Trapping of the Intermediate Formed in the E1cB Hydrolysis of Some Alkyl and Aryl N-(4-Nitrophenyl) carbamates in a Hydroxy Functionalized Micelle

1985 ◽  
Vol 38 (1) ◽  
pp. 77 ◽  
Author(s):  
TJ Broxton
Keyword(s):  
Hydroxy Group ◽  
Alkaline Solution ◽  
Cetyltrimethylammonium Bromide ◽  
Rate Of Reaction ◽  
Hydrolysis Of

The basic hydrolyses of some alkyl and aryl N-(4-nitrophenyl) carbamates in the presence of micelles of cetyl (2-hydroxyethyl) dimethylammonium bromide ( chedab )were studied. For compounds which react by the BAC2 mechanism, verysimilar results were obtained in cetyltrimethylammonium bromide ( ctab ) and in chedab micelles. However, for compounds which react by the E1cB mechanism, the intermediate p- nitrophenyl isocyanate was trapped by the hydroxy group of the functional micelle to form a new carbamate directly bound to the detergent molecules of the micelle. It was shown that this new carbamate decomposed by a BAC2 mechanism. p- Nitrophenyl isocyanate added to an alkaline solution of chedab gave N-(4-nitrophenyl)- carbamate ion. Thus, the isocyanate has to be generated within the micelle for trapping to occur. The rate of reaction of p-nitrophenyl isocyanate with OH-/H2O is faster than the rate of solubilization within the micelle.

The hydrolysis of maleimide in alkaline solution

1976 ◽  
Vol 54 (9) ◽  
pp. 1400-1404 ◽  
Author(s):  
Remigio Germano Barradas ◽  
Stephen Fletcher ◽  
John Douglas Porter
Keyword(s):  
Alkaline Solution ◽  
Reaction Scheme ◽  
Rate Equations ◽  
Bulk Concentration ◽  
Rate Of Reaction ◽  
Ph Range ◽  
Derived Data ◽  
Hydrolysis Of

The hydrolysis of maleimide has been investigated in the pH range 8.5–14. Polarographic limiting currents were well-defined, so that the bulk concentration of reactant during reduction could be clearly followed as a function of time. Logarithmic analysis of derived data indicated an arrest in the rate of reaction at circa pH 12, and a reaction scheme is proposed to explain this. In this scheme, the neutral maleimide molecule exists in equilibrium with its anion, and both of these species may undergo hydrolysis at the appropriate pH. From derived rate equations, the pKa of maleimide was found to be 10.0, whilst estimates of the rates of hydrolysis were also calculated.

Micellar catalysis of organic reactions. Part 33. Amide hydrolysis in neutral solution in the presence of a copper-containing micelle

1993 ◽  
Vol 71 (5) ◽  
pp. 670-673 ◽  
Author(s):  
Trevor J. Broxton ◽  
Robin A. Coa
Keyword(s):  
Cetyltrimethylammonium Bromide ◽  
Cupric Chloride ◽  
Buffer Concentration ◽  
Neutral Solution ◽  
Hydroxide Ion ◽  
Amide Hydrolysis ◽  
Mechanism Of Reaction ◽  
Rate Of Reaction ◽  
Hydrolysis Of ◽  
Micelle Surface

The hydrolysis of 5-nitro-2-(trifluoroacetylamino)benzoic acid (1) has been studied at pH 7 in water and in the presence of micelles of cetyltrimethylammonium bromide (ctab) and of copper-containing micelles formed from the reaction of N,N,N′-trimethyl-N′-hexadecylethylenediamine and cupric chloride. It has been found that the hydrolysis of 1 is inhibited by micelles of ctab but strongly catalysed by the copper-containing micelle at this pH. At a higher pH where the hydroxide ion reaction becomes important the reaction is catalysed by micelles of ctab as well, but the catalysis is stronger by the copper-containing micelle. The effect of added sodium chloride on the rate of reaction is shown to be larger for reaction in the presence of ctab than for reaction in the presence of the copper micelles. Also reported are the effects of the buffer concentration on the rate of reaction at various pH for both micelles. It is concluded that the mechanism of reaction in the copper-containing micelle involves a metal-bound hydroxyl rather than a free hydroxide ion loosely associated with the cationic micelle surface. It is interesting that the catalysis of this reaction by the copper-containing micelle is large enough to allow amide hydrolysis at a reasonable rate at neutral pH at ambient temperature.

Micellar catalysis of organic reactions. VII. The effect of the micellar counter ion in nucleophilic reactions of hydroxide and nitrite ions

1981 ◽  
Vol 34 (11) ◽  
pp. 2313 ◽  
Author(s):  
TJ Broxton
Keyword(s):  
Sodium Nitrite ◽  
Cetyltrimethylammonium Bromide ◽  
Ion Pairs ◽  
Micellar Catalysis ◽  
Nucleophilic Reactions ◽  
Counter Ion ◽  
Rate Of Reaction ◽  
Exchange Constants ◽  
Basic Hydrolysis ◽  
Hydrolysis Of

The rates of basic hydrolysis of N-methyl-N-(4'-nitrophenyl)octanamide and N,4-dimethyl-N- (3'-nitrophenyl)benzamide in the presence of cetyltrimethylammonium fluoride and acetate and the SNAr reactions of sodium nitrite with 2,4-dinitrofluorobenzene and 1-chloro-2,4-dinitrobenzene in the presence of cetyltrimethylammonium fluoride have been measured and compared to the rate in the presence of cetyltrimethylammonium bromide. The identity of the micellar counter ion (i.e. fluoride, acetate or bromide) has only a small effect on the rate of reaction despite quite substantial differences in exchange constants for the appropriate nucleophile/counter ion pairs; this is explained by a considerable amount of reaction between substrate molecules in the micellar pseudophase and the nucleophile in the aqueous intermicellar phase.

Micellar catalysis of organic reactions. VIII. Kinetic studies of the hydrolysis of 2-acetyloxybenzoic acid (aspirin) in the presence of micelles

1982 ◽  
Vol 35 (7) ◽  
pp. 1357 ◽  
Author(s):  
TJ Broxton
Keyword(s):  
Aqueous Solution ◽  
Cetyltrimethylammonium Bromide ◽  
Cetylpyridinium Chloride ◽  
Kinetic Studies ◽  
Base Catalysis ◽  
Plateau Region ◽  
General Base ◽  
Mechanism Of Hydrolysis ◽  
Ph Range ◽  
Hydrolysis Of

The hydrolysis of 2-acetyloxybenzoic acid in the pH range 6-12 has been studied in the presence of micelles of cetyltrimethylammonium bromide (ctab) and cetylpyridinium chloride (cpc). In the plateau region (pH 6-8) the hydrolysis is inhibited by the presence of micelles, while in the region where the normal BAC2 hydrolysis (pH > 9) occurs the reaction is catalysed by micelles of ctab and cpc. The mechanism of hydrolysis in the plateau region is shown to involve general base catalysis by the adjacent ionized carboxy group both in the presence and absence of micelles. This reaction is inhibited in the presence of micelles because the substrate molecules are solubilized into the micelle and water is less available in this environment than in normal aqueous solution.

scholarly journals Kinetics of the alkaline hydrolysis of crystal violet in micelles, reverse micelles and microemulsions of cetyltrimethylammonium bromide

1970 ◽  
Vol 24 (2) ◽  
pp. 173-184 ◽  
Author(s):  
Ferdousi Begum ◽  
Md Yousuf A Molla ◽  
M Muhibur Rahman ◽  
Md Abu Bin Hasan Susan
Keyword(s):  
Crystal Violet ◽  
Alkaline Hydrolysis ◽  
Reverse Micelles ◽  
Cetyltrimethylammonium Bromide ◽  
Specific Conductivity ◽  
Water System ◽  
Chemical Society ◽  
Order Rate Constant ◽  
Kinetics Of ◽  
Hydrolysis Of

Kinetics of the alkaline hydrolysis of crystal violet (CV) in micelles, reverse micelles and microemulsions of a cationic surfactant, cetyltrimethylammonium bromide (CTAB) was studied at 25 ± 0.1 oC using spectrophotometric method. The rate of alkaline hydrolysis of CV was catalyzed by micellar solutions of CTAB. The pseudo first order rate constant (k') has been found to decrease upon incorporation of 1-butanol to cationic CTAB micelles, which displaces the substrate from the micellar into the aqueous phase. In CTAB/cyclohexane/1-butanol/water system, as the content of 1-butanol increases, specific conductivity and density of the microemulsions and reverse micelles decrease. The change in physical properties also causes change in reaction environment. A change from a micelle-rich (o/w) to a reverse micelle-rich (w/o) condition is apparent for microemulsions and consequently the k' vs. % wt. of 1-butanol profiles show an initial decrease in the k' followed by a gradual increase and finally, to a sharp increase with increasing 1-butanol content. Microemulsions and reverse micelles thus offer the potential to control rate of a reaction by formation of micelles in water phase and reverse micelles in oil phase. DOI: http://dx.doi.org/10.3329/jbcs.v24i2.9706 Journal of Bangladesh Chemical Society, Vol. 24(2), 173-184, 2011

Micelle Catalyzed Hydrolysis of Carboxylic Acid Esters in Water–β‐Cyclodextrin–Cetyltrimethylammonium Bromide Systems

2003 ◽  
Vol 24 (1) ◽  
pp. 97-101 ◽  
Author(s):  
Jiaqing Xie ◽  
Yi Zhang ◽  
Juan Du ◽  
Xian‐cheng Zeng ◽  
Ying‐jin Liu ◽  
...  
Keyword(s):  
Carboxylic Acid ◽  
Cetyltrimethylammonium Bromide ◽  
Hydrolysis Of ◽  
Acid Esters

Effect of cationic surfactant cetyltrimethylammonium bromide on the enzymatic hydrolysis of cellulose

Cellulose ◽  
2016 ◽  
Vol 24 (1) ◽  
pp. 61-68 ◽  
Author(s):  
Xuliang Lin ◽  
Cheng Cai ◽  
Hongming Lou ◽  
Xueqing Qiu ◽  
Yuxia Pang ◽  
...  
Keyword(s):  
Enzymatic Hydrolysis ◽  
Cationic Surfactant ◽  
Cetyltrimethylammonium Bromide ◽  
Enzymatic Hydrolysis Of Cellulose ◽  
Hydrolysis Of Cellulose ◽  
Hydrolysis Of
Sign in / Sign up

Export Citation Format

Share Document