Introduction to Organic Chemistry and Alkanes

1. Introduction to Organic Chemistry and Alkanes

2. Organic Chemistry • Molecules made up of carbon,hydrogen, and a few other elements (oxygen, nitrogen, sulfur, or halogens) • Amazing array of organic molecules: • Many are essential to life (phospholipids and enzymes) • Glucose and fructose • Penicillin and aspirin • Fossil fuels

3. Why so many Organic Compounds? • Carbon can form stable, covalent bonds with other carbon atoms. 3 allotropes of carbon (forms of an element that have the same physical state but different properties) 1. Diamond 2. Graphite 3. Buckminsterfullerene

4. 3 Allotropes of Carbon 1. Diamond • A large 3-dimensional network of carbon-to-carbon bonds • results in an extremely hard substance

5. 3 Allotropes of Carbon 2. Graphite -Planar layers of carbon-to-carbon bonds that extend in 2-dimensions -Planar units slide over one another

6. 3 Allotropes of Carbon 3. Buckminsterfullerene - “Buckey Ball” -60 Carbon atoms in the shape of a soccer ball -discovered in the 1980’s

7. Why so many Organic Compounds? II. Carbon can form stable bonds with other elements. -Several families of organic compounds contain oxygen atoms bonded to carbon. Others contain nitrogen, sulfur or halogens. -The presence of these elements allows for a wide variety of new chemical and physical properties on the organic compound.

8. Why so many Organic Compounds? III. Carbon can form double or triple bonds with other Carbon atoms. This produces a variety of organic molecules with very different properties.

9. Why so many Organic Compounds? IV. The structure of the compounds creates limitless possibilities. The number of ways in which carbon and other atoms can be arranged is nearly limitless. (Ex: linear chains, ring structures, and branched chains).

10. Isomers ISOMERS - same number and kinds of atoms but with different structures, therefore different properties “STRUCTURE determines FUNCTION”

11. Comparison of Organic and Inorganic Compounds

12. Families of Organic Compounds

13. Families of Organic Compounds Hydrocarbon– contains only hydrogens and carbon Substituted Hydrocarbon- one or more hydrogen atoms is replaced by another atom or group of atoms (functional group)

14. Families of Organic Compounds Aliphatic Hydrocarbon - alkanes, alkenes, & alkynes Saturated Hydrocarbon - alkanes contain only C and H have only single bonds Unsaturated Hydrocarbon – alkenes & alkynes contain only C and H have at least one carbon to carbon double or triple bond

15. Families of Organic Compounds Cycloalkane – carbon atoms bonded to one another to produce a ring Aromatic Hydrocarbon – contains a “benzene ring” (6 carbon atoms bonded to one another with alternating single and double bonds to form a ring)

16. Common Functional Groups “Structure determines Function”

17. H H H H-C-C-C-H H H H Three types of formulas • Molecular formula – gives the type and number of each atom present in a molecule but does not show bonding pattern • EXAMPLE: C3H8 • Structural formula – shows each atom and bond in a molecule • EXAMPLE: • Condensed formula – shows all the atoms and places them in sequential order that indicates which atoms are bonded to which • EXAMPLE: CH3CH2CH3

18. Another way to draw structures • Line or skeletal structure • Only the bonds and not the atoms are shown. • A carbon atom is assumed to be at the ends and junctions of the lines • Correct number of hydrogens is mentally supplied Cl 3-methylpentane 3-chloropentane

19. Alkyl Groups

20. Carbons are classified according to the number of other carbons to which they are attached. • Primary (1°) bonded to one other carbon • Secondary (2°) bonded to two other carbons • Tertiary (3°) bonded to three other carbons H C-C- H C H-C-C H C C-C- C

21. H H H H-C-C-C-H H H H I.U.P.A.C. Nomenclature • International Union of Pure and Applied Chemistry – organization responsible for establishing and maintaining a standard, universal system for naming compounds • All alkanes are the alkyl group name followed with the suffix –ane. Contains 3 carbons – propyl group; Add –ane Propane

22. Nomenclature of Alkanes • Find the parent chain. • Find the longest continuous chain of carbon atoms present in the molecule, and use the name of that chain as the parent name. CH3CH2CH2CHCH3 CH2CH3 CH2CH3 CH3CHCHCH2CH3 CH2CH2CH3

23. Nomenclature of Alkanes 1. Find the parent chain. B. If two different chains of equal length are present, choose the one with the larger number of branches. CH3 CH3CHCHCH2CH2CH3 CH2CH3

24. Nomenclature of Alkanes • Number the atoms in the main chain. • Beginning at the end nearer the first branch point, number each carbon atom in the parent chain. CH2CH3 CH3CHCHCH2CH3 CH2CH2CH3

25. Nomenclature of Alkanes • Number the atoms in the main chain. B. If there is branching an equal distance away from both ends of the parent chain, begin numbering at the end nearer the second branch point. CH3CH2 CH3 CH2CH3 CH3CHCH2CH2CHCHCH2CH3

26. Nomenclature of Alkanes • Identify and number the substituents. • Assign a number to each substituent according to its point of attachment to the main chain. B. If there are two substituents on the same carbon, assign them both the same number. There must be as many numbers in the name as there are substituents.

27. Nomenclature of Alkanes 3. Identify and number the substituents CH3 CH3CH2CCH2CH2CH3 CH2 CH3

28. Nomenclature of Alkanes • Write the name as a single word, using hyphens to separate the different prefixes and using commas to separate numbers. • If two or more different substituents are present, cite them in alphabetical order. • If two or more identical substituents are present, use one of the prefixes di-, tri-, tetra-, etc but do NOT use these for alphabetizing purposes.

29. Name These Alkanes! CH2CH3 CH3CH2CH2CHCH3 CH3 CH3CHCHCH2CH2CH3 CH2CH3

30. Name These Alkanes! CH2CH3 CH3 CH2CH3 CH3CHCH2CH2CHCHCH2CH3 CH3 CH2 CH3CHCHCH2CH3 CH2CH2CH3

31. Name These Alkanes! CH3 CH3CH2CCH2CHCH3 CH2 CH3

32. Nomenclature for HALOGENATED ALKANES • Step 1: name the parent chain CH3CHCH3 Br propane • Step 2: number the parent chain CH3CHCH3 Br 1 2 3

33. Nomenclature for HALOGENATED ALKANES • Step 3: name & number each ATOM or GROUP attached to the parent (the “substituent”) CH3CHCH3 Br parent: propane substituent: 2-bromo

34. Nomenclature for HALOGENATED ALKANES • Step 4: If the same substituent occurs more than once, a separate number AND a prefix (di, tri, tetra-, etc.) are used Br Br CH3CHCH2CH2CHCH3 Parent: hexane Substituent: 2,5-dibromo

35. Nomenclature for HALOGENATED ALKANES • Step 5: Place the names of the branches in alphabetical order before the parent name. Separate numbers with commas Separate names & numbers with hyphens HALOGEN substituents are placed BEFORE alkyl substituents in the name

36. Nomenclature for HALOGENATED ALKANES CH3 CH3 CH C CH2CH3 Br CH3 Parent: pentane Subs: 2-bromo 3,3-dimethyl 2-bromo-3,3-dimethylpentane

37. Practice 1) CH3CH2CH2CH2CHCH3 Br 2) CH2CHCH2 Br BrBr

38. Practice 3) Br HCH CH3CCH2Br CH3 4) CH3CHCH2CH2CHCH2Br Cl CH3

39. Practice 5) CH3CHCHCH2CH2CH2Cl CH3