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1. Chapter five Classes of Hydrocarbons

2. Organic chemistry is the study of carbon compounds (except CO, CO 2 , carbonates, hydrogencarbonates, carbides and cyanides) obtained from natural sources or synthesized in the laboratories.

3. Natural Sources of Organic Compounds Living things Carbohydrates / Proteins / Fats / Vitamins / Antibiotics A variety of organic products obtained from living things

4. Crude oil or coal Fractional distillation / destructive distillation Alkanes / Alkenes / Alkynes / Aromatic hydrocarbons A variety of useful products derived from crude oil and coal

5. The Unique Nature of Carbon Ability to form four strong covalent bonds Ability to Catenate Carbon atoms link together to form chains of varying length, branched chains and rings of different sizes Catenation:  Ability of atoms in forming stable bonds with itself , hence joining up into chains or rings

6. C n H 2n+2 n = 1,2,3,…(no limit for n) Si n H 2n+2 n = 1 to 6 only  silanes Ge n H 2n+2 n = 1 to 3 only  germanes Sn n H 2n+2 Only SnH 4 (stannane) exists

7. Ability to Form Multiple Bonds sp 3 4  bonds sp 2 1  bond, 3  bonds sp 2  bonds, 2  bonds Carbon (excited state)

8. Hydrocarbons Aromatic Aliphatic

9. Hydrocarbons Aromatic Aliphatic Alkanes Alkynes Alkenes

10. Hydrocarbons Aliphatic Alkanes Alkanes are hydrocarbons in which all of the bonds are single bonds. C C H H H H H H

11. Hydrocarbons Aliphatic Alkenes Alkenes are hydrocarbons that contain a carbon-carbon double bond. C C H H H H

12. Hydrocarbons Aliphatic Alkynes Alkynes are hydrocarbons that contain a carbon-carbon triple bond. HC CH

13. Hydrocarbons Aromatic The most common aromatic hydrocarbons are those that contain a benzene ring. H H H H H H

14. Reactive Sites in Hydrocarbons

15. Functional Group Functional group is where re action take place. A structural unit in a molecule responsible for its characteristic behavior under a particular set of reaction conditions

16. Alkanes functional group is a hydrogen reaction that takes place is substitution one of the hydrogens is replaced by some other atom or group R— H R— X

17. Alkanes functional group is a hydrogen reaction that takes place is substitution one of the hydrogens is replaced by some other atom or group R— H R— X + Cl 2 C C H H H H H H + H Cl C C H Cl H H H H

18. Functional Groups in Hydrocarbons alkanes RH alkenes double bond alkynes triple bond arenes ArH

19. Families of organic compounds and their functional groups Alcohols ROH Alkyl halides RX (X = F, Cl, Br, I) Amines primary amine: RNH 2 secondary amine: R 2 NH tertiary amine: R 3 N

20. Carboxylic acids The functional group present in a carboxylic acid is a combination of a carbonyl group and a hydroxyl group; however, the resulting carboxyl group ( -COOH) possesses properties that are unlike those present in aldehydes/ketones and alcohols.

21. Carboxylic acids have the following general formula: Some simple carboxylic acids: Since carbon can have only four bonds, there are no cyclic carboxylic acids (i.e. the carboxyl group cannot form part of a carbon ring)

22. IUPAC nomenclature for carboxylic acids For mono carboxylic acids (one –COOH group): Select the longest, continuous carbon chain that involves the carboxyl group. This is the parent chain and the –COOH carbon is designated as C-1. Name the parent chain by dropping the “e” from the corresponding alkane name and changing to “ oic acid” Indicate the identity and location of substituents on the parent chain at the front of the carboxylic acid’s name

23. Dicarboxylic acids: For these compounds, both ends of a chain will end with a –COOH group. The parent chain is the one that involves both –COOH groups. The parent chain is named as an alkane and the term “ dioic acid” is added afterwards to indicate the diacid structure.

24. Common names for carboxylic acids

25. Common names for carboxylic acids For common-name carboxylic acids and diacids , substituents are often numbered using a Greek system: So the following molecule could be called a - Methylpropionic acid (or, using the IUPAC system, 2-Methylpropanoic acid)

26. Polyfunctional carboxylic acids Carboxylic acids that contain other functional groups besides the –COOH group are called polyfunctional carboxylic acids. Some examples are shown below:

27. Unsaturated acids possess a unit of unsaturation (double/triple C-C bond) in the structure. Three of the most common unsaturated acids are shown

28. Four of the simplest hydroxy acids:

29. Keto group For keto acids, a carbonyl group is present as part of a carbon chain that involves a carboxyl group: For IUPAC naming of this structure, the O-atom of the carbonyl group is treated as an “ oxo ” substituent and the molecule is called 2-Oxopropanoic acid

30. Uses of carboxylic acid salts Because of their enhanced solubility in water compared to the acid form, many drugs and medicines that possess acid groups are marketed as carboxylic acid salts (sodium or potassium salts).

31. esters Esters are carboxylic acid derivatives having an alkoxy group instead of a hydroxyl group.

32. Preparation of esters Esters are prepared by condensation reactions involving carboxylic acids and alcohols. Such reactions are called esterification reactions : This an ester consists of an acid portion and an alcohol portion :

33. Selected common esters Flavor/fragrance agents

34. Pheromones Medications

35. Synthesis of Aspirin Synthesis of oil of wintergreen

36. Aldehydes and Ketones Before you can learn about aldehydes and ketones, you must first know something about the nomenclature of carboxylic acids since many of the names of aldehydes and ketones are derived from the names of the corresponding carboxylic acids.

37. Carboxylic acids: R-COOH, R-CO 2 H, Common names : HCO 2 H formic acid L. formica ant CH 3 CO 2 H acetic acid L. acetum vinegar CH 3 CH 2 CO 2 H propionic acid G. “first salt” CH 3 CH 2 CH 2 CO 2 H butyric acid L. butyrum butter CH 3 CH 2 CH 2 CH 2 CO 2 H valeric acid L. valerans

38. Carboxylic acids, common names : … CH 3 (CH 2 ) 4 CO 2 H caproic acid L. caper goat CH 3 (CH 2 ) 5 CO 2 H --- CH 3 (CH 2 ) 6 CO 2 H caprylic acid CH 3 (CH 2 ) 7 CO 2 H --- CH 3 (CH 2 ) 8 CO 2 H capric acid CH 3 (CH 2 ) 9 CO 2 H --- CH 3 (CH 2 ) 10 CO 2 H lauric acid oil of lauryl

39. ALDEHYDES AND KETONES “carbonyl” functional group: Aldehydes Ketones

40. Nomenclature Aldehydes, common names: Derived from the common names of carboxylic acids; drop – ic acid suffix and add –aldehyde. CH 3 CH 3 CH 2 CH 2 CH=O CH 3 CHCH=O butyraldehyde isobutyraldehyde ( α- methylpropionaldehyde )

41. Ketones, common names : Special name : acetone “alkyl alkyl ketone” or “dialkyl ketone”

42. (o)phenones : Derived from common name of carboxylic acid, drop –ic acid, add –(o)phenone.

43. Aldehydes, syntheses: Oxidation of 1 o alcohols Oxidation of methylaromatics Reduction of acid chlorides Ketones, syntheses: Oxidation of 2 o alcohols Friedel -Crafts acylation Coupling of R 2 CuLi with acid chloride

44. A ldehydes synthesis 1) oxidation of primary alcohols: RCH 2 -OH + K 2 Cr 2 O 7 , special conditions  RCH=O RCH 2 -OH + C 5 H 5 NHCrO 3 Cl  RCH=O ( pyridinium chlorochromate ) [ With other oxidizing agents, primary alcohols  RCOOH ]

45. Aldehyde synthesis: 2) oxidation of methylaromatics

46. Ketone synthesis: 1) oxidation of secondary alcohols

47. Ketone synthesis: 2) Friedel-Crafts acylation Aromatic ketones (phenones) only!

48. Aldehydes, syntheses : Oxidation of 1 o alcohols Oxidation of methylaromatics aromatic only Reduction of acid chlorides Ketones, syntheses: Oxidation of 2 o alcohols Friedel -Crafts acylation aromatic only Coupling of R 2 CuLi with acid chloride

49. aldehyde 1 o alcohol Ar-CH 3 acid chloride CrO 3 H 2 O (AcO) 2 O LiAlH(O- t -Bu) 3 K 2 Cr 2 O 7 , special cond. or C 5 H 5 NHCrO 3 Cl

50. ketone 2 o alcohol acid chloride + ArH acid chloride + R 2 CuLi NaOCl, etc. AlCl 3

51. Uses of Aldehydes Formaldehyde is a gas. With 40% solution in water, it forms Formalin which is used in preserving biological specimens. Formaldehyde is used in embalming, tanning, preparing glues and polymeric products, as germicides, insecticides, and fungicides for plants. It is also used in drug testing and photography.

52. When reacted with phenol, formaldehyde forms Bakelite, which is used in plastics, coatings, and adhesives. Acetaldehyde is largely used for the production of acetic acid and pyridine derivatives. Benzaldehyde is used in perfumes, cosmetic products, and dyes. It is added to provide almond flavor to food products and also used as a bee repellent

53. Uses of Ketones The most common ketone is acetone which is an excellent solvent for a number of plastics and synthetic fibers. In the household, acetone is used as a nail paint remover and paint thinner. In medicine, it is used in chemical peeling and for acne treatments. Methyl ethyl ketone (MEK), chemically butanone, is a common solvent. It is used in the production of textiles, varnishes, plastics, paint remover, paraffin wax, etc.