17794-44-4Relevant articles and documents
Amide proton exchange in micelles
Perrin, Charles L.,Chen, Jung-Hui,Ohta, Brian K.
, p. 2448 - 2455 (1999)
Rate constants for acid- and base-catalyzed NH exchange of long-chain amides have been measured in cationic and anionic micelles and compared with NH exchange of model amides in aqueous solution. The data show that the rates can be strongly influenced by the electrostatic environment. Anionic micelles, where k(OH) decreases by a factor of about 2500 and where k(H) increases by a factor of about 100, show the largest effects. The effects of cationic micelles are smaller: a 30-fold decrease in k(H) (for ureas, or 6- fold for ordinary amides) and essentially no change in k(OH), which was unexpected. Other effects are negligible (less than a factor of about 2): counterion, nonionic surfactant, headgroup, chain length, etc. The data are discussed in terms of electrostatic effects, steric retardation, competition of counterions for the micellar surface, the Bronsted formulation of medium effects, charge exposure, and the nature of the transition state.
Tuning the solid-state emission of the analogous GFP chromophore by varying alkyl chains in the imidazolinone ring
Shen, Xiang,Huang, Guangxi,Li, Kan,Zhang, Guanxin,Zhang, Deqing
, p. 1197 - 1203 (2013/09/23)
New analogues of green fluorescent protein (GFP) chromophore m GFP-C n (n = 1, 3, 5, 11) with alkyl chains of different lengths in the imidazolinone rings were synthesized and their crystal structures were determined. These GFP-like chromophores are all emissive in the solid state. And the solid-state emission quantum yields of increase by extending the lengths of alkyl chains, owing to the fact that the intermolecular pi-pi interactions are significantly weakened based on their crystal structures.
Lawesson's reagent for direct thionation of hydroxamic acids: Substituent effects on LR reactivity
Przychodzen, Witold
, p. 676 - 684 (2007/10/03)
To explore the generality and scope of direct thionation of hydroxamic acids (HAs), the reaction of various structurally diverse HAs with Lawesson's reagent was investigated. The yield of thiohydroxamic acid (THAs) is poor when HAs possess bulky acyl and/or N-substituents, acidic α-hydrogen atoms, or an N-phenyl ring. THAs yields were correlated with Brown sigma parameter. The relative rates of two subsequent processes kT2 and kR2 were also measured. Correlation was also found for methine proton chemical shifts of N-isopropyl benzothiohydroxamic acids.
