write down the possible isomers of the C4H3NO2 give their IUPAC name?
Answers
Given molecular formula -
=> C₄H₃NO₂
=> This is a molecular formula that does not show the structure of the isomers.
=> We have to first find probable structural formulae for the given molecular formula.
Note -
=> I have assumed that the isomers are can be aliphatic (open-chain) or non-aromatic cyclic.
Understanding the structural formula -
=> The isomers will have nitro (-NO2) group in them, here, the Nitro Group is bonded by means of a single bond to any of the Carbon atoms
=> Thus, for understanding the structure and bonding, we can consider the Nitro group to be a Hydrogen atom , doing so, we will get a molecular formula of C₄H₄ .
=> Let us find the type of Carbon-Carbon bonds (single, double, triple) and the possible arrangements of the longest C-C chain (open or closed chain) that may be present in the molecule.
=> C₄H₄ clearly does not follow any of the general formulae for simple alkanes, alkenes and alkynes (CₙH₂ₙ₊₂ , CₙH₂ₙ and CₙH₂ₙ₋₂), thus, it is a hydrocarbon containing two different types of bonds or a cyclic compound .
=> C₄H₄ follows the general formula CₙH₂ₙ₋₄ (C₄H₄*₂₋₄ = C₄H₈₋₄ = C₄H₄)
=> This is also the general formula for simple alkenynes which are hydrocarbons containing one carbon-carbon double and one carbon-carbon triple bond.
=> Also, CₙH₂ₙ₋₄ is the general formula for cycloalkynes which are cyclic non-aromatic hydrocarbons containing one C-C triple bond.
=> We can also have a chain isomer of the cycloalkyne by making one methyl group as a substituent.
Conclusion :
Thus, C₄H₃NO₂ can contain a nitro group, one C-C double bond and one C-C triple bond and the rest are C-C single bonds.
Also, C₄H₃NO₂ could be a cycloalkyne with the nitro group acting as a substituent.
Some points to note -
=> If we consider this molecule to be a substituted alkenyne, a double bond and a triple bond are present, we generally give a lower locant (numbering) to the double bond than to the triple bond.
=> If we are drawing an isomer of C₄H₃NO₂ which is a substituted cycloalkyne with a Nitro group, we obviously begin numbering from the C-C triple bond.
=> The isomers can be position isomers with respect to the Nitro group and/or the double and triple C-C bonds.
=> The isomers can also be cyclic (non-aromatic) chain isomers with respect to the branches in the C-C chain .
The isomers -
=> There are 5 isomers of C₄H₃NO₂ .
=> They are -
- 3-Nitrocyclobut-1-yne
- 3-Methyl-3-nitrocycloprop-1-yne
- 1-Nitrobut-1-en-3-yne
- 2-Nitrobut-1-en-3-yne
- 4-Nitrobut-1-en-3-yne
=> 1-Nitrobut-1-en-3-yne, 2-Nitrobut-1-en-3-yne and 4-Nitrobut-1-en-3-yne are all position isomers .
=> 3-Nitrocyclobut-1-yne and 3-Methyl-3-nitrocycloprop-1-yne are all chain isomers.
=> Refer to the attachment for their structural formula, IUPAC names and locants (numbering).
Answer is in the attachments
