1121-74-0Relevant articles and documents
Ambident Reactivity of Phenolate Anions Revisited: A Quantitative Approach to Phenolate Reactivities
Mayer, Robert J.,Breugst, Martin,Hampel, Nathalie,Ofial, Armin R.,Mayr, Herbert
, p. 8837 - 8858 (2019/07/08)
Prompted by the observation that the regioselectivities of phenolate reactions (C versus O attack) are opposite to the predictions by the principle of hard and soft acids and bases, we performed a comprehensive experimental and computational investigation of phenolate reactivities. Rate and equilibrium constants for the reactions of various phenolate ions with benzhydrylium ions (Aryl2CH+) and structurally related quinone methides have been determined photometrically in polar aprotic solvents. Quantum chemical calculations at the SMD(MeCN)/M06-2X/6-31+G(d,p) level confirmed that O attack is generally favored under kinetically controlled conditions, whereas C attack is favored under thermodynamically controlled conditions. Exceptions are diffusion-limited reactions with strong electrophiles, which give mixtures of products arising from O and C attack, as well as reactions with metal alkoxides in nonpolar solvents, where oxygen attack is blocked by strong ion pairing. The Lewis basicity (LB) and nucleophilicity (N, sN) parameters of phenolates determined in this work can be used to predict whether their reactions with electrophiles are kinetically or thermodynamically controlled and whether the rates are activation- or diffusion-limited. Comparison of the measured rate constants for the reactions of phenolates with carbocations with the Gibbs energies for single-electron transfer manifests that these reactions proceed via polar mechanisms.
Design, synthesis, insecticidal, and acaricidal activities of novel pyrimidinamine derivatives containing a biphenyl ether
Li, Lizhong,Zhou, Chunge,Liu, Minhua,Zhang, Ping,Zhang, Ning,Li, Jianming,Li, Tao,Liu, Xingping,Cheng, Shufen,Li, Qianhe,Liu, Aiping
, p. 3206 - 3214 (2019/11/13)
A series of original pyrimidinamine derivatives containing a biphenyl ether moiety were designed and synthesized. Their structures were confirmed by 1H NMR, MS, and elemental analyses. Their insecticidal activities against lepidopteran and hemiptera insects and acaricidal activities were tested. The results of bioassay demonstrated that 9k showed the best activity (LC50 = 2.08 mg/L) against Tetranychus urticae, which is comparable with the positive control, spirotetramat (LC50 = 2.27 mg/L), and 9g showed better activity (LC50 = 0.52 mg/L) against Aphis fabae than the positive control, imidacloprid (LC50 = 1.02 mg/L), and relatively good activity (LC50 = 2.49 mg/L) against T urticae. Their structure-activity relationships indicated that both an ethyl group on the 4-position of the pyrimidine ring and alkyl chain as a para-substituent group of the benzene ring showed good biological activity.
Enthalpy-entropy correlations in reactions of aryl benzoates with potassium aryloxides in dimethylformamide
Khalfina, Irina A.,Vlasov, Vladislav M.
, p. 266 - 282 (2013/05/21)
Temperature dependences of the relative reactivity of potassium aryloxides XC6H4O-K+ toward 4-nitrophenyl (1), 3-nitrophenyl (2), 4-chlorophenyl (3), and phenyl (4) benzoates in dimethylformamide (DMF) were studied using the competitive reactions technique. The rate constants kX for the reactions of 1 with potassium 4-cyanophenoxide, 2 with potassium 3-bromophenoxide, 3 with potassium 3-bromo-, 4-bromo-, and unsubstituted phenoxides, 4 with potassium 4-methoxy- and 3-methylphenoxides were measured at 25°C. Correlation analysis of the relative rate constants kX/kH(3-Me) and differences in the activation parameters (δδH≠and δ δS ≠) of competitive reactions revealed the existence of six isokinetic series. We investigated the substituent effect of X on the activation parameters for each isokinetic series and concluded that the reactions of aryl benzoates PhCO2C6H4Y with potassium aryloxides in DMF proceed via a four-step mechanism. The large ρ0(Y) and ρXY values at 25°C obtained for the reactions of 1-3 with potassium aryloxides with an electron-donating substituent refer to the rate-determining formation of the spiro-σ-complex. The Hammett plots for the reactions of 1 and 2 exhibit a downward curvature, causing the motion of the transition state for the rate-determining step according to a Hammond effect as the substituent in aryloxide changes from electron-donating to electron-withdrawing. Analysis of data in the terms of two-dimensional reaction coordinate diagrams leads to the conclusion that significant anti-Hammond effects arise in the cases of ortho-substituted and unsubstituted substrates. It was shown that the isokinetic and compensation effects observed for the reactions of aryl benzoates with potassium aryloxides in DMF can be interpreted in the terms of the electrostatic bonding between the reaction centers.
A kinetic study on nucleophilic displacement reactions of phenyl Y-substituted-phenyl carbonates with alkali metal ethoxides: Metal ion effect and reaction mechanism
Um, Ik-Hwan,Seo, Ji-Yoon,Kang, Ji-Sun,An, Jun-Sung
, p. 1007 - 1013,7 (2020/08/24)
Pseudo-first-order rate constants (kobsd) have been measured for reactions of phenyl Y-substituted-phenyl carbonates with alkali metal ethoxides (EtOM, M = Li, Na, and K). The plot of kobsd vs. [EtOM] curves upward for the reaction of diphenyl carbonate with EtOM but is linear for that with EtOK in the presence of 18-crown-6-ether (18C6), indicating that the reaction is catalyzed by M+ ions and the catalytic effect disappears in the presence of 18C6. The kobsd values for the reactions with EtOK have been dissected into fEtO- and kEtOK, i.e., the second-order rate constants for the reactions with dissociated EtO- and ion-paired EtOK, respectively. The Hammett plots correlated with σ- and σ-0 constants exhibit highly scattered points, while the Yukawa-Tsuno plots result in an excellent linear correlation with p = 2.11 and r = 0.21 for kEtO-, and P = 1.62 and r = 0.26 for kEtOK, implying that the reaction proceeds through a concerted mechanism. The catalytic effect (i.e., the kEtOK/kEtOr ratio) is independent of the electronic nature of the substituent Y. Thus, it has been concluded that K+ ion catalyzes the reaction by increasing the electrophilicity of the reaction center.
Kinetics and mechanism of nucleophilic displacement reactions of Y-substituted phenyl benzoates with cyanide Ion
Kim, Song-I,Kim, Eun-Hee,Um, Ik-Hwan
experimental part, p. 689 - 693 (2010/08/19)
Second-order rate constants (kCN-) have been measured for nucleophilic substitution reactions of Y-substituted phenyl benzoates (1a-r) with CN- ion in 80 mol % H2O/20 mol % DMSO at 25.0 ± 0.1 °C. The Bronsted-type plot is linear with βlg = -0.49, a typical βlg value for reactions reported to proceed through a concerted mechanism. Hammett plots correlated with σo and σ-constants exhibit many scattered points. In contrast, the Yukawa-Tsuno plot for the same reaction exhibits excellent linearity with pY = 1.37 and r = 0.34, indicating that a negative charge develops partially on the oxygen atom of the leaving aryloxide in the rate-determining step (RDS). Although two different mechanisms are plausible (i.e., a concerted mechanism and a stepwise pathway in which expulsion of the leaving group occurs at the RDS), the reaction has been concluded to proceed through a concerted mechanism on the basis of the magnitude of βlg and pY values.
Combined dual substituent constant and activation parameter analysis assigns a concerted mechanism to alkaline ethanolysis at phosphorus of Y-substituted phenyl diphenylphosphinates
Um, Ik-Hwan,Park, Jee Eun,Shin, Young-Hee
, p. 3539 - 3543 (2008/09/20)
Second-order rate constants have been measured for reactions of Y-substituted phenyl diphenylphosphinates (1a-h) with EtO-K + in anhydrous ethanol. A linear Bronsted-type plot is obtained with βLg = -0.54, a typical βLg value for reactions which proceed through a concerted mechanism. The Hammett plots correlated with σo and σ- constants are linear but exhibit many scattered points, while the corresponding Yukawa-Tsuno plot results in excellent linear correlation with r = 0.41. The r value of 0.41 indicates that the leaving group departs at the rate-determining step (RDS) whether the reactions proceed through either a concerted or a stepwise mechanism. However, a stepwise mechanism in which departure of the leaving group occurs at the RDS is excluded since the incoming EtO- ion is much more basic and a poorer leaving group than the leaving aryloxide. The ΔH? values determined in the current reactions are strongly dependent on the nature of the substituent Y, while the ΔS ? values remain constant on changing the substituent Y in the leaving group, i.e., from Y = H to Y = 4-NO2 and Y = 3,4-(NO 2)2. These ΔH? and ΔS ? trends also support a concerted mechanism. The Royal Society of Chemistry.
REACTION OF DIARYL ETHERS WITH ALKALI-METAL NITRITES
Plakhtinskii, V. V.,Ustinov, V. A.,Ryabukhina, N. S.,Mironov, G. S.,Kaninskii, P. S.
, p. 507 - 509 (2007/10/02)
The nucleophilic substitution of the aryloxy group in diaryl ethers by the nitrite ion leads to the formation of the corresponding substituted phenolates.The reaction rate increases with increase in the electron-withdrawing characteristics of the substituents both in the ring in which substitution occurs and in the leaving aryloxy group.
Mechanism of the Base-Catalyzed Elimination of Para-Substituted Phenoxides from 4-(Aryloxy)azetidin-2-ones
Fedor, Leo R.
, p. 5094 - 5097 (2007/10/02)
4-(Aryloxy)azetidin-2-ones 4-7 react in dilute aqueous alkali to give 3-hydroxyacrylamide oxyanion and para-substituted phenolate ions.Similarly, 4-(aryloxy)-3,3-dimethylazetidin-2-ones 8-11 give 2,2-dimethylcarboxaldoacetamide and para-substituted phenolate ions.Reactivity is proportional to the fraction of (aryloxy)azetidin-2-one anions, Ka/(Ka + ).Kinetic pKa's of 4-11 and first-order k2's for (suggested) reversible E1cB elimination of para-substituted phenoxide ions from N-1 anions are reported.Reactions are further characterized kinetically by solvent deuterium isotope effects: kOH/kOD = ca. 0.5, ρ(k2) = 2.2 for 4-7 and ρ(k2) = 2.7 for 8-11, and βlg = -0.65 for 4-7 and βlg = -0.75 for 8-11.
Process for production of 8-NHR quinolines
-
, (2008/06/13)
An improved process for producing 8-NHR quinolines from 8-aminoquinolines disclosed. The process comprises reacting 8-aminoquinolines with a substituted alkyl halide in the presence of an amine having a boiling point of 80°-90° C. The amine functions as an acid acceptor whereby the amine salt formed may be efficiently separated from the 8-NHR quinoline formed without expensive or time consuming purification steps. The reaction may be carried out in the presence of a solvent such as an alcohol.
