Nucleophilic cleavage of the silicon–oxygen bond: acid-catalysed hydrolysis of tributylphenoxysilanes in aqueous organic solvents

1974 ◽  
pp. 1324-1331 ◽  
Author(s):  
John R. Chipperfield ◽  
Geoffrey E. Gould
Keyword(s):  
Organic Solvents ◽  
Nucleophilic Cleavage ◽  
Hydrolysis Of ◽  
Oxygen Bond ◽  
Silicon Oxygen

scholarly journals Influence of Water Activity on Protease Adsorbed on Biochar in Organic Solvents

2017 ◽  
Vol 6 (4) ◽  
pp. 96 ◽  
Author(s):  
Hidetaka Noritomi ◽  
Jumpei Nishigami ◽  
Nobuyuki Endo ◽  
Satoru Kato ◽  
Katsumi Uchiyama
Keyword(s):  
Thermal Stability ◽  
Catalytic Activity ◽  
Organic Solvents ◽  
Water Activity ◽  
Initial Rate ◽  
Butyl Ester ◽  
Nitrogen Atmosphere ◽  
Bamboo Charcoal ◽  
Influence Of Water ◽  
Hydrolysis Of

We have found that the organic solvent-resistance of Alpha-chymotrypsin (Alpha-CT) is enhanced by adsorbing Alpha-CT onto bamboo charcoal powder (BCP), which is obtained by pyrolyzing bamboo waste under nitrogen atmosphere, and is markedly dependent on the thermodynamic water activity (aw) in organic solvents. When BCP-adsorbed　Alpha-CT was immersed in acetonitrile at an appropriate water activity, it effectively enhanced the transesterification of N-acetyl-L-tyrosine ethyl ester (N-Ac-Tyr-OEt) with n-butanol (BuOH) to produce N-acetyl-L-tyrosine butyl ester (N-Ac-Tyr-OBu), compared to the hydrolysis of N-Ac-Tyr-OEt with water to give N-acetyl-L-tyrosine (N-Ac-Tyr-OH). When the water activity was 0.28, the initial rate of transesterification catalyzed by BCP-adsorbed Alpha-CT was about sixty times greater than that catalyzed by free Alpha-CT. Regarding the reaction selectivity which is defined as a ratio of the initial rate of transesterification to that of hydrolysis, BCP-adsorbed α-CT was much superior to free Alpha-CT. The catalytic activity of BCP-adsorbed Alpha-CT was markedly dependent on the reaction temperature. Furthermore, concerning the thermal stability at 50 oC, the half-life of BCP-adsorbed Alpha-CT exhibited 3.8-fold, compared to that of free Alpha-CT.

Thermodynamics of the Hydrolysis of N-Acetyl-L-phenylalanine Ethyl Ester in Water and in Organic Solvents

1995 ◽  
Vol 99 (5) ◽  
pp. 1594-1601 ◽  
Author(s):  
Y. B. Tewari ◽  
M. M. Schantz ◽  
P. C. Pandey ◽  
M. V. Rekharsky ◽  
R. N. Goldberg
Keyword(s):  
Ethyl Ester ◽  
Organic Solvents ◽  
Hydrolysis Of

Reactions of acyl phosphates. Base hydrolysis of [Co(NH3)5OPO3COCH3]+ and the metal hydroxide promoted hydrolysis of acetyl phenyl phosphate

1981 ◽  
Vol 34 (8) ◽  
pp. 1769 ◽  
Author(s):  
DA Buckingham ◽  
CR Clark
Keyword(s):  
Hydroxo Complex ◽  
Metal Hydroxide ◽  
Base Hydrolysis ◽  
Acetyl Phosphate ◽  
Carbonyl Carbon ◽  
Phenyl Phosphate ◽  
Hydrolysis Of ◽  
Oxygen Bond

Tracer 18O studies have established that base hydrolysis of coordinated acetyl phosphate in [(NH3)5Co-OPO3COCH3]+ (kOH 0.53 mol-1 dm3 s-1, 25°C, I 1.0 NaClO4) proceeds with exclusive carbon-oxygen bond fission. The hydrolysis of acetyl phenyl phosphate monoanion is significantly catalysed by the exchange-inert hydroxo complex [(NH3)5Co-OH]2+ (kMOH 2.9 × 10-2 mol-1 dm3 s-1, 25°) which operates through a nucleophilic pathway involving attack at carbonyl carbon.

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