《有机化学》课程PPT教学课件（Organic Chemistry, William A. Price, Ph.D. PPT, La Salle University, L.G.WADE, JR., 8th Edition）Stereochemistry

Stereochemistry Stereochemistry refers to the 3-dimensional properties and reactions of molecules.It has its own language and terms that need to be learned in order to fully communicate and understand the concepts. 2013 Pearson Education,Inc

© 2013 Pearson Education, Inc. Stereochemistry Stereochemistry refers to the 3-dimensional properties and reactions of molecules. It has its own language and terms that need to be learned in order to fully communicate and understand the concepts

Definitions 。 Stereoisomers-compounds with the same connectivity,different arrangement in space Enantiomers -stereoisomers that are non- superimposible mirror images;only properties that differ are direction (or-) of optical rotation Diastereomers -stereoisomers that are not mirror images;different compounds with different physical properties 2013 Pearson Education,Inc

© 2013 Pearson Education, Inc. Definitions • Stereoisomers – compounds with the same connectivity, different arrangement in space • Enantiomers – stereoisomers that are non￾superimposible mirror images; only properties that differ are direction (+ or -) of optical rotation • Diastereomers – stereoisomers that are not mirror images; different compounds with different physical properties

More Definitions Asymmetric center-sp3 carbon with 4 different groups attached Optical activity -the ability to rotate the plane of plane -polarized light Chiral compound-a compound that is optically active (achiral compound will not rotate light) Polarimeter-device that measures the optical rotation of the chiral compound 2013 Pearson Education,Inc

© 2013 Pearson Education, Inc. More Definitions • Asymmetric center – sp3 carbon with 4 different groups attached • Optical activity – the ability to rotate the plane of plane –polarized light • Chiral compound – a compound that is optically active (achiral compound will not rotate light) • Polarimeter – device that measures the optical rotation of the chiral compound

Chirality right hand left hand ·“Handedness”:Right-hand glove does not fit the left hand. An object is chiral if its mirror image is different from the original object. 2013 Pearson Education,Inc. Chapter 5 4

© 2013 Pearson Education, Inc. Chirality • “Handedness”: Right-hand glove does not fit the left hand. • An object is chiral if its mirror image is different from the original object. Chapter 5 4

Achiral Mirror images that can be superposed are achiral(not chiral) 2013 Pearson Education,Inc. Chapter 5 5

© 2013 Pearson Education, Inc. Achiral • Mirror images that can be superposed are achiral (not chiral). Chapter 5 5

Stereoisomers Enantiomers:Compounds that are nonsuperimposable mirror images.Any molecule that is chiral must have an enantiomer. mimor CH3 CH: CHCH2 Br Br CH>CH3 2013 Pearson Education,Inc. Chapter 5 6

© 2013 Pearson Education, Inc. Stereoisomers Enantiomers: Compounds that are nonsuperimposable mirror images. Any molecule that is chiral must have an enantiomer. Chapter 5 6

Chiral Carbon Atom Also called asymmetric carbon atom. Carbon atom that is bonded to four different groups is chiral. Its mirror image will be a different compound (enantiomer). 2013 Pearson Education,Inc. Chapter5 7

© 2013 Pearson Education, Inc. Chiral Carbon Atom • Also called asymmetric carbon atom. • Carbon atom that is bonded to four different groups is chiral. • Its mirror image will be a different compound (enantiomer). Chapter 5 7

Stereocenters An asymmetric carbon atom is the most common example of a chirality center. Chirality centers belong to an even broader group called stereocenters.A stereocenter (or stereogenic atom)is any atom at which the interchange of two groups gives a stereoisomer. Asymmetric carbons and the double-bonded carbon atoms in cis-trans isomers are the most common types of stereocenters. 2013 Pearson Education,Inc. Chapter 5 8

© 2013 Pearson Education, Inc. Stereocenters • An asymmetric carbon atom is the most common example of a chirality center. • Chirality centers belong to an even broader group called stereocenters. A stereocenter (or stereogenic atom) is any atom at which the interchange of two groups gives a stereoisomer. • Asymmetric carbons and the double-bonded carbon atoms in cis-trans isomers are the most common types of stereocenters. Chapter 5 8

Examples of Chirality Centers CH2CH3 CH2CH2CH3 CH2CH3 H3 H3C Br CH(CH3)2 asymmetric carbon chirality centers (* stereocenters(circled) 2013 Pearson Education inc Asymmetric carbon atoms are examples of chirality centers,which are examples of stereocenters. 2013 Pearson Education,Inc. Chapter 5 9

© 2013 Pearson Education, Inc. Examples of Chirality Centers Asymmetric carbon atoms are examples of chirality centers, which are examples of stereocenters. Chapter 5 9

R enantiomer S enantiomer binding site of the receptor binding site of the receptor 2015 Pearson Euucduon,InC

© 2013 Pearson Education, Inc