Hydroxycarboxylic Acids, Aliphatic

Abstract

The article contains sections titled: 1. Introduction 2. General Characteristics 2.1. Physical Properties 2.2. Chemical Properties 3. Preparation 4. Analysis 5. Specific Aliphatic Hydroxycarboxylic Acids of Commercial Significance 5.1. Glycolic Acid (Hydroxyacetic Acid, 2‐Hydroxyethanoic Acid) 5.1.1. Preparation 5.1.2. Uses 5.1.3. Derivatives 5.2. Hydroxypropionic Acids and β‐Propiolactone 5.3. Hydroxybutyric Acids 5.4. ( R,S )‐Malic Acid [( R,S )‐Hydroxysuccinic Acid, ( R,S )‐Hydroxybutanedioic Acid] 6. Toxicology

Understanding Hydrogen in Bayer Process Emissions. 1. Hydrogen Production during the Degradation of Hydroxycarboxylic Acids in Sodium Hydroxide Solutions

“…In alkaline solutions, β-hydroxycarboxylates exist in equilibrium with their corresponding α,β-unsaturated carboxylates . The nature and amounts of products observed are the same when either the β-hydroxycarboxylates or their corresponding unsaturated carboxylates are used as the starting materials, consistent with the regioselective hydration of the CC double bond.…”

Understanding Hydrogen in Bayer Process Emissions. 1. Hydrogen Production during the Degradation of Hydroxycarboxylic Acids in Sodium Hydroxide Solutions

“…In alkaline solutions, β-hydroxycarboxylates exist in equilibrium with their corresponding α,β-unsaturated carboxylates . The nature and amounts of products observed are the same when either the β-hydroxycarboxylates or their corresponding unsaturated carboxylates are used as the starting materials, consistent with the regioselective hydration of the CC double bond.…”

Kinetics of Wet Oxidation of Propionic and 3-Hydroxypropionic Acids

“…Deeper oxidation of 3-oxopropionic acid (3-OPA) may proceed via malonic acid and could probably produce tartronic acid (HOOCCHOHCOOH) with the molecular mass of 120. On the other hand, the presence of these compounds at 280 °C and above is rather doubtful as it is mentioned in the literature that the pure compounds decarboxylate around 200 °C. , However, the normalized concentration profiles for the mother compound as well as for the intermediate products that appeared in a typical oxidation experiment is shown in Figure . The concentration of the 120 compound was estimated on the basis of the peak heights during the MS analysis.…”

Understanding Hydrogen in Bayer Process Emissions. 2. Hydrogen Production during the Degradation of Unsaturated Carboxylic Acids in Sodium Hydroxide Solutions

“…In alkaline solutions, α,β-unsaturated carboxylates exist in equilibrium with their corresponding β-hydroxycarboxylates . We recently confirmed that the production of hydrogen from β-hydroxycarboxylates, such as 3-hydroxybutanoate and malate, can occur via an ionic degradation mechanism involving base-catalyzed oxidation by water. , Above 200 °C, all of these compounds decompose to produce about 1 mol of hydrogen per mole of starting compound.…”

Understanding Hydrogen in Bayer Process Emissions. 1. Hydrogen Production during the Degradation of Hydroxycarboxylic Acids in Sodium Hydroxide Solutions

“…In alkaline solutions, β-hydroxycarboxylates exist in equilibrium with their corresponding α,β-unsaturated carboxylates . The nature and amounts of products observed are the same when either the β-hydroxycarboxylates or their corresponding unsaturated carboxylates are used as the starting materials, consistent with the regioselective hydration of the CC double bond.…”

Kinetics of Wet Oxidation of Propionic and 3-Hydroxypropionic Acids

“…Deeper oxidation of 3-oxopropionic acid (3-OPA) may proceed via malonic acid and could probably produce tartronic acid (HOOCCHOHCOOH) with the molecular mass of 120. On the other hand, the presence of these compounds at 280 °C and above is rather doubtful as it is mentioned in the literature that the pure compounds decarboxylate around 200 °C. , However, the normalized concentration profiles for the mother compound as well as for the intermediate products that appeared in a typical oxidation experiment is shown in Figure . The concentration of the 120 compound was estimated on the basis of the peak heights during the MS analysis.…”

Understanding Hydrogen in Bayer Process Emissions. 2. Hydrogen Production during the Degradation of Unsaturated Carboxylic Acids in Sodium Hydroxide Solutions

“…In alkaline solutions, α,β-unsaturated carboxylates exist in equilibrium with their corresponding β-hydroxycarboxylates . We recently confirmed that the production of hydrogen from β-hydroxycarboxylates, such as 3-hydroxybutanoate and malate, can occur via an ionic degradation mechanism involving base-catalyzed oxidation by water. , Above 200 °C, all of these compounds decompose to produce about 1 mol of hydrogen per mole of starting compound.…”

Understanding Hydrogen in Bayer Process Emissions. 1. Hydrogen Production during the Degradation of Hydroxycarboxylic Acids in Sodium Hydroxide Solutions

“…In alkaline solutions, β-hydroxycarboxylates exist in equilibrium with their corresponding α,β-unsaturated carboxylates . The nature and amounts of products observed are the same when either the β-hydroxycarboxylates or their corresponding unsaturated carboxylates are used as the starting materials, consistent with the regioselective hydration of the CC double bond.…”

Kinetics of Wet Oxidation of Propionic and 3-Hydroxypropionic Acids

“…Deeper oxidation of 3-oxopropionic acid (3-OPA) may proceed via malonic acid and could probably produce tartronic acid (HOOCCHOHCOOH) with the molecular mass of 120. On the other hand, the presence of these compounds at 280 °C and above is rather doubtful as it is mentioned in the literature that the pure compounds decarboxylate around 200 °C. , However, the normalized concentration profiles for the mother compound as well as for the intermediate products that appeared in a typical oxidation experiment is shown in Figure . The concentration of the 120 compound was estimated on the basis of the peak heights during the MS analysis.…”

Understanding Hydrogen in Bayer Process Emissions. 2. Hydrogen Production during the Degradation of Unsaturated Carboxylic Acids in Sodium Hydroxide Solutions

“…In alkaline solutions, α,β-unsaturated carboxylates exist in equilibrium with their corresponding β-hydroxycarboxylates . We recently confirmed that the production of hydrogen from β-hydroxycarboxylates, such as 3-hydroxybutanoate and malate, can occur via an ionic degradation mechanism involving base-catalyzed oxidation by water. , Above 200 °C, all of these compounds decompose to produce about 1 mol of hydrogen per mole of starting compound.…”