URGENT : ALKANE HALOGENATION

[mixed-cutie]

Which of the following minor products could not arise from the halogenation reaction below?

isobutane + Br2 ----> 1-bromo-2-methyl propane + HBr + minor products

a)2,5 dimethylhexane
b)2 bromo-2 methyl propane
c)1,3 dibromo, 2 methyl propane
d) 2,4 dimethylhexane
e)2,2,5 trimethyl pentane

plz can someone help me...i kno its not b) or c) but im leaning towards d) or e) so can someone clarify this.
Thanks

[kingchemist]

To my knowledge, any of the H atoms can be replaced by Br so starting with methylpropane, b and c are possible.

In the reaction you get radicals such as methyl propane radical. Such radical can also join together with other radicals (as well as Br atoms). If this is true, the the products are likely to have twice as many C atom as methyl propane, so a and d are possible.  With the position of the methyl groups in methylpropane (on C2)

However, e is not possible and there is no such substance. You cannot have a methyl group on C5 of a C5 compound such as pentane as this is an end C atom which would make the parent chain = hexane. You could have 2,2,4-trimethylpentane