1. Dr. Wolf's CHM 201 & 202 4- 1 Chapter 4 Alcohols and Alkyl Halides

2. Dr. Wolf's CHM 201 & 202 4- 2 (1) alcohol + hydrogen halide ROH + HX  RX + H 2 O (2) alkane + halogen RH + X 2  RX + HX Both are substitution reactions Overview of Chapter This chapter introduces chemical reactions and their mechanisms by focusing on two reactions that yield alkyl halides.

3. Dr. Wolf's CHM 201 & 202 4- 3 4.1 Functional Groups

4. Dr. Wolf's CHM 201 & 202 4- 4 a structural unit in a molecule responsible for its characteristic behavior under a particular set of reaction conditions Functional Group

5. Dr. Wolf's CHM 201 & 202 4- 5 AlcoholROH Alkyl halideRX (X = F, Cl, Br, I) Amineprimary amine: RNH 2 secondary amine: R 2 NH secondary amine: R 2 NH tertiary amine: R 3 N tertiary amine: R 3 N Families of organic compounds and their functional groups

6. Dr. Wolf's CHM 201 & 202 4- 6 EtherROR' NitrileRCN NitroalkaneRNO 2 SulfideRSR' ThiolRSH Epoxide C C O Families of organic compounds and their functional groups

7. Dr. Wolf's CHM 201 & 202 4- 7 O C Carbonyl group O C Acyl group R Many classes of organic compounds contain a carbonyl group

8. Dr. Wolf's CHM 201 & 202 4- 8 O C Carbonyl group O C Aldehyde R H Many classes of organic compounds contain a carbonyl group

9. Dr. Wolf's CHM 201 & 202 4- 9 O C Carbonyl group O C Ketone R R' Many classes of organic compounds contain a carbonyl group

10. Dr. Wolf's CHM 201 & 202 4- 10 O C Carbonyl group O C Carboxylic acid R OH Many classes of organic compounds contain a carbonyl group

11. Dr. Wolf's CHM 201 & 202 4- 11 O C Carbonyl group O C Ester R OR' Many classes of organic compounds contain a carbonyl group

12. Dr. Wolf's CHM 201 & 202 4- 12 O C Carbonyl group O C Amide R NH 2 Many classes of organic compounds contain a carbonyl group

13. Dr. Wolf's CHM 201 & 202 4- 13 4.2 IUPAC Nomenclature of Alkyl Halides

14. Dr. Wolf's CHM 201 & 202 4- 14 The two that are most widely used are: functional class nomenclature substitutive nomenclature Both types can be applied to alcohols and alkyl halides. IUPAC Nomenclature There are several kinds of IUPAC nomenclature.

15. Dr. Wolf's CHM 201 & 202 4- 15 Name the alkyl group and the halogen as separate words (alkyl + halide) Functional Class Nomenclature of Alkyl Halides CH 3 F CH 3 CH 2 CH 2 CH 2 CH 2 Cl CH 3 CH 2 CHCH 2 CH 2 CH 3 Br H I

16. Dr. Wolf's CHM 201 & 202 4- 16 Name the alkyl group and the halogen as separate words (alkyl + halide) Functional Class Nomenclature of Alkyl Halides CH 3 F CH 3 CH 2 CH 2 CH 2 CH 2 Cl CH 3 CH 2 CHCH 2 CH 2 CH 3 Br Methyl fluoride Pentyl chloride 1-Ethylbutyl bromide Cyclohexyl iodide H I

17. Dr. Wolf's CHM 201 & 202 4- 17 Name as halo-substituted alkanes. Number the longest chain containing the halogen in the direction that gives the lowest number to the substituted carbon. Substitutive Nomenclature of Alkyl Halides CH 3 CH 2 CH 2 CH 2 CH 2 F CH 3 CHCH 2 CH 2 CH 3 Br CH 3 CH 2 CHCH 2 CH 3 I

18. Dr. Wolf's CHM 201 & 202 4- 18 Name as halo-substituted alkanes. Number the longest chain containing the halogen in the direction that gives the lowest number to the substituted carbon. Substitutive Nomenclature of Alkyl Halides CH 3 CH 2 CH 2 CH 2 CH 2 F CH 3 CHCH 2 CH 2 CH 3 Br 1-Fluoropentane 3-Iodopentane 2-Bromopentane CH 3 CH 2 CHCH 2 CH 3 I

19. Dr. Wolf's CHM 201 & 202 4- 19 Substitutive Nomenclature of Alkyl Halides Halogen and alkyl groups are of equal rank when it comes to numbering the chain. Number the chain in the direction that gives the lowest number to the group (halogen or alkyl) that appears first. CH 3 Cl Cl

20. Dr. Wolf's CHM 201 & 202 4- 20 Substitutive Nomenclature of Alkyl Halides 5-Chloro-2-methylheptane 2-Chloro-5-methylheptane CH 3 Cl Cl

21. Dr. Wolf's CHM 201 & 202 4- 21 4.3 IUPAC Nomenclature of Alcohols

22. Dr. Wolf's CHM 201 & 202 4- 22 Name the alkyl group and add "alcohol" as a separate word. Functional Class Nomenclature of Alcohols CH 3 CH 2 OH CH 3 CHCH 2 CH 2 CH 2 CH 3 OH CH 3 CCH 2 CH 2 CH 3 OH CH 3

23. Dr. Wolf's CHM 201 & 202 4- 23 Name the alkyl group and add "alcohol" as a separate word. Functional Class Nomenclature of Alcohols CH 3 CH 2 OH CH 3 CHCH 2 CH 2 CH 2 CH 3 OH CH 3 CCH 2 CH 2 CH 3 OH CH 3 Ethyl alcohol 1-Methylpentyl alcohol 1,1-Dimethylbutyl alcohol

24. Dr. Wolf's CHM 201 & 202 4- 24 Name as "alkanols." Replace -e ending of alkane name by -ol. Number chain in direction that gives lowest number to the carbon that bears the —OH group. Substitutive Nomenclature of Alcohols CH 3 CH 2 OH CH 3 CHCH 2 CH 2 CH 2 CH 3 OH CH 3 CCH 2 CH 2 CH 3 OH CH 3

25. Dr. Wolf's CHM 201 & 202 4- 25 Name as "alkanols." Replace -e ending of alkane name by -ol. Number chain in direction that gives lowest number to the carbon that bears the —OH group. Substitutive Nomenclature of Alcohols CH 3 CH 2 OH CH 3 CHCH 2 CH 2 CH 2 CH 3 OH CH 3 CCH 2 CH 2 CH 3 OH CH 3 Ethanol 2-Hexanol 2-Methyl-2-pentanol

26. Dr. Wolf's CHM 201 & 202 4- 26 OH CH 3 Substitutive Nomenclature of Alcohols Hydroxyl groups outrank alkyl groups when it comes to numbering the chain. Number the chain in the direction that gives the lowest number to the carbon that bears the OH group CH 3 OH

27. Dr. Wolf's CHM 201 & 202 4- 27 Substitutive Nomenclature of Alcohols 6-Methyl-3-heptanol 5-Methyl-2-heptanol OH CH 3 OH

28. Dr. Wolf's CHM 201 & 202 4- 28 4.4 Classes of Alcohols and Alkyl Halides

29. Dr. Wolf's CHM 201 & 202 4- 29 Alcohols and alkyl halides are classified as primary secondary tertiary according to their "degree of substitution." Degree of substitution is determined by counting the number of carbon atoms directly attached to the carbon that bears the halogen or hydroxyl group. ClassificationClassification

30. Dr. Wolf's CHM 201 & 202 4- 30 CH 3 CH 2 CH 2 CH 2 CH 2 F CH 3 CHCH 2 CH 2 CH 3 Br primary alkyl halide secondary alkyl halide ClassificationClassification CH 3 CCH 2 CH 2 CH 3 OH CH 3 tertiary alcohol H OH secondary alcohol

31. Dr. Wolf's CHM 201 & 202 4- 31 4.5 Bonding in Alcohols and Alkyl Halides

32. Dr. Wolf's CHM 201 & 202 4- 32 H H H alcohols and alkyl halides are polar  = 1.7 D  = 1.9 D H H C O H H C Cl ++++ –––– –––– ++++ ++++ Dipole Moments

33. Dr. Wolf's CHM 201 & 202 4- 33 alcohols and alkyl halides are polar  = 1.7 D  = 1.9 D Dipole Moments

34. Dr. Wolf's CHM 201 & 202 4- 34  +  –  –  +  +  – Dipole-Dipole Attractive Forces

35. Dr. Wolf's CHM 201 & 202 4- 35  +  –  –  +  +  – Dipole-Dipole Attractive Forces

36. Dr. Wolf's CHM 201 & 202 4- 36 Boiling point Solubility in water Density 4.6 Physical Properties of Alcohols and Alkyl Halides: Intermolecular Forces

37. Dr. Wolf's CHM 201 & 202 4- 37 444846 -42-32+78 01.91.7 CH 3 CH 2 CH 3 CH 3 CH 2 F CH 3 CH 2 OH Molecular weight Boiling point, °C Dipole moment, D Effect of Structure on Boiling Point

38. Dr. Wolf's CHM 201 & 202 4- 38 44-420 CH 3 CH 2 CH 3 Molecular weight Boiling point, °C Dipole moment, D Intermolecular forces are weak. Only intermolecular forces are induced dipole-induced dipole attractions. Effect of Structure on Boiling Point

39. Dr. Wolf's CHM 201 & 202 4- 39 48-321.9 CH 3 CH 2 F Molecular weight Boiling point, °C Dipole moment, D A polar molecule; therefore dipole-dipole and dipole-induced dipole forces contribute to intermolecular attractions. Effect of Structure on Boiling Point

40. Dr. Wolf's CHM 201 & 202 4- 40 46+781.7 CH 3 CH 2 OH Molecular weight Boiling point, °C Dipole moment, D Highest boiling point; strongest intermolecular attractive forces. Hydrogen bonding is stronger than other dipole-dipole attractions. Effect of Structure on Boiling Point

41. Dr. Wolf's CHM 201 & 202 4- 41 ++++ –––– –––– ++++ Figure 4.4 Hydrogen bonding in ethanol

42. Dr. Wolf's CHM 201 & 202 4- 42 Figure 4.4 Hydrogen bonding in ethanol

43. Dr. Wolf's CHM 201 & 202 4- 43 Boiling point increases with increasing number of halogens CH 3 Cl -24°C CH 2 Cl 2 40°C CHCl 3 61°C CCl 4 77°C CompoundBoiling Point Even though CCl 4 is the only compound in this list without a dipole moment, it has the highest boiling point. Induced dipole-induced dipole forces are greatest in CCl 4 because it has the greatest number of Cl atoms. Cl is more polarizable than H.

44. Dr. Wolf's CHM 201 & 202 4- 44 But trend is not followed when halogen is fluorine CH 3 CH 2 F -32°C CH 3 CHF 2 -25°C CH 3 CF 3 -47°C CF 3 CF 3 -78°C CompoundBoiling Point

45. Dr. Wolf's CHM 201 & 202 4- 45 But trend is not followed when halogen is fluorine CH 3 CH 2 F -32°C CH 3 CHF 2 -25°C CH 3 CF 3 -47°C CF 3 CF 3 -78°C CompoundBoiling Point Fluorine is not very polarizable and induced dipole- induced dipole forces decrease with increasing fluorine substitution.

46. Dr. Wolf's CHM 201 & 202 4- 46 Solubility in water Alkyl halides are insoluble in water. Methanol, ethanol, isopropyl alcohol are completely miscible with water. The solubility of an alcohol in water decreases with increasing number of carbons (compound becomes more hydrocarbon-like).

47. Dr. Wolf's CHM 201 & 202 4- 47 ++++ –––– –––– ++++ –––– ++++ Figure 4.5 Hydrogen Bonding Between Ethanol and Water

48. Dr. Wolf's CHM 201 & 202 4- 48 DensityDensity Alkyl fluorides and alkyl chlorides are less dense than water. Alkyl bromides and alkyl iodides are more dense than water. All liquid alcohols have densities of about 0.8 g/mL.

49. Dr. Wolf's CHM 201 & 202 4- 49 4.7 Preparation of Alkyl Halides from Alcohols and Hydrogen Halides ROH + HX  RX + H 2 O

50. Dr. Wolf's CHM 201 & 202 4- 50 ROH + HX  RX + HOH Hydrogen halide reactivity HFHClHBrHI Reaction of Alcohols with Hydrogen Halides least reactive most reactive

51. Dr. Wolf's CHM 201 & 202 4- 51 Alcohol reactivity CH 3 OH RCH 2 OH R 2 CHOH R 3 COH MethanolPrimarySecondaryTertiary ROH + HX  RX + HOH Reaction of Alcohols with Hydrogen Halides least reactive most reactive

52. Dr. Wolf's CHM 201 & 202 4- 52 (CH 3 ) 3 COH + HCl (CH 3 ) 3 CCl + H 2 O 78-88% 25°C CH 3 (CH 2 ) 5 CH 2 OH + HBr CH 3 (CH 2 ) 5 CH 2 Br + H 2 O 87-90%120°C Preparation of Alkyl Halides 73% 80-100°C OH + HBr Br + H2OH2OH2OH2O

53. Dr. Wolf's CHM 201 & 202 4- 53 CH 3 CH 2 CH 2 CH 2 OH CH 3 CH 2 CH 2 CH 2 Br NaBr H 2 SO 4 70-83% heat A mixture of sodium bromide and sulfuric acid may be used in place of HBr. Preparation of Alkyl Halides