26798-33-4Relevant articles and documents
Kinetic effects induced by cellulose on water-catalyzed reactions. Hydrolysis of 2,4-dinitrophenyl cellulose xanthate and some sugar xanthate ester analogues
Humeres, Eduardo,Sequinel, Luiz Fernando,Nunes, Mauricea,Oliveira, Celia M.S.,Barrie, Patrick J.
, p. 960 - 965 (1998)
The hydrolysis of 2,4-dinitrophenyl cellulose xanthate (CelXDNP) was studied in 10% v/v aqueous ethanol at 25°C and μ = 0.1 (KCl). The water- catalyzed hydrolysis showed that, as for p-nitrobenzyl cellulose xanthate, it occurs through two parallel reactions with rate constants k'(H2O) = 4.40 x 10-3 s-1 for the fast hydrolysis, and k''(H2O) = 6.90 x 10-5 s-1 for the slow hydrolysis. The entropy of activation of the fast hydrolysis was 0.7 ± 1.8 cal K-1 mol-1. External nucleophiles such as hydroxide and simple amines show simple first-order kinetics. The spontaneous hydrolysis of CelXDNP in acetone-water mixtures indicates that the fast reaction does not occur through water polymers and that for water molarity higher than 30 M there are no acetone molecules (or very few) in the highly ordered cybotactic region of cellulose. The spontaneous hydrolysis of methyl 4,6-O-benzylidene- α-D-glucopyranoside 3-(S-p-nitrobenzyl-xanthate) although is faster than the 6-isomer, it is slower than the fast hydrolysis of p-nitrobenzyl cellulose xanthate (CelXNB). Also ΔS(+) is highly negative (-41.0 cal K-1 mol-1), as it is for alkyl and sugar analogues. Only for the fast hydrolyses of CelXDNP and CelXNB is the entropy of activation almost zero. It is concluded that there is no neighbouring OH effect on the fast hydrolysis of cellulose xanthate esters. The hydrolysis of 2,4-dinitrophenyl cellulose xanthate (CelXDNP) was studied in 10% v/v aqueous ethanol at 25°C and μ = 0.1 (KCl). The water-catalyzed hydrolysis showed that, as for p-nitrobenzyl cellulose xanthate, it occurs through two parallel reactions with rate constants k′H2O = 4.40 × 10-3 s-1 for the fast hydrolysis, and k″H2O = 6.90 × 10-5 s-1 for the slow hydrolysis. The entropy of activation of the fast hydrolysis was 0.7 ± 1.8 cal K-1 mol-1. External nucleophiles such as hydroxide and simple amines show simple first-order kinetics. The spontaneous hydrolysis of CelXDNP in acetone-water mixtures indicates that the fast reaction does not occur through water polymers and that for water molarity higher than 30 M there are no acetone molecules (or very few) in the highly ordered cybotactic region of cellulose. The spontaneous hydrolysis of methyl 4,6-O-benzylidene-α-D-glucopyranoside 3-(S-p-nitrobenzyl-xanthate) although is faster than the 6-isomer, it is slower than the fast hydrolysis of p-nitrobenzyl cellulose xanthate (CelXNB). Also ΔS≠ is highly negative (-41.0 cal K-1 mol-1), as it is for alkyl and sugar analogues. Only for the fast hydrolyses of CelXDNP and CelXNB is the entropy of activation almost zero. It is concluded that there is no neighbouring OH effect on the fast hydrolysis of cellulose xanthate esters.
Precise imaging of mitochondria in cancer cells by real-time monitoring of nitroreductase activity with a targetable and activatable fluorescent probe
Gu, Xianfeng,Tan, Jiahui,Wang, Rongchen,Xu, Ge,Zhao, Chunchang,Zhu, Ning,Zhu, Tianli
supporting information, p. 7761 - 7764 (2020/07/27)
An activatable and mitochondrial-targetable fluorescent probe was developed. This designed probe showed ratiometric fluorescence and light-up near-infrared emission responsiveness to nitroreductase, achieving precise imaging of mitochondria in cancer cells by real-time monitoring of nitroreductase activity.
Phosphorus pentasulfide mediated conversion of organic thiocyanates to thiols
Maurya, Chandra Kant,Mazumder, Avik,Gupta, Pradeep Kumar
supporting information, p. 1184 - 1188 (2017/07/03)
In this paper we report an efficient and mild procedure for the conversion of organic thiocyanates to thiols in the presence of phosphorus pentasulfide (P2S5) in refluxing toluene. The method avoids the use of expensive and hazardous transition metals and harsh reducing agents, as required by reported methods, and provides an attractive alternative to the existing methods for the conversion of organic thiocyanates to thiols.