CHAPTER 11 Introduction to Organic Molecules & Functional Groups

1. CHAPTER 11 Introduction to Organic Molecules & Functional Groups General, Organic, & Biological Chemistry Janice GorzynskiSmith

2. CHAPTER 11: Intro to Organic Molecules & Functional Groups • Learning Objectives: • Difference between organic and inorganic molecules • Name characteristic features of organic compounds • Draw organic compounds, including skeletal structures • Identify common bond types, angles, and molecule shapes • Name functional groups • Understand polarity and its effect on solubility and boiling point • Explain the difference between fat and water soluble vitamins Smith. General Organic & Biolocial Chemistry 2nd Ed.

3. CHAPTER 11: Intro to Organic Molecules & Functional Groups Lecture Outline: Define Organic Chemistry Review the shape of organic molecules How to Draw organic compounds Overview of functional groups Review intermolecular forces Review polarity Smith. General Organic & Biolocial Chemistry 2nd Ed.

4. Organic Chem Definition • Organic Chemistry is the study of compounds containing carbon. • Both naturally occurring and synthetic compounds • C, H, O, N, S, P, Halides (Cl, F, Br, I) Smith. General Organic & Biolocial Chemistry 2nd Ed.

5. Group Problem Brainstorm examples of organic and inorganic compounds.

6. Organic Chem Definition Smith. General Organic & Biolocial Chemistry 2nd Ed.

7. Organic Chem Bonding • Covalent Bond? • Valence electron? • Octet Rule? Smith. General Organic & Biolocial Chemistry 2nd Ed.

8. Organic Chem Bonding • A COVALENT BOND shares a pair of electrons between atoms. • non-metal to non-metal bond • The OCTET RULE states that atoms of main group elements make bonds by gaining, losing, or sharing electrons to achieve an outer shell containing 8 electrons. How many valence electrons do Carbon and Hydrogen have? Oxygen? Nitrogen? Sulfur? Phosphorous? Chlorine? Smith. General Organic & Biolocial Chemistry 2nd Ed.

9. Group Problem How many bonds does each atom need to satisfy the octet rule? C H O N S P

10. Group Problem Draw these molecules: Ethane: C2H6 Cyclohexane: C6H12 Propene: C3H6 Propyne: C3H4

11. Molecule Shape Bond Angle VSEPR Theory: The most stable arrangement of atoms in a molecule maximized the distance between atoms and lone pairs. Smith. General Organic & Biolocial Chemistry 2nd Ed.

12. Group Problem Draw the lewis dot structures for water and ethanol. How many lone pairs of electrons do they have? What are the bond angles within the molecules?

13. Group Problem Draw the lewis dot structure for ammonia. How many lone pairs of electrons does it have? What are the bond angles within the molecule?

14. Molecule Shape Drawing Molecules SIMPLIFY! H H H H H C C C C H H H H H CH3CH2CH2CH3 Smith. General Organic & Biolocial Chemistry 2nd Ed.

15. Group Problem Practice: 1) convert to condensed structure 2) simplify further if possible 3) skeletal structure

16. Functional Groups Overview Alkane Alkene Alkyne Aromatic C − C C = C C = C Hydrocarbon Functional Groups Smith. General Organic & Biolocial Chemistry 2nd Ed.

17. Functional Groups Overview Alkyl halides Alcohols Ethers Amines Single Bond to a Heteroatom Functional Groups Smith. General Organic & Biolocial Chemistry 2nd Ed.

18. Functional Groups Overview Aldehydes Carboxylic Acids Esters Ketones Amides Carbonyl Functional Groups Smith. General Organic & Biolocial Chemistry 2nd Ed.

19. Group Problem Identify all of the functional groups pentabromodiphenyl ether

20. Group Problem Identify all of the functional groups Estradiol Genistein A soy isoflavone

21. Group Problem Identify all of the functional groups (other then alkanes) in Gliadin C29H41N7O9

22. Properties of Organics Overview • Organic compounds experience weaker intermolecular interactions because they form covalent bonds. • no ion-ion interactions • Usually clear or yellowish color • Often a liquid or a gas at room temperature • Lower melting points and boiling points relative to ionic compounds Smith. General Organic & Biolocial Chemistry 2nd Ed.

23. Properties of Organics Polarity The difference in electronegativity between two atoms bonded together creates a polar dipole moment. The more electronegative atom has a slight negative charge (more electron density). Smith. General Organic & Biolocial Chemistry 2nd Ed.

24. Group Problem What is the dipole moment of each bond, and what is the overall dipole moment for each molecule? Water Acetone Isopropanol Acetic Acid Diethyl Ether

25. Properties of Organics Intermolecular Forces Intermolecular Forces weaker then intramolecular forces (bonding) London Dispersion Dipole-Dipole Hydrogen Bonding Instantaneous dipole-induced attractions that occur between all molecules, even non-polar. Partial charges of polar compounds attract each other . Strong dipole-dipole attraction when H is covalently bonded to a highly electronegative atom. Smith. General Organic & Biolocial Chemistry 2nd Ed.

26. Properties of Organics Intermolecular Forces Intermolecular Forces weaker then intramolecular forces (bonding) London Dispersion Smith. General Organic & Biolocial Chemistry 2nd Ed.

27. Properties of Organics Intermolecular Forces Intermolecular Forces weaker then intramolecular forces (bonding) Dipole-Dipole Smith. General Organic & Biolocial Chemistry 2nd Ed.

28. Properties of Organics Intermolecular Forces Intermolecular Forces weaker then intramolecular forces (bonding) Hydrogen Bonding Smith. General Organic & Biolocial Chemistry 2nd Ed.

29. Group Problem Rank the three intermolecular forces discussed in order of strength.

30. Properties of Organics Solubility LIKE DISSOLVES LIKE polar molecules dissolve in polar solvents nonpolar molecules dissolve in nonpolar solvents Polar Solvents Water: H2O Methanol: CH3OH Ethanol: CH3CH2OH Acetone: (CH3)2CO Acetic Acid: CH3CO2H Ammonia: NH3 Acetonitrile: CH3CN Nonpolar Solvents Pentane: C5H12 Hexane: C6H14 Cyclohexane: C6H12 Benzene: C6H6 Toluene: CH3C6H5 Chloroform: CHCl3 Diethylether: (CH3CH2)2O Smith. General Organic & Biolocial Chemistry 2nd Ed.

31. Group Problem Draw all of the solvents from the previous slide and prove they are polar or nonpolar.

32. Properties of Organics Water & Fat Soluble Vitamins Which type of solvent would the following molecules dissolve in? Vitamin A Vitamin B12 32 Smith. General Organic & Biolocial Chemistry 2nd Ed.

34. Molecules BONDING: Lewis Bond Theory strategy to tackle problems NH3 Start with the least electronegative element as the central element Surround the central element with the bonding elements and indicate their initial electrons Add extra electrons, from surrounding atoms, to the central atom to satisfy the octet rule Use multiple bonds if necessary   H N H      H     N H H     H   N H H H

35. Molecules BONDING: Lewis Bond Theory strategy to tackle problems H    H  N  NH3   Initial electron bookkeeping: Find the difference, this is the number of electrons that must be shared ÷ 2 to know the # of bonds shared Arrange atoms around the most electronegative element Final electron bookkeeping: H  Need: 3x(1H x 2 e-) + (1N x 8 e-) = 14 e- Have: 3x(1H x 1 e-) + (1N x 5 e-) = 8 e- (14 e-) – (8 e-) = 6 e- (6 e-) ÷ 2 = 3 bonds      N H H  N H H     H H