Lecture Presentation Chapter 14 Ketones, and Chiral Molecules Karen C Timberlake General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Chapter 14 Aldehydes, Ketones, and Chiral Molecules A dermatology nurse performs many duties for the dermatologist, including treating skin conditions, assisting in surgeries, performing biopsies and excisions, writing prescriptions, freezing skin lesions, and screening patients for skin cancer To become a dermatology nurse, you first become a nurse or physician assistant and then specialize in dermatology General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Chapter 14 Readiness Core Chemistry Skills • • • Naming and Drawing Alkanes (12.2) Naming Alcohols and Phenols (13.1) Writing Equations for the Oxidation of Alcohols (13.4) General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc 14.1 Aldehydes and Ketones • Formaldehyde is the simplest aldehyde It is a colorless gas with a pungent odor • An aqueous solution called formalin, which contains 40% formaldehyde, is used as a germicide and to preserve biological specimens Learning Goal Identify compounds with carbonyl groups as aldehydes and ketones Write the IUPAC and common names for aldehydes and ketones; draw their condensed or line-angle structural formulas General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Carbonyl Group A carbonyl group in • • an aldehyde is bonded to at least one H atom a ketone is bonded to two carbon groups Aldehydes and ketones contain a carbonyl group that consists of a carbon–oxygen double bond with two groups of atoms attached to the carbon at angles • of 120° General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Carbonyl Polarity • The oxygen atom with two lone pairs of electrons is much more electronegative than the carbon atom • The carbonyl group has a strong dipole with a partial negative charge on the oxygen and a partial positive charge on the δ − carbon • The polarity of the carbonyl group strongly influences the physical δ + and chemical properties of aldehydes and ketones General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Naming Aldehydes In the IUPAC system, • • • an aldehyde is named by replacing the e of the corresponding alkane name with al no number is needed for the aldehyde group because it always appears at the end of the chain aldehydes with carbon chains of one to four carbons are often referred to by their common names, which end in aldehyde Core Chemistry Skill Naming Aldehydes and Ketones General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Naming Aldehydes The IUPAC system names the aldehyde of benzene as benzaldehyde General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Guide to Naming Aldehydes General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Study Check Give the IUPAC name for the following aldehyde: General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Drawing Fischer Projections Fischer projections can also be drawn for compounds that have two or more chiral carbons: • • In the mirror images of erythrose, both of the carbon atoms at the intersections are chiral The mirror image for L-erythrose is drawn by reversing the positions of all the — H and — OH groups on the horizontal lines of D-erythrose General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Drawing Fischer Projections The designation as a D or an L stereoisomer of a Fischer projection is determined by the position of the — OH group attached to the chiral carbon farthest from the carbonyl group General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Chemistry Link to Health: Enantiomers in Biological Systems Molecules in nature also have mirror images, and often one stereoisomer has a different biological effect than the other one • One enantiomer of carvone, produced by the spearmint plant, smells and tastes like spearmint, whereas its mirror image, produced by the caraway plant, has the odor and taste of caraway in rye bread • Our senses of smell and taste are responsive to the chirality of molecules General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Chemistry Link to Health: Enantiomers in Biological Systems General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Chemistry Link to Health: Enantiomers in Biological Systems Molecules in nature also have mirror images, and often one stereoisomer has a different biological effect than the other one • One enantiomer of carvone, produced by the spearmint plant, smells and tastes like spearmint, whereas its mirror image, produced by the caraway plant, has the odor and taste of caraway in rye bread • Our senses of smell and taste are responsive to the chirality of molecules General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Chemistry Link to Health: Enantiomers in Biological Systems • A substance used to treat Parkinson’s disease is L-dopa, which is converted to dopamine in the brain, where it raises the serotonin level • The D-dopa enantiomer is not effective for the treatment of Parkinson’s disease General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Study Check Identify each as a chiral or an achiral compound A C General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake B © 2016 Pearson Education, Inc Solution Identify each as a chiral or an achiral compound A C chiral General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake B chiral achiral © 2016 Pearson Education, Inc Study Check Indicate whether each of the following pairs of Fischer projections can or cannot be superimposed: A B and and General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Solution Indicate whether each of the following pairs of Fischer projections can or cannot be superimposed: A B cannot be superimposed and and General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake can be superimposed © 2016 Pearson Education, Inc Study Check Identify the following Fischer Projection as a d or an l enantiomer: General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Solution Identify the following Fischer Projection as a d or an l enantiomer: The –OH group is on the right, it is a d- enantiomer General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Study Check Draw the Fischer projection for the following dash-wedge structure: General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Solution Draw the Fischer projection for the following dash-wedge structure: General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Concept Map General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc ... benzaldehyde General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Guide to Naming Aldehydes General, Organic, and Biological Chemistry: Structures. .. numbers General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Guide to Naming Ketones General, Organic, and Biological Chemistry: Structures. .. to by their common names, which end in aldehyde Core Chemistry Skill Naming Aldehydes and Ketones General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson