxacin, ibuprofen, and paracetamol. The other feature of the methodology includes gram-scale synthetic applicability, recyclability, and short reaction time.
Reticular Synthesis of tbo Topology Covalent Organic Frameworks
Kang, Xing,Han, Xing,Yuan, Chen,Cheng, Cheng,Liu, Yan,Cui, Yong
supporting information, p. 16346 - 16356 (2020/10/26)
The metal-organic framework (MOF) HKUST-1 with a tbo topology serves as an archetypal tunable and isoreticular framework platform for targeting desired applications, but the design and synthesis of tbo-covalent organic frameworks (COFs) remains a formidable challenge. Here we demonstrate the successful use of reticular chemistry as an appropriate strategy for the design and deliberate construction of COFs with a tbo topology. The judicious selection of the perquisite planar building blocks, 4-connected square tetramine of porphyrin and 3-connected trigonal trialdehydes of triphenylamine, allows the condensation of two tbo-COFs, the first examples of COFs with a tbo topology. The resulting COFs both crystallize in the cubic Pm3ˉ space group and adopt a non-interpenetrated open framework, in which each tritopic linker connects to three square units forming a truncated Td-octahedron and occupies the alternating triangular faces of the truncated octahedron. Owing to the presence of two different types of photoredox-active moieties, the two COFs can be efficient heterogeneous photocatalysts for the oxidative hydroxylation of arylboronic acids and the reductive defluoroalkylation of trifluoromethyl aromatics with alkenes. The present finding will provide an impetus to examine the potential of tbo-COFs as a new platform for engineering multifunctional materials via expansion and functionalization of building blocks.
Synthesis method for 3,5-dimethyl benzaldehyde
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Paragraph 0006; 0015, (2016/10/10)
The invention discloses a synthesis method for 3,5-dimethyl benzaldehyde, and belongs to the technical field of organic chemical synthesis.The synthesis method comprises the steps that 3,5-dichlorophenol is generated by taking phenol as a raw material and introducing nitrogen; a phosphorus trichloride solution, a H2SO4 solution, zinc powder and iron powder are added into 3,5-dichlorophenol, and 3,5-dimethoxyphenol is generated through a reaction; a NaHCO3 solution and a HCl solution are added into generated 3,5-dimethoxyphenol, after reacting under stirring is performed, ZnO, ZrO2, CaO and MgO are added, and then light yellow 3,5-dimethyl benzaldehyde is prepared.According to the synthesis method, operation is easy to achieve, and the final yield is 85% or above.
Oxidative hydroxylation of arylboronic acids to phenols catalyzed by copper nanoparticles ellagic acid composite
Affrose, Abdullah,Azath, Ismail Abulkalam,Dhakshinamoorthy, Amarajothi,Pitchumani, Kasi
, p. 500 - 505 (2014/12/10)
Copper nanoparticles (Cu NPs) were prepared by in situ reduction of CuSO4·5H2O using ellagic acid (EA) as the reducing agent as well as stabilizer and its catalytic activity is tested in the oxidative hydroxylation of phenylboronic acids to phenol without any added base or ligand. The synthesized Cu NPs-EA composite was characterized by UV-Vis., FT-IR, powder XRD and HRTEM analyses. The average particle size of Cu NPs is found to be in the range of 20-25 nm as evident from HRTEM and copper content is estimated to be 3.18 wt%. EA acts both as a reducing agent as well as a stabilizer for the in situ formation of Cu NPs. A small portion of Cu NPs is also found to undergo aerobic oxidation to give Cu2O NPs which does not take part in the reactions. A series of arylboronic acids are converted to the corresponding phenols in high yields at short reaction time under milder reaction conditions. It is also observed that Cu NPs-EA composite can be reused at least four times with a significant decrease in the yield.
2-(Trimethylsilyl)ethanol as a new alcohol equivalent for copper-catalyzed coupling of aryl iodides
Dibakar, Mullick,Prakash, Anjanappa,Selvakumar, Kumaravel,Ruckmani, Kandasamy,Sivakumar, Manickam
supporting information; experimental part, p. 5338 - 5341 (2011/10/19)
2-(Trimethylsilyl)ethanol as a new alcohol equivalent has been employed for copper-catalyzed coupling of aryl iodides. Using mild reaction conditions, it has been observed that substituted phenols and phenols with sensitive functional groups can be readily prepared.
Mechanisms of hydrolysis of phenyl- and benzyl 4-nitrophenyl-sulfamate esters
Spillane, William J.,Thea, Sergio,Cevasco, Giorgio,Hynes, Michael J.,McCaw, Cheryl J. A.,Maguire, Neil P.
supporting information; experimental part, p. 523 - 530 (2011/03/17)
The kinetics of hydrolysis at medium acid strength (pH interval 2-5) of a series of phenylsulfamate esters 1 have been studied and they have been found to react by an associative SN2(S) mechanism with water acting as a nucleophile attacking at sulfur, cleaving the S-O bond with simultaneous formation of a new S-O bond to the oxygen of a water molecule leading to sulfamic acid and phenol as products. In neutral to moderate alkaline solution (pH ≥ ～ 6-9) a dissociative (E1cB) route is followed that involves i) ionization of the amino group followed by ii) unimolecular expulsion of the leaving group from the ionized ester to give N-sulfonylamine [HNSO2] as an intermediate. In more alkaline solution further ionization of the conjugate base of the ester occurs to give a dianionic species which expels the aryloxide leaving group to yield the novel N-sulfonylamine anion [ -NSO2]; in a final step, rapid attack of hydroxide ion or a water molecule on it leads again to sulfamic acid. A series of substituted benzyl 4-nitrophenylsulfamate esters 4 were hydrolysed in the pH range 6.4-14, giving rise to a Hammett relationship whose reaction constant is shown to be consistent with the E1cB mechanism.
Methanolysis of organophosphorus esters promoted by an M2+ catalyst supported on polystyrene-based copolymers
Didier, Benoit,Mohamed, Mark F.,Csaszar, Elizabeth,Colizza, Kate G.,Neverov, Alexei A.,Brown, R. Stan
, p. 91 - 100 (2008/09/18)
The methanolysis of three neutral organophosphorus esters (a phosphonate, a phosphonothioate, and a phosphorothionate) promoted by several polymer-supported Zn(II) or Cu(II) containing catalysts was studied. The catalysts consist of a Zn(II) or Cu(II) complex with 1,5,9-triazacyclododecane or phenanthroline attached to a porous polystyrene resin. In each case, the polymer supported catalyst showed activity at near neutral s spH in methanol (8.38) and ambient temperature and provided accelerations of up to a factor of 2.9 × 106 relative to the background reaction at sspH 9.05. The solid materials could be reused several times and could be reactivated when the activity diminished. Various polymers of different porosity and extent of cross-linking were studied, with the net result being that larger porosities offer the best reactivity for catalyzed methanolysis of these OP species in methanol. This is explained by different parameters including the accessibility to reactive sites, the increase of concentration of catalytic sites on the surface of the polymer, and some cooperative effects between neighboring catalytic groups.
New metabolites in the degradation of α- and γ- hexachlorocyclohexane (HCH): Pentachlorocyclohexenes are hydroxylated to cyclohexenols and cyclohexenediols by the haloalkane dehalogenase LinB from Sphingobium indicum B90A
Raina, Vishakha,Rentsch, Daniel,Geiger, Thomas,Sharma, Poonam,Buser, Hans Rudolf,Holliger, Christof,Lal, Rup,Kohler, Hans-Peter E.
experimental part, p. 6594 - 6603 (2010/04/06)
Technical hexachlorocyclohexane (HCH) and lindane are obsolete pesticides whose former production and use led to widespread contaminations posing serious and lasting health and environmental risks. Out of nine possible stereoisomers, α-, β-, γ-, and -HCH are usually present at contaminated sites, and research for a better understanding of their biodegradation has become essential for the development of appropriate remediation technologies. Because haloalkane dehalogenase LinB was recently found responsible for the hydroxylation of β-HCH, δ-HCH, and δ-pentachlorocyclohexene (δ-PCCH), we decided to examine whether β- and γ-PCCH, which can be formed by LinA from α-and γ-HCH, respectively, were also converted by LinB. Incubation of such substrates with Escherichia coli BL21 expressing functional LinB originating from Sphingobium indicum B90A showed that both β-PCCH and γ-PCCH were direct substrates of LinB. Furthermore, we identified the main metabolites as 3,4,5,6-tetrachloro-2-cyclohexene-1-ols and 2,5,6-trichloro-2-cyclohexene-1,4-diols by nuclear magnetic resonance spectroscopy and gas chromatography-mass spectrometry. In contrast to α-HCH, γ-HCH was not a substrate for LinB. On the basis of our data, we propose a modified γ-HCH degradation pathway in which γ-PCCH is converted to 2,5-cyclohexadiene-1,4-diol via 3,4,5,6-tetrachloro-2-cyclohexene- 1-ol and 2,5,6-trichloro-2-cyclohexene-1,4-diol.
Process for the synthesis of phenols from arenes
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Page 19-21, (2008/06/13)
A process to synthesize substituted phenols such as those of the general formula RR′R″Ar(OH) wherein R, R′, and R″ are each independently hydrogen or any group which does not interfere in the process for synthesizing the substituted phenol including, but not limited to, halo, alkyl, alkoxy, carboxylic ester, amine, amide; and Ar is any variety of aryl or hetroaryl by means of oxidation of substituted arylboronic esters is described. In particular, a metal-catalyzed C—H activation/borylation reaction is described, which when followed by direct oxidation in a single or separate reaction vessel affords phenols without the need for any intermediate manipulations. More particularly, a process wherein Ir-catalyzed borylation of arenes using pinacolborane (HBPin) followed by oxidation of the intermediate arylboronic ester by OXONE is described.
