1.HOW TO CLASSIFY LIPIDS

2. 17.1 biological functions of lipids As an energy source, lipids provide 9 kcal of energy per gram Triglycerides provide energy storage in adipocytes Phosphoglycerides, sphiggolipids and steriods are structural components of cell membranes 3. HOW TO CLASSIFY LIPIDS By solubility And molecular weight And the functional groups biological structure vs Molecular properties Was our main theme 4. biological structure vs Molecular properties It also enables classification of such compounds as gangliosides as lipids, although they are more soluble in water than in organic solvents. 5. Eicosanoids and star lipids!! Examples of biologically important fatty acids are the eicosanoids, derived primarily from arachidonic acid and eicosapentaenoic acid, that include prostaglandins, leukotrienes, and thromboxanes. 6. They usually contain even numbers of carbon atoms in straight chains (commonly C14 to C24), and may be saturated or unsaturated; they can also contain other substituent groups. 7. CLASSIFY AMINES NOW Amines Amines are derivatives of ammonia in which one or more hydrogen atoms are replaced by alkyl groups. We indicate the degree of substitution by labeling the amine as either primary (RNH2), secondary (R2NH), or tertiary (R3N). The common names of these compounds are derived from the names of the alkyl groups. 8. common names Amines Amines are derivatives of ammonia in which one or more hydrogen atoms are replaced by alkyl groups. We indicate the degree of substitution by labeling the amine as either primary (RNH2), secondary (R2NH), or tertiary (R3N). The common names of these compounds are derived from the names of the alkyl groups. 9. common names: the parent alkane 10. systematic names The systematic names of primary amines are derived from the name of the parent alkane by adding the prefix -amino and a number specifying the carbon that carries the -NH2 group. 11. amines mirrors the chemistry of ammonia 12. amines mirrors the chemistry of ammonia The chemistry of amines mirrors the chemistry of ammonia. Amines are weak bases that pick up a proton to form ammonium salts. Trimethylamine, for example, reacts with acid to form the trimethylammonium ion. 13. IMPORTANT CONCEPT These salts are more soluble in water than the corresponding amines, and this reaction can be used to dissolve otherwise insoluble amines in aqueous solution. 14. Amides It is tempting to assume that carboxylic acids will react with amines to form the class of compounds known as amides. In practice, when aqueous solutions of carboxylic acids and amines are mixed all we get is an acid-base reaction. 15. aqueous solutions of carboxylic acids and amines are mixed all we get is an acid-base reaction. 16. The best way to prepare an amide is to react the appropriate acyl chloride with an amine. 17. Excess amine is used to drive the reaction to completion by absorbing the HCl given off in this reaction