How do you draw and name all isomers of #C_3H_4Cl_2#?

1 Answer
Sep 22, 2016

You first draw the parent compound propene #C_3H_6#

Explanation:

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There is a double bond in it: #CH_2=CH-CH_3#

Now replace two of the #H#'s with #Cl#. You can do this in 5 ways. (remember the double bond always has the lowest number)

#C Cl_2=CH-CH_3# 1,1-dichloropropene

#CHCl=C Cl-CH_3# 1,2-dichloropropene

#CHCl=CH-CH_2Cl# 1,3-dichloropropene

#CH_2=C Cl-CH_2Cl# 2,3-dichloropropene

#CH_2=CH-CHCl_2# 3,3-dichloropropene

Then there's another parent compound #C_3H_6# called cyclopropane , where the #C#'s form a triangle of #CH_2#'s
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Here there are only two possibilities to replace two #H#'s:

Both on the same #C# 1,1-dichlorocyclopropane

On two neighbouring #C#'s 1.2-dichlorocyclopropane