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
I'm puzzled as to what the minor products are. I'm pretty sure the first 3 are correct but the last two im unsure about. Can someone plz help me ?
To determine which of the given options could not arise as minor products from the halogenation reaction, we need to understand the reaction mechanism and the possible reactions that can occur.
In the halogenation of isobutane with Br2, the primary reaction forms 1-bromo-2-methylpropane and HBr as the major products:
isobutane + Br2 ----> 1-bromo-2-methylpropane + HBr
However, minor products can also be formed due to side reactions. One possible side reaction is the abstraction of a hydrogen atom from one of the methyl groups in isobutane, resulting in the generation of a free radical and the subsequent combination with another generated free radical. These side reactions can lead to the formation of different minor products.
Now, let's analyze each option:
a) 2,5-dimethylhexane: This compound consists of a hexane backbone with two methyl groups attached at the 2nd and 5th carbon atoms. This compound could potentially be formed as a minor product if the abstraction of hydrogen atoms occurs at the methyl groups, generating free radicals that combine to form 2,5-dimethylhexane. So, this option could be a minor product.
b) 2-bromo-2-methylpropane: This compound is the same as one of the major products generated in the primary reaction. So, it could be formed as a minor product in this reaction.
c) 1,3-dibromo-2-methylpropane: This compound contains two bromine atoms attached to different carbons. Formation of this compound would require substitution of two hydrogen atoms. It's possible for a minor amount of this compound to form, but it would be less favorable than the major product due to steric hindrance. So, this option could potentially be a minor product.
d) 2,4-dimethylhexane: This compound consists of a hexane backbone with two methyl groups attached at the 2nd and 4th carbon atoms. Similar to option a, this compound could be formed as a minor product if the abstraction of hydrogen atoms occurs at the methyl groups, generating free radicals that combine to form 2,4-dimethylhexane.
e) 2,2,5-trimethylpentane: This compound contains three methyl groups attached to the pentane backbone. The formation of this compound would require the abstraction of three hydrogen atoms, which is less likely than the formation of compounds with only one or two hydrogen abstractions. Therefore, the formation of 2,2,5-trimethylpentane is less likely to occur as a minor product.
Based on the analysis above, option e, 2,2,5-trimethylpentane, is the answer that could not arise from the halogenation reaction as a minor product, while the other options could potentially be formed as minor products.