What are isomers?
Isomers are molecules that have the same molecular formula, but different structural formulas. They possess the same number of atoms of each element but exhibit different arrangements of these atoms in space.
- What are the main types of isomerism?
The main types of isomerism are structural (or constitutional) isomerism and stereoisomerism. Structural isomers have different connectivity of atoms, while stereoisomers have the same connectivity but different spatial arrangements.
- What are structural isomers?
Structural isomers are compounds that have the same molecular formula but different connections among their atoms. Types of structural isomerism include chain isomerism, functional group isomerism, positional isomerism, and tautomeric isomerism.
- What are stereoisomers?
Stereoisomers are compounds that have the same molecular formula and sequence of bonded atoms but differ in the three-dimensional orientations of their atoms in space. Stereoisomerism includes geometric (cis-trans) isomerism and optical isomerism.
- What is chain isomerism?
Chain isomerism, a type of structural isomerism, occurs when there is a difference in the arrangement of the carbon skeleton. For example, butane (C₄H₁₀) and 2-methylpropane (C₄H₁₀) are chain isomers.
- What is functional group isomerism?
Functional group isomerism, a type of structural isomerism, occurs when compounds have the same molecular formula but different functional groups. For example, ethanol (C₂H₅OH) and dimethyl ether (CH₃OCH₃) are functional group isomers.
- What is positional isomerism?
Positional isomerism, a type of structural isomerism, occurs when the position of a functional group changes in the molecule. For example, 1-propanol (CH₃CH₂CH₂OH) and 2-propanol (CH₃CHOHCH₃) are positional isomers.
- What is tautomeric isomerism?
Tautomeric isomerism, a special kind of functional group isomerism, involves the relocation of a proton. Keto-enol tautomerism, for example, involves the shifting of a hydrogen between a carbon and an oxygen in a molecule.
- What is geometric isomerism?
Geometric isomerism, a type of stereoisomerism, occurs when there is a different spatial arrangement of groups around a double bond or a ring system. It includes cis-trans isomerism and E-Z isomerism.
- What is optical isomerism?
Optical isomerism, a type of stereoisomerism, occurs in molecules that are non-superimposable mirror images of each other, known as enantiomers. These compounds can rotate plane-polarized light in different directions and have a chiral center, typically a carbon atom bonded to four different groups.
- What are enantiomers?
Enantiomers are pairs of molecules that are mirror images of each other but are not superimposable. They exhibit optical isomerism and have opposite effects on the rotation of plane-polarized light.
- What are diastereomers?
Diastereomers are stereoisomers that are not mirror images of each other. They have different physical properties and can exhibit differences in boiling points, melting points, solubilities, etc.
- What is a chiral center?
A chiral center is typically a carbon atom that is bonded to four different groups. It results in optical isomerism because it can exist in two non-superimposable arrangements known as enantiomers.
- What does it mean for a molecule to be achiral?
A molecule is achiral if it is superimposable on its mirror image. Achiral molecules do not exhibit optical isomerism.
- What is a meso compound?
A meso compound is a molecule that has multiple chiral centers but is achiral as a whole due to an internal plane of symmetry. Meso compounds do not exhibit optical activity.
- What is the significance of isomerism in biological systems?
Isomerism is crucial in biological systems as different isomers of a compound can have different biological activities. For example, one enantiomer of a drug may be beneficial, while the other may be harmful.
- How can isomers be separated?
Methods to separate isomers include distillation (for isomers with different boiling points), chromatography (based on differences in polarity or molecular size), and crystallization (for isomers with different solubilities).
- What does the E and Z notation in isomerism represent?
In E-Z notation, used to name geometric isomers, E stands for “entgegen,” German for “opposite,” indicating that the highest-priority groups are on opposite sides of the double bond. Z stands for “zusammen,” German for “together,” indicating that the highest-priority groups are on the same side of the double bond.
- What is the role of isomers in petroleum refining?
Isomerization is used in petroleum refining to convert straight-chain hydrocarbons into branched-chain isomers, which have higher octane numbers and are more desirable as components of gasoline.
- How is chirality determined?
Chirality is determined by looking for a chiral center, usually a carbon atom bonded to four different groups. If such a center exists, the molecule is chiral and can exist as two enantiomers. If the molecule is superimposable on its mirror image, it is achiral.
