Kinetic Studies on the Nucleophilic Substitution Reaction of 4-X-Substituted-2,6-dinitrochlorobenzene with Pyridines in MeOH-MeCN Mixtures

The reaction rates of 4-X-2,6-dinitrochlorobenzenes (X=NO 2 , CN, CF 3 ) with Y-substituted pyridines (Y=3-OCH 3 , H, 3-CH 3 , 4-CH 3 ) in methanol-acetonitrile mixtures were measured by conductometry at 25 °C. It was observed that the rate constant increased in the order of X = 4-NO 2 > 4-CN > 4-CF3 and the rate constant also increased in the order of Y= 4-CH 3 > 3-CH3 > H > 3-OCH 3 . When the solvent composition was varied, the rate constant increased in order of MeCN > 50% MeOH > MeOH. The electrophilic catalysis by methanol may be ascribed to the formation of hydrogen bonds between alcoholic hydrogen and nitrogen of pyridines in ground state. Based on the transition parameters, ρ S , ρ N , β Y , ρ XY and solvent effects, the reaction seems to proceed via S N Ar-Ad.E mechanism. We also estimated the isokinetic solvent mixtures (ρ XY = 0) based on cross-interaction constants, where the substituent effects of the substrate and nucleophile are compensated.

[1]  Young Don Yoo,et al.  Simulation of DME synthesis from coal syngas by kinetics model , 2009 .

[2]  S. Ross.  Nucleophilic Aromatic Substitution Reactions , 2007 .

[3]  H. Oh,et al.  Kinetics and Mechanism of the Addition of Benzylamines to α-Thiophenyl-β-phenylacrylonitriles in Acetonitrile , 2007 .

[4]  R. Glaser,et al.  Ab initio study of the SN1Ar and SN2Ar reactions of benzenediazonium ion with water. On the conception of "unimolecular dediazoniation" in solvolysis reactions. , 2004, Journal of the American Chemical Society.

[5]  I. A. Babatunde,et al.  Rationalization of the conflicting effects of hydrogen bond donor solvent on nucleophilic aromatic substitution reactions in non-polar aprotic solvent: reactions of phenyl 2,4,6-trinitrophenyl ether with primary and secondary amines in benzene-methanol mixtures , 2004 .

[6]  P. Mancini,et al.  Kinetics of the reactions between 1-fluoro-2,6-dinitrobenzene and pyrrolidine and piperidine in binary solvent systems: Influence of the nucleophile structure , 2004 .

[7]  Jinhai Yang,et al.  Kinetics and Mechanism of the Addition of Benzylamines to Ethyl-α-cyanocinnamates in Acetonitrile , 2002 .

[8]  Oh,et al.  Kinetics and mechanism of the addition of benzylamines to benzylidenemalononitriles in acetonitrile , 2000, Journal of Organic Chemistry.

[9]  Chang Kon Kim,et al.  THEORETICAL STUDIES OF SOLVENT EFFECT ON THE BASICITY OF SUBSTITUTED PYRIDINES , 1999 .

[10]  H. Lee,et al.  Cross-Interaction Constants. A Mechanistic Tool , 1999 .

[11]  H. Lee,et al.  Kinetics and Mechanism of the Pyridinolysis of Phenyl Chloroformates in Acetonitrile , 1998 .

[12]  Ikchoon Lee.  Isokinetic Behaviors in the Addition Reactions of Aniline Nucleophiles with Benzylic Carbocations , 1996 .

[13]  Ikchoon Lee.  SECONDARY KINETIC ISOTOPE EFFECTS INVOLVING DEUTERATED NUCLEOPHILES , 1995 .

[14]  Ikchoon Lee.  Characterization of transition states for reactions in solution by cross-interaction constants , 1990 .

[15]  C. F. Bernasconi.  Kinetic behavior of short-lived anionic .sigma. complexes , 1978 .

[16]  G. Musumarra,et al.  Solvent effects in the benzylation of aniline , 1977 .

[17]  Andrew Streitwieser,et al.  Progress in Physical Organic Chemistry , 1976 .

[18]  J. Coetzee,et al.  Solute-Solvent Interactions , 1976 .

[19]  Ç. Erk,et al.  Aromatic Nucleophilic Substitution Reactions With Carbanions Part. II , 1971 .

[20]  C. Kingsbury.  The Mechanism of Dimethyl Sulfoxide Catalysis in Nucleophilic Displacement , 1964 .

[21]  A. Parker.  865. Solvation of ions. Part III. The SN2 reactivity of some group VI anions, pyridine, and alkyl halides in dipolar aprotic solvents , 1961 .

[22]  Joseph F. Bunnett,et al.  Aromatic Nucleophilic Substitution Reactions. , 1951 .