Chemistry 121(01) Winter 2012 Introduction to rganic Chemistry and Biochemistry Instructor Dr. Upali Siriwardane (Ph.D. hio State) E-mail: upali@chem.latech.edu ffice: 311 Carson Taylor Hall ; Phone: 318-257-4941; ffice Hours: MTW 9:00 am - 11:00 am; TR 9:00-10:00 am & 1:00-2:00 pm. December 16, Test 1 (Chapters 12-13) January 20 Test 2 (Chapters 14-16) February 6 (Chapters 17-19) February 27, (Chapters 20-22) February 28, 2012, Make Up Exam: Bring Scantron Sheet 882-E Chapter 15: Aldehyde and Ketones Sections 1-1 1-2 Chapter 15: Aldehyde and Ketones 15.1 The Carbonyl Group 15.2 Structure of Aldehydes and Ketones 15.3 Nomenclature for Aldehydes 15.4 Nomenclature for Ketones 15.5 Isomerism for Aldehydes and Ketones 15.6 Selected Common Aldehydes and Ketones 15.7 Physical Properties of Aldehydes and Ketones 15.8 Preparation of Aldehydes and Ketones 15.9 xidation and Reduction of Aldehydes and Ketones 15.10 Reaction of Aldehydes and Ketones with Alcohols Carbonyl Group 1-3 1-4 1
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 HCH CH 3 CH CH 3 CCH 3 Methanal (Formaldehyde) Ethanal (Acetaldehyde) Propanone (Acetone) 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. aldehyde, -CH use -al ending. Ketones -RCR use -one ending. 1-5 1-6 Example Nomenclature C - C - C - C - CH Base contains 5 carbon - aldehyde name is pentane - remove -e and add -al C - C - C - C - C-C-C Base contains 7 carbon - aldehyde name is heptane - remove -e and add -one 3-heptanone 1-7 3-Methylbutanal 4 3 2-Methylcyclohexanone 5-Methyl-3- hexanone 2 1 H 3 1 H 2-Propenal (Acrolein) CH H 4 1 CH 2 Cyclopentanecarbaldehyde trans-4-hydroxycyclohexanecarbaldehyde 7 5 3 1 8 H 6 4 2 (2E)-3,7-Dimethyl-2,6-octadienal (Geranial) Acetophenone Benzophenone 1-8 2
Nomenclature Name the Aldehyde Functional Group Suffix Prefix Carboxyl Aldehyde -oic acid -al oxo- Ketone -one oxo- Example of When the Functional Group Has a Lower Priority 3-xopropanoic acid 3-xobutanoic acid H CH CH Alcohol -ol hydroxy- 4-Hydroxybutanoic acid H CH Amino -amine amino- 3-Aminobutanoic acid Sulfhydryl -thiol mercapto- 2-Mercaptoethanol NH 2 CH HS H 2,4-dimethylpentanal 1-9 1-10 Common Names Aldehydes: Fomaldehyde: HCH Acetaldehyde: CH 3 CH Propionaldehyde: CH 3 CH 2 CH Butyraldehyde: CH 3 CH 2 CH 2 CH Valeraldehyde: CH 3 CH 2 CH 2 CH 2 CH Ketones: Acetone: CH 3 CCH 3 Methyl ethyl ketone CH 3 CH 2 CCH 3 Butyl propyl ketone CH 3 CH 2 CH 2 CH 2 CCH 2 CH 2 CH 3 Simplest Aldehyde 1-11 1-12 3
Important Aldehydes Bakelite Methanal or formaldehyde Ethanal or acetaldehyde 2-Propanone or acetone 2-Butanone or methyl ethyl ketone il of almonds or benzaldehyde il of Cinnamon or cinnamaldehyde il of vanilla beans or vanillin Mushroom flavoring or 2-octanone il of lemongrass or citral: 1-13 1-14 Preapration of Aldehydes: Partial oxidation of primary alcohols with H 2 Cr 4 : Preapration of ketones: xidation of secondary alcohols with KMn 4, or H 2 Cr 4 1-15 1-16 4
xidation of alcohol xidation of alcohol 1-17 1-18 Physical properties of aldehydes and ketones. Chemical Reactions xidation of aldehyde. Benedict's Test for aldehydes: 1-19 1-20 5
Test for Urine Glucose: Benedict s Test Tollen's Test: xidation of aldehyde. The commercial manufacture of silver mirrors uses a similar process. 1-21 1-22 Reduction of als & ones compounds to alcohols: Addition reactions of als & ones Hemiacetal or hemiketal formation 1-23 1-24 6
Hemiacetal form of cyclic sugars Formation of Acetals and Ketals. 1-25 1-26 Addition of HCN and H 2 Aldol Condensation In biological systems this reaction is catalysed by an enzyme named aldolase. 1-27 1-28 7
Keto & Enol tautomers keto form enol from Keto & Enol tautomers in sugars aldehyde enol ketone 1-29 1-30 8