UNIT 1 – ORGANIC CHEMISTRY

1. UNIT 1 – ORGANIC CHEMISTRY

2. Chapter 1Classifying Organic Compounds • Organic chemistry: study of compounds that are based on carbon. • Usually contain carbon-carbon and hydrogen-carbon bonds.

3. The Carbon Atom • usually forms a total of 4 covalent bonds. • Can form strong single bonds (_____ pair(s) of electrons shared, double bonds (_____ pair(s) of electrons shared), or triple bonds (______ pair(s) of electrons shared) with other carbons.

4. Saturated molecules: carbon atoms have maximum bonding capacity of __________. • Molecules containing double or triple carbon-carbon bonds are called ________________.

5. Common Molecular Shapes in Organic Molecules

6. 3-D Structural Diagrams • Rules for drawing a 3-D molecule • Let’s use methane, CH4, as an example. • “Wedges” are used to give the impression that an atom or group is coming forward. • Dashed/dotted lines are used to show that an atom or group is receding.

7. Relate this to electronegativities...

8. Which of the following bonds are polar? Non-polar? C – O O – H N – H C – C C -H

9. Predicting Molecular Polarity • Polar Molecule: molecule has an overall imbalance of _________________. • Not all molecules with polar bonds are polar molecules. (e.g. CO2 has two polar C=O bonds, but is not a polar molecule). • Is water a polar molecule?

10. RULE 1 • If equal bond dipoles act in opposite directions in three-dimensional space, they counteract each other. The molecule is _________________________. E.g. CCl4, (four identical dipoles, pointing toward the vertices of a tetrahedron, counteract eachother can prove mathematically)

11. RULE 2 If the bond dipoles in a molecule do not counteract each other exactly, the molecule is _________________. E.g. Water E.g. CHCl3 , chloroform (bond dipoles do not act in opposite directions, therefore, do not counteract each other, and molecule is polar).

12. Steps for Predicting the Polarity of a Molecule CLASSWORK Read page 9, steps 1, 2 and 3. Create a dichotomous key in order to determine the polarity of the molecule, with one example at each ‘end’ of each ‘branch.’ Read sample problem, pg. 10, and do PPs # 1-4

13. Section Review • Page 11, #2, 4, 5

14. 1.2 – Hydrocarbons • Hydrocarbons: simplest type of organic compound. • Composed entirely of hydrogen and carbon. • Widely used as fuels. E.g. Gasoline, propane, and natural (non-polar). • Aliphatic: carbon atoms bonded in one or more chains and rings. Single, double, triple bonds. • Aromatic: based on aromatic benzene group (later!)

15. Alkanes, Alkenes, and Alkynes • Alkane: single bonds. • Linear: CnH2n+2 • Cycloalkane: CnH2n • Alkene: at least one double bond. • Linear with one double bond: CnH2n. • Alkyne: at least one triple bond. • Linear with one triple bond: CnH2n-2.

16. The Strengths of Bonds • Double and triple bonds contain more than one bond. • First bond is always strongest. • Second and third bonds are weaker: therefore, react faster • C=C bonds are ________________________ than C-C bonds.

17. Functional Groups • Functional Group: reactive group • Each group helps to determine the physical and chemical properties of compounds. • E.g. Reactive double bond of an alkene is the functional group.

18. Naming Organic Compounds • The International Union of Pure and Applied Chemistry (IUPAC) has standard rules for naming organic compounds PREFIX + ROOT + SUFFIX Root • Number of carbons in the main chain/ring. Suffix • Depends on functional group present. • E.g. –ane, -ene, and –yne. (there are many others) Prefix • Indicates the name and location of each branch and functional group in the main carbon chain. • Alkyl groups: branches on main chain.

20. How to Name Hydrocarbons • Find the root: identify the longest chain or ring. • If cyclic compound, add prefix –cyclo- before the root. 2) Find the suffix: -ane, -ene, and –yne. - if more than one double/triple bond, use prefix di-, tri- before suffix. 3) Number the carbons - start at end giving the lowest possible number for the double or triple bond OR - start at end giving the lowest possible number for the branches. 4) Find the prefix - name each branch as an alkyl group with position number. - if more than one branch, list in alphabetical order. - put the position number of any double or triple bonds after the position numbers and names of the branches, just before the root. 5) Put the name together: prefix + root + suffix.

21. Name the following Compounds • The main chain has ___ C. Root: _________ • Only ___________ bonds. Suffix:_________ • A _____________ group is attached to carbon __________. Prefix: ____________ 5) Full name: ____________________________.

22. Main ring (____________) has ___ Cs. Root: ______________. 2) Only _____________ bonds. Suffix: ______. 3) And 4) A(n) ______________ group is attached to carbon _____. Prefix: ________. 5) Full name: __________________________.

23. Main chain has _____ C. Root: ___________. • Contains one ________ bond. Suffix: ______. • Two __________ groups on carbon ___. One ____________ group on carbon ___. The = bond is at carbon _____. Prefix: ________________________________. 5) Full name: __________________________.

24. Problem Tips • Use hyphens (-) to separate words from numbers. • Use commas to separate numbers from each other.

25. Drawing Hydrocarbons • Draw a condensed structural diagram for 1-ethyl-2-methylhexane.

26. Let’s Build Hydrocarbons! Build one of the following hydrocarbons: • 3-ethyl-2, 3, 4-trimethylnonane (SR, #2 d) • 3-methyl-2,4,6-octatriene (PP #6, c) • 4-ethyl-3-methylheptane (PP #6, b) Large balls count as carbons. Small balls count as hydrogen. Carbons in the MAIN CHAIN do not require hydrogens (will take up too much room).

27. Aromatic Compounds • Aromatic Compound: have a special form of sharing of electrons, such as benzene. • Benzene • Cyclic compound with three double bonds and three single bonds. • Wacky molecule: electrons that form double bonds in benzene are spread out and shared over the whole molecule. • Therefore, six identical bonds, each one half-way between single and double.

28. Section Review Page 20. #1, 2, 3, 6.

29. 1.3 – Single-Bonded Functional Groups Functional Group: a group of bonded atoms in an organic compound that reacts in a characteristic way. E.g.

30. General Formula: the general formula for a family of organic compounds is R + Functional group. • R: any alkyl group. • E.g. R – OH

31. Functional Groups are Useful in classifying organic compounds for two reasons: • Compounds with the same functional group often have similar properties. • Compounds with the same functional group react chemically in very similar ways.

32. Common Functional Groups

33. Physical Properties of Families(same functional group) • Similar boiling points, melting points, and solubilities. • Due to intermolecular forces: forces of attraction and repulsion between particles. • Hydrogen Bonding: strong intermolecular attraction between H atom of N-H, O-H, or F-H group on one molecule, and N, O, or F on another. • Dipole-dipole interactions: polar molecules are attracted to eachother. • Dispersion forces: occurs between all covalent molecules due to temporary dipoles.

34. Intermolecular Forces and Physical Properties 1) What kinds of molecules are usually soluble in water? Why do you think this is? 2) Do polar or non-polar molecules usually have a higher boiling point? Why? 3) Substances A and B are both pure substances composed of polar molecules. Substance A also has the ability to hydrogen bond. Which one has a higher boiling point? 4) Polar molecules with a _____________ non-polar hydrocarbon part are less polar than polar molecules with a smaller non-polar hydrocarbon part. 5) Polar molecules with a large hydrocarbon part are less ____________ in water than polar molecules with a smaller hydrocarbon part. 7) Dispersion forces are stronger when _____________________________________ ________________________________________________.

35. ThoughtLab See page 24 of your Textbook. Follow the procedure and answer the questions in the thought lab. Report is due next class.

36. Compounds with Single-Bonded Functional Groups • Alcohols • Alkyl halides • Ethers • Amines

37. Compounds with Single-Bonded Functional Groups 1) Alcohols • Contains the –OH functional group. • Can be primary, secondary, or tertiary depending on the position of the hydroxyl group.

40. Naming an Alcohol: Read page 26 and go through SP. Do PP # 14, 15, 16.

42. Alkyl Halides • One or more hydrogen atoms replaced with halogen atoms: F, Cl, Br, or I. • Functional group is R –X (x represents halogen).

44. Physical Properties of Alkyl Halides • similar to alcohols. Naming an Alkyl Halide: Read page 28, and do SP. Do PPs 18 – 21.

45. Ethers • An organic compound that has two alkyl groups joined by an oxygen atom. • R – O – R • Think of alcohols and ethers as derivatives of the water molecules:

46. Ether examples:

48. How to Name an Ether Read pg. 29 and do SP on pg. 30 PPs 22-24

49. Physical Properties of Ethers

50. Amines • - NH2, - NHR, -NR2, where R is an alkyl group attached to the nitrogen. • General formula: R – NR’2 • Thought of as derivatives of the ammonia molecules, NH3. • Classified as primary, secondary, or tertiary, depending on how many alkyl groups attached to the nitrogen atom.