15875-44-2Relevant academic research and scientific papers
Ultrasonic Velocity and Isentropic Compressibility Studies of Monoalkylammonium Salts in Binary Mixtures of Acetonitrile and N,N-Dimethylacetamide at Variable Temperature and Atmospheric Pressure
Pathania, Vivek,Sharma, Shrutila,Vermani, Shashi Kiran,Vermani,Grover, Navya
, p. 798 - 813 (2020)
Ultrasonic velocities and densities of alkyl substituted ammonium perchlorates-RNH3ClO4, where R is methyl (Me), ethyl (Et),n-propyl (Pr),n-butyl (Bu),n-hexyl (Hx) and n-octyl (Oc), have been measured in the concentration range 0.03–0.28?mol·kg?1 in binary mixtures of acetonitrile (AN) and N,N-dimethylacetamide (DMA) containing 0, 20, 40, 60, 80 and 100?mol% DMA at temperatures 298–328?K in 10?K intervals, using an Anton Paar density and sound velocity meter (DSA 5000?M). The experimental data of ultrasonic velocities and densities have been used for calculating isentropic compressibilities (KS) and apparent molal isentropic compressibilities (KS,?). Limiting apparent molal isentropic compressibilities (KS,?o) for all the electrolytes have been evaluated from KS,? against m1/2 plots and split into contributions of individual ion (KS,?,±o). The variation of KS,?,±o values with solvent composition shows preferential solvation of alkylammonium (RNH3+) ions by DMA in the AN rich region and by AN in the DMA rich region. The extent of solvation of the alkylammonium ions, at all studied temperatures, was found to increase with decreasing alkyl chain length; that is OcNH3+ a decrease in the solvation of the ions with increasing temperature.
Hydrolysis of Aryl and Alkyl Isothiocyanates in Aqueous Perchloric Acid
Joseph, V. Bernadette,Satchell, Derek P. N.,Satchell, Rosemary S.,Wassef, Wasfy N.
, p. 339 - 342 (2007/10/02)
The slow hydrolysis of aromatic and aliphatic isothiocyanates in water is promoted by added perchloric acid.The hydrolysis leads first to the thiocarbamic acid, but this species decomposes rapidly to the (protonated) amine, and is not normally detected.Convenient rates of hydrolysis are obtained at 50 deg C when >/= 6.0 mol dm-3.The effects of substituents, temperature, and acid concentration on the observed rate constants have been studied.Aliphatic isothiocyanates are somewhat more reactive than aromatic derivatives, but the effect of substituent changes is generally small, with electron release favouring reaction.Substit uents close to the nitrogen atom hinder reaction.The value of ΔS(excit.) is typically -120 to -220 J K-1 mol-1, and analysis of the acidity dependence by the excess acidity approach shows m(excit.) ca. 0.8.Addition of water to the isothiocyanate N=C double bond via a mechanism involving simultaneously proton transfer to nitrogen and nucleophilic attack by water at carbon with a cyclic transition state is proposed.The carbamic acids formed by the aliphatic isothiocyanates are sufficiently basic for them to be increasingly trapped as their protonated forms when > 9.0 mol dm-3.
