Chemistry of Non-Enzymic Browning. VIII. The Hydrolytic reactions of Aldose Bisulphite addition compounds

1959 ◽  
Vol 12 (2) ◽  
pp. 288
Author(s):  
DL Ingles
Keyword(s):  
Acetic Acid ◽  
Sodium Hydroxide ◽  
Hydroxyl Group ◽  
Amine Group ◽  
Enzymic Browning

A study has been made of the hydrolytic reactions of aldose bisulphite addition compounds (Ingles 1959a, 19596). Addition compounds which had a hydroxyl group at C1 were stable in 10 per cent, acetic acid but decomposed in water and sodium hydroxide forming the a-form of the parent D-aldose. Compounds in which the hydroxyl at C1 was replaced by an amine group were unstable in water, 10 per cent. acetic acid, and sodium hydroxide. In the last solvent breakdown to the α-form of the D-glycosylamine was observed. Decomposition in sodium hydroxide appears to occur with inversion of configuration at C1. The configurations at C1 of the bisulphite addition compounds have been listed.

Production of monosaccharides from poplar by a two-step hydrogen peroxide-acetic acid and sodium hydroxide pretreatment

2021 ◽  
Vol 170 ◽  
pp. 113820
Author(s):  
Hong Liao ◽  
Jiaxin You ◽  
Peiyao Wen ◽  
Wenjun Ying ◽  
Qianqian Yang ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Acetic Acid ◽  
Sodium Hydroxide

scholarly journals Kinetics and Mechanism of the Change of the 4-Nitrobenzylthio-System into 4,4′-Diformylazoxybenzene in Alkaline Dioxane-Water Media

1985 ◽  
Vol 40 (11) ◽  
pp. 1128-1132
Author(s):  
Y. Riad ◽  
Adel N. Asaad ◽  
G.-A. S. Gohar ◽  
A. A. Abdallah
Keyword(s):  
Acetic Acid ◽  
Sodium Hydroxide ◽  
Rate Constants ◽  
Main Product ◽  
Reaction Medium ◽  
Aqueous Dioxane ◽  
Proton Abstraction ◽  
First Order ◽  
Water Media ◽  
Different Temperatures

Sodium hydroxide reacts with α -(4-nitrobenzylthio)-acetic acid in aqueous-dioxane media to give 4,4'-diformylazoxybenzene as the main product besides 4,4'-dicarboxyazoxybenzene and a nitrone acid. This reaction was kinetically studied in presence of excess of alkali in different dioxane-water media at different temperatures. It started by a fast reversible a-proton abstraction step followed by two consecutive irreversible first-order steps forming two intermediates (α -hydroxy, 4-nitrosobenzylthio)-acetic acid and 4-nitrosobenzaldehyde. The latter underwent a Cannizzaro's reaction, the products of which changed in the reaction medium into 4,4'-diformylazoxybenzene and 4,4'-dicarboxyazoxybenzene. The rate constants and the thermodynamic parameters of the two consecutive steps were calculated and discussed. A mechanism was put forward for the formation of the nitrone acid.Other six 4-nitrobenzyl, aryl sulphides were qualitatively studied and they gave mainly 4,4'-diformylazoxybenzene beside 4,4'-dicarboxyazoxybenzene or its corresponding azo acid.

scholarly journals How Small Molecules Affect the Thermo-Oxidative Aging Mechanism of Polypropylene: A Reactive Molecular Dynamics Study

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1243
Author(s):  
Fan Zhang ◽  
Yufei Cao ◽  
Xuan Liu ◽  
Huan Xu ◽  
Diannan Lu ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Acetic Acid ◽  
Small Molecules ◽  
Aging Process ◽  
Experimental Studies ◽  
Hydroxyl Group ◽  
Oxidative Aging ◽  
Reactive Molecular Dynamics ◽  
Aging Mechanism ◽  
Effects Of Temperature

Understanding the aging mechanism of polypropylene (PP) is fundamental for the fabrication and application of PP-based materials. In this paper, we present our study in which we first used reactive molecular dynamics (RMD) simulations to explore the thermo-oxidative aging of PP in the presence of acetic acid or acetone. We studied the effects of temperature and oxygen on the aging process and discussed the formation pathways of typical small molecule products (H2, CO, CO2, CH4, C2H4, and C2H6). The effect of two infection agents, acetic acid and acetone, on the aging reaction was analyzed emphatically. The simulation results showed that acetone has a weak impact on accelerating the aging process, while acetic acid has a significant effect, consistent with previous experimental studies. By tracking the simulation trajectories, both acetic acid and acetone produced small active free radicals to further react with other fragment products, thus accelerating the aging process. The first reaction step of acetic acid is often the shedding of the H atom on the hydroxyl group, while the reaction of acetone is often the shedding of the H atom or the methyl. The latter requires higher energy at lower temperatures. This is why the acceleration effect of acetone for the thermo-oxidative aging of PP was not so significant compared to acetic acid in the experimental temperature (383.15 K).

Thermochemical Ablation in an Ex-vivo Porcine Liver Model Using Acetic Acid and Sodium Hydroxide: Proof of Concept

2010 ◽  
Vol 21 (10) ◽  
pp. 1573-1578 ◽  
Author(s):  
Joseph L. Farnam ◽  
Benjamin C. Smith ◽  
Brandon R. Johnson ◽  
Rodolfo Estrada ◽  
Theresa L. Edelman ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Sodium Hydroxide ◽  
Ex Vivo ◽  
Proof Of Concept ◽  
Porcine Liver ◽  
Liver Model

N-Methylamino Acids in Peptide Synthesis. III. Racemization during Deprotection by Saponification and Acidolysis

1973 ◽  
Vol 51 (15) ◽  
pp. 2555-2561 ◽  
Author(s):  
John R. McDermott ◽  
N. Leo Benoiton
Keyword(s):  
Acetic Acid ◽  
Sodium Hydroxide ◽  
Hydrogen Bromide ◽  
Aqueous Sodium Hydroxide ◽  
Acid Strength ◽  
Carboxyl Group ◽  
Aqueous Sodium ◽  
Aqueous Acid ◽  
Amino Acid Analyzer ◽  
Anhydrous Acetic Acid

The racemization of N-methylamino-acid derivatives in aqueous sodium hydroxide and hydrogen bromide in anhydrous acetic acid and other solvents has been investigated by determining the products of the reaction with an amino-acid analyzer after deprotection. Whereas MeIle-OMe, Z-MeIle, and the N-unmethylated derivatives were only slightly racemized ( <2%), Z-MeIle-OMe (18–24%), Z-Ala-MeLeu-OMe (22%), and Z-Ala-MeLeu-OBu′ (7%) were appreciably racemized by aqueous sodium hydroxide. It is suggested that these derivatives racemize because of the absence of an > N—H or carboxyl group whose ionization would suppress ionization of the neighboring α-C—H bond. Z-Melle and Z-Ala-MeLeu were substantially racemized (68% in 4 h and 34% in 1 h, respectively) by 5.6 N hydrogen bromide in acetic acid. The extent of racemization by acid varied with acid strength, polarity of solvent, and time. Incorporation of label into both isomers of Ala-MeLeu from a solution of the tritiated reagent established that ionization at the α-C—H bond had occurred. No racemization was caused by aqueous acid or by hydrogen chloride.

Studies on soil phosphorus. I. A method for the partial fractionation of soil phosphorus

1950 ◽  
Vol 40 (3) ◽  
pp. 233-242 ◽  
Author(s):  
Colin H. Williams
Keyword(s):  
Acetic Acid ◽  
Calcium Carbonate ◽  
Sodium Hydroxide ◽  
Soluble Fraction ◽  
Soil Phosphorus ◽  
Acid Soils ◽  
Alkaline Reaction ◽  
Single Extractions ◽  
Phosphate Compounds

Ghani's method for the partial fractionation of soil phosphorus has been simplified. From results obtained with soils and representative phosphatic minerals it has been shown that successive single extractions with 2·5% acetic acid-l% 8-hydroxyquinoline and 0·1 N-sodium hydroxide gives a good fractionation of the phosphate compounds present.The relative effects of cupferron and 8-hydroxyquinoline as reagents for blocking the adsorption of phosphate were also investigated. Cupferron precipitated aluminium more completely than did 8-hydroxyquinoline at the pH used for the extraction. However, because of its instability and also because of indications that it may attack organic forms of phosphorus cupferron was considered to be of less value than 8-hydroxyquinoline in the fractionation of soil phosphorus.The recovery of phosphate added to soil, the reaction of which had been varied by the use of sulphur or calcium carbonate, was almost complete at all reactions used (pH 4·5–8·2) for amounts of phosphate up to the equivalent of 500 parts of PO4 per million parts of soil. The distribution of this added phosphate between the acid and alkali soluble fraction showed that in acid soils the phosphate tended to be fixed mainly by adsorption or as a basic ferric and aluminium phosphates, while at an alkaline reaction most of the fixation was due to precipitation by calcium.

THE ISOBUTYL GROUP IN SPRUCE AND BIRCH LIGNINS

1949 ◽  
Vol 27b (6) ◽  
pp. 572-579 ◽  
Author(s):  
Alan Bell ◽  
George F Wright
Keyword(s):  
Acetic Acid ◽  
Formic Acid ◽  
Hydroxyl Group ◽  
Acid Extraction ◽  
Acid Extract ◽  
Permanganate Oxidation ◽  
Perbenzoic Acid ◽  
Acetic Acid Extraction ◽  
Acid Titration

Acetone has been isolated by permanganate oxidation of birch and spruce lignins extracted from wood by acetic or formic acid. Acetone was obtained also when the formic acid lignins were ozonized but not from the acetic acid – extracted lignins. This difference was confirmed when perbenzoic acid titration indicated unsaturation in the formic acid extract which was not present in the acetic acid extract. It is suggested that an α-hydroxy-β-methoxyisobutyl group is present in lignin; during acetic acid extraction the hydroxyl group is acetylated but during formic acid extraction the formic acid reduces the group to isobutenyl, which will give acetone when it is ozonized.

Organic sulfur compounds. VII. Some reactions of benzothiazine hydroxamic acids

1970 ◽  
Vol 48 (23) ◽  
pp. 3727-3732 ◽  
Author(s):  
R. T. Coutts ◽  
Sharon J. Matthias ◽  
E. Mah ◽  
N. J. Pound
Keyword(s):  
Acetic Acid ◽  
Hydrochloric Acid ◽  
Sodium Hydroxide ◽  
Unsaturated Acid ◽  
Hydroxamic Acids ◽  
Sulfur Compounds ◽  
The Other ◽  
Complex Reaction ◽  
Organic Sulfur Compounds ◽  
Derivatives Of

Treatment of (3,4-dihydro-4-hydroxy-3-oxo-2H-1,4-benzothiazin-2-yl)acetic acid (1a) with sodium hydroxide yields the corresponding lactam, i.e. (3,4-dihydro-3-oxo-2H-1,4-benzothiazin-2-yl)acetic acid, together with the α,β-unsaturated acid, 3,4-dihydro-3-oxo-2H-1,4-benzothiazine-Δ2,α-acetic acid. The 6-methyl- and 6-bromo-derivatives of 1a behaved similarly when reacted with sodium hydroxide but when 3,4-dihydro-4-hydroxy-3-oxo-2H-1,4-benzothiazine was so treated a more complex reaction occurred.Methyl (6-bromo-3,4-dihydro-4-hydroxy-3-oxo-2H-1,4-benzothiazin-2-yl)acetate was also treated with hydrochloric acid. The two products isolated were (6-bromo-3,4-dihydro-3-oxo-2H-1,4-benzothiazin-2-yl)acetic acid and (6-bromo-7-chloro-3,4-dihydro-3-oxo-2H-1,4-benzothiazin-2-yl)acetic acid.The action of hydrochloric acid on 3,4-dihydro-4-hydroxy-7-methyl-3-oxo-2H-1,4-benzothiazine also gave two products. One was the corresponding lactam; the other was unexpected and has been tentatively identified as bis[2-(3,4-dihydro-7-methyl-3-oxo-2H-1,4-benzothiazine].

Acetic Acid and Sodium Hydroxide-Aided Hydrothermal Carbonization of Woody Biomass for Enhanced Pelletization and Fuel Properties

2017 ◽  
Vol 31 (11) ◽  
pp. 12200-12208 ◽  
Author(s):  
Tengfei Wang ◽  
Yunbo Zhai ◽  
Yun Zhu ◽  
Chuan Peng ◽  
Bibo Xu ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Sodium Hydroxide ◽  
Woody Biomass ◽  
Hydrothermal Carbonization ◽  
Fuel Properties
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