16999-97-6Relevant articles and documents
Ultrasonic relaxation due to complexation reaction between β-cyclodextrin and alkylammonium ions
Nishikawa, Sadakatsu,Yamaguchi, Kyohei,Fukahori, Takanori
, p. 6415 - 6418 (2003)
Ultrasonic absorption coefficients in an aqueous solution of propylammonium chloride (PACL) and butylammonium chloride (BACL) (pH ≈ 7.2) were measured in the presence and absence of β-cyclodextrin (β-CD) at 25 °C in the frequency range 0.8-220 MHz. There was no relaxation in the solution of individual alkylammonium chloride or β-CD. Also, in the solution with PACL and β-CD, the relaxation was not observed. However, a single relaxational absorption was found in the solution of BACL when β-CD coexisted. The cause of the relaxation was attributed to a perturbation of a chemical equilibrium associated with an interaction between β-CD and the butylammonium ion from the concentration dependence of the relaxation frequency and the maximum absorption per wavelength. The rate and thermodynamic constants were determined for the association and dissociation reactions of the complex in the system of BACL with β-CD. The results obtained were compared with those for other similar systems, e.g., propionate ion or propionic acid and alcohols with β-CD. It was ascertained that the stability of the complex formed between BACL and β-CD is relatively lower than those between other guests and β-CD.
Kinetic and Equilibrium Studies of ?-Adduct Formation and Nucleophilic Substitution in the Reactions of Ethyl Thiopicrate with Aliphatic Amines in Dimethyl Sulfoxide
Chamberlin, Rachel,Crampton, Michael R.
, p. 75 - 82 (2007/10/02)
Kinetic and equilibrium results are reported for the reaction of ethyl thiopicrate with butylamine, pyrrolidine and piperidine in dimethyl sulfoxide.The most rapid reaction involves attack at the unsubstituted 3-position to give anionic ?-adducts.The rate-limiting step in this process changes from nucleophilic attack by amine with butylamine to proton transfer from the zwitterionic intermediate with piperidine; pyrrolidine shows intermediate behaviour.Attack by amine at the 1-position results in displacement of the ethylthio group, although intermediates are notobserved during this process.It is suggested that base catalysis observed in the reaction with pyrrolidine may result from rate-limiting proton transfer from the zwitterionic intermediate. 1H NMR measurements using 0.1 mol dm-3 solutions of substrate show that the displaced ethanethiolate ion may attack ring-carbon atoms of either unreacted substrate or substitution products.
Temperature and Pressure Effects on the Reversible Reaction of a Parent Phenol (GH) Corresponding to Galvinoxyl with Aliphatic Amines
Nishimura, Norio,Iga, Siroh,Satoh, Masahiro,Yamamoto, Shunzo
, p. 2437 - 2441 (2007/10/02)
The effects of temperature and pressure on the reversible reaction between GH and aliphatic amines in acetonitrile have been studied spectrophotometrically.The formation of the free ions rather than that of ion pairs has been confirmed by the modified Benesi-Hildebrand (B-H) plot.From the plot the equilibrium constants were estimated.From the temperature dependence of the equilibrium constant (K), the heat and entropy of reactions were estimated to be: (ΔH0)av=-44.5 kJ mol-1, and (ΔS0)av=-193 J K-1 mol-1.From the pressure dependence of K the reaction volume (ΔV0)av was estimated to be -40 dm3 mol-1.When unbranched primary amines were used, a side reaction took place for which an explanation has been given.
