Kinetics of the reactions of 2-bromo-3,5-dinitrothiophen with ortho-substituted anilines in methanol. An application of the Fujita–Nishioka equation

Abstract

The rates of anilino-debromination of 2-bromo-3,5-dinitrothiophen (I) by some ortho-substituted anilines (I1 ; X = OMe, Me, Et, CI, Br, and F) have been measured in methanol. The kinetic results have been treated according to the multiparameter analysis of ortho-effects proposed by Fujita and Nishioka. This treatment of data has also been applied to acid-base equilibria of anilinium ions. The susceptibility constants obtained in the two series of reactions (respectively p -2.96 and -2.90, 6 1.31 and 0.56, f -1.83 and -1.70) have been explained by taking into account the structure of the transition states involved.RECENTLY we examined the reaction of 2-bromo-All the reactions were first order both in (I) and ( 11). On 3,5-dinitrothiophen (I) with 14 metaor paya-substituted changing from aniline to ortho-substituted anilines, irrespecanilines in methanol and showed that the kinetic data tive of the nature Of the electron-withdrawing or -repelling

Kinetics and reactivity of substituted anilines with 2‐chloro‐5‐nitropyridine in dimethyl sulfoxide and dimethyl formamide

“…The generally accepted mechanism of S N Ar reactions, when primary or secondary amines are used as nucleophiles, is well established 7, 14, 16–21, (Scheme ).…”

Efficient Synthesis of N,N-Disubstituted 5-Aminothiophene-2-carboxaldehydes by Nucleophilic Aromatic Substitution in Water

“…The reaction could be extended to various secondary amines (entries [6][7][8][9][10][11][12][13][14][15][16], allowing the formation of 5-aminothiophene-2-carboxaldehydes 2 in high yields under simple reaction conditions ( Table 1). The low yield obtained for compound 2g (entry 11) can be explained by difficulties of removal of dibutylamine at the purification step.…”

“…Since 1934 when Steinkopf reported the formation of colored reaction intermediates by reacting nitrothiophene with nucleophiles 1 , Nucleophilic Aromatic Substitution (SNAr) at the thiophene ring has received much attention [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] and is an attractive method for introducing nucleophiles such as alkoxy [3][4][5][6][7][8][9] , alkylthio 8,14,21 or amino 6,8,[14][15][16][17][18] groups at the thiophene ring.…”

“…In these SNAr reactions, the thiophene nucleus is generally substituted by one electron withdrawing group like nitro 3,6,[16][17][18] or by a combination of a nitro group and other electron attracting functions like nitro 7,9 , cyano 7,19 , carboxylate 14,16,19 , acetyl 8,14,19 , trifluoromethanesulfinyl 4 , carboxamido. 14,19 Leaving groups are usually halides 4,5,8,14,15,18 or methoxy 7,15,16 but also phenylsulfonyl 17,18 or nitrophenoxy. 17,18 The solvents used in these studies are benzene, toluene, xylene, methanol, dimethylsulfoxide, dimethylformamide or acetonitrile.…”

Catalysis in aromatic nucleophilic substitution. Part 7. Kinetics of the reactions of some 5-substituted 2-methoxy-3-nitrothiophenes with piperidine in benzene

“…On going from methanol to benzene kz/k-l is strongly reduced and the substitution of (Ia) by piperidine responds linearly to catalysis by piperidine. 4 Evidence based on the remarkable difference in behaviour between pyrrolidine and piperidine in the reactions of these amines with (Ia) in benzene favours the SB-GA mechanism for base catalysis in benzene also. ' In order to obtain information about the role of the 5substituent in (I) in affecting the catalytic coefficients and to elucidate further the base catalysis mechanism, we have measured the kinetics of substitution in benzene of compounds (Ib-g) by piperidine, in the temperature range 20-40 "C. For comparison we have also measured the kinetic constants for the corresponding reactions with n-butylamine in benzene .…”