- Anilinolysis of nitro-substituted diphenyl ethers in acetonitrile: the effect of some ortho-substituents on the mechanism of SNAr reactions
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Rate data are reported for the reactions of a series of X-phenyl 2,4,6-trinitrophenyl ethers 1a-e [X = H, 4-NO2,2-NO2, 2,4-(NO2)2, or 2,6-(NO2)2] with substituted anilines 2a-e [Y = H, 2-CH
- Isanbor., Chukwuemeka,Emokpae, Thomas A.
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- Steric and electronic effects on the mechanism of nucleophilic substitution (SnAr) reactions of some phenyl 2,4,6-trinitrophenyl ethers with aniline and N-methylaniline in acetonitrile and in dimethyl sulfoxide
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Rate data are reported for the reactions of a series of 3′- and 4′-substituted phenyl 2,4,6-trinitrophenyl ethers, 4, with aniline in acetonitrile, leading to 2,4,6-trinitrodiphenylamine. The main reaction flux occurs through a base catalysed pathway invo
- Isanbor, Chukwuemekh,Emokpae, Thomas A.,Crampton, Michael R.
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- Modification of the Order of Reaction and Reaction Rate of Nucleophilic Aromatic Substitution in Micellar Solutions
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The rate of formation of 2,4,6-trinitrodiphenylamine following the attack of aniline on 1-methoxy-2,4,6-trinitrobenzene has been studied in micellar media.The partial order with reference to the nucleophilic reagent (aniline) is unity in solutions of cationic detergents (positive micelles) and 3/2 in water or solutions of anionic detergents.For such reactions there are two main steps in the reaction scheme: first, the formation of an adduct between reagents, favoured by the effect of local higher concentration in the two kinds of micellar solutions and secondly, ejection of a proton from the adduct formed.The latter reaction is catalysed largely by positive micelles and in this case the kinetics are not limited by the deprotonation step.On the other hand, negative micelles inhibit the ejection of a proton and this opposes, in part, the effect of higher local concentrations.
- Lelievre, Joel,Haddad-Fahed, Omaima,Gaboriaud, Rene
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- Anilinolysis of picryl benzoate derivatives in methanol: Reactivity, regioselectivity, kinetics, and mechanism
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The reaction of picryl benzoate derivatives 1a-g with aniline in methanol proceeds through CO-O and Ar-O bond cleavage pathways. Furthermore, the reactivity of these esters toward anilinolysis is correlated to the energy gap between highest occupied molecular orbital aniline and lowest unoccupied molecular orbital of each ester. The regioselectivity of acyl-oxygen versus aryl-oxygen cleavage is also discussed. The overall rate constants k tot split into kCO-O (the rate constant of acyl-oxygen cleavage) and kAr-O (rate constant of aryl-oxygen cleavage). The CO-O bond cleavage advances through a stepwise mechanism in which the formation of the tetrahedral intermediate is the rate-determining step. The Ar-O bond cleavage continues through a SNAr mechanism in which the departure of the leaving group from the Meisenheimer complex occurs rapidly after its formation in the rate-determining step.
- Ibrahim, Mahmoud F.,El-Atawy, Mohamed A.,El-Sadany, Samir K.,Hamed, Ezzat A.
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supporting information
p. 551 - 559
(2013/08/23)
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- The synthesis of vinylogous amidine heterocycles
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We report herein a convenient synthetic methodology for the conversion of meta-dinitro heterocyclic rings to iminoquinones with vinylogous amidine functionality. These structures are found in nature, particularly in marine organisms, and may be important
- Labarbera, Daniel V.,Skibo, Edward B.
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p. 11887 - 11895
(2014/01/06)
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- Catalytic effects of hydrogen-bond acceptor solvent on nucleophilic aromatic substitution reactions in non-polar aprotic solvent: Reactions of phenyl 2,4,6-trinitrophenyl ether with amines in benzene-acetonitrile mixtures
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The effect of addition of small amounts of hydrogen-bond acceptor solvent, acetonitrile, to the benzene medium of the reactions of phenyl 2,4,6-trinitrophenyl ether with aniline and cyclohexylamine, respectively have been investigated. The addition produc
- Banjoko, Olayinka,Babatunde, Ibitola A.
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p. 8035 - 8040
(2007/10/03)
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- The influence of some steric and electron effects on the mechanism of aromatic nucleophilic substitution (SNAr) reactions in nonpolar solvent
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Kinetic studies are reported for the reactions with aniline in benzene of a series of X-phenyl 2,4,6-trinitrophenyl ethers [X = H; 2-, 3-, 4-CH 3; 2,4-, or 2,6-(CH3)2] 1a-f, and the results compared with those of the corre
- Emokpae, Thomas A.,Atasie, Nkechi V.
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p. 744 - 750
(2008/04/18)
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- Leaving group effects on the mechanism of aromatic nucleophilic substitution (SnAr) reactions of some phenyl 2,4,6-trinitrophenyl ethers with aniline in acetonitrile
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Kinetic studies are reported for the reactions with aniline in acetonitrile of a series of X-phenyl 2,4,6trinitrophenyl ethers [X = H, 2-, 3-, 4-CH3,2,4-, 2,6-(CH3)2,2-, 3-, 4-NO 2,2,4-, 2,6-(NO2)2]. X-ray crystal structures for X = H, 2,6-(CH3)2 and 2,6-(NO2) 2 are reported and provide evidence for steric crowding around the 1-position of these molecules. Nevertheless, the kinetic data show that increasing substitution does not sterically inhibit nucleophilic attack by aniline and an 'early' transition state is likely. In general, the reactions are base catalysed; interpreted as rate-limiting deprotonation of the zwitterionic intermediates. Only with the dinitro derivatives is an uncatalysed reaction involving intramolecular proton transfer observed and when X = 2,6-(NO2)2 this pathway takes all the reaction flux. Copyright
- Crampton, Michael R.,Emokpae, Thomas A.,Howard, Judith A.K.,Isanbor, Chukwuemeka,Mondal, Raju
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- Relative reactivity and kinetic pattern of aniline and N-methylaniline as nucleophiles in aromatic substitution (SNAr) reactions
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Kinetic results are reported for the reactions of 4-nitrophenyl-2,4,6-trinitrophenyl ether 3 with aniline and N-methylaniline in dimethyl sulphoxide, acetonitrile, methanol, and benzene. The reactions gave the expected 2,4,6-trinitrodiphenylamine and were
- Emokpae, Thomas A.,Isanbor, Chukwuemeka
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p. 188 - 196
(2007/10/03)
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- Kinetic studies of σ-adduct formation and nucleophilic substitution in the reactions of ethyl 2,4,6-trinitrophenyl ether, some phenyl 2,4,6- trinitrophenyl ethers, and phenyl 2,4-dinitronaphthyl ether with aniline in dimethyl sulfoxide
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The reaction of ethyl 2,4,6-trinitrophenyl ether with aniline in dimethyl sulfoxide containing Dabco occurs in two stages. The first gives 5, the σ-adduct intermediate on the substitution pathway, which has been identified spectroscopically. The second yields 2,4,6-trinitrodiphenylamine, the substitution product. Kinetic studies show that proton transfer is rate limiting both in the formation of the intermediate and in its subsequent acid-catalysed decomposition. Phenoxide is a considerably better leaving group than ethoxide and the substitution reactions of phenyl 2,4,6- trinitrophenyl ethers and phenyl 2,4-dinitronaphthyl ether with aniline in DMSO occur without the accumulation of intermediates. The kinetics indicate both uncatalysed and base-catalysed pathways. The kinetic and equilibrium data for reaction of the ethyl and phenyl ethers are compared with data for σ-adduct formation from 1,3,5-trinitrobenzene and aniline.
- Crampton, Michael R.,Robotham, Ian A.
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p. 627 - 634
(2007/10/03)
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- Synthesis and Explosive Properties of Benzotriazoles
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Treatment of nitro-substituted 2-aminodiphenylamines in acetic acid with either nitric acid or nitrous acid yielded nitro-substituted 1-phenylbenzotriazoles, which may be further nitrated with nitric or mixed acid.These materials have been examined as pot
- Flippen-Anderson, Judith L.,Gilardi, Richard D.,Pitt, Adrian M.,Wilson, William S.
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p. 513 - 524
(2007/10/02)
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- Aromatic nucleophilic substitution reactions of 1-dialkylamino-substituted activated benzenes with various amines in dimethyl sulfoxide
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In the reactions of 1-dlalkylamino-2,4,6-trinitro- and 1-dialkylamlno-2, 4-dinitrobenzenes with various amines in dimethyl sulfoxide, 1-dialkylamino group is easily replaced with primary n-alkylamines at room temperature, and in a low yield with pyrrolidine only among secondary amines.
- Sekiguchi, Shizen,Ishikura, Hiromi,Hirosawa, Yukitoshi,Ono, Nobuyuki
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p. 5567 - 5578
(2007/10/02)
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- REACTIVITE DE SUBSTRATS IONIQUES EN PRESENCE DE SYSTEMES MICELLAIRES. Attaque nucleophile de l'anion trinitrobenzenesulfonate par l'aniline et les anions aminobenzoate
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The aim of this work is to show the influence of several micellar solutions forming either negative or positive micelles, upon the reaction of nucleophilic aromatic substitution between 2,4,6-trinitrobenzenesulfonate ion (TNBS) and aniline (AnH2) or various aminobenzoate anions.This reaction has been investigated also in absence of detergent.Under such conditions, the classical mechanism of aromatic substitution fit in well with the experimental results.Generally the sulfonate substituent can be considered as a better leaving group than the methoxy group; we observe effectively (in aqueous solutions) kinetics faster with TNBS than with 2,4,6-trinitroanisole (TNA) when the nucleophilic reagent is AnH2 or paraaminobenzoate anion.On the contrary, metaaminobenzoate ion reacts more rapidly upon the TNBS than upon the TNA.When the micellar solutions are formed by negative micelles, the reaction of nucleophilic substitution is always faster with the TNBS than with the TNA, even in the case of TNBS and aminobenzoate anions, and although the reaction is then the issue of a mixture of two anions.This last situation is not in favour of a good extraction by the micellar aggregates.For micellar solutions formed by positives micelles, although the organic substrates and reagents are totally extracted by the aggregates, the aromatic substitution is surprisingly increased only in the case of aniline or amino-3 benzoate anion when TBNS replace TNA.In any case, the extraction effect of the micelles is one of the dominating facts, however this effect is not uniform according to the different reagents.In the discussion, we had to take into account the situation of organic compounds into the micellar aggregates and particularly on the surface of such assemblies.The difference in the behaviour of various reagents are imputed to constraints of positionning on the surface of micelles and for that reason the reaction is more or less difficult according to the relative location between the charged substituent and the reactional group.
- Haddad-Fahed, O.,Lelievre, J.,Gaboriaud, R.
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p. 647 - 654
(2007/10/02)
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- Catalysis of Nucleophilic Aromatic Substitution Reactions in Mixed Solvents. Part 1. Reaction of Phenyl 2,4,6-Trinitrophenyl Ether with Aniline in Benzene-Methanol Mixtures: Strong Evidence against the 'Dimer' Mechanism
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The reaction of phenyl 2,4,6-trinitrophenyl ether with aniline in benzene and benzene-methanol was studied at different amine concentrations.Addition of increasing amounts of methanol (from 0.1 to 90percent) to benzene resulted in a continuous increase in
- Banjoko, Olayinka,Bayeroju, Ibitola A.
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p. 1853 - 1858
(2007/10/02)
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- QUANTITATIVE RELATIONSHIPS OF BASE CATALYSIS IN THE REACTIONS OF PICRYL FLUORIDE WITH ANILINE IN BENZENE
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The catalytic action of ammonium salts, ring-substituted pyridines, and their N-oxides in the reaction of picryl fluoride with aniline in benzene was studied.Partial linear relationships were discovered between the logarithms of the catalytic rate constants and the capacity of the catalyst for the formation of a hydrogen bond (pKHB) and its susceptibility to the addition of a proton (pKa).The pKa values of the halide ions in the alkyl ammonium salts and the pKHB values for the ring-substituted pyridine N-oxides were determined.
- Titskii, G. D.,Turovskaya, M. K.,Shumeiko, A. E.
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p. 2171 - 2175
(2007/10/02)
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- CATALYSE MICELLAIRE DANS LE CAS D'UN REACTIF ELECTRIQUEMENT CHARGE: EXEMPLE DE L'ATTAQUE DU TRINITRO-2,4,6 ANISOLE PAR LES IONS AMINOBENZOATE
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A previous kinetic study, upon the attack of 1-methoxy-2,4,6-trinitrobenzene (TNA) on aniline in water and water-methanol mixtures has shown that the rate of reaction is dependent or not on pH according to the range of acidity.The same general trend is observed in the presence of positive or negative micelles in aqueous media and the whole observed effects are consistent with the classical mechanism of the reaction of aromatic nucleophilic substitution.The aim of this paper is to study the effect of the presence of charged substituent upon the reaction rate.Consequently, we have investigated the reaction of TNA upon the ortho, meta and paraaminobenzoate anions.In every case, the reaction scheme is unchanged and the presence of carboxylate group -COO- is found always as a decreasing of the rate.However, the effect of substituents are modified in different way if the reaction is carried out in the presence of positive or negative micelles.The apparent kinetic constant of the reaction is increased by addition of positive micelles and, on the contrary, decreased by addition of negative micelles.The direction of these effects is governed by the sign of the micelles but their range largely depends on the relative position of the functional group -NH2 and the charged substituent -COO-.The discussion shows the relation between these unusual effects and the solubility parameter of each compound.
- Haddad-Fahed, O.,Lelievre, J.,Gaboriaud, R.
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p. 637 - 646
(2007/10/02)
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- EFFECTS DE SOLVANT ET CATALYSE MICELLAIRE DANS LE CAS D'UNE SUBSTITUTION NUCLEOPHILE AROMATIQUE TYPE: LA RECTION DE L'ANILINE SUR LE TRINITRO-2,4,6 ANISOLE
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The reaction between aniline and 1-methoxy 2,4,6-trinitrobenzene (TNA) is governed by the general rules of nucleophilic aromatic substitution.Considering the weak basicity of aromatic amine and the bad leaving group methoxy, this system is able to describe two kinds of kinetic behaviours according to the pH range.The range of the reaction is independent on pH in basic solutions while on the contrary it is dependent on pH in neutral or weakly acid solutions.This reaction have been investigated in aqueous solution, several mixtures of water and methanol and micellar solutions of anionic and cationic surfactants.The general form of kinetic diagrams are preserved for every kind of the solution, consequently the mechanism of reaction is always the same.It is possible to describe the effects of various additives on every steps of the kinetic process.In this way, the first step of the reaction, corresponding to the formation of a zwitterionic intermediate complex formed by attack of aniline on TNA is modified a few by methanol addition.On the contrary, it is a modified by micelles whatever the charge of amphiphile ion (effect of higher local concentration).The second part of the mechanism implies the lost of proton from the previous zwitterionic complex.The ejection of proton is more difficult in the presence of methanol or negative mivelles while is favoured in the presence of positive micelles.When the rate of the reaction is limited by the second step of mechanism, the addition of background electrolyte into the micellar solutions modified the rate such as it is accelerated in negative micellar solutions and slowed down in positive micellar solutions.The previoys model describing the micellar systems allows us to depict qualitatively and quantitatively all these effects.
- Lelievre, Joel,Haddad-Fahed, Omaima,Gaboriaud, Rene
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p. 449 - 458
(2007/10/02)
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- Base Catalysis in Nucleophilic Aromatic Substitution Reactions: Evidence for Cyclic Transition State Mechanism over the Dimer Mechanism in a Non-polar Aprotic Solvent
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The reactions of X-phenyl 2,4,6-trinitrophenyl ethers with aniline in benzene display three distinct mechanisms even though all except the 2,6-dinitrophenyl ether are base catalysed.The catalysis of the mononitro-substituted ethers involves two aniline molecules and proceeds at a temperature-independent rate in the temperature range 5 - 35 deg C while that of the dinitro-substituted ones involves only one aniline molecule and proceeds at a temperature-dependent rate over the same temperature range.The results are interpreted in terms of a cyclic mechanism involving four-, six-, and eight-membered rings in the transition state.
- Banjoko, Olayinka,Ezeani, Chike
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p. 531 - 536
(2007/10/02)
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- Mechanism of the Uncatalysed Path of Aromatic Nucleophilic Substitution in Dipolar Aprotic Solvents when Primary and Secondary Amines are the Nucleophiles; a Search for Electrophilic Catalysis of these Reactions
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The kinetics of the reactions of 1-chloro- and 1-fluoro-2,4-dinitrobenzene with morpholine have been studied in dimethyl sulphoxide, dimethylformamide, and nitromethane.The results confirm that the decomposition of the intermediate to products by the uncatalysed path takes place by a unimolecular mechanism.The kinetics of the reactions of 2,4-dinitroanisole with n-butylamine and piperidine in dipolar aprotic solvents have been determined.They show that when primary amines are the nucleophiles, reaction by the uncatalysed path does not occur by the unimolecular mechanism, but by the specific base-general acid (SB-GA) route.The reactions in dimethyl sulphoxide give another example of secondary amines reacting by a base catalysis mechanism whereas the corresponding reaction of a primary amine of the same basicity is not base-catalysed.In a search for electrophilic catalysis the effects of lithium, trialkylammonium, and tetraalkylammonium ions on the reactions of piperidine with 2,4-dinitroanisole and of morpholine with 2,4-dinitrophenyl phenyl ether in dimethyl sulphoxide were investigated.No catalysis was found and a tentative reason is given.When aniline reacts with 2,4,6-trinitrophenyl methyl ether in dimethyl sulphoxide, 82percent of the reaction occurs at the methyl carbon atom, and when the substrate is 2,4,6-trinitrophenyl phenyl ether the reaction is not base-catalysed.The first two observations of the change from base-catalysed to uncatalysed aromatic nucleophilic substitution reactions brought about by a change from protic to dipolar aprotic solvent are recorded.
- Hirst, Jack,Hussain, Ghazanfar,Onyido, Ikenna
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p. 397 - 404
(2007/10/02)
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- REACTION OF BIS(2,4,6-TRINITROPHENYL) SULFONE AND ITS DERIVATIVES WITH AMINES
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The reaction of bis(2,4,6-trinitrophenyl) sulfone and some of its 3- and 3,3'-substituted derivatives with organic bases leads to the formation of an adduct of 1,3,5-trinitrobenzene or its substituted derivative and the respective amine, sulfur trioxide, and 2,4,6-trinitrodiphenylamine and its derivatives or derivatives of 2,4,6-trinitroaniline.The direction of reaction does not depend on the ratio of the initial compounds or on the temperature.It was established that attack by the nucleophilic reagent takes place at the ring in which the largest positive charge is induced at the carbon atom attached to the sulfur.
- Nurgatin, V. V.,Sharnin, G. P.,Nurgatina, R. B.,Ginzburg, B. M.
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p. 306 - 309
(2007/10/02)
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- The ambident reactivity of aromatic amines in their reactions with N-2-(2,4,6-trinitrophenyl)-4,6-dinitrobenzotriazole-1-oxide, a new heterocyclic super-electrophile
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Reaction between the title compound 2 and 2,6-dimethylaniline, or N,N-dimethylaniline, gives rise to spectrally observable Meisenheimer type ?-complexes in which bonding has occurred between the para carbon of the aromatic amine and the benzotriazole moiety of 2; however, aniline reacts at the picryl moiety to give the product of displacement 5, via the aniline nitrogen as the nucleophilic atom.
- Buncel, Erwin,Renfrow, Richard A.,Strauss, Michael J.
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p. 1690 - 1692
(2007/10/02)
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- REACTIVITY OF 5-CHLORO-4,6-DINITROBENZOFUROXANE
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For a comparative assessment of the effect of the furoxane ring and nitro group on the mobility of the halogen atom the kinetic and activation parameters of the nucleophilic substitution of chlorine by aniline in 5-chloro-4,6-dinitrobenzofuroxane and 2,4,
- Sharnin, G. P.,Mukharlyamov, R. I.,Golovin, V. V.
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p. 2062 - 2064
(2007/10/02)
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- Mechanism of the Reactions of Substituted Anilines with Phenyl 2,4,6-Trinitrophenyl Ether in Benzene: Evidence for a Cyclic Transition State involving an Eight-membered Ring
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Rates and activation parameters have been determined for the reactions of phenyl 2,4,6-trinitrophenyl ether with substituted anilines in benzene.For some of the nucleophiles, the rates decrease with increasing temperature in the range 5-35 deg C resulting in negative activation enthalpies (ΔH(excit.) -3.1 to -27.3 kJ mol-1).This is strong evidence for a stepwise mechanism involving (at least) a pre-equilibrium.These base-catalysed nucleophilic substitution reactions are sensitive to the nature of the arylated amine as indicated by the Hammett's constant (ρ -7.7).
- Banjoko, Olayinka,Ezeani, Chike
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p. 1357 - 1360
(2007/10/02)
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- ACTION OF NITRIC ACID ON 2,4,6-TRINITROPHENYL ARENE AND ALKANECARBOTHIOATES
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For the case of the reaction of S,S'-bis(2,4,6-trinitrophenyl)dithiooxalate with concentrated nitric acid it was found that the sulfur-containing groups in the esters of thiocarboxylic acids are substituted by hydroxy and nitroso groups.The reaction, which is accompanied by copious release of nitrogen oxides and increase in temperature, leads to 2,4,6-trinitrophenol or 2,4,6-trinitronitrosobenzene.The structure of the latter was confirmed by IR and UV spectroscopy and by oxidation to 1,2,3,5-tetranitrobenzene. 2,4,6-Trinitrophenyl benzenecarbothioates give the nitroderivative only when the acids contain not more than one nitro group in the phenyl radical.The nitroso group in 2,4,6-trinitronitrosobenzene, like the halogen in picryl halides, is readily substituted by the action of nucleophilic reagents.
- Nurgatin, V. V.,Sharnin, G. P.,Savel'eva, L. A.,Nurgatina, R. B.
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p. 2167 - 2169
(2007/10/02)
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- The Kinetics of the Reaction of Phenyl 2,4,6-Trinitrophenyl Ether with Aniline in Methanol, Acetonitrile, Tetrahydrofuran, Ethyl Acetate, and Benzene
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The kinetics of the reaction of phenyl 2,4,6-trinitrophenyl ether with aniline have been investigated as a function of the amine concentration in methanol,acetonitrile, tetrahydrofuran, ethyl acetate, and benzene.Base catalysis was observed in all the solvents.The second-order rate constant kA shows a linear correlation with the aniline concentration except in benzene where the linearity is with the square of the aniline concenration.The k3B/k2 ratios for the solvents provide information on the mechanism of the uncatalysed decomposition of the intermediate formed in nucleophilic aromatic substitution.A mechanism is proposed for the base-catalysed pathway in solvents of low dielectric constant and basicity.
- Banjoko, Olayinka,Otiono, Paul
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p. 399 - 402
(2007/10/02)
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- Kinetics of the Reactions of Phenyl 2,4,6-Trinitrophenyl Ether with Piperidine, n-Butylamine, Aniline, Benzylamine, and Morpholine in Benzene
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The kinetics of the reactions of phenyl 2,4,6-trinitrophenyl ether with piperidine, n-butylamine, benzylamine, and morpholine have been investigated as a function of the amine concentration in benzene and the results compared with that of aniline.Base-cat
- Banjoko, Olayinka,Khalil-Ur-Rahman
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p. 1105 - 1108
(2007/10/02)
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