Isomerism Flashcards
What are isomers?
Isomers are molecules that have the same molecular formula but atoms arranged differently
How many types of isomerism are there?
What are the different types of isomerism?
There are two types of isomerism, being structural isomerism and stereoisomerism
What are structural isomers?
Structural isomers are defined as having the same molecular formula but different structural formulae
There are three subdivisions within structural isomerism, what is the name of each subdivisions?
1* Positional isomerism
2* Functional group isomerism
3* Chain isomerism
What is positional isomerism?
Positional isomerism is when the same functional groups are attached to the main chain but at different points
What is functional group isomerism?
Functional group isomerism is when functional groups are different
What is a feature of functional group isomerisms?
Functional group isomerism have different physical and chemical properties
What is chain isomerism?
Chain isomerism is when there is a different arrangement of gthe hydrocarbon chain,
What is stereoisomerism?
Stereoisomerism is when two (or more) compounds have the same structural formula
How do stereoisomers differ?
Stereoisomers differ in the arrangement of the bonds in space
What are the two types of stereoisomerism?
There is E-Z isomerism and Optical isomerism
What does E-Z isomerism show?
E-Z isomerism shows the positions of substituents at either side of a carbon - carbon double bond
What does an E isomer show?
What does a Z isomer show?
An E isomer shows atoms or groups of atoms on the opposite sides of the C=C bond
A Z isomer shows atoms or groups of atoms on the same sides of the C=C bond
There is also the cis and trans naming system, what does the cis prefix represent when naming a isomer?
What does the trans prefix represent when naming a isomer?
Cis isomers represent isomers which have both functional groups on the same side above/below the carbon double bond
Trans isomers represent isomers which have the functional groups on opposite sides
There are E-Z notations and Cis/ Trans notations, what is each equivalent to?
E notations are equivalent to Trans notations
Z notations are equivalent to Cis notations
How can isomers be identified as either E or Z isomers?
Isomers are identified as either E or Z depending on what “priority” is given to the groups attached to the carbon atoms in the double bond
What set of rules can be used to identify the priority of each group?
The Cahn - Ingold - Prelog rules (CIP)
How do you use the CIP rules?
1) You would look at the atoms directly attached to the carbon
2) Then the atom with the highest atomic number has the highest priority
How do you deduce whether an isomer is an E or Z isomer?
An E isomer has the highest priority groups on the opposite sides of the C=C bond, having one above, one below
A Z isomer has the highest priority groups on the same sides of the C=C bond, having both either above or below the C=C bond
