Maximum number of structural isomers on photochemical monochlorination of 2,3-Dimethyl Pent-2-ene (including allylic rearrangement)

The photochemical monochlorination of 2,3-Dimethyl Pent-2-ene involves the addition of a chlorine atom to the molecule. This can occur at different positions, leading to different structural isomers.

Step 1: Identify the molecule 2,3-Dimethyl Pent-2-ene is a hydrocarbon with 7 carbon atoms. The double bond is at the second carbon atom, and there are methyl groups attached to the second and third carbon atoms.

Step 2: Identify the possible positions for chlorination The chlorine atom can be added to any of the hydrogen atoms in the molecule. There are 3 unique positions for the chlorine atom:

• The carbon atoms at the ends of the molecule (1st and 7th positions)
• The carbon atoms with the methyl groups (2nd and 3rd positions)
• The carbon atoms in the middle of the molecule (4th, 5th, and 6th positions)

Step 3: Count the number of possible isomers Adding the chlorine atom to the 1st or 7th position will give the same isomer, so there are 2 possible isomers from these positions. Adding the chlorine atom to the 2nd or 3rd position will give 2 unique isomers (one for each position), so there are 2 possible isomers from these positions. Adding the chlorine atom to the 4th, 5th, or 6th position will give the same isomer, so there are 3 possible isomers from these positions.

Step 4: Consider the allylic rearrangement The allylic rearrangement can occur when the chlorine atom is added to the 2nd or 3rd position. This can lead to 2 additional isomers.

So, the maximum number of structural isomers on photochemical monochlorination of 2,3-Dimethyl Pent-2-ene (including allylic rearrangement) is 2 (from the 1st and 7th positions) + 2 (from the 2nd and 3rd positions) + 3 (from the 4th, 5th, and 6th positions) + 2 (from the allylic rearrangement) = 9 isomers.