129804-47-3Relevant academic research and scientific papers
Kinetic and Equilibrium Studies of ?-Adduct Formation and Nucleophilic Substitution in the Reactions of Hydroxide Ions with 2,4,6-Trinitrophenyl Sulfides and Ethers
Chamberlin, Rachel,Crampton, Michael R.,Knight, Roland L.
, p. 2986 - 2998 (2007/10/02)
Kinetic and equlibrium data are reported for reaction of hydroxide ions in 20/80 DMSO/water (v/v) with a series of 4'-substituted phenyl 2,4,6-trinitrophenyl sulfides, 1, and with ethyl thiopicrate, 2, ethyl picrate, 3, phenyl picrate, 4, and 1,3,5-trinitrobenzene, 5.In each case a rapid reaction is observed involving reversible hydroxide addition at an unsubstituted ring-position.In the case of 1-4 this is followed by slower, irreversible attack at the 1-position leading to the formation of picric acid.The Hammett ρ value for equilibrium addition of hydroxide to the 3-position of 1 is 0.98, and the ρ value for rate constants for attack at the 1-position is 0.62.The results are discussed in terms of the electronic and steric effects of the 1-substituents.Comparison of 1-5 indicates that changing from an OR to SR group introduces additional steric crowding.However for the reactions studied changing from R = Et to R = Ph has little steric consequence.
Kinetic and Thermodynamic Preferences in the Reactions of Thiolate Ions with 1-Substituted-2,,4,6-trinitrobenzene
Crampton, Michael R.,Stevens, J. Andrew
, p. 1097 - 1103 (2007/10/02)
Kinetic and equilibrium data are reported for reaction in water of ethanethiolate, thioglycolate, and thiomalate ions with 1-X-2,4,6-trinitrobenzenes (X=H, SEt, OEt, and Cl).The thiolate ions show strong kinetic preference for attack at unsubstituted ring positions.However, the isomeric 1:1 adducts formed by attack at substituted and unsubstituted positions have similar thermodynamic stabilities.The latter is in marked contrast with corresponding reactions of alkoxides.Adducts of stoicheiometry thiolate:nitro compound (2:1) are formed by thiolate attack at two unsubstituted ring positions and are stabilised in water by the good solvation of negative charge localised on the nitro groups.A 3:1 adduct has been identified by reaction of ethanethiolate ions with 1,3,5-trinitrobenzene and the kinetic data recorded.Comparison of nucleophilic attack by thiolate ions and by hydroxide ions indicates that the kinetic barrier to reaction with thiolates is considerably lower than for reaction with the oxygen base; a consequence is that (5; X=OEt) is an observable intermediate during nucleophilic substitution. 1H NMR measurements in DMSO have been used to examine the structures of intermediates and reaction products; they show the irreversible displacement of nitro groups by thiolate ions.
