Rate and Product Studies with 1-Adamantyl Chlorothioformate under Solvolytic Conditions

• Published in: International journal of molecular sciences Vol. 22; no. 14; p. 7394
• Main Authors: Park, Kyoung Ho, Seong, Mi Hye, Kyong, Jin Burm, Kevill, Dennis N.
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 09.07.2021; MDPI
• Subjects: 1-adamantyl chlorothioformate; Carbon dioxide; Carbonyl compounds; Carbonyl sulfide; Carbonyls; carboxylium ion; Chloroformate; Decomposition; Ethanol; Grunwald–Winstein equation; Ion pairs; Ionization; ionization pathway; Salt effect; Solvation; Solvents; Solvolysis; solvolysis–decomposition; Sulfur
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms22147394

A study was carried out on the solvolysis of 1-adamantyl chlorothioformate (1-AdSCOCl, 1) in hydroxylic solvents. The rate constants of the solvolysis of 1 were well correlated using the Grunwald–Winstein equation in all of the 20 solvents (R = 0.985). The solvolyses of 1 were analyzed as the following two competing reactions: the solvolysis ionization pathway through the intermediate (1-AdSCO)+ (carboxylium ion) stabilized by the loss of chloride ions due to nucleophilic solvation and the solvolysis–decomposition pathway through the intermediate 1-Ad+Cl− ion pairs (carbocation) with the loss of carbonyl sulfide. In addition, the rate constants (kexp) for the solvolysis of 1 were separated into k1-Ad+Cl− and k1-AdSCO+Cl− through a product study and applied to the Grunwald–Winstein equation to obtain the sensitivity (m-value) to change in solvent ionizing power. For binary hydroxylic solvents, the selectivities (S) for the formation of solvolysis products were very similar to those of the 1-adamantyl derivatives discussed previously. The kinetic solvent isotope effects (KSIEs), salt effects and activation parameters for the solvolyses of 1 were also determined. These observations are compared with those previously reported for the solvolyses of 1-adamantyl chloroformate (1-AdOCOCl, 2). The reasons for change in reaction channels are discussed in terms of the gas-phase stabilities of acylium ions calculated using Gaussian 03.