19348-30-2Relevant articles and documents
Reaction of NN'-dimethylimidazolidine-2-thione with Methyl Iodide. Kinetic and Thermodynamic Aspects
Kondo, Yasuhiko,Yamada, Tetsuya,Kusabayashi, Shigekazu
, p. 414 - 418 (1981)
The reaction of NN'-dimethylimidazolidine-2-thione with methyl iodide followed simple second-order kinetics in polar solvents, whereas in less polar solvents the reverse process made a significant contribution to the overall rate.The solvent effects on the forward rate constant were linearly correlated with those on the rate of the reaction of tetramethylthiourea with methyl iodide.However, the reactions of two 1,2,4-triazole-3-thione derivatives with methyl iodide did not show any such correlations.From the volume changes and enthalpy changes measured, three transition state indices, , nT, and α were determined in acetonitrile, ca. 0.28, 0.35, and 0.43, respectively.
Efficient Catalysts of Acyclic Guanidinium Iodide for the Synthesis of Cyclic Carbonates from Carbon Dioxide and Epoxides under Mild Conditions
Aoyagi, Naoto,Endo, Takeshi,Furusho, Yoshio
, p. 150 - 158 (2019/12/26)
We have studied the synthesis of five-membered cyclic carbonates through the cycloaddition of CO 2 to epoxides by using acyclic guanidinium salts. We have found that the cycloaddition reactions proceed smoothly at ordinary temperatures and pressures and result in good yields when acyclic guanidinium iodides are employed as catalysts. Both cation moiety and anion moiety of the guanidinium salts play important roles in their catalytic activity. It is essential to have active hydrogens on the cation moiety as well as an iodide ion as the anion moiety so as to achieve good catalytic activity. Guanidinium iodides with three or more active hydrogens give cyclic carbonates in high yields in polar solvents such as 1-methylpyrrolidin-2-one, whereas the guanidinium iodides with one or two active hydrogens show good catalytic activity in less polar solvents such as 2-methyltetrahydrofuran.
Specific Molecular Orbital Contributions to Nucleophilicity. The Thiocarbonyl Group as Privileged Monitor To Pinpoint Active and Less Active Molecular Orbitals in Reactions with Methylating Agents
Arbelot, M.,Allouche, A.,Purcell, K. F.,Chanon, M.
, p. 2330 - 2343 (2007/10/02)
The rate constants for 41 compounds bearing a C=S function reacting with MeX (X = I, Tos) span 7 orders of magnitude.The PES spectra of these compounds display two very low energy peaks, which stand clearly apart from the other peaks.These two peaks correspond to the ? orbitals of the C-S group; one is its CS ? bonding orbital oriented out of the molecular plane (?CS) and the other its p-type in-plane lone pair orbital (?S).For some of the compounds, the HOMO is the ?CS orbital and for others the HOMO is the ?S lone pair orbital.The best correlation (R = 0.96) between rate constants k and PES data is obtained when ln(k) is plotted against the inverse of PES energy of the ?S lone pair orbital.Whether this lone pair orbital is the HOMO or the next lower HOMO has no importance.A modest correlation (R = 0.78) is obtained when ln(k) is plotted against the inverse of PES energy of the ?CS bonding orbital.An attempt to correlate the calculated energy of the third highest occupied orbital (from AM1 calculations) with ln(k) provides a complete scattering of data (R S (ca. 90 kcal mol-1 deeper than the HOMO) correlates reasonably with ln(k) (R = 0.88).The energies of the S 2s and 2p core orbitals (calculated for 13 cyclic compounds with the HF/3-21G technique to be 4000 to 5500 kcal mol-1 deeper than HOMO) correlate with ln(k) (R = 0.86) as well as does that of the second lone pair orbital ?S.These results are the first where both frontier orbitals and core orbitals display correlation with overall reactivity.They are discussed in terms of direct (perturbational) versus indirect (nonperturbational) concepts.
