1. C HAPTER 10 I NTRODUCTION TO O RGANIC C HEMISTRY : A LKANES 10.1 Organic Compounds 1 Copyright © 2009 by Pearson Education, Inc.

2. O RGANIC C HEMISTRY An organic compound is a compound made from carbon atoms. has one or more C atoms. has many H atoms. may also contain O, S, N, and halogens. 2

3. O RGANIC C OMPOUNDS Typical organic compounds have covalent bonds. have low melting points. have low boiling points. are flammable. are soluble in nonpolar solvents. are not soluble in water. 3 oil (organic) and water (inorganic )

4. O RGANIC VS. I NORGANIC Propane, C 3 H 8, is an organic compound used as a fuel. NaCl, salt, is an inorganic compound composed of Na + and Cl − ions. Why is propane organic, but NaCl is not? 4

5. C OMPARING O RGANIC AND I NORGANIC C OMPOUNDS 5

6. E XAMPLES Identify each characteristic as most typical of compounds that are 1) inorganic or 2) organic. A. has a high melting point. B. is not soluble in water. C. has a formula CH 3 ─CH 2 ─CH 3. D. has a formula MgCl 2. E. burns easily in air. F. has covalent bonds. 6

7. W RITING F ORMULAS FOR A LKANES In organic compounds, carbon has 4 valence electrons and hydrogen has 1. C H carbon achieves an octet by forming four bonds. H H  H  C  H H C H  H H CH 4, methane 7

8. T ETRAHEDRAL S TRUCTURE OF C ARBON VSEPR theory predicts that a carbon atom with four single, covalent bonds has a tetrahedral shape. 8

9. O RGANIC M OLECULES In organic molecules, valence electrons are shared. covalent bonds form between carbon atoms. H H H H H  C  C  HH C C H H H H H Ethane, CH 3 ─CH 3 9

10. T ETRAHEDRAL S TRUCTURE OF C ARBON In molecules with two or more carbon atoms, each carbon atom with four single bonds has a tetrahedral shape. 10

11. C HAPTER 10 I NTRODUCTION TO O RGANIC C HEMISTRY : A LKANES 10.2 Alkanes 11

12. 10.2 – A LKANES Structural Formulas Alkanes are written with structural formulas that are expanded to show each bond. condensed to show each carbon atom and its attached hydrogen atoms. Expanded Condensed H H C H CH 4, methane H 12

13. S TRUCTURAL F ORMULAS Condensed formulas are written for expanded structural formula by showing each carbon and the attached hydrogen atoms. E.g C 2 H 6 Expanded Condensed H H │ H─C ─C ─ H CH 3 ─CH 3 │ H H 13

14. E XAMPLE Write an expanded formula and condensed formula for C 4 H 10

15. N AMES OF A LKANES The names of alkanes are determined by the IUPAC (International Union of Pure and Applied Chemistry) system. end in – ane. with 1-4 carbons in a chain use prefixes as follows: Name # Carbons Condensed Structural Formula Meth ane1 C H 4 Eth ane2 C H 3 ― C H 3 Prop ane3 C H 3 ― C H 2 ― C H 3 But ane4 C H 3 ― C H 2 ― C H 2 ― C H 3 15

16. N AMES OF A LKANES Alkanes with 5-10 carbon atoms in a chain use Greek prefixes. Name # Carbons Structural Formula Pent ane 5CH 3 CH 2 CH 2 CH 2 CH 3 Hex ane 6 CH 3 CH 2 CH 2 CH 2 CH 2 CH 3 Hept ane 7 CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3 Oct ane 8 CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3 Non ane 9 CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3 Dec ane 10 CH 3 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 3 16

17. W RITING S TRUCTURAL F ORMULAS Carbon atoms in a chain maintain tetrahedral shape. are connected in a zigzag pattern. are drawn as 2-dimensional. can be written in several conformations 17

18. H EXANE H AS S IX C ARBON A TOMS Hexane is an alkane with six carbon atoms in a continuous chain. has a “zigzag” look because each carbon atom is at the center of a tetrahedron. is represented by a ball-and-stick model as shown below. 18 Ball-and-stick

19. E XAMPLES Write the condensed and skeletal formula for A. ethane. B. heptane. 19

20. EXAMPLES A. Write the condensed formula for: B. What is its molecular formula? C. What is its name? 20

21. C YCLOALKANES Cycloalkanes are cyclic alkanes. have two hydrogen atoms fewer than the open chain. are named by using the prefix cyclo - before the name of the alkane chain with the same number of carbon atoms. 21

22. C YCLOALKANES 22 The structural formulas of cycloalkanes are usually represented by geometric figures.

23. 10.3 A LKANES WITH S UBSTITUENTS Isomers of Butane have the same molecular formula. have different atom arrangements. of butane (C 4 H 10 ) are a straight chain and a branched chain. 23

24. A LKYL GROUPS Alkyl groups are alkanes that are missing one H. substituents attached to carbon chains. named with a –yl ending. CH 3 methyl CH 3 CH 2 ethyl 24

25. A LKANES WITH S UBSTITUENTS CH 3 CH 3 CH CH 3 methylpropane methyl groups CH 3 CH 3 CH 3 CH CH 2 CH CH 3 2,4-dimethylpentane 25

26. N AMING S UBSTITUENTS In the IUPAC system, a carbon branch is named as an alkyl group. halogen atoms are named as halo. 26

27. N AMING H ALO - ALKANES Step 1: determine the long chain Name it as parent chain Step 2: identify substituents Akyl – all CH Halo – halogen Chlorine  Chloro Bromine  bromo number carbon starting from the end closet to the substituent Step 3: name the molecule in alphabetical order. Location-substituentparent chain

28. N AMING A LKANES Give the name of CH 3 CH 3  CH 3 ─CH─CH─CH 3 STEP 1: Name the longest continuous chain. STEP 2: Number chain. STEP 3: Locate substituents and name. 28

29. E XAMPLE Name the following molecules

30. EXAMPLE Write the name of Cl CH 3  CH 3 ─CH 2 ─CH─CH─CH 3 30

31. L EARNING C HECK Give the IUPAC name for each of the following: A. CH 3 CH 3 | CH 3 ─CH─CH 2 ─CH─CH 3 B. Cl CH 3 | | CH 3 ─CH 2 ─CH─CH 2 ─C─CH 2 ─CH 3 | Cl 31

32. L EARNING C HECK Draw the condensed structural formula for 3-bromo-1-chlorobutane. 32 STEP 1: Longest chain has 4 carbon atoms. STEP 2: Number chain and add substituents. TEP 3: Add hydrogen to complete 4 bonds to each C.

33. N AMING C YCLOALKANES WITH S UBSTITUENTS The name of a substituent is placed in front of the cycloalkane name. CH3 methyl cyclobutane Cl Chloro cyclopentane 33

34. L EARNING C HECK Name each of the following. 1. CH 3 CH 2 ─CH 3 2. 3. 34

35. EXAMPLES Name the following. A. CH 3 ─CH 2 ─CH 2 ─CH 3 B. C. D. 35

36. 10.4 P ROPERTIES OF A LKANES Alkanes are nonpolar. insoluble in water. less dense than water. flammable in air. 36

37. S OME P ROPERTIES OF A LKANES Alkanes with 1-4 carbon atoms are methane, ethane, propane, and butane. gases at room temperature. used as heating fuels. 37

38. S OME P ROPERTIES OF A LKANES Alkanes with 5-8 carbon atoms are liquids at room temperature. pentane, hexane, heptane, and octane. very volatile. used to make gasoline. Alkanes with 9-17 carbon atoms are liquids at room temperature have higher boiling points. are found in kerosene, diesel, and jet fuels. 38

39. S OME P ROPERTIES OF A LKANES Alkanes with 18 or more carbon atoms have high molar masses. are waxy solids at room temperature. used in waxy coatings of fruits and vegetables. 39 Copyright © 2009 by Pearson Education, Inc.

40. C OMBUSTION In combustion reactions, alkanes react with oxygen. CO 2, H 2 O, and energy are produced. Alkane + O 2 CO 2 + H 2 O + heat 40 Copyright © 2009 by Pearson Education, Inc.

41. L EARNING C HECK Write a balanced equation for the complete combustion of a. Propane b. Octane 41

42. 10.5 F UNCTIONAL G ROUPS In organic molecules, carbon atoms bond with four bonds. mostly with H and other C atoms. sometimes to O, N, S. sometimes to halogens F, Cl, and Br. 42

43. F UNCTIONAL G ROUPS Functional groups are a characteristic feature of organic molecules that behave in a predictable way. composed of an atom or group of atoms. groups that replace a hydrogen atom in the corresponding alkane. a way to classify families of organic compounds. 43

44. A LKENES, A LKYNES, AND A ROMATIC C OMPOUNDS Alkenes contain a double bond between adjacent carbon atoms. Alkynes contain a triple bond. Aromatic compounds contain a ring of six carbon atoms called benzene. 44

45. C OMPARING A LKENES, A LKYNES, AND A ROMATIC C OMPOUNDS 45

46. A LCOHOLS AND E THERS An alcohol contains the hydroxyl (-OH) functional group. A thiol contains the thiol (-SH) functional group. An ether contains an oxygen atom bonded to two carbon atoms. 46 R = alkyl groups (carbon groups)

47. A LDEHYDES AND K ETONES An aldehyde contains a carbonyl group (C=O), which is a carbon atom with a double bond to an oxygen atom. The carbonyl is attached to a hydrogen. In a ketone, the carbon of the carbonyl group (C=O) is attached to two carbon atoms. 47

48. C ARBOXYLIC A CIDS AND E STERS Carboxylic acids contain the carboxyl group, which is a carbonyl group attached to a hydroxyl group. O ║ — C—OH An ester contains the carboxyl group between carbon atoms. 48

49. A MINES AND A MIDES In amines, the functional group is a nitrogen atom. | —N — In amides, the hydroxyl group of a carboxylic acid is replaced by a nitrogen group. 49 Copyright © 2009 by Pearson Education, Inc. Amines An amide

50. S UMMARY OF F UNCTIONAL G ROUPS 50

51. L EARNING C HECK Classify each of the following as: alcohol, ether, aldehyde, ketone, carboxylic acid, ester, amine, or amide. 51