586-11-8Relevant academic research and scientific papers
A convenient synthesis of phenols
Kristianslund, Renate,Vik, Anders,Hansen, Trond V.
supporting information, p. 2809 - 2814 (2018/12/04)
Anilines are rapidly, often within 60 minutes, converted into the corresponding phenols in up to 87% isolated yield. The presented experimentally simple protocol display broad compatibility with a variety of functional groups, and in particular, well suited for the preparation of methyl-substituted phenols. Such phenols are not easily available by other synthetic approaches. The formation of phenolic radical coupling products was not observed even for activated anilines using this open flask method.
Interaction of hexamethylphosphoric triamide with m-dinitrobenzenes
Dutov, Mikhail D.,Serushkina, Olga V.
, p. 174 - 175 (2013/07/26)
Heating of 1-X-3,5-dinitrobenzenes (X is an electron-withdrawing group) in hexamethylphosphoric triamide affords the corresponding 1-X-3-dimethylamino-5- nitrobenzenes.
Ethyl acetate as a pro-reducing agent in an one-pot reductive deamination of nitroanilines
Bacherikov, Valeriy A.,Wang, May-Jane,Cheng, Shu-Yun,Chen, Ching-Huang,Chen, Kuo-Tung,Su, Tsann-Long
, p. 1027 - 1032 (2007/10/03)
The reductive deamination of various nitro-substituted anilines by the new method (20% H2SO4/NaNO2/ethyl acetate, Method 1) was studied and compared that with a similar procedure previously developed by Pare et al. (i.e., concentrated H2SO4/NaNO2/ethanol, Method 2) for the dediazonization of 4-methyl-2,6-dinitroaniline. The deaminated products derived from the mononitro-substituted anilines were obtained in good-to-high yield by Method 1 depending upon the position of the nitro group to the amino function. The higher yield of the de-aminated products was observed from the substituted meta-nitroanilines. Method 1 was more suitable for the deamination of 3-nitroanilines. Method 2 was more favorable for the de-amination of denitro-substituted anilines than that for the mononitroanilines. Ethyl acetate was more suitable for the reductive deamination of mononitroanilines, while ethanol was more appropriate for dinitroanilines.
Kinetics and mechanism of base-catalysed degradations of substituted aryl-N-hydroxycarbamates, their N-methyl and N-phenyl analogues
Beier, Petr,Mindl, Jaromir,Sterba, Vojeslav,Hanusek, Jiri
, p. 562 - 569 (2007/10/03)
The kinetics and mechanism of the degradation reactions of substituted phenyl N-hydroxycarbamates and their N-methyl and N-phenyl analogues have been studied at pseudo-first-order reaction conditions in aqueous buffers and sodium hydroxide solutions at 20°C and 60°C and at I = 1 mol·1 -1. The dependence of log kobs on pH for phenyl N-hydroxycarbamates at pH 13 is linear with the unit slope; at pH 10-12 log kobs is pH independent. The Bronsted coefficient βlg is about -1 (pH 7-13) and -1.53 (pH > 13) indicating that the degradation reaction of phenyl N-hydroxycarbamates follows an ElcB mechanism giving the corresponding phenol/phenolate and HO-N=C=O. The latter species undergoes further decomposition to give carbonate, nitrogen and ammonia as final products. In contrast to the phenyl N-hydroxycarbamates the N-methyl derivatives at pH 7-9 undergo degradation to the corresponding phenol/phenolate, carbonate and methylamine via a concerted mechanism (βlg is about - 0.75). The only exception is 4-nitrophenyl N-hydroxy-N-methylcarbamate in which the predominant break down pathway proceeds via the Smiles rearrangement to give sodium N-methyl-(4-nitrophenoxy)carbamate. At pH > 9 the reaction of N-hydroxy-N-methylcarbamates is kinetically complex: the dependence of absorbance on time is not exponential and it proceeds as a consecutive two-step reaction. N-Hydroxy-N-phenylcarbamate under the same conditions undergoes degradation to phenol, carbonate, aniline and azoxybenzene.
Substitution for a nitro group in 1,3,5-trinitrobenzene and meta-substituted 1,3-dinitrobenzenes under the action of oximes
Shevelev, Svyatoslav A.,Vatsadze, Irina A.,Dutov, Mikhail D.
, p. 196 - 198 (2007/10/03)
The title reaction was performed with 1,3,5-trinitrobenzene and 1-X-3,5-dinitrobenzenes (X = CF3, ArO) in the presence of K2CO3in N-methylpyrrolidone or DMF solutions to form O-3,5-dinitrophenyl oximes or O-3-X-5-nitrophenyl oximes, respectively.
Urea-linked, iodinated bis phenyl compounds for X-ray contrast media
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, (2008/06/13)
The invention provides iodinated bis phenyl compounds, useful as X-ray contrast agents, of formula I STR1 (wherein each C6 R5 moeity may be the same or different; each R denotes a hydrogen or iodine atom or a group M, two or three non-adjacent R groups on each C6 R5 moiety denoting iodine atoms and one, two or three R groups on each C6 R5 moiety denoting M groups; X denotes a group providing a 1, 2 or 3 atom chain linking the two C6 R5 groups, preferably where X is or contains in the bridging chain a carbonyloxy group each C6 R5 group being a triodophenyl group or a group in which each R is other than hydrogen; and each M is independently a non-ionic hydrophilic moiety, M preferably being a non-ionic hydrophilic moiety comprising a monohydroxy- or polyhydroxy-alkyl group) and isomers, especially stereoisomers and rotamers, thereof.
Synthesis of aryl 3-O-β-cellobiosyl-β-D-glucopyranosides for reactivity studies of 1,3-1,4-β-glucanases
Planas, Antoni,Abel, Mireia,Millet, Oscar,Palasi, Josep,Pallares, Cristina,Viladot, Josep-Lluis
, p. 53 - 64 (2007/10/03)
A series of substituted aryl β-glycosides derived from 3-O-β-cellobiosyl-D-glucopyranose with different phenol-leaving group abilities as measured by the pK(a) of the free phenol group upon enzymatic hydrolysis has been synthesised. Aryl β-glycosides with a pK(a) of the free phenol leaving group>5 were prepared by phase-transfer glycosidation of the per-O-acetylated α-glycosyl bromide with the corresponding phenol, whereas the 2,4-dinitrophenyl β-glycoside was obtained by condensation of 1-fluoro-2,4-dinitrobenzene with the partially acetylated trisaccharide followed by acid de-O-acetylation. The aryl β-glycosides have been used for reactivity studies of the wild-type Bacillus licheniformis 1,3-1,4-β-d-glucan 4-glucanohydrolase. The Hammett plot log k(cat) versus pK(a) is biphasic with an upward curvature at low pK(a) values suggesting a change in transition-state structure depending on the aglycon. Copyright (C) 1998 Elsevier Science Ltd.
A convenient method of meta-directing nitration of 3-substituted phenol by lanthanide (III) nitrates
Gu, Shangxiang,Jing, Huanwang,Wu, Jigui,Liang, Yongmin
, p. 2793 - 2797 (2007/10/03)
Thirteen compounds of 3-substituted phenols were nitrated by lanthanide(III) nitrates in a solution of ethyl acetate. Whether the substituents were ortho-, para-directing groups or meta-directing groups, only one kind nitrated product, 3-substituted-5-nitropenol, and its intermediate were obtained respectively.
Concerted displacement mechanism at trigonal carbon: the aminolysis of 4-aryloxy-2,6-dimethoxy-1,3,5-triazines
Shakes, Janice,Raymond, Christel,Rettura, Donatella,Williams, Andrew
, p. 1553 - 1558 (2007/10/03)
4-Aryloxy-1,3,5-triazines undergo bimolecular nucleophilic displacement reactions with amines and pyridines to yield the 4-substituted triazine and aryloxide ion.Rate constants in aqueous solution for the bimolecular reaction of morpholine and 4-dimethylaminopyridine with the title ethers obey the Hammett ? evaluation with Hammett ρlg values 1.65 and 0.82, respectively.Comparison of the ρlg values with the Hammett ρeq for the equilibrium constants indicates that build-up of effective charge on the departing ether oxygen in the transition structures is less than half of that for complete bond fission.Rate constants for the reaction of substituted pyridines with the 4-nitro- and 3,4-dinitro-phenyl ethers obey Broensted equations with exponents βnuc of 0.68 and 1.06, respectively.The build-up of effective charge in bond formation is greater than half of that expected for complete bond formation.Variation in βnuc and ρlg as a function of leaving group and nucleophile structure, respectively, is consistent with substantial coupling between bond forming and bond breaking.The ratio of the Leffler exponents in the pyridinolysis reactions, αnuc/αlg, is greater than unity, consistent with an imbalance between bond fission and bond formation and indicating an accumulation of negative charge in the heteroaromatic nucleus in the transition structure 29percent of that expected for adduct formation.
Stepwise versus concerted mechanisms at trigonal carbon: Transfer of the 1,3,5-triazinyl group between aryl oxide ions in aqueous solution
Renfrew, A. Hunter M.,Rettura, Donatella,Taylor, John A.,Whitmore, James M. J.,Williams, Andrew
, p. 5484 - 5491 (2007/10/02)
Displacements of 4-nitrophenolate ions from 2-(4-nitrophenoxy)-4,6-dimethoxy-1,3,5-triazine by substituted phenolate ions in aqueous solution obey a linear Br?nsted-type equation, log kArO = 0.951pKa - 10.98, over a range of pKa values greater than and less than the pKa of the leaving phenol. The absence of curvature is consistent with a mechanism involving a single transition state. This conclusion is supported by the existence of cross-correlation effects (Pxy = 0.0561) on βnuc of the pKa of the leaving group and on β1g of the pKa of the nucleophile on β1g. The value of βeq, the Br?nsted selectivity for transfer of the triazinyl function between phenolate ions, is calculated from the Br?nsted data to be 1.48. The identity reaction of 3,4-dinitrophenolate ion with the (3,4-dinitrophenoxy)triazine is calculated to have a Kreevoy-Albery τ value of 1.04, indicating that in this case changes in effective charge on entering and leaving ligands are approximately balanced.
