Substituent Effects on the Micelle-Catalysed and Uncatalysed Basic Hydrolysis of a Series of Substituted N-Methyl-p-toluanilides

1979 ◽  
Vol 32 (8) ◽  
pp. 1717 ◽  
Author(s):  
TJ Broxton ◽  
NW Duddy
Keyword(s):  
Substituent Effects ◽  
Cationic Micelles ◽  
Mechanism Of Reaction ◽  
Rate Of Reaction ◽  
Hammett Correlation ◽  
Rate Of Hydrolysis ◽  
Linear Plot ◽  
Basic Hydrolysis ◽  
Hydrolysis Of ◽  
Reaction In Water

The rate of hydrolysis of a series of substituted N-methyl-p-toluanilides has been measured in water and in the presence of cationic micelles [cetyltrimethylammonium bromide (ctab)]. A Hammett correlation of the rates of hydrolysis gave a curved Hammett plot for the reaction in water (k2,W) but a linear plot for the rate of reaction at optimal concentrations of ctab (k2,max) and for derived rate constants within the micelle (k2,m) These results are discussed in terms of the mechanism of reaction, and for two compounds a micelle-induced change of mechanism is indicated.

Micellar catalysis of the basic hydrolysis of anilides. III. α-Substituted N-methyl-N-p-nitrophenylacetamides

1980 ◽  
Vol 33 (8) ◽  
pp. 1771 ◽  
Author(s):  
TJ Broxton ◽  
NW Duddy
Keyword(s):  
Cetyltrimethylammonium Bromide ◽  
Substituent Effects ◽  
Micellar Catalysis ◽  
Single Parameter ◽  
Parameter Analysis ◽  
Basic Hydrolysis ◽  
Presence And Absence ◽  
Hydrolysis Of ◽  
Acetic Acids

The basic hydrolysis of a number of α-substituted N-methyl-N-p- nitrophenylacetamides has been studied both in the presence and absence of micelles of cetyltrimethylammonium bromide (ctab). Unlike the related p-nitrophenyl esters of a-substituted acetic acids, no evidence for the operation of the E1cb mechanism in the basic hydrolysis has been detected. Reasons for the differences between the amides and esters are discussed. Substituent effects on the hydrolysis of the amides have been studied both by single-parameter and dual-parameter analysis.

scholarly journals SN2 Mechanism of Cationic Micelles on the Hydrolysis of Bis-p-Methoxyphenyl Phosphate Ester

2015 ◽  
Vol 58 (3) ◽  
pp. 117-121
Author(s):  
Abanish Kumar
Keyword(s):  
Head Group ◽  
Phosphate Ester ◽  
Polar Head Group ◽  
Polar Groups ◽  
First Order Kinetics ◽  
Cationic Micelles ◽  
Pseudophase Model ◽  
Group Form ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

Hydrolysis of bis-p-methoxyphenyl phosphate ester (bis-p-MPPE) was studied in micellar solutions of cityltrimethylammoniumbromide n-C16H33N+(CH3)3Br- (CTABr) at pH-9.0. The hydrolysis followed first order kinetics with respect to bis-p-MPPE concentration. At the concentration of critical micelle concentration (CMC) the rate of hydrolysis increased with increasing CTABr concentration. Surfactant with cationic or polar head group form micelles in water with hydrocarbon like interior or polar groups at the surface and bind cationic solute. The binding constant of micelle for bis-p-MPPE and the rate constant in micellar pseudo phase were determined from kinetic data using the pseudophase model. 

Micellar catalysis of organic reactions. 22. A comparison of the basic hydrolysis of benzodiazepinones in the presence of reactive counterion micelles and vesicles

1988 ◽  
Vol 66 (7) ◽  
pp. 1566-1570 ◽  
Author(s):  
Trevor J. Broxton ◽  
Xenia Sango ◽  
Sallyanne Wright
Keyword(s):  
Surfactant Concentration ◽  
Biological Membranes ◽  
Micellar Catalysis ◽  
Organic Reactions ◽  
Conductivity Measurements ◽  
Amide Hydrolysis ◽  
Rate Of Hydrolysis ◽  
Basic Hydrolysis ◽  
Hydrolysis Of ◽  
Good Agreement

The basic hydrolysis of diazepam and several N-alkyl nitrazepam derivatives has been studied in the presence of reactive counterion micelles of cetyltrimethylammonium hydroxide (CTAOH) and vesicles of didodecyldimethylammonium hydroxide (DDAOH). In both surfactants, the rate of hydrolysis of all compounds was found to be dependent on the hydroxide concentration at constant surfactant concentration and this was interpreted as evidence for initial amide hydrolysis. The hydrolysis in CTAOH was inhibited by added salts in the order Br− < NO3− < SO42−. At concentrations above 3 mM surfactant, the rate of hydrolysis of each compound was similar in CTAOH and in DDAOH. At lower concentrations of CTAOH, however, the rate of hydrolysis was significantly lower than that in DDAOH. On the basis of this evidence, it was concluded that the cmc of CTAOH was between 2–3 mM, which is in good agreement with the value of 1.8 mM obtained by Zana from conductivity measurements. For diazepam, a mechanistic change is indicated on transfer from water to either micelles or vesicles and since vesicles are considered good models of biological membranes, this suggests that conclusions concerning the bioavailability of diazepam should not be based on studies in water but rather on studies in either micelles or vesicles.

scholarly journals The mechanism of the solvolysis of p-methoxybenzyl chloride in aqueous acetone containing pyridine or thiourea. Evidence for concurrent substitution by unimolecular and bimolecular processes

1979 ◽  
Vol 57 (19) ◽  
pp. 2646-2651 ◽  
Author(s):  
Alan Queen
Keyword(s):  
Aqueous Acetone ◽  
Rate Of Reaction ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

The overall rate of reaction of p-methoxybenzyl chloride with 70% aqueous acetone is increased by the addition of pyridine but the rate of hydrolysis is decreased. Comparison of these data with those for benzhydryl chloride under the same conditions shows that the rate of hydrolysis of p-methoxybenzyl chloride is less than the rate of ionisation. These results are discussed in terms of concurrent operation of the SN1 mechanism and a bimolecular process. Similar results are obtained when thiourea is used instead of pyridine.

Micellar catalysis of anilide hydrolysis

1978 ◽  
Vol 31 (7) ◽  
pp. 1525 ◽  
Author(s):  
TJ Broxton ◽  
LW Deady ◽  
NW Duddy
Keyword(s):  
Cetyltrimethylammonium Bromide ◽  
Sodium Lauryl Sulfate ◽  
Micellar Catalysis ◽  
Lauryl Sulfate ◽  
Cationic Micelles ◽  
Ring Nitrogen ◽  
Rate Of Hydrolysis ◽  
Anionic Micelles ◽  
Hydrolysis Of ◽  
Ring Nitrogen Atom

The rate of hydrolysis of several anilides is catalysed by cationic micelles (cetyltrimethylammonium bromide), and inhibited by anionic micelles (sodium lauryl sulfate). The magnitude of catalysis is greatest for those anilides which contain the most hydrophobic R groups (R = C7H15 and Ph) and is less for those containing less hydrophobic R groups (R = Me). The magnitude of catalysis is greater for compounds activated by nitro groups than for those activated by a ring nitrogen atom. The catalysis is inhibited by added sodium bromide. There is no evidence that anilide hydrolysis in a micellar environment involves dianionic intermediates. Micellar catalysis of anilide hydrolysis is much greater than for ester hydrolysis.

REACTIONS OF ARYLSULPHONIC ESTERS: III. ON THE HYDROLYSIS OF METHYL p-METHYLBENZENESULPHONATE

1955 ◽  
Vol 33 (10) ◽  
pp. 1536-1543 ◽  
Author(s):  
R. E. Robertson
Keyword(s):  
Specific Heat ◽  
Temperature Dependence ◽  
Specific Solvation ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of ◽  
Reaction In Water

A study of the temperature dependence for the rate of hydrolysis of methyl p-methylbenzenesulphonate shows the specific heat of activation for this reaction in water to be 33.45 ± 3 cal./mole degree. A comparison with the corresponding term for other methyl compounds reveals differences apparently characteristic of the anionic portion of the molecule. These differences are discussed in terms of specific solvation.

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.

Solvent reorganization for hydrolysis with hydrogen participation

1969 ◽  
Vol 47 (24) ◽  
pp. 4599-4605 ◽  
Author(s):  
Y. Inomoto ◽  
R. E. Robertson ◽  
G. Sarkis
Keyword(s):  
Acetic Acid ◽  
Isotope Effect ◽  
Activation Process ◽  
Solvent Isotope Effect ◽  
Butyl Bromide ◽  
Rate Of Hydrolysis ◽  
Solvent Isotope ◽  
Hydrolysis Of ◽  
Reaction In Water

A study of the rates of hydrolysis of 3-Me-2-butyl bromide and methanesulfonate in water leads to values of ΔCp≠ of −80 and −40 cal deg−1 mole−1, respectively. The product was about 85–95 % t-pentanol, the remainder being olefin. The value of ΔCp≠ for the solvolysis of the methanesulfonate in D2O was −44 cal deg−1 mole−1. The kinetic solvent isotope effect (k.s.i.e.) for the latter was unusually low (k.s.i.e. = 1.047 at 5 °C and 1.025 at 25 °C). Deuteration at C-3 led to a reduction in the rate of hydrolysis by a factor of about 2.25. This is consistent with an activation process involving "hydrogen participation" as previously reported by Winstein and Takahashi for solvolysis of the corresponding tosylate in acetic acid. In contrast to the latter work, the reaction in water appears to be uncomplicated.

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