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Structure and chemical properties of carboxylic acids. Lipids

Structure and chemical properties of carboxylic acids. Lipids. Classification of carboxylic acids. A carboxylic acid is an organic compound that contains a carboxyl group -COOH. Acidic Properties.

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Structure and chemical properties of carboxylic acids. Lipids

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  1. Structure and chemical properties of carboxylic acids. Lipids

  2. Classification of carboxylic acids A carboxylic acid is an organic compound that contains a carboxyl group -COOH.

  3. Acidic Properties Carboxylic acids react with metal hydroxides to form salts. Polycarboxylic acids form acid and neutral salts.

  4. Nucleophilic Substitution (SN) • esterification reaction • formation of acyl chlorides • formation of amides • formation of anhydrides • acyl phosphate formation

  5. Acetyl-CoA is a very important molecule in metabolism, characterized by its thioester group. It activates carboxylic acids, converting them into reactive thiol esters. CoA: adenosine diphosphate (ADP), pantothenic acid (vitamin B3), 2-aminoethanol. Choline Acetyl-CoA Acetylcholine

  6. Amide Formation Amides are commonly formed via reactions of a carboxylic acid halide with an amine. Decarboxylation Decarboxylation, or loss of carbon dioxide (CO2), is one of the most important transformation of a carboxyl group in the biochemistry of carboxylic acids, and especially  -  -oxo acid and -amino acids in the organism under the action of the decarboxylase enzyme. Electron-withdrawing substituents at α-carbon (-COOH, -CO-R, -C≡N, -NO2) facilitate decarboxylation.

  7. Hydroxy acids Hydroxy acids are a class of chemical compounds that consist of a carboxylic acid substituted with a hydroxyl group on the adjacent carbon. • monobasic Glycolic acid • dibasic Malic acid • Tartaric acid • tribasic Citric acid Lactic acid β-hydroxybutyrate γ-hydroxyvaleric acid

  8. Specific reaction -hydroxy acid β-hydroxy acid -hydroxy acid

  9. Oxoacids Keto acids (also called oxoacids) are organic compounds that contain a carboxylic acid group and a keto group.

  10. Classification of lipids Lipids are oily, fatty or waxy substances whichare present in living organisms

  11. Functions of lipids • Energy reserve. • Structural components of membranes. • Protective function. • Thermoregulating function • Source of endogenous water

  12. Fatty acids Saturated fatty acids Lauric acid: C11H23COOH Myristic acid: C13H27COOH Palmitic acid: C15H31COOH Stearicacid: C17H35COOH Unsaturated fatty acids Oleic acid: C17H33COOH (one double bond) Linoleic acid: C17H31COOH (two double bonds) Linolenic acid: C17H29COOH (three double bonds) Arachidonic acid C19H31COOH (four double bonds) Linoleic, linolenic and arachidonic acids are essential fatty acids!

  13. + 3H2O Simple lipids Oilsand fatsare simple lipids. triglyceride

  14. Fats and oils Fats – glycerides containing large proportion of saturated acids. Oils– glycerides containing large proportion of unsaturated acids. Cis Trans

  15. Hydrolysis Hydrolysis is catalyzed by acids or basis.

  16. 3 soap Saponification Saponification number is a quantity of KOH in mg necessary to saponify 1 g of fat. Saponification number characterizes the length of the chain in alkyl group of fatty acids.

  17. Analytical characteristics of fats Iodine number is a quantity of grams of iodine that may be added to 100g of fat. Iodine number < 70 - the fat is solid Iodine number > 70 - the fat is liquid.

  18. Hydrogenation Tristearine Oleic triglyceride

  19. Lipids digestion and metabolism The digestion of lipids takes place in small intestine. The food mixes up with thebile fluid. In this case, the fats get emulsified and allow enzymes such as lipases to hydrolyze fat into glycerol and fatty acids which then pass into blood stream. Most of the energy in fats is contained in the long hydrocarbon chains of fatty acids. They are the main energy reserves of the body. Fatty acids are transferred to the cells by the blood stream and are oxidized in mitochondria. This oxidation is called β-oxidation.

  20. β-oxidation Acyl-CoA Acetyl-CoA

  21. Waxes Waxes are fatty acids esters of long chain monohydric alcohols. C15H31COO C30H61 - myriciyl palmitate C15H31COO C16H33 - cetyl palmitate

  22. Complex lipids. Phospholipids

  23. Spingolipids Sphingolipids and Glycolipids are contained in nerve tissue. sphingosine Sphingomyelin

  24. From D-galactose From oligosaccharide Glycolipids Cerebroside C23H45COOH – nervonic acid C23H47COOH – lignoceric acid Ganglioside

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