Lecture on Carbons and Isomerism
Types of Carbons
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Primary Carbon
- Carbon connected to one other carbon atom.
- Example: In isobutane (C₄H₁₀), there are 3 primary carbons each attached to 3 hydrogens, totaling 9 primary hydrogens.
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Secondary Carbon
- Carbon connected to two other carbon atoms.
- No secondary carbons were found in the discussed structure (isobutane).
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Tertiary Carbon
- Carbon connected to three other carbon atoms.
- Example: In isobutane, there is 1 tertiary carbon with 1 tertiary hydrogen.
Isomerism
Types of Alkanes
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Straight-chain Alkanes
- All carbons are connected in a straight line.
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Branched-chain Alkanes
- Alkanes with branching connections of carbon atoms.
- Example: Isobutane can have a branched or straight-chain configuration.
Definition of Isomers
- Compounds with the same molecular formula but different structures.
- Differences can be in connectivity or geometrical arrangement.
Examples
- C₄H₁₀
- Straight-chain and branched-chain forms are isomers.
Bond Rotation
- Rotation around single bonds (sp³ hybridized) does not result in different isomers.
Determining Isomers
- General Strategy
- For small hydrocarbons (8 or fewer carbons), use trial and error.
- Example: C₆H₁₄ can form a maximum of 5 isomers.
Steps to Draw Isomers
- Start with a Straight Chain:
- Connect all carbon atoms in a line.
- Adjust Carbon Skeleton:
- Vary the position of remaining carbons to form different structures.
- Fill in Hydrogens:
- Ensure each carbon has four bonds.
Example: Drawing Isomers for C₆H₁₄
- Maximum of 5 Isomers
- Six carbons in a row.
- Five carbons with one branching carbon.
- Four carbons with two branching carbons.
Example: C₅H₁₂
- Maximum of 3 Isomers
- Five carbons in a line.
- Four carbons in a line with one branching carbon.
Example: C₄H₁₀
- Maximum of 2 Isomers
- Four carbons in a straight line or branched arrangement.
This concludes the lecture on carbons and isomerism, covering the basics of carbon types and the concept of structural isomers.