Chiral Molecules Chapter 12 Organic Compounds with Oxygen and Sulfur Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

2 Chiral Objects Chiral objects have the same number of atoms arranged differently in space. have one or more chiral carbon atoms each of which is bonded to four different groups. are like your hands. Try to superimpose your thumbs, palms, back of hands, and little fingers. Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

3 Mirror Images The mirror images of chiral compounds cannot be superimposed. When the H and I atoms are aligned, the Cl and Br atoms are on opposite sides.

4 Achiral Structures are Superimposable When the mirror image of an achiral structure is rotated, the structure can be aligned with the initial structure. Thus this mirror image is superimposable.

5 Some Everyday Chiral and Achiral Objects

6 Learning Check Identify each as a chiral or achiral compound. A CH 2 CH 3 HCH 3 Cl C B H HCH 3 Cl C C Br HCH 3 Cl C

7 Solution Identify each as a chiral or achiral compound. chiral achiral chiral A CH 2 CH 3 HCH 3 Cl C B H HCH 3 Cl C C Br HCH 3 Cl C

8 Fischer Projections A Fischer projection is a 2-dimensional representation of a 3-dimensional molecule. places the most oxidized group at the top. uses vertical lines in place of dashes for bonds that go back. uses horizontal lines in place of wedges for bonds that come forward.

9 Drawing Fischer Projections

10 D and L Notations By convention, the letter L is assigned to the structure with the —OH on the left. The letter D is assigned to the structure with the —OH on the right. Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

11 Learning Check Indicate whether each pair is a mirror image that cannot be superimposed (enantiomers).

12 Solution Indicate whether each pair is a mirror image that cannot be superimposed (enantiomers). Yes No

13 Good practice problems Draw a star on the carbon atoms to denote chirality in menthol (peppermint)

14 Answer: There are three chiral carbon atoms in menthol (peppermint)

15 Try this popular antidepressant Zoloft (Sertraline)

16 Answer Two

17 Try the following Lipitor (atorvastatin)

18 Answer Two

19 Another anticholesterol drug Zocor

20 Answer Seven

21 Chapter 13 Carboxylic Acids, Esters, Amines, and Amides 13.1 Carboxylic Acids Copyright © 2005 by Pearson Education, Inc. Publishing as Benjamin Cummings

22 A carboxylic acid contains a carboxyl group, which is a carbonyl group (C=O) attached to a hydroxyl group (—OH). is found on carbon 1 in carboxylic acids. O  CH 3 — C—OHhydroxyl group or CH 3 COOH carbonyl group Carboxylic Acids

23 Models of Carboxylic Acids The three-dimensional models show the geometry of atoms in carboxylic acid molecules.

24 The IUPAC names of carboxylic acids: Replace the -e in the alkane name with -oic acid. CH 4 methane HCOOH methanoic acid CH 3 —CH 3 ethane CH 3 —COOH ethanoic acid Number substituents from the carboxyl carbon 1. CH 3 O | ║ CH 3 —CH—CH 2 —C—OH methylbutanoic acid IUPAC Names

25 Names and Sources of Some Carboxylic Acids

26 Common Carboxylic Acids Methanoic acid (formic acid) O ║ H─C─OH ethanoic acid (acetic acid) O ║ CH 3 ─C─OH

27 Aromatic Carboxylic Acids Benzoic acid is the aromatic carboxylic acid. locates substituents by numbering the ring from carbon 1 in the carboxyl group. 3-chlorobenzoic acid 4-aminobenzoic acid benzoic acid

28 Learning Check Give the IUPAC names of each compound. A. CH 3 ─CH 2 ─COOH CH 3 | B. CH 3 ─CH─CH 2 ─COOH C.

29 Solution A. CH 3 ─CH 2 ─COOH propanoic acid CH 3 | B. CH 3 ─CH─CH 2 ─COOH3-methylbutanoic acid C.3-bromobenzoic acid