A Systematic Investigation of Factors Influencing the Decarboxylation of Imidazolium Carboxylates
摘要:
A series of 1,3-disubstituted-2-imidazolium carboxylates, an adduct of CO2 and N-heterocyclic carbenes, were synthesized and characterized using single crystal X-ray, thermogravimetric, IR, and NMR analysis. The TGA analysis of the NHC-CO2's shows that as steric bulk on the N-substituent increases, the ability of the NHC-CO2 to decarboxylate increases. The comparison of NHC-CO2's with and without methyls at the 4,5-position indicate that extra electron density in the imidazolium ring enhances the stability of an NHC-CO2 thereby making it less prone to decarboxylation. Single crystal X-ray analysis shows that the torsional angle of the carboxylate group and the C-CO2 bond length with respect to the imidazolium ring is dependent on the steric bulk of the N-substituent. Rotamers in the unit cell of a single crystal of I'BuPrCO2 (2f) indicate that the C-CO2 bond length increases as the N-substituents rotate toward the carboxylate moiety, which suggests that rotation of the N-substituents through the plane of the C-CO2 bond may be involved in the bond breaking event to release CO2.
CATALYST FOR DISSOCIATION OF BLOCKING AGENT FOR BLOCKED ISOCYANATES, AND THERMOSETTING COMPOSITION CONTAINING SAID CATALYST FOR DISSOCIATION OF BLOCKING AGENT
申请人:Koei Chemical Company, Limited
公开号:EP3689931A1
公开(公告)日:2020-08-05
A blocking agent dissociation catalyst for blocked isocyanates comprising a nitrogen-containing compound represented by Formula (1a):
wherein D is represented by Formula (2):
wherein R1, R2, R3, R4, and a are as described in the specification.
一种用于封端异氰酸酯的封端剂解离催化剂,由式(1a)代表的含氮化合物组成:
其中 D 由式(2)表示:
其中 R1、R2、R3、R4 和 a 如说明书所述。
A Systematic Investigation of Factors Influencing the Decarboxylation of Imidazolium Carboxylates
作者:Bret R. Van Ausdall、Jeremy L. Glass、Kelly M. Wiggins、Atta M. Aarif、Janis Louie
DOI:10.1021/jo901791k
日期:2009.10.16
A series of 1,3-disubstituted-2-imidazolium carboxylates, an adduct of CO2 and N-heterocyclic carbenes, were synthesized and characterized using single crystal X-ray, thermogravimetric, IR, and NMR analysis. The TGA analysis of the NHC-CO2's shows that as steric bulk on the N-substituent increases, the ability of the NHC-CO2 to decarboxylate increases. The comparison of NHC-CO2's with and without methyls at the 4,5-position indicate that extra electron density in the imidazolium ring enhances the stability of an NHC-CO2 thereby making it less prone to decarboxylation. Single crystal X-ray analysis shows that the torsional angle of the carboxylate group and the C-CO2 bond length with respect to the imidazolium ring is dependent on the steric bulk of the N-substituent. Rotamers in the unit cell of a single crystal of I'BuPrCO2 (2f) indicate that the C-CO2 bond length increases as the N-substituents rotate toward the carboxylate moiety, which suggests that rotation of the N-substituents through the plane of the C-CO2 bond may be involved in the bond breaking event to release CO2.