THE CHEMISTRY OF ETHYLENE OXIDE: V. THE REACTION OF ETHYLENE OXIDE WITH HALIDE IONS IN NEUTRAL AND ACID SOLUTION

1952 ◽  
Vol 30 (3) ◽  
pp. 169-176 ◽  
Author(s):  
A. M. Eastham ◽  
G. A. Latremouille
Keyword(s):  
Aqueous Solution ◽  
Ethylene Oxide ◽  
Acid Solution ◽  
Activation Energies ◽  
Hydrogen Halide ◽  
Halide Ions ◽  
Neutral Aqueous Solution ◽  
Rate Of Hydrolysis ◽  
Acid Catalyzed ◽  
Hydrolysis Of

The rates of reaction of halide ions with ethylene oxide in neutral aqueous solution and the rate of hydrolysis of ethylene oxide in acid solution have been measured and the activation energies determined. From these data and from the ratio of glycol to chlorohydrin formed when ethylene oxide reacts with excess aqueous hydrogen halide, the rates of the acid-catalyzed addition of halide ions to ethylene oxide at 25 °C. have been estimated.

The effect of polymeric and model imidazolium halides on the rate of hydrolysis of 4-acetoxy-3-nitrobenzoic acid

1985 ◽  
Vol 50 (4) ◽  
pp. 845-853 ◽  
Author(s):  
Miloslav Šorm ◽  
Miloslav Procházka ◽  
Jaroslav Kálal
Keyword(s):  
Catalyst Concentration ◽  
Low Molecular Weight ◽  
Imidazolium Chloride ◽  
First Order ◽  
Nitrobenzoic Acid ◽  
Rate Of Hydrolysis ◽  
Acid Catalyzed ◽  
Hydrolysis Of ◽  
Ethanol In Water ◽  
Direct Attack

The course of hydrolysis of an ester, 4-acetoxy-3-nitrobenzoic acid catalyzed with poly(1-methyl-3-allylimidazolium bromide) (IIa), poly[l-methyl-3-(2-propinyl)imidazolium chloride] (IIb) and poly[l-methyl-3-(2-methacryloyloxyethyl)imidazolium bromide] (IIc) in a 28.5% aqueous ethanol was investigated as a function of pH and compared with low-molecular weight models, viz., l-methyl-3-alkylimidazolium bromides (the alkyl group being methyl, propyl, and hexyl, resp). Polymers IIb, IIc possessed a higher activity at pH above 9, while the models were more active at a lower pH with a maximum at pH 7.67. The catalytic activity at the higher pH is attributed to an attack by the OH- group, while at the lower pH it is assigned to a direct attack of water on the substrate. The rate of hydrolysis of 4-acetoxy-3-nitrobenzoic acid is proportional to the catalyst concentration [IIc] and proceeds as a first-order reaction. The hydrolysis depends on the composition of the solvent and was highest at 28.5% (vol.) of ethanol in water. The hydrolysis of a neutral ester, 4-nitrophenyl acetate, was not accelerated by IIc.

Vinyl ether hydrolysis. XVII. Oxacyclonon-2,8-diene and the question of the unorthodox reaction mechanism for 9-methoxyoxacyclonon-2-ene

1984 ◽  
Vol 62 (1) ◽  
pp. 74-76 ◽  
Author(s):  
R. A. Burt ◽  
Y. Chiang ◽  
A. J. Kresge ◽  
S. Szilagyi
Keyword(s):  
Reaction Mechanism ◽  
Vinyl Ether ◽  
Membered Ring ◽  
Specific Rate ◽  
Ether Group ◽  
Reaction Proceeds ◽  
Great Reactivity ◽  
Rate Of Hydrolysis ◽  
Acid Catalyzed ◽  
Hydrolysis Of

The acid-catalyzed hydrolysis of the nine-membered ring cyclic vinyl ether, oxacyclonon-2,8-diene, occurs with a normal isotope effect, [Formula: see text], which indicates that this reaction proceeds by the conventional vinyl ether hydrolysis mechanism involving rate-determining proton transfer to carbon. The specific rate of this reaction, [Formula: see text], may then be used to show that there is no significant ring-size effect on the rate of hydrolysis of a vinyl ether group in a nine-membered ring. The previously noted unusually great reactivity of the vinyl ether group in 9-methoxyoxacyclonon-2-ene, for which an unorthodox reaction mechanism has been claimed, must therefore be due to some other cause.

scholarly journals Structure Determination of Two New Monocillin I Derivatives

2010 ◽  
Vol 5 (5) ◽  
pp. 1934578X1000500
Author(s):  
Jixun Zhan ◽  
E. M. Kithsiri Wijeratne ◽  
A. A. Leslie Gunatilaka
Keyword(s):  
Double Bond ◽  
Acid Solution ◽  
Beauveria Bassiana ◽  
Structure Determination ◽  
Spectroscopic Data ◽  
Enzymatic Process ◽  
Acid Catalyzed ◽  
Hydrolysis Of

Biotransformation of monocillin I (1) by Beauveria bassiana ATCC 7159 was investigated. Two new derivatives 2 and 3 were isolated and identified on the basis of the spectroscopic data. Compounds 2 and 3 are synthesized by hydration at 10,11-double bond and hydrolysis of 14,15-epoxide, respectively. The R configuration of 11-OH in 2 was established by the modified 2-methoxy-2-trifluoromethylphenylacetic acid (MTPA) method. The conversion of 1 to 2 and 3 was reconstituted in an acid solution, indicating that the formation of 2 and 3 is an acid-catalyzed instead of an enzymatic process.

THE ACID HYDROLYSIS OF GLYCOSIDES: I. GENERAL CONDITIONS AND THE EFFECT OF THE NATURE OF THE AGLYCONE

1964 ◽  
Vol 42 (6) ◽  
pp. 1456-1472 ◽  
Author(s):  
T. E. Timell
Keyword(s):  
Acid Hydrolysis ◽  
Equilibrium Concentration ◽  
Rate Coefficients ◽  
Acidity Function ◽  
Tertiary Alcohols ◽  
Conjugate Acid ◽  
Rate Of Hydrolysis ◽  
Acid Catalyzed ◽  
Opposing Effects ◽  
Hydrolysis Of

First-order rate coefficients and energies and entropies of activation have been determined for the acid-catalyzed hydrolysis of a number of methyl D-glycopyranosides and disaccharides. The relation between the logarithm of the rate coefficients and values for Hammett's acidity function was linear, although different for different acids. All compounds had entropies of activation indicating a unimolecular reaction mechanism. Glucosides of tertiary alcohols were hydrolyzed very rapidly, triethylmethyl β-D-glucopyranoside, for example, 30,000 times taster than the corresponding methyl compound.Increase in size of the aglycone caused a slight increase in the rate of hydrolysis of β-D-glucopyranosides, steric hindrance thus being of no significance. Electron-attracting substituents in the aglycone had little or no influence on the rate of hydrolysis, obviously because they would tend to lower the equilibrium concentration of the conjugate acid, while facilitating the subsequent heterolysis, the two opposing effects more or less cancelling out. These results were discussed in connection with recent studies on the acid hydrolysis of various phenyl glycopyranosides and with reference to the postulated occurrence of an activating inductive effect in oligo- and poly-saccharides containing carboxyl or other electronegative groups at C-5. It was concluded that there is little evidence for the existence of any such effect and that, for example, pseudoaldobiouronic acids should be hydrolyzed at the same rate as corresponding neutral disaccharides.

Acid-catalyzed hydrolysis of 2-methylene-1,3-dithiolane. 2. Remarkable effects of β substitution on reversibility of the carbon protonation

1986 ◽  
Vol 64 (6) ◽  
pp. 1116-1123 ◽  
Author(s):  
Tadashi Okuyama ◽  
Masayoshi Toyoda ◽  
Takayuki Fueno
Keyword(s):  
Aqueous Solution ◽  
Rate Constants ◽  
Isotope Exchange ◽  
Relative Stabilities ◽  
The Third ◽  
Initial Carbon ◽  
Acid Catalyzed ◽  
The Individual ◽  
Individual Rate ◽  
Hydrolysis Of

Hydrolyses of 2-ethylidene-(1b), 2-isopropylidene-(1c), and 2-benzylidene-1,3-dithiolane (1d) were kinetically investigated in aqueous solution. All the individual rate constants involved in this three-step reaction were evaluated. Initial carbon protonation is only partially reversible (k2/k−1 = 1.33, 0.68, and 1.02 for 1b, 1c, and 1d, respectively) at higher pH, while the protonation becomes completely reversible below pH 2 where the third step is rate determining. Complete H–D isotope exchange at the β-carbon of 1b and 1d was observed in deuterium media before appreciable hydrolysis took place. It was demonstrated that reversion from the tetrahedral intermediate 3 to 1 occurs extensively during the reaction in the latter acidity range. Relative stabilities and reactivities of the olefinic substrates 1 are discussed.

THE HYDROLYSIS OF ACID AMIDES IN CONCENTRATED HYDROCHLORIC ACID SOLUTIONS

1942 ◽  
Vol 20b (5) ◽  
pp. 73-81 ◽  
Author(s):  
B. S. Rabinovitch ◽  
C. A. Winkler
Keyword(s):  
Activation Energy ◽  
Hydrochloric Acid ◽  
Acid Concentration ◽  
Reaction Rates ◽  
Activation Energies ◽  
Acid Solutions ◽  
Hydrochloric Acid Solutions ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

The Arrhenius constants have been evaluated for the hydrolysis of formamide, acetamide, propionamide, and benzamide in hydrochloric acid solutions over the concentration range 1 to 10 N. There is approximate correspondence between reaction rates and activation energies for the series of amides. An increase in observed activation energy with increasing acid concentration was found for all amides. The maximum in rate of hydrolysis, which occurs at higher acid concentrations, is discussed and accounted for by the variation in the Arrhenius constants with acid concentration.

Photochemical hydrolysis of some nitrophenyl acetates

1986 ◽  
Vol 51 (6) ◽  
pp. 1293-1300 ◽  
Author(s):  
Petr Kuzmič ◽  
Libuše Pavlíčková ◽  
Milan Souček
Keyword(s):  
Aqueous Solution ◽  
Excited State ◽  
Triplet State ◽  
Quantum Yields ◽  
Ester Bond ◽  
Acidic Media ◽  
Effective Lifetime ◽  
Product Molecule ◽  
Neutral Aqueous Solution ◽  
Hydrolysis Of

Nitro substituent exhibits a meta-activating effect on the course of photochemical hydrolysis of phenyl acetates since UV photolysis of isomeric 4- and 3-nitrophenyl acetates in neutral aqueous solution leads to the formation of the corresponding phenols with quantum yields 0.002 and 0.006, respectively; 2-methoxy-4-nitro- and 2-methoxy-5-nitrophenyl acetates showed still greater difference in their photochemical reactivity (Φr 0.002 and 0.129, respectively). Quenching of the photohydrolysis of the latter compound with 2,4-hexadienoic acid indicates the participation of a triplet state with the effective lifetime of 0.15 μs. The photoreaction is accelerated in acidic media which means that one of the early photochemical steps is the protonation of the excited state. No incorporation of 18O into the product molecule was observed after the photolysis of 2-methoxy-5-nitrophenyl acetate in H218O, which is an unambiguous evidence that the photoreaction proceeds as a light-induced hydrolysis of the ester bond.

THE HYDROLYSIS OF THE CONDENSED PHOSPHATES: III. SODIUM TETRAMETAPHOSPHATE AND SODIUM TETRAPHOSPHATE

1956 ◽  
Vol 34 (7) ◽  
pp. 969-981 ◽  
Author(s):  
Joan Crowther ◽  
A. E. R. Westman
Keyword(s):  
Phosphate Glass ◽  
Sodium Phosphate ◽  
Hydrogen Ion ◽  
Ion Concentrations ◽  
First Order ◽  
Condensed Phosphates ◽  
Rate Of Hydrolysis ◽  
Acid Catalyzed ◽  
Ph Range ◽  
Hydrolysis Of

The rates of hydrolysis of sodium tetrametaphosphate and tetraphosphate (in the presence of tetrametaphosphate) have been measured at 65.5 °C. over the pH range 2.5 to 13.3. Tetrametaphosphate anions hydrolyze to tetraphosphate which in turn hydrolyzes to triphosphate and orthophosphate and not to pyrophosphate. Thus the terminal oxygen bridges in the tetraphosphate and not the central one are attacked preferentially. The reactions were first order and acid catalyzed. The tetrametaphosphate hydrolysis was also base catalyzed with a minimum rate in solutions of pH approximately 7.5. The rate of hydrolysis of tetraphosphate was greater than triphosphate at the hydrogen ion concentrations studied. Hydrolysis of a sodium phosphate glass indicated that preferential attack on terminal oxygen bridges takes place also with higher polymers. However, trimetaphosphate is formed at the same time.

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