Isomerism and Stereochemistry Flashcards
same chemical formula but differ in chemical and physical properties
isomerism
study of the different spatial arrangements of atoms in molecules
stereochemistry
stereochemistry is also known as __ __
3D chemistry
stereo means __
three-dimensional
one of the reasons why there is a huge array of different organic compounds that exist
isomers
Two classifications of isomers
- Structural Isomerism
- Stereochemical Isomerism
Three types of Structural Isomerism
- Skeletal Isomerism
- Positional Isomerism
- Functional Isomerism
Two types of Stereochemical Isomerism
- Configurational Isomers
- Conformational Isomers
Two types of Configurational Isomers
- Geometric Isomerism
- Optical Isomerism
Geometric Isomerism
Cis-Trans Isomerism in Cyclic Compounds
Two types of Optical Isomerism
- Diastereomers
- Enantiomerism
Two types of Enantiomerism
- Fischer Projection
- Chiral Center
Structural Isomerism or __ __ in IUPAC nomenclature
Constitutional isomerism
occurs when two or more compounds have the same molecular formula but different structural formula due to different arrangements of how atoms are connected
Structural Isomerism
skeletal isomerism is also called __ __
chain isomerism
differ only in the arrangement of atoms in the carbon skeleton
skeletal isomerism
dimethylbenzene is knwon collectively as __
xylenes
difference with the position of the same functional group in a carbon chain
positional isomerism
same molecular formula, but different functional groups
functional isomerism
same molecular formula and sequence of bonded atoms, but differ in the three-dimensional orientations of their atoms in space
- Geometric Isomerism
- Optical Isomerism
occurs when a compound contains a double bond, and has two different atoms or groups that are attached to each of the carbons in the double bond
geometric isomerism
formed when two hydrogen are on the same side (top or bottom) of the double bond
cis isomers
occur when two hydrogens are on opposite sides
trans isomers
- non-interconvertable
- interconversion must need bond breaking and making
configurational isomers
stereoisomers that cannot be converted into one another by rotating the molecule around a single bond
configurational isomers
ability of a chiral molecule to rotate the plane of plane-polarised light
optical activity
used to measure plane of plane-polarised light
polarimeter
simple polarimeter consists of:
- light source
- polarising lens
- sample tube
- analysing lens
stereoisomers that are non-superimposable mirror images of one another
enantiomers
structural basis of enantiomerism
chirality
any molecule that is superimposable on its mirror image
achiral
tetrahedral atom in a molecule bearing four different ligands, with lone pairs, if any, treated as ligands (or substituents)
chiral center
in determining chiral center, keep going down the __
chain
a way to represent three-dimensional molecules in two dimensions
fischer projections
two-step procedure to determine absolute configuration of a chiral center in Fischer projection
- Assign priority numbers to four lgans on chiral center
- trace three highest-priority ligands
partial stereoisomers that have at least two stereocenters and differ in configuration at some, but not all, of these stereocenters
diastereomers
- non-mirror image stereomers
- do not have a relationship of symmetry or chirality between them
diastereomers
to identify a diastereomer of a chiral compound, it must only…
have different configurations at some stereocenters but not all
diastereomers that are optically inactive due to their symmetry
meso compounds
two identical substituents are present on the same side of a compound
cis configuration
two identical substituents are present on the opposite side of a compound
trans configuration