1. Chapter 20 Organic Chemistry

2. Organic Compounds Organic compounds all contain carbon –CO, CO 2, carbonates are inorganic –Other common elements found in organic compounds are H, O, N, P, S The majority of the 50+ million known compounds are organic

3. What is so special about Carbon ? Structural Diversity Versatile bonding patterns –Chains, rings. multiple bonds –With 4 valence electrons, carbon can form 4 bonds to reach an octet with a variety of geometries 4 single bonds a double bond and two single bonds 2 double bonds A triple bond and a single bond

4. What is so special about Carbon? Structural Diversity Isomers: compounds having the same composition but different structures –Structural isomers –Stereoisomers Geometric isomers Optical isomers Site for viewing

5. What is so special about Carbon? Stability –Strong bonds C-C (346kJ/mol), C-H (413kJ/mol) Si-Si (222kJ/mol), Si-H (318kJ/mol) –C-C bonds unreactive (stable) Oxidation reactions are slow and these reactions need to be initiated

6. How are Carbon compounds represented Molecular formula : C 5 H 12 Condensed: CH 3 CH(CH 3 )CH 2 CH 3 Structural formula

7. Line-Bond Structures Shows only C-C bonds Ends of lines and corners are understood to be carbon atoms Proper number of hydrogens are understood Oxygens and nitrogens are shown

8. How are Carbon compounds represented Models –Ball and stick –Space filling

9. Hydrocarbons Alkanes: C n H 2n+2 –Unreactive –Saturated (all single bonds within compound)

10. Hydrocarbons: Alkanes Names end in “ane” Can form many structural isomers: same formula but atoms arranged differently –straight chain –Branched chain

12. Naming Alkanes Find the longest continuous carbon chain Number the chain from end closest to a branch Name branches as alkyl groups –Branch name related to number of C –End in -yl –Locate each branch by preceding its name with the carbon number on the chain

13. Naming Alkanes (cont.) List branches alphabetically Use prefix if more than one of same group present –di, tri, tetra, penta, hexa –Do not count in alphabetizing

15. Nomenclature: Alkanes n- pentane 2-methyl butane 2,2,dimethyl propane

17. Hydrocarbons: cycloalkanes C n H 2n

18. Alkenes Aunsaturated Formula of chain alkenes - C n H 2n C=C double bonds Much more reactive than alkanes Polyunsaturated = many double bonds

19. Alkenes (cont.) Trigonal shape around C –Flat No rotation –cis-trans isomerism

20. Alkenes: Cis Trans Isomerism Cis Trans

21. Naming Alkenes Change suffix on main name from -ane to –ene Number from end closest to double bond Number in front of main name indicates first carbon of double bond

23. Alkynes unsaturated Formula of chain alkynes - C n H 2n-2 C  C triple bond –Linear shape –No rotation More reactive than alkenes

24. Hydrocarbons: Alkynes

25. Aromatics Compounds that contain 1 more unsaturated rings –Benzene rings

26. Aromatics Benzene –All C-C bond lengths and bond angles identical 120° Bond lengths between C-C and C=C –Planar molecule

27. Functional Groups Alcohols Ethers Carboxylic acids Ketones Aldehydes Esters Amines Amides

28. Functional Groups In many organic compounds, C-to-H bonds are replaced by bonds to other atoms. –C-Halogen, C-to-O, C-to-N, occasionally (C-to-S) These substituted bonds are more reactive than C-H bonds. Have influences on intermolecular attractions and therefore physical properties

29. Functional Groups: Alcohols R-OH

30. Alcohols R-OH

31. Naming Alcohols Select the longest chain of carbon atoms containing the –OH group Number the chain from the end closest to the –OH group Determine the parent name from the number of C in the chain, replace the final - e with –ol Name alkyl branches as usual

32. Functional Groups: Ethers R-OR´

33. Ethers R-O-R′ contain an –O– between two carbon groups that are simple are named by listing the alkyl names in alphabetical order followed by ether CH 3 -O-CH 3 CH 3 -CH 2 -O-CH 3 Dimethyl ether Ethyl methyl ether

34. Functional Groups: Ketones Contain a carbonyl group

35. Naming Ketones Select the longest chain of carbon atoms containing the carbonyl group Number the chain from the end closest to the carbonyl group Determine the parent name from the number of C in the chain, replace the final -e with -one Name alkyl branches as usual

36. Functional Groups: Aldehydes Contain a carbonyl group H

37. Common Aldehydes

38. Naming Aldehydes Select the longest chain of carbon atoms containing the aldehyde group Number the chain calling the carbonyl C position 1 Determine the parent name from the number of C in the chain, replace the final -e with -al Name alkyl branches as usual

39. Carboxylic Acids Have carboxyl group, R1-COOH Always on end of chain Acid functional group –Weak acid

40. Functional Groups: Carboxylic acids

41. Copyright © Houghton Mifflin Company. All rights reserved. 20 | 41 Carboxylic Acids

42. Esters Replace acid H of carboxyl group with R group, R1-COO-R2 Sweet, fruity odors

43. Functional Groups: Esters Contain a carbonyl group

44. Naming Esters Select the longest chain of carbon atoms containing the ester group Name R2 as alkyl group Name R1 and carboxyl C like acid except change the –ic ending to -ate Put the pieces together, alkyl group first