cas 329-71-5, 2,5-DINITROPHENOL | Articles data

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Reactivity of α-amino acids in the N-acylation with benzoic acid esters in aqueous dioxane
The effect of the nitro group as a substituent in the phenoxide part of phenyl benzoate on the rate of N-acylation of glycine, L-proline,and L-valine in the water (40 wt %)-dioxane solvent was studied. The activation parameters of glycine reactions with the esters were measured. The existence of compensation effect and the linear relation of the logarithms of the acylation constants to the Hammett constants were revealed. The energy of the LUMO of esters can serve as the descriptors of the easters reactivity. Pleiades Publishing, Ltd., 2010.
Ishkulova,Oparina,Kochetova,Kustova,Kalinina,Kuritsin
experimental part
p. 964 - 967
(2011/01/07)

Conjugation and proton exchange equilibria. Heteroconjugation constants in substituted phenol-piperidine systems in acetonitrile
It has been shown by mathematical transformations that the final equations and expressions required for determining equilibrium concentrations of major species in HA + B systems are analogous to those used previously for HA + A1- systems. Heteroconjugation constants K→AHB = [AHB]/([HA][B]) for eight substituted phenol (HA)-piperidine (B) systems in acetonitrile (AN) were determined from emf measurements. A fairly linear dependence between log K→AHB and ΔpKaAN = pKBH+AN - pKHAAN was observed with a slope of 0.52. The [KAHB2/(KAHA - KBHB+)]atδpKa=0 quotient appeared to be much greater than [KAHA1-2/(KAHA - KA1HA1-)]atΔpKa=0 calculated from results obtained previously for HA + A1- type systems. From this fact it has been concluded that the formation of AHB type complexes (relative to the AHA- and BHB+ type complexes) is likely to be favoured by their overall neutrality ensuring weaker peripheral interactions.
Magonski, Jozef,Rajzer, Barbara
p. 1181 - 1185
(2007/10/03)

Associative and Dissociative Pathways in the Alkaline Hydrolysis of Aryl 2-Hydroxycinnamates
Aryl 2-hydroxycinnamate esters hydrolyze in alkaline solutions (20percent dioxane-water v/v) obeying the rate law kobs = ka + kb/(1 + aH/Ka), where Ka is the ionization constant of the hydroxy group of the ester and kb is the second-order rate constant for the attack of hydroxide ion on the ionized ester.Kinetic data and activation parameters for the hydrolysis of the 2,4-dinitrophenyl ester show that the mechanism giving rise to the ka term cannot be a simple BAc2 type process and suggest the occurrence of a E1cB mechanism involving an "extended" o-oxoketene intermediate.The Broensted plot of the apparent second-order rate constante (kaKa/kw) versus the pK of the leaving group indicates that the reaction mechanism changes from E1cB to BAc2 for esters with leaving groups having pK higher than about 6.
Cevasco, Giorgio,Thea, Sergio
p. 70 - 73
(2007/10/02)

RADICAL-ANIONS OF AROMATIC COMPOUNDS. XV. ELECTRONIC STRUCTURE OF THE RADICAL-ANIONS AND THE DIRECTION OF PARTIAL REDUCTION OF POLYNITROPHENOLS AND N,N-DIALKYLANILINES. THE EFFECT OF pH ON THE REGIOSELECTIVITY
The radical products formed during the reduction of 2,3-, 2,5-, 3,4-, and 2,4-dinitrophenols in DMFA and aqueous solutions at various pH values were studied by the ESR method.The radical-anions of the phenols and corresponding phenolates exist in two forms, which differ in the position of the negatively charged nitro group in relation to the substituent (OH or O-).The direction of partial reduction of the dinitrophenols by the complex of titanium trichloride with Trilon B was investigated, and at was shown that it can be varied by variation of the pH of the medium.The effect of the pH on the relative content of the reaction products (isomeric aminonitrophenols) correlates with the effect of this factor on the ratio of the two forms of the radical-anions of the initial phenols.It was shown for the case 2,4,6-trinitro-N,N-dimethylaniline that it is possible to change the direction of partial reduction of N,N-dialkylpolynitroanilines by varying the pH.
Bilkis, I. I.,Goidin, V. V.,Uskov, S. I.,Shteingarts, V. D.
p. 21 - 31
(2007/10/02)

Synthese von Di- und Tri(o-phenylendiamin)-Liganden
The o-phenylenediamine ligand trisamine, TRIPACEN (4) and bisamine, DIPACEN (8) are obtained by Williamson coupling of the potassium salt of 2,3-dinitrophenole (1) to tris(3-chlorpropyl)amine (2) or benzylbis(3-chlorpropyl)amine (5), respectively, followed by reduction of the nitro functions with Sn/HCl or Pd(OH)2/H2.
Hahn, Ekkehardt F.,Dittler-Klingemann, Andreas
p. 779 - 782
(2007/10/02)

Effective Charge Distribution for Attack of Phenoxide Ion on Aryl Methyl Phosphate Monoanion: Studies Related to the Action of Ribonuclease
The reaction of phenoxide ion with aryl methyl phosphate monoanions and aryl diethyl phosphates obeys second-order kinetics in aqueous solution at 39 deg C and 1 M ionic strength.The second-order rate constants (M-1s-1) for these reaction obey the following Broensted equations: log k2 = -0.51pKlg + 0.72 (r = 0.970) (aryl diethyl phosphate) log k2 = -0.64pKlg - 2.53 (r = 0.898) (aryl methyl phosphate monoanion) The monoanion is some 104-fold less reactive toward attack by phenolate ion than is the diethyl ester with 4-nitrophenol leaving group, consistent in part with the operation of an electrostatic effect.The similarity between the Broensted exponents in both reactions indicates that the effective charge change on the leaving oxygen from ground state to transition state is similar in both cases; this indicates that the oxyanion in the monoanion case does not assist leaving group expulsion.The date are consistent with little coupling between proton abstraction from the 2'-hydroxyl group and the leaving group expulsion in the ribonuclease reaction.
Ba-Saif, Salem A.,Davis, Andrew M.,Williams, Andrew
p. 5483 - 5486
(2007/10/02)

SULPHOQUINONES IN THE HYDROLYSIS OF ARYL p-HYDROXYARENESULPHONATES. THE INFLUENCE OF THE LEAVING GROUP BASICITY ON THE REACTIVITY OF ARYL 3,5-DIMETHYL-4-HYDROXYBENZENESULPHONATES IN AQUEOUS SOLUTION
Results of studies on Bronsted selectivities for variation in the leaving-group substituents in the hydrolysis of the title esters give strong support to the hypothesis of E1cB mechanism in which the S-O bond cleavage is well advanced in the transition state of the rate-determining step.At high pH's, however, a bimolecular mechanism involving the attack of a hydroxide ion to the ionised form of the substrate takes place in all cases.
Thea, Sergio,Cevasco, Giorgio,Guanti, Giuseppe
p. 705 - 706
(2007/10/02)

Base Catalysis in Nucleophilic Aromatic Substitution Reactions: Evidence for Cyclic Transition State Mechanism over the Dimer Mechanism in a Non-polar Aprotic Solvent
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
p. 531 - 536
(2007/10/02)

The Rearrangement of Aromatic Nitro-compounds in Strongly Acid Media
2-Nitro-m-xylene and a number of nitrophenols undergo a 1,3-nitro-group rearrangement in trifluoromethanesulphonic acid at 70-110 deg C.
Barrow, Peter,Bullen, John V.,Dent, Andrea,Murphy, Timothy,Ridd, John H.,Sabek, Omaima
p. 1649 - 1650
(2007/10/02)

A Novel Dissociative Mechanism in Acyl Group Transfer from Aryl 4-Hydroxybenzoate in Aqueous Solvents.
The hydrolysis of ary 4-hydroxybenzoates esters exibits the kinetic rate law kobsd=(ka+kb->/(1++>/Ka) where kb is the second-order rate constant for hydroxide ion attack on the ionized ester and Ka is the ionization constant.The apparent second-order rate constant for the hydrolysis of the 2,4-dinitrophenyl ester (kaKa/Kw) is some 340-fold larger than that determined from the Hammett correlation for the alkaline hydrolysis of substituted 2,4-dinitrophenyl benzoates known to possess a BAc2 mechanism.A slightly positive entropy of activation for ka and aniline trapping experiments for the 2,4-dinitrophenyl ester are consistent with a mechanism where a p-oxo ketene intermediate takes the reaction flux. Correlation of kaKa/Kw with the pK of the leaving phenol fits the equation kaKa/Kw-10(-1.33pK+9.57)+10(-0.35pK+3.51) which favors the BAc2 mechanism for poor leaving groups and the E1cB pathway for good leaving groups.There is no reason to postulate a borderline concerted displacement process in this case.
Cevasco, Georgio,Guanti, Giuseppe,Hopkins, Andrew R.,Thea, Sergio,Williams, Andrew
p. 479 - 484
(2007/10/02)

Evidence for a Single Transition State in the Intermolecular Transfer of a Sulfonyl Group between Oxyanion Donor and Acceptors
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D'Rozario, Peter,Smyth, Richard L.,Williams, Andrew
p. 5027 - 5028
(2007/10/02)

Water-soluble trisazo 8-amino-naphthol-1 dyes
Very effective direct dyeing of cotton and other hydroxyl- or nitrogen-containing fibers is effected with water-soluble triasazo dyes having the formula: where A is a radical of a diazoconstituent and A3 is a radical of a coupling constituent STR1 and A1 or A2 or both can have their azo linkages reversed. These dyes are very fast particularly to washing and to perspiration, and are so effective with cotton that dye baths for such use are rapidly exhausted and the disposal of used bath is less of a problem.
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(2008/06/13)