1. 15-1 Chemistry 121, Winter 2011, LA Tech Introduction to Organic Chemistry and Biochemistry Instructor Dr. Upali Siriwardane (Ph.D. Ohio State) E-mail: upali@chem.latech.edu Office: 311 Carson Taylor Hall ; Phone: 318-257-4941; Office Hours: MWF 8:00 am - 10:00 am; TT 9:00 – 10:00 am & 1:00-2:00 pm. December 17, 2010 Test 1 (Chapters 12-13) January 19, 2011 Test 2 (Chapters 14,15 & 16) February 7, 2011 Test 3(Chapters 17, 18 & 19) February 23, 2011 Test 4 (Chapters 20, 21 & 22) February 24, 2011 Comprehensive Make Up Exam: Chemistry 121(01) Winter 2010-11

2. 15-2 Chemistry 121, Winter 2011, LA Tech Chapter 15: Aldehyde and Ketones 15.1The Carbonyl Group 15.2Compounds Containing a Carbonyl Group 15.3The Aldehyde and Ketone Funcitonal Groups 15.4Nomenclature for Aldehydes 15.5Nomenclature for Ketones 15.6Isomerism for Aldehydes and Ketones 15.7Selected Common Aldehydes and Ketones 15.8Physical Properties of Aldehydes and Ketones 15.9Preparation of Aldehydes and Ketones 15.10 Oxidation and Reduction of Aldehydes and Ketones 15.11 Reaction of Aldehydes and Ketones with Alcohols 15.12 Formaldehyde-Based Polymers 15.13Sulfur-Containing Carbonyl Groups

3. 15-3 Chemistry 121, Winter 2011, LA Tech Aldehydes: Carbonyl is attached to at least one H atom in aldehydes Ketones: Carbonyl is directly attached with two carbon atoms in ketones Carboxylic acids: carbonyl carbon atom bonded to a hydroxyl group. Esters: carbonyl carbon atom bonded to an oxygen atom Amide: carbonyl carbon atom bonded to a nitrogen atom Aldehydes and KetonesAldehydes and Ketones

4. 15-4 Chemistry 121, Winter 2011, LA Tech Aldehyde functional group: –CHO Ketone functional group: carbonyl carbon (C=O) attached to carbon atoms Cyclic aldehydes are not possible but cyclic ketones are known Cyclic ketones are not heterocyclic ring systems Aldehyde Functional GroupAldehyde Functional Group

5. 15-5 Chemistry 121, Winter 2011, LA Tech Structure the functional group of an aldehyde is a carbonyl group bonded to a H atom the functional group of a ketone is a carbonyl group bonded to two carbon atoms

6. 15-6 Chemistry 121, Winter 2011, LA Tech Carbonyl group: A carbon atom double-bonded to an oxygen atom Aldehydes and ketones are the compounds which contain a carbonyl functional group C=O bond is polar (oxygen gets partial negative and carbon gets partial positive charge) C=C is non polar All carbonyl groups have a trigonal planar structure Compounds with C=O and C=C both exhibit different chemistry Carbonyl Polarity of Carbonyl Group Geometry of Carbonyl Group Carbonyl group:Carbonyl group:

7. 15-7 Chemistry 121, Winter 2011, LA Tech IUPAC Nomenclature of Aldehyde and Ketones The IUPAC system deals with functional groups two different ways. Modification of the hydrocarbon name to indicate the presence of a functional group. al aldehyde, -CHOuse -al ending. one Ketones -RCOR’ use -one ending.

8. 15-8 Chemistry 121, Winter 2011, LA Tech IUPAC Rules Rule 1: Select as the parent carbon chain the longest carbon chain that includes the carbon atom of the carbonyl group. Rule 2: Name the parent chain by changing the “-e” ending of the corresponding alkane name to “-one.” Rule 3: Number the carbon chain such that the carbonyl carbon atom receives the lowest possible number. The position of the carbonyl carbon atom is noted by placing a number immediately before the name of the parent chain. Rule 4: Determine the identity and location of any substituents, and append this information to the front of the parent chain name. Rule 5: Cyclic ketones are named by assigning the number 1 to the carbon atom of the carbonyl group. The ring is then numbered to give the lowest number(s) to the atom(s) bearing substituents.

9. 15-9 Chemistry 121, Winter 2011, LA Tech Example C - C - C - C - CHO Base contains 5 carbon -aldehyde name is pentane -e -al -remove -e and add -al C - C - C - C - CO-C-C Base contains 7 carbon -aldehyde name is heptane -e -one -remove -e and add -one 3-heptanone

10. 15-10 Chemistry 121, Winter 2011, LA Tech Common Names Aldehydes: Fomaldehyde: HCHO Acetaldehyde: CH 3 CHO Propionaldehyde: CH 3 CH 2 CHO Butyraldehyde: CH 3 CH 2 CH 2 CHO Valeraldehyde: CH 3 CH 2 CH 2 CH 2 CHOKetones: Acetone: CH 3 COCH 3 Methyl ethyl ketone CH 3 CH 2 COCH 3 Butyl propyl ketone CH 3 CH 2 CH 2 CH 2 COCH 2 CH 2 CH 3

11. 15-11 Chemistry 121, Winter 2011, LA Tech Nomenclature

12. 15-12 Chemistry 121, Winter 2011, LA Tech Nomenclature

13. 15-13 Chemistry 121, Winter 2011, LA Tech Name the Aldehyde 2,4-dimethylpentanal

14. 15-14 Chemistry 121, Winter 2011, LA Tech Constitutional isomers exist for aldehydes and ketones Isomers between aldehydes and ketones are called functional group isomers Two types of isomers: Skeletal isomers: arrangements of atoms in space is different. Positional isomers: Position of the functional group is different. Skeletal isomers Positional isomers Constitutional isomers of aldehydes and ketones

15. 15-15 Chemistry 121, Winter 2011, LA Tech Examples of Aldehyde and Ketones Formaldehyde Simplest aldehyde and has one carbon atom It is synthesized by oxidation of methanol It is synthesized by oxidation of methanol Mainly used for the manufacturing of polymers Mainly used for the manufacturing of polymers Bubbling formaldehyde through water produces formalin (formaldehyde in water with pungent smell) Bubbling formaldehyde through water produces formalin (formaldehyde in water with pungent smell) Formalin is used for preserving biological specimens In formalin formaldehyde is present in the form of HO-CH 2 -OH

16. 15-16 Chemistry 121, Winter 2011, LA Tech Examples of Aldehyde and Ketones Acetone is the simplest ketone. Colorless liquid with mild sweet odor. Excellent solvent: it is miscible in both water and organic solvents. Acetone is the main ingredient in gasoline treatments designed to solubilize water in the gas tank and allow it to pass through the engine in miscible form. Major component of nail polish remover. Patients with diabetes produce large amounts of acetone. Diabetic breath has mild sweet odor because of acetone. Presence of acetone in urine indicates diabetes.

17. 15-17 Chemistry 121, Winter 2011, LA Tech Important Aldehydes Methanal or formaldehyde Ethanal or acetaldehyde 2-Propanone or acetone 2-Butanone or methyl ethyl ketone Oil of almonds or benzaldehyde Oil of Cinnamon or cinnamaldehyde Oil of vanilla beans or vanillin Mushroom flavoring or 2-octanone Oil of lemongrass or citral:

18. 15-18 Chemistry 121, Winter 2011, LA Tech Naturally Occurring Aldehydes and Ketones Aldehydes and ketones occur widely in nature Such compounds have higher molecular masses, pleasant odors and flavors Often used in consumer products such as perfumes, air fresheners, etc). Example: Butanedione The unmistakable odor of melted butter is largely due to the four-carbon diketone - butanedione.

19. 15-19 Chemistry 121, Winter 2011, LA Tech Physical properties of aldehydes and ketones.

20. 15-20 Chemistry 121, Winter 2011, LA Tech Physical State at Room Temperature Aldehydes: C 1 -C 2 aldehydes are gases C 3 -C 11 straight-chain aldehydes are liquids >C 11 aldehydes are solids Ketones: Lower molar mass ketones are colorless liquids

21. 15-21 Chemistry 121, Winter 2011, LA Tech Boiling and Melting Points Intermediate between alcohols and alkanes Higher boiling points than alkanes because of dipole–dipole attractions between carbonyl groups in these molecules.

22. 15-22 Chemistry 121, Winter 2011, LA Tech Solubility Water molecules can hydrogen-bond with aldehyde and ketone molecules, which causes low-molecular-mass aldehydes and ketones to be water soluble. Aldehydes and ketones with longer hydrocarbon chains are less soluble or insoluble in water.

23. 15-23 Chemistry 121, Winter 2011, LA Tech Oxidation of Alcohols Aldehydes produced by the mild oxidation of primary alcohols Ketones are produced by the mild oxidation of secondary alcohols Oxidizing agents(mild): KMnO 4 or K 2 Cr 2 O 7 Preparation of Aldehydes and KetonesPreparation of Aldehydes and Ketones

24. 15-24 Chemistry 121, Winter 2011, LA Tech Oxidation of Aldehydes and Ketones: Aldehydes readily undergo oxidation to carboxylic acids Ketones are resistant to oxidation Reactions of Aldehydes and KetonesReactions of Aldehydes and Ketones

25. 15-25 Chemistry 121, Winter 2011, LA Tech Preapration of Aldehydes: Partial oxidation of primary alcohols with H 2 CrO 4 :

26. 15-26 Chemistry 121, Winter 2011, LA Tech Oxidation of alcohol

27. 15-27 Chemistry 121, Winter 2011, LA Tech Preapration of ketones: Oxidation of secondary alcohols with KMnO 4, or H 2 CrO 4

28. 15-28 Chemistry 121, Winter 2011, LA Tech Oxidation of alcohol

29. 15-29 Chemistry 121, Winter 2011, LA Tech Chemical Reactions Oxidation of aldehyde. Benedict's Test for aldehydes:

30. 15-30 Chemistry 121, Winter 2011, LA Tech Test for Urine Glucose: Benedict’s Test

31. 15-31 Chemistry 121, Winter 2011, LA Tech Oxidation of aldehyde. The commercial manufacture of silver mirrors uses a similar process. Tollen's Test:

32. 15-32 Chemistry 121, Winter 2011, LA Tech Reduction of als & ones compounds to alcohols:

33. 15-33 Chemistry 121, Winter 2011, LA Tech Addition reactions of als & ones Hemiacetal or hemiketal formation

34. 15-34 Chemistry 121, Winter 2011, LA Tech Hemiacetal form of cyclic sugars

35. 15-35 Chemistry 121, Winter 2011, LA Tech Formation of Acetals and Ketals.

36. 15-36 Chemistry 121, Winter 2011, LA Tech Addition of HCN and H 2 O

37. 15-37 Chemistry 121, Winter 2011, LA Tech Aldol Condensation In biological systems this reaction is catalysed by an enzyme named aldolase.

38. 15-38 Chemistry 121, Winter 2011, LA Tech Keto & Enol tautomers keto form enol from

39. 15-39 Chemistry 121, Winter 2011, LA Tech Keto & Enol tautomers in sugars aldehyde enol ketone

40. 15-40 Chemistry 121, Winter 2011, LA Tech Tollens test: Test for Aldehyde Tollens test (silver mirror test): Tollens reagent [aqueous silver nitrate (AgNO 3 ) and ammonia (NH 3 )] when added to an aldehyde, Ag + ion is reduced to silver metal, which deposits on the inside of the test tube, forming a silver mirror. The appearance of this silver mirror is a positive test for the presence of the aldehyde group. The Ag ion will not oxidize ketones.

41. 15-41 Chemistry 121, Winter 2011, LA Tech Benedict’s Test: Test for Aldehyde Similar to the Tollens test except that the metal ion oxidizing agent is Cu 2+ Cu 2+ ion is reduced to Cu ion, which precipitates from solution as Cu 2 O (brick-red colored solid)

42. 15-42 Chemistry 121, Winter 2011, LA Tech Reduction of Aldehydes and Ketones Aldehydes and ketones are easily reduced by hydrogen gas (H 2 ), in the presence of a catalyst (Ni, Pt, or Cu), to form alcohols. Aldehydes produces primary alcohols. Ketones yield secondary alcohols.

43. 15-43 Chemistry 121, Winter 2011, LA Tech Aldehydes and ketones react with alcohols to form hemiacetals and acetals. Hemiacetal formation: A hemiacetal is an organic compound in which a carbon atom is bonded to both a hydroxyl group (—OH) and an alkoxy group (—OR). A hemiacetal can also be formed due to the reaction between an —OH and C=O functional groups with in the same molecule. Such a reaction produces a cyclic hemiacetal Cyclic hemiacetals are more stable Formation of Hemiacetals and AcetalsFormation of Hemiacetals and Acetals

44. 15-44 Chemistry 121, Winter 2011, LA Tech Simplest Aldehyde

45. 15-45 Chemistry 121, Winter 2011, LA Tech Practice Exercise Answers: a.Yes b.Yes c.No d.Yes

46. 15-46 Chemistry 121, Winter 2011, LA Tech Acetal Formation and Hydrolysis Acetal Formation: An acetal is an organic compound in which a carbon atom is bonded to two alkoxy groups (—OR). Acetal Hydrolysis: Undergo hydrolysis in acidic solution to form the aldehyde or ketone and alcohols that originally reacted to form the acetal.

47. 15-47 Chemistry 121, Winter 2011, LA Tech Bakelite

48. 15-48 Chemistry 121, Winter 2011, LA Tech Formaldehyde is a prolific “polymer former” Under acidic conditions, reaction between formaldehyde and phenol forms a phenol– formaldehyde network polymer

49. 15-49 Chemistry 121, Winter 2011, LA Tech Replacement of carbonyl oxygen with sulfur produces thioaldehydes (thials) and thioketones (thiones) These are unstable and readily decompose. Replacement of the carbonyl carbon atom with sulfur produces sulfoxides. Sulfoxides are much more stable than thiocarbonyls Most important example: DMSO (dimethyl sulfoxide) DMSO is an odorless liquid with excellent solvent properties DMSO is quickly absorbed into the body and is known to relieve pain and inflammation Not approved by the FDA for medical uses because of possible side effects Thioaldehydes (thials) and ThioketonesThioaldehydes (thials) and Thioketones