The Alkaline Hydrolysis of Some Lignin Model 2-Arylcoumarans

1972 ◽  
Vol 25 (7) ◽  
pp. 1529 ◽  
Author(s):  
AA Wallis
Keyword(s):  
Sodium Hydroxide ◽  
Alkaline Hydrolysis ◽  
Mechanism Of Formation ◽  
Lignin Model ◽  
A Minor ◽  
Hydrolysis Of

Reaction of the 2-arylcoumaran (2b) with 2b sodium hydroxide at 170� gave predominantly the (E)- and (2)-stilbenes (4a) and (5a) in the ratio 1 : 2, and the 2-arylbenzofuran (6) as a minor product. The isomeric 1,2-diarylpropan-1-ols (7b) and (8b) were prepared and gave on treatment with 2N sodium hydroxide at 170� an analogous mixture of stilbene isomers to that obtained from the coumaran (2b). The mechanism of formation of compounds (4a), (5a), and (6) is discussed.

Mechanism of formation of trimethylisoxazole and intermediates upon alkaline hydrolysis of nitroethane

1969 ◽  
Vol 47 (17) ◽  
pp. 3107-3112 ◽  
Author(s):  
R. W. Lockhart ◽  
K. W. Ng ◽  
P. E. Nott ◽  
A. M. Unrau
Keyword(s):  
Alkaline Hydrolysis ◽  
Initial Step ◽  
Mechanism Of Formation ◽  
Reaction Sequence ◽  
Simple Mechanism ◽  
Basic Hydrolysis ◽  
Elimination Reactions ◽  
Hydrolysis Of

Nitroethane and higher homologous primary nitroalkanes undergo a base-catalyzed condensation yielding the corresponding 2,3,4-trialkyisoxazoles. Basic hydrolysis of nitroethane to acetaldehyde is the key initial step followed by a series of condensation and elimination reactions. Through the use of appropriately 14C-labelled intermediates and acetaldehyde-d4, a relatively simple mechanism is indicated which will satisfactorily account for all observed intermediates indicated in a summary of the reaction sequence.[Formula: see text]

scholarly journals MICELLAR CATALYZED REACTION IN AQUEOUS GLYCEROL SOLUTIONS AND THE INTERNAL PRESSURE OF THE MEDIUM

2008 ◽  
Vol 16 (16) ◽  
pp. 41-57
Author(s):  
Lavinel G. IONESCU ◽  
Vera Lucia Trindade ◽  
Elizabeth Fatima de Souza
Keyword(s):  
Aqueous Solution ◽  
Internal Pressure ◽  
Sodium Hydroxide ◽  
Alkaline Hydrolysis ◽  
Cetyltrimethylammonium Bromide ◽  
Reaction Medium ◽  
Phosphate Ester ◽  
Cohesive Forces ◽  
Diphenyl Phosphate ◽  
Hydrolysis Of

The experimental results obtained/or the hydrolysis of p-nitrophenyl diphenyl phosphate (NPDPP) in the presence of sodium hydroxide (NaOH), micelles of cetyltrimethylammonium bromide (CTAB), and an aqueous solution of glycerol were analyzed taking into consideration the internal pressure and the cohesive forces of the reaction medium. The effect of glycerol on mice/le formation and also its influence on the internal pressure of the reaction medium are large enough to affect the micellar catalyzed alkaline hydrolysis of the phosphate ester.

Effect of the α- and γ-Hydroxyls on the Alkaline Hydrolysis Rate of Nonphenolic β-0-4 Lignin Diastereomers

Holzforschung ◽  
2002 ◽  
Vol 56 (1) ◽  
pp. 67-72 ◽  
Author(s):  
Dexter L. Criss ◽  
Thomas Elder ◽  
Thomas H. Fisher ◽  
Tor P. Schultz
Keyword(s):  
Computational Modeling ◽  
Alkaline Hydrolysis ◽  
Rate Ratio ◽  
Electronic Effect ◽  
Activation Parameters ◽  
Hydrolysis Rate ◽  
Significant Extent ◽  
Hydrolysis Rates ◽  
Lignin Model ◽  
Hydrolysis Of

Summary Nonphenolic β-0-4 erythro and threo lignin model diastereomers with various γ-groups (CH3, CH2-O-CH3, and CH2OH) and Cα-substituents (OH, OCH3) were synthesized, and the alkaline hydrolysis rates and activation parameters determined. In addition, two of the diastereomer pairs were computationally modeled and the thermodynamic values for the ionization of the α- or γ-hydroxyl, and subsequent displacement of the phenolate group to form an epoxide intermediate, were determined. The results suggest that the erythro γ-hydroxyl may participate in the hydrolysis to a significant extent, which results in a relatively high erythro/threo rate ratio for the α,γ-di-OH isomers. The influence of the erythro γ-hydroxyl on the hydrolysis rate may be due to the relatively favorable stability of the erythro γ-oxyanion. The electronic effect of the g-substituent appears to influence how fast the α-hydroxyl displaces the phenoxyl. We had previously suggested that the γ-substituent sterically inhibits hydrolysis of the threo isomer, and computational modeling confirmed this.

Alkaline Hydrolysis of Nonphenolic ß-O-4 Lignin Model Dimers: Further Studies of the Substituent Effect on the Leaving Phenoxide

Holzforschung ◽  
1996 ◽  
Vol 50 (5) ◽  
pp. 420-424 ◽  
Author(s):  
Willard E. Collier ◽  
Thomas H. Fisher ◽  
Leonard L. Jr. Ingram ◽  
Angela L. Harris ◽  
Tor P. Schultz
Keyword(s):  
Alkaline Hydrolysis ◽  
Substituent Effect ◽  
Lignin Model ◽  
Hydrolysis Of

KINETICS OF THE ALKALINE HYDROLYSIS OF PROPIONITRILE

1942 ◽  
Vol 20b (9) ◽  
pp. 185-188 ◽  
Author(s):  
B. S. Rabinovitch ◽  
C. A. Winkler
Keyword(s):  
Activation Energy ◽  
Sodium Hydroxide ◽  
Alkaline Hydrolysis ◽  
Aqueous Sodium Hydroxide ◽  
Alkali Concentration ◽  
Aqueous Sodium ◽  
Velocity Constant ◽  
Total Ammonia ◽  
Kinetics Of ◽  
Hydrolysis Of

Some contradictory points recorded for the alkaline hydrolysis of nitriles have been clarified by a study of propionitrile hydrolysis in aqueous sodium hydroxide solutions of concentration 0.3 to 4 N. It has been shown that the rate of alkaline hydrolysis of propionitrile is given by the rate of formation of total ammonia and intermediate amide and not by that of ammonia alone. The relative rates of propionitrile and propionamide hydrolysis were found to be approximately 1:10 over the whole alkali concentration range. The bimolecular velocity constant is essentially independent of alkali concentration. An activation energy of 20,300 cal. was determined for the reaction in 0.65 N alkali.

Reexamination of the Kirkwood–Westheimer theory of electrostatic effects. V. Effect of charged substituents on the rates of alkaline hydrolysis of substituted strychnines

1997 ◽  
Vol 75 (4) ◽  
pp. 441-448
Author(s):  
Khamis A. Abbas ◽  
Phillip Hurst ◽  
John T. Edward
Keyword(s):  
Sodium Hydroxide ◽  
Alkaline Hydrolysis ◽  
Kinetic Data ◽  
Aqueous Sodium Hydroxide ◽  
Second Order ◽  
Electrostatic Effects ◽  
Third Order ◽  
Aqueous Sodium ◽  
Hydrolysis Of ◽  
Positively Charged

The rates of hydrolysis in aqueous sodium hydroxide of the alkaloid strychnine and seven of its derivatives have been determined at 50 and 75 °C. The kinetic data indicate that all the compounds, except strychninesulfoni acid-I, hydrolyze by competing second- and third-order mechanisms, involving one and two hydroxide ions, respectively; strychninesulfonic acid-I hydrolyzes by the second-order mechanism only. The quantitative effect of positively charged groups in enhancing, and negatively charged groups in depressing, the rates of hydrolysis is in rough agreement with calculations using Kirkwood–Westheimer theory. Keywords: Kirkwood–Westheimer theory; strychnine derivatives, hydrolysis of; lactams, hydrolysis of; electrostatic effects on rates of alkaline hydrolysis; alkaloids, reactions of.

THE ALKALINE HYDROLYSIS OF N-ACYLTHIOUREAS

1974 ◽  
Vol 52 (5) ◽  
pp. 697-701 ◽  
Author(s):  
Wayne I. Congdon ◽  
John T. Edward
Keyword(s):  
Carboxylic Acid ◽  
Sodium Hydroxide ◽  
Alkaline Solution ◽  
Alkaline Hydrolysis ◽  
Potassium Hydroxide ◽  
Ion Concentration ◽  
Hydroxide Ion ◽  
Arrhenius Parameters ◽  
Hydrolysis Of

N-Benzoylthiourea (pKHA 10.9) and other N-acylthioureas ionize in alkaline solution, and then are rapidly hydrolyzed to thiourea and a carboxylic acid. The rates become independent of hydroxide ion concentration when this exceeds about 0.1 M and point to a mechanism in which hydrolysis takes place by attack of an hydroxide ion on the un-ionized molecule of N-acylthiourea. This mechanism accords with the Arrhenius parameters for the hydrolysis of N-benzoylthiourea in 0.2 N sodium hydroxide, and with the Hammett ρ value of 0.10 for the hydrolysis of m- and p-substituted N-benzoylthioureas in 1.0 N potassium hydroxide.

THE HYDROLYSIS OF PHOSPHATE DIESTERS WITH BARIUM HYDROXIDE

1955 ◽  
Vol 33 (4) ◽  
pp. 705-710 ◽  
Author(s):  
C. W. Helleiner ◽  
G. C. Butler
Keyword(s):  
Sodium Hydroxide ◽  
Alkaline Hydrolysis ◽  
Small Proportion ◽  
Inorganic Phosphate ◽  
Barium Hydroxide ◽  
Phosphate Ester ◽  
Purine Nucleotides ◽  
Diphenyl Phosphate ◽  
Phosphate Diesters ◽  
Hydrolysis Of

The rate of alkaline hydrolysis of diphenyl phosphate has been found to be increased by the presence of barium. Similarly, desoxyribonucleate (DNA), which is not hydrolyzed rapidly by hot sodium hydroxide, is hydrolyzed by barium hydroxide. Only a very small proportion of the total phosphorus of either diphenyl phosphate or DNA is converted to inorganic phosphate during this hydrolysis. In addition to hydrolysis of the phosphate ester bonds of DNA, hot alkali also causes the deamination of desoxycytidylic acid residues and probably of the amino-purine nucleotides as well.

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