Chem questions (rep for help)

Need help quick, Rep for help:

C) One of the isomers of C4H8 reacts with HBR to give 2 diff products, the major one of which is a chiral molecule.

i) Identify this isomer of C4H8
ii) Give the mechanism for the reaction of this isomer with HBr
iii)why is the major product Chiral, but the minor one not?

i)But-1-ene, I think.

ii) It's just an electrophilic addition, forming a primary or secondary carbocation which then gets attacked by the bromide.

iii)The major product is chiral because its mirror image cannot be superimposed upon it.

Ben

WHy would it be but-1-ene instead of 2-methylpropene

Apologies - yes, that's what I meant to say.

Ben

Kool, Why is it 2-methylpropene instead of but-1-ene? Why wouldn't but-1-ene form 2 diff products aswell?

WHy would it be but-1-ene instead of 2-methylpropene

After the addition 2-methylpropene would not be optically active for either isomer.

Ah yes, it would not have any chiral carbons- ie carbons with 4 different groups attached to it.

Need help quick, Rep for help:

C) One of the isomers of C4H8 reacts with HBR to give 2 diff products, the major one of which is a chiral molecule.

i) Identify this isomer of C4H8
ii) Give the mechanism for the reaction of this isomer with HBr
iii)why is the major product Chiral, but the minor one not?
iv) Why is the chiral product the major one, and the non-chiral the minor one?
v) The major product of this addition reaction is found to be optically inactive, explain why?

Rep will come tomorrow.

I'll have a go
iv) Why is the chiral product the major one, and the non-chiral the minor one?
v) The major product of this addition reaction is found to be optically inactive, explain why?


iv)You can get 1-bromobutane or 2-bromobutane. The major product is 2-bromobutane "because the H from HBr prefers to go with its hydrogen friends" (I dunno the proper scientific reason behind major and minor products). Only 2-bromobutane has a chiral carbon which is carbon 2.


v) Because a racemic mixture is produced?

I'll have a go
iv) Why is the chiral product the major one, and the non-chiral the minor one?
v) The major product of this addition reaction is found to be optically inactive, explain why?


iv)You can get 1-bromobutane or 2-bromobutane. The major product is 2-bromobutane "because the H from HBr prefers to go with its hydrogen friends" (I dunno the proper scientific reason behind major and minor products). Only 2-bromobutane has a chiral carbon which is carbon 2.


v) Because a racemic mixture is produced?

Ok cool cheers.

Could ya go into wat a racemic mixture is moreso please.

It's a mixture containing equal quantities of two enantiomers - both of which have equal and opposing optical properties and so the mixture is optically inactive overall.

Ben

I'll have a go
iv) Why is the chiral product the major one, and the non-chiral the minor one?
v) The major product of this addition reaction is found to be optically inactive, explain why?


iv)You can get 1-bromobutane or 2-bromobutane. The major product is 2-bromobutane "because the H from HBr prefers to go with its hydrogen friends" (I dunno the proper scientific reason behind major and minor products). Only 2-bromobutane has a chiral carbon which is carbon 2.


v) Because a racemic mixture is produced?