Reaction rate with suspended lipase catalyst shows similar dependence on water activity in different organic solvents

1992 ◽  
Vol 1118 (3) ◽  
pp. 218-222 ◽  
Author(s):  
Rao H. Valivety ◽  
Peter J. Halling ◽  
Alasdar R. Macrae
Keyword(s):  
Organic Solvents ◽  
Water Activity ◽  
Reaction Rate ◽  
Similar Dependence

Polar organic solvents accelerate the rate of DNA strand replacement reaction

The Analyst ◽  
2015 ◽  
Vol 140 (6) ◽  
pp. 2023-2028 ◽  
Author(s):  
Tianchi Zhang ◽  
Chunli Shang ◽  
Ruixue Duan ◽  
Abdul Hakeem ◽  
Zhenyu Zhang ◽  
...  
Keyword(s):  
Organic Solvents ◽  
Reaction Rate ◽  
Replacement Reaction ◽  
Polar Organic Solvents ◽  
Dna Strand

Acceleration of the reaction rate by polar organic solvents during both simple and complicated DNA strand replacement reactions is reported.

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.

scholarly journals Continuous Flow Bioamination of Ketones in Organic Solvents at Controlled Water Activity using Immobilized ω‐Transaminases

2020 ◽  
Vol 362 (9) ◽  
pp. 1858-1867 ◽  
Author(s):  
Wesley Böhmer ◽  
Alexey Volkov ◽  
Karim Engelmark Cassimjee ◽  
Francesco G. Mutti
Keyword(s):  
Organic Solvents ◽  
Water Activity ◽  
Continuous Flow

Recent development in functionalized ionic liquids as reaction media and promoters

2012 ◽  
Vol 90 (1) ◽  
pp. 1-16 ◽  
Author(s):  
Wing-Leung Wong ◽  
Kwok-Yin Wong
Keyword(s):  
Ionic Liquids ◽  
Organic Solvents ◽  
Chemical Reactions ◽  
Reaction Rate ◽  
Bond Formation ◽  
Catalytic Reactions ◽  
Important Chemical ◽  
Reaction Media

The recent development in the use of functionalized ionic liquids as both reaction media and promoters is reviewed. Ionic liquids designed with special functionality can enhance the reaction rate, selectivity, and productivity in various chemical reactions. In this context, some important chemical reactions involving C–C, C–O, C–N, and C–S bond formation in functionalized ionic liquids are discussed. These functionalized ionic liquids were found to provide distinct advantages over conventional organic solvents in these catalytic reactions.

Kinetic equations for reactions in concentrated aqueous acids based on the concept of "excess acidity"

1979 ◽  
Vol 57 (22) ◽  
pp. 2944-2951 ◽  
Author(s):  
Robin A. Cox ◽  
Keith Yates
Keyword(s):  
Water Activity ◽  
Acid Concentration ◽  
Function Method ◽  
Reaction Rate ◽  
Kinetic Equations ◽  
Slope Parameter ◽  
Rate Data ◽  
Standard State ◽  
Acidity Functions ◽  
Aqueous Standard

Kinetic equations, applicable to A-1, A-SE2, and A-2 reactions in concentrated aqueous acids, are derived. The variation in reaction rate with varying acid concentration is treated in terms of the "excess acidity" of the medium (X-function), rather than in terms of Hammett-type acidity functions or the water activity. The parameters obtained are the medium-independent rate constant k0, in the aqueous standard state, as an intercept, and a slope parameter m≠ hydration parameters (r-values) are also obtained, for A-2 reactions. The equations derived are shown to apply to A-1 acetal hydrolyses, A-SE2 electrophilic aromatic substitutions, and mixed A-2/A-1 ester hydrolyses. In a general discussion of available methods for analyzing rate data in these media, it is shown that the X-function method encompasses most, if not all, of the others, and that classical acidity functions are no longer necessary.

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