Flashcards in Chapter 20.7: Stereoisomerism II: Configurational Isomerism Deck (24):
molecules in which the atoms are bonded in the same order, but have different spatial arrangement
define configurational isomersim
a type of stereoisomerism in which atoms or functional groups are connected in the same sequence, but there is a difference in spatial locations of atoms or groups
the only way to interconvert configurational isomers is to...?
break the covalent bonds
What are the two categories configurational isomers can be divided into?
two molecules that are nonsuperimposable mirrior images of one another
configurational isomers that are not mirror images
define cis-trans isomersim
cis-isomers have the same functional group on the same side of a bond and trans-isomers have the same functional groups on opposite sided of the bond
what type of isomers are cis and trans isomers?
diastereomers (under the broader category of configurational isomers)
define E, Z system
the protocol for assigning stereochemical configuration of an alkene with three or more different groups
what are the priority of substituents determined by?
by Cahn-Ingold-Prelog rules
what are the three Cahn-Ingold-Prelog rules?
1. priority is first determined on the basis of the atomic mass of the atoms that are directly bonded to the carbons in the double bond
2. if the atoms are directly attached to a double-bonded carbon atom are the same, then the second atoms of the substituents are compared. again the priority assigned on the basis of atomic mass. if there is no difference in priority among the second atoms, then third atoms are considered, and so on.
3. if a substituent contains a double or triple bond, then multiply bonded atom is treated as if it were two or three atoms bonded atom is treated as if it were two or three atoms bonded to the same carbon atom.
the type of isomersim in which molecules are nonsuperimposible
define chirality center
a carbon atom with 4 different substituents in a tetrahedral arrangement
define optical activity
the ability of chiral compounds to rotate the plane of plane-polarized light
define dextrorotary isomer (the d isomer)
the enantiomer that rotates plane-polarized light CLOCKWISE
define levorotatory (the l isomer)
capable of rotating the polarization of light COUNTER CLOCKWISE
define racemic mixture
an equimolar mixture of two enantiomers that does not rotate the plain of polarization at all
what is the only physical property that is not identical between enantiomers?
the way they interact with plain polarized light
define absolute configuration
the exact three-dimensional spatial arrangement of atoms at a chirality center
define R, S system
the protocol for assigning stereochemical configuration of a chirality center
what is the configuration if 1-3 is clockwise according to the R, S system?