scholarly journals Ion Pair-Directed Regiocontrol in Transition-Metal Catalysis: A Meta-Selective C–H Borylation of Aromatic Quaternary Ammonium Salts

2016 ◽  
Vol 138 (39) ◽  
pp. 12759-12762 ◽  
Author(s):  
Holly J. Davis ◽  
Madalina T. Mihai ◽  
Robert J. Phipps
Keyword(s):  
Transition Metal ◽  
Quaternary Ammonium ◽  
Ion Pair ◽  
Quaternary Ammonium Salts ◽  
Transition Metal Catalysis ◽  
Ammonium Salts ◽  
Metal Catalysis

scholarly journals Evaluation of Ion-pair Formation of Adefovir to Improve Permeation across Artificial and Biological Membranes

2018 ◽  
Vol 21 ◽  
pp. 160-170 ◽  
Author(s):  
Bahar Darsazan ◽  
Alireza Shafaati ◽  
Afshin Zarghi ◽  
Seyed Alireza Mortazavi
Keyword(s):  
Quaternary Ammonium ◽  
Adefovir Dipivoxil ◽  
Ion Pair ◽  
Pair Formation ◽  
Quaternary Ammonium Salts ◽  
Ammonium Salts ◽  
Apparent Permeability ◽  
Ion Pair Formation ◽  
Counter Ion ◽  
Everted Gut Sac

Purpose: Adefovir is an antiviral drug that exhibits high hydrophilic properties and negligible bioavailability (less than 12%). It is only applied in the form of the ester prodrug adefovir dipivoxil (ADV). The oral bioavailability of ADV is limited (32% to 45%) by its low permeability (Class 3) and biological conversion of the prodrug to adefovir. Ion-pair formation is considered as an alternative approach to a covalent prodrug (ADV) to enhance intestinal permeation of adefovir. Methods: The effect of various counter-ions (anionic, cationic and two quaternary ammonium salts) on the lipophilicity of adefovir was investigated by means of the n-octanol/buffer partitioning system, an in vitro transport model (PAMPA) and a biological membrane (everted gut sac). Results: Quaternary ammonium salts, cetylpyridinium chloride (CPC) and cetrimide enhanced the lipophilicity of adefovir 136- and 87-fold, respectively. The apparent permeability of adefovir in combination with CPC (counter-ion) was 2.5-fold greater than ADV permeability in the PAMPA model. The apparent permeability of adefovir-CPC (counter-ion) was 1.3-fold greater than that of adefovir dipivoxil permeability in a biologic membrane (everted gut sac). Conclusion: These results suggest that the adefovir-CPC ion-paired system has potential for improving the permeation of adefovir across the intestinal membrane. This article is open to POST-PUBLICATION REVIEW. Registered readers (see “For Readers”) may comment by clicking on ABSTRACT on the issue’s contents page.

Epoxidation of 1-butene to 1,2-butene oxide by transition metal disubstituted P–W–Mo ternary heteropoly quaternary ammonium salts

2015 ◽  
Vol 41 (11) ◽  
pp. 8891-8906 ◽  
Author(s):  
Meng Wang ◽  
Panpan Wang ◽  
Qingwen Tian ◽  
Jiahui Liu ◽  
Jinquan Deng ◽  
...  
Keyword(s):  
Transition Metal ◽  
Quaternary Ammonium ◽  
Quaternary Ammonium Salts ◽  
Ammonium Salts

Electrical conductivities of quaternary ammonium salts in acetone.: Part I. Pressure and temperature effects

1968 ◽  
Vol 46 (12) ◽  
pp. 1977-1988 ◽  
Author(s):  
W. A. Adams ◽  
K. J. Laidler
Keyword(s):  
Concentration Dependence ◽  
Quaternary Ammonium ◽  
Temperature Effects ◽  
Dissociation Constants ◽  
Ion Pair ◽  
Quaternary Ammonium Salts ◽  
Ammonium Salts ◽  
Electrical Conductivities ◽  
Pressure And Temperature Effects ◽  
Tetraethylammonium Iodide

The equivalent conductivities of tetramethylammonium iodide, tetraethylammonium iodide, and tetra-n-propylammonium iodide in acetone solution were determined at concentrations from 1 to 10 × 10−4 mole/liter and at temperatures of 25 to 55 °C and pressures from atmospheric to 1.1 kbar. The concentration dependence of the equivalent conductivities was analyzed by the Shedlovsky method. Limiting equivalent conductivities and ion-pair dissociation constants are tabulated.

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