ochem destroyer #78 question

[kies89]

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actually i got the answer for #78
so i changed the question

the question asks monochlorination of 2-methylbutane and how many products are expected if stereoisomers were counted

the answer says 1 chloro 2 methyl butane and 2 chloro 3 methly butane are chiral
but i dont get why these are chiral

and why other possible products 2-chloro-2methly butane and 1 chloro 3 methyl butane is not chiral

 

[kies89]

oh never mind i got this
how do i delete this thread??

 

[Neil45]

LOL, found out after 2 minutes.

 

[kies89]

i changed the q!

 

[Neil45]

actually i got the answer for #78
so i changed the question

the question asks monochlorination of 2-methylbutane and how many products are expected if stereoisomers were counted

the answer says 1 chloro 2 methyl butane and 2 chloro 3 methly butane are chiral
but i dont get why these are chiral

and why other possible products 2-chloro-2methly butane and 1 chloro 3 methyl butane is not chiral

2-chloro-2-methyl is achiral because the carbon attached to the Cl atom is attached to two methyl groups. A chiral compound needs 4 different substituents. There are no carbons in the compound that are attached to four different groups.

Similarly,1-chloro-3-methyl butane is achiral because the tertiary carbon is attached to two methyl groups. No chiral carbons exist in the compound.


1-chloro-2-methyl butane is definitely chiral because that tertiary carbon is attached to 4 different substituents. Similarly for the tertiary carbon (connected to Cl) in 2-chloro-3-methyl butane. Since both of these compounds have a chiral carbon, they have stereoisomers. You have to include their enantiomers to the total number of products formed. So, a total of 4 products are formed from these two compounds.

But overall, a total of 6 products are formed from the reaction when you include 1-chloro-3-methyl butane and 2-chloro-2-methyl.