11.4 Hydroxycarboxylic acids (aliphatic and aromatic acids).
Explains what hydroxycarboxylic acids are, with both hydroxyl and carboxyl groups, and how aliphatic saturated and unsaturated forms differ from aromatic ones. Gives examples such as lactic, citric and salicylic acid, and notes their natural sources and uses. Covers L and D stereoisomers of lactic acid, decarboxylation on heating, metal complex formation by citric acid, and salicylic acid-derived NSAIDs and their mechanism via cyclooxygenase inhibition.
Topic 29 of 42 in the MU Sofia syllabus for Chemistry (Dental Medicine, Year 1). The free AceMed note covers it in 5 sections, about 390 words (3 min of reading), with 14 flashcards.
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Hydroxycarboxylic acids (aliphatic and aromatic acids).
Stereoisomerism in saturated hydroxy carboxylic acids.
Chemical properties.
Reactions on heating and complex formation.
Medicines derived from salicylic acid.
Hydroxycarboxylic acids (aliphatic and aromatic acids).
Definition:
Hydroxycarboxylic acids contain both a hydroxyl group (-OH) and a carboxyl group (-COOH) in their structure.
Classification:
1. Aliphatic Hydroxycarboxylic Acids:
Can be further categorized into:
Saturated: No carbon-carbon double bonds.
Unsaturated: Contain one or more carbon-carbon double bonds.
2. Aromatic Hydroxycarboxylic Acids:
Contain an aromatic ring in their structure along with -OH and -COOH groups.
Examples:
Saturated Aliphatic: Lactic acid
Unsaturated Aliphatic: Citric acid
Aromatic: Salicylic acid
Sources:
Found naturally in fruits, vegetables, and microorganisms.
Applications:
Used in food, pharmaceuticals, cosmetics, and chemical synthesis.
Stereoisomerism in saturated hydroxy carboxylic acids.
L-lactic acid is the L stereoisomer, commonly found in the L-form in biological systems and is often produced during anaerobic respiration in muscle cells. Hence, it's often referred to as "L-muscle."D-lactic acid is the D stereoisomer, and it's found in D-form in certain fermented dairy products like milk. Hence, it's often referred to as "D-milk." These terms, L and D, denote the configuration of the asymmetric carbon atom in the molecule. L refers to the "levorotatory" configuration (meaning it rotates plane-polarized light counterclockwise), while D refers to the "dextrorotatory" configuration (rotating plane -polarized light clockwise). The L and D forms are not related to the terms "left" and "right" but rather originate from Latin terms for "left" and "right" handedness in terms of optical activity.
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