How many structural and cis-trans isomers are there for dichloropropene, C3 H4 Cl

[mutineer]

20 How many structural and cis-trans isomers are there for dichloropropene,
C3H4Cl2. I could find a total of 4, with 2 structural and 2 cis trans. But the answer sheet says 7! can someone tell me all the isomers it can form?

 

[Borek]

7 there are.

List those you have (or draw them).

 

[mutineer]

I found five
the first is 1,1 dichloropropene
the second is 1,3 dichloropropene(since this has cis-trans I count it as two)
the fourth is 1,2 dichlropropene (again this shows cis-trans so I count it as two)
Thats it, i can't find anymore!

 

[Borek]

What if neither Cl atom is in the 1 position?

 

[LudusRex]

I can confirm that there are a total of 7 isomers for dichloropropene, C3H4Cl2. These include 2 structural isomers and 5 cis-trans isomers. The structural isomers are 1,2-dichloropropene and 2,3-dichloropropene, which differ in the placement of the two chlorine atoms on the carbon chain. The cis-trans isomers are 1,3-dichloropropene (cis and trans), 2,3-dichloropropene (cis and trans), and 1,2-dichloropropene (cis and trans). These isomers differ in the orientation of the two chlorine atoms with respect to each other.

To visualize these isomers, imagine a carbon chain with two hydrogen atoms attached to the first and third carbon, and two chlorine atoms attached to the second and third carbon. In 1,2-dichloropropene, the two chlorine atoms are on the same side of the carbon chain, while in 1,3-dichloropropene, they are on opposite sides. The cis and trans isomers of 1,3-dichloropropene have the two chlorine atoms on the same or opposite sides, respectively, but with respect to the carbon chain, they are in different positions.

In 2,3-dichloropropene, the two chlorine atoms are attached to the second and third carbon, but the positions of the two chlorine atoms can vary, leading to cis and trans isomers. Lastly, in 2,3-dichloropropene, the two chlorine atoms are attached to the same carbon, but again the positions can vary, resulting in cis and trans isomers.

In summary, the 7 isomers of dichloropropene are: 1,2-dichloropropene, 2,3-dichloropropene, 1,3-dichloropropene (cis and trans), and 2,3-dichloropropene (cis and trans). I hope this explanation helps clarify the confusion.