- C-H nickellation of phenol-derived phosphinites: Regioselectivity and structures of cyclonickellated complexes
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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.
- Mangin, Lo?c P.,Zargarian, Davit
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Read Online
- Highly efficient heterogeneous V2O5@TiO2 catalyzed the rapid transformation of boronic acids to phenols
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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.
- Upadhyay, Rahul,Singh, Deepak,Maurya, Sushil K.
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supporting information
p. 3925 - 3931
(2021/08/24)
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- Reticular Synthesis of tbo Topology Covalent Organic Frameworks
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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.
- Kang, Xing,Han, Xing,Yuan, Chen,Cheng, Cheng,Liu, Yan,Cui, Yong
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supporting information
p. 16346 - 16356
(2020/10/26)
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- Synthesis method for 3,5-dimethyl benzaldehyde
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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.
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Paragraph 0006; 0015
(2016/10/10)
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- Oxidative hydroxylation of arylboronic acids to phenols catalyzed by copper nanoparticles ellagic acid composite
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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.
- Affrose, Abdullah,Azath, Ismail Abulkalam,Dhakshinamoorthy, Amarajothi,Pitchumani, Kasi
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p. 500 - 505
(2014/12/10)
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- 2-(Trimethylsilyl)ethanol as a new alcohol equivalent for copper-catalyzed coupling of aryl iodides
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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.
- Dibakar, Mullick,Prakash, Anjanappa,Selvakumar, Kumaravel,Ruckmani, Kandasamy,Sivakumar, Manickam
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p. 5338 - 5341
(2011/10/19)
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- Mechanisms of hydrolysis of phenyl- and benzyl 4-nitrophenyl-sulfamate esters
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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.
- Spillane, William J.,Thea, Sergio,Cevasco, Giorgio,Hynes, Michael J.,McCaw, Cheryl J. A.,Maguire, Neil P.
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supporting information; experimental part
p. 523 - 530
(2011/03/17)
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- Methanolysis of organophosphorus esters promoted by an M2+ catalyst supported on polystyrene-based copolymers
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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.
- Didier, Benoit,Mohamed, Mark F.,Csaszar, Elizabeth,Colizza, Kate G.,Neverov, Alexei A.,Brown, R. Stan
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- 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
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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.
- Raina, Vishakha,Rentsch, Daniel,Geiger, Thomas,Sharma, Poonam,Buser, Hans Rudolf,Holliger, Christof,Lal, Rup,Kohler, Hans-Peter E.
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experimental part
p. 6594 - 6603
(2010/04/06)
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- Process for the synthesis of phenols from arenes
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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.
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- Process for functionalising a phenolic compound carrying an electron-donating group
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The invention concerns a method for functionalizing a phenolic compound bearing an electron-donor group, in said group para position, inter alia a method for the amidoalkylation of a phenolic compound bearing an electron-donor group, and more particularly, a phenolic compound bearing an electron-donor group preferably, in the hydroxyl group ortho position. The method for functionalizing in para position with respect to an electron-donor group carried by a phenolic compound is characterised in that the phenolic compound bearing an electron-donor group is subjected to the following steps: a first step which consists of protecting the hydroxyl group in the form of a sulphonic ester function; a second step which consists in reacting the protected phenolic compound with an electrophilic reagent; optionally, a third step deprotecting the hydroxyl group.
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- 6-(Nonsubstituted or substituted) phenoxy picolinic acids, process of preparing the same, and agricultural/horticultural germicides containing the same
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An agricultural or horticultural fungicide containing 6-(unsubstituted or substituted) phenoxy picolinic acid represented by the general formula (I), as an effective ingredient. wherein R is a halogen atom, a C1to C4alkyl group, a C1to C4haloalkyl group, a C1to C4alkoxy group, a C1to C4haloalkoxy group, a C1to C4alkylthio group, a C1to C4alkylamino group, a di(C1to C4alkyl)amino group or a C7to C8aralkyl(C1to C4alkyl)amino group; n2is an integer of 0 to 3; Y is a C1to C4alkyl group, a C1to C4haloalkyl group, a C1to C4alkoxy group, a C1to C4haloalkoxy group, a C1to C4alkylthio group, a C1to C4haloalkylthio group or a halogen atom; and m is an integer of 0 to 5, and when m and n2are not less than 2, Rs and Ys may be the same or different, respectively. The compound is useful as an effective ingredient of agricultural or horticultural fungicides.
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- Hydrogen bonding Part 44 1Thermodynamics of complexation of 3,5-dichlorophenol with ketones and ethers in cyclohexane: The badger-Bauer relationship
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Equilibrium constants for 1 : 1 hydrogen bond complexation between 3,5-dichioropheno' (DCP) and 17 ketones and 12 ethers in cyclohexane solution have been obtained by an FTIR method that takes into account both diiaerization of the acid and formation of 2 :1 complexes. Enthalpies of complexation for the same ketones and ethers have been determined by a calorimeiric method, leading to values of log K, AG, AH and AS0 for 1 :1 complexation in the 29 systems, as well as log K2 for the 2 :1 complexation between 2 mol of acid and 1 mol of base. For the ketone systems there is very little variation in the three thermodynamic parameters with alkyl substitution, but for the ethers there are systematic variations depending on the alkyl substituent or if the ethers are cyclic. Values of the OH stretching frequency in the DCP complexes with the ketones and ethers in cyclohexane have been obtained. The band shapes for the DCP-ketone complexes are very asymmetric, possibly due to the presence of stereoisomeric complexes, but the VOH band for DCP-ether complexes is symmetric and very suitable for the evaluation of any relationship between v()H and A/f. It is found that for the complexation of DCP with the 12 aliphatic ethers in cyclohexane, there is almost no connection between the calorimetrically determined AH° values and values of AvOH.
- Abraham, Michael H.,Prior, David V.,Schulz, Ronald A.,Morris, Jeffrey J.,Taylor, Peter J.
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p. 879 - 885
(2007/10/03)
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- Para-hydroxyalkylation of hydroxylated aromatic compounds
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Hydroxylated aromatic compounds devoid of substituents in the para-position to the hydroxyl group thereof are para-hydroxyalkylated, e.g., into optionally substituted p-hydroxymandelic acid compounds, more particularly p-hydroxymandelic acid and 3-methoxy-p-hydroxymandelic acid, by condensing same with an organic carbonyl compound in the presence of a quaternary ammonium hydroxide.
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- Liquid-phase fluorination and dehydrochlorination of 1,1,1-trichloroethane
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During the liquid-phase fluorination of 1,1,1-trichloroethane with SbCl5*HF, 1,1-dichloroethene is formed.This reacts to give linear and branched oligomers.The hydrolysis of these by-products affords 3,5-dichlorophenol, 6-methyl-4-chloro-2-pyran-2-one and 2-methyl-5,7-dichlorochromone whose source is the acid-catalyzed reaction of water with the trimer and pentamer of 1,1-dichloroethene.
- Brunet, Sylvette,Batiot, Catherine,Barrault, Joeel,Blanchard, Michel,Coustard, Jean-Marie
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p. 227 - 232
(2007/10/02)
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- Cleavage of ethers and geminal diacetates using the boron triiodide-N,N-diethylaniline complex
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The boron triiodide-N,N-diethylaniline complex, generated in situ from borane:N,N-diethylaniline and iodine cleaves ethers and regenerates carbox-aldehydes from the corresponding geminal diacetate derivatives under mild conditions in good yields. Recently a simple procedure for the preparation of alkyl and alkenyl iodides in good yields using boron triiodide-N,N-diethylaniline complex and acetic acid was reported.1 This prompted us to report our results on the cleavage of ethers and regeneration of aldehydes from geminal diacetates using the boron triiodide-N,N-diethylaniline reagent.
- Narayana, Chatla,Padmanabhan, Seetharamaiyer,Kabalka, George W.
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p. 6977 - 6978
(2007/10/02)
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- Charge Description of Base-Catalyzed Alcoholysis of Aryl Phosphodiesters: A Ribonuclease Model
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The release of substituted phenol from aryl uridine-3'-phosphates is catalyzed by bases and involves cyclization to form the 2',3'-cyclic nucleotide.The rate constants for imidazole and hydroxide ion catalysis (kim and kOH, respectively) obey the Broensted equations (25 deg C and 0.25 M ionic strength) log kim = -0.59 pKArOH + 1.40 (n = 7, r = 0.955) and log kOH = -0.54 pKArOH + 6.68 (n = 9, r = 0.967).General-base-catalyzed release of 4-nitrophenol from the 4-nitrophenyl ester (kB) obeys the Broensted relationship log kB = 0.67 pKBH - 7.50 (n = 7, r = 0.989).Charge changes on base and leaving group atoms as determined from the corresponding β and βeq values do not balance.Comparison with data in the literature indicates that the difference in charge may be assigned to the attacking oxygen (2'-hydroxyl) rather than to the phosphoryl oxygens in the O...PO2... group of atoms.Both P-O bond forming and bond fission components of the reaction are considered to be only weakly advanced in a transition state that lies on a concerted pathway.
- Davis, Andrew M.,Hall, Adrian D.,Williams, Andrew
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p. 5105 - 5108
(2007/10/02)
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- Vapour-phase Chemistry of Arenes. Part 10. Formation of Phenols in Air Oxidation of Benzene, Chlorobenzene, m-Dichlorobenzene, and Benzonitrile in the Presence of Cyclohexa-1,3-diene at ca. 600 K
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In a flow reactor at 573-623 K, flow time ca. 2 min, vapours of benzene and derivatives, e.g. chlorobenzene and benzonitrile, are not measurably oxidized by air.In the presence of small amounts of cyclohexa-1,3-diene (1), however, substantial conversion of (1) is accompanied by formation of phenols from arenes.The main oxidation product of (1) is benzene, but some phenol, and cyclohex-3-enone (2) is also formed.Conversion of (1) is largely due to hydrogen abstraction by O2, log(A2/l mol-1 s-1)=8.9, E2 ca. 104 kJ mol-1.The resulting cyclohexadienyl radicalgives benzene by disproportionation with O2.Formation of phenol is explained by addition of O2 to cyclohexadienyl radical, followed by rearrangement and reaction with O2.Addition of HO2 to (1) is shown to be the likely first step in forming non-aromatic oxygenated products such as (2).This slow combustion of (1) leads to OH radicals which must be responsible for conversion of arene.Product data, especially isomeric composition of substituted phenols, as well as thermochemical-kinetic analysis indicate that, at ca. 600 K, a mechanistic transition occurs, from addition of OH (prevailing at lower temperatures) to hydrogen abstraction to give aryl radicals, which lead to phenol via ArO2 and ArO.
- Mulder, Peter,Louw, Robert
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p. 1135 - 1142
(2007/10/02)
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- STUDIES ON 1-ARYLOXYSILATRANES, II. - HYDROLYTIC STABILITY OF 1-ARYLOXYSILATRANES
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The effect of substituents in the benzene ring on the rate constants of the hydrolysis of 1-aryloxysilatranes was investigated.A good correlation of log k vs. Σ? was obtained suggesting SN2-Si mechanism of the hydrolysis of all the compounds studied.The influence of the salt effect and reaction medium on the rate constant was also examined.The activation energies were determined for six compounds.
- Lukasiak, J.,Jamrogiewicz, Z.
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p. 167 - 172
(2007/10/02)
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- REDUCTION OF CARBON-CARBON DOUBLE BONDS AND HYDROGENOLYSIS BY SODIUM HYPOPHOSPHITE
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Sodium hypophosphite plus palladium-charcoal is a mild, economical, selective system for the reduction of carbon-carbon double bonds and hydrogenolysis of benzyl ethers and benzyl carbonates.
- Sala, Roberto,Doria, Gianfederico,Passarotti, Carlo
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p. 4565 - 4568
(2007/10/02)
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- THE REACTIONS OF UNACTIVATED ARYL HALIDES WITH SODIUM METHOXIDE IN HMPA; SYNTHESIS OF PHENOLS, ANISOLES, AND METHOXYPHENOLS
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Sodium methoxide reacts with dichlorobenzenes in HMPA to give the chloroanisoles as a result of a SNAr process.Excess MeONa then effects the demethylation of the ethers to give the chlorophenols via an SN2 reaction.With tri- and tetrachlorobenzenes the initially formed chloroanisoles can be dealkylated to chlorophenols or can suffer further substitution to give the chlorodimethoxybenzenes; these react with excess MeONa to give the chloromethoxyphenols.The results obtained with the various isomers of the di-, tri-, and tetrachlorobenzenes are presented and discussed on the basis of the electronic effects of the substituents.
- Testaferri, L.,Tiecco, M.,Tingoli, M.,Chianelli, D.,Montanucci, M.
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p. 193 - 198
(2007/10/02)
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- Process for producing polyhalogenated phenols
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A process for producing polyhalogenated phenol by mixing a polyhalogenated aniline with an aqueous sulfuric acid solution to obtain a suspension of fine particles of polyhalogenated aniline sulfate having the particle size of 50 μ or less, diazotizing the polyhalogenated aniline sulfate to obtain polyhalogenate benzenediazonium sulfate, hydrolyzing the resulting benzenediazonium sulfate by heating it as such, recycling to the diazotization step the aqueous sulfuric acid solution from which the desired polyhalogenated phenol has been separated.
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