Question

What is the balanced chemical equation for the reaction of 3-ethyl-2-methylhexane with Br2.

Answer 1

First of all, the name of the compound is wrong. It should be 2-ethyl 1-methyl cyclohexane. or 3-ethyl 1-methyl cyclohexane. You should always give the substituent the lower number, isnt it? Check your question.
I will assume it is 2-ethyl 1-methyl cyclohexane.
Free radical substitution reaction will take place.
2-ethyl 1-methyl cyclohexane + Br2 = (1-bromo 2-ethyl 1-methyl cyclohexane) + HBr
The product can also be 2-bromo 2-ethyl 1-methyl cyclohexane. All the stoichiometric coefficients are 1 in the equation.
Do you need me to explain how I got that product?

Answer 2

I've checked the question, and it is 3-ethyl-2-methylhexane. I guess it follow the IUPAC rule of naming. The answer is C9H20 + Br2 → C9H19Br + HBr, but I don't know how to get this answer.

Answer 3

To the person above, how on earth did you go from a linear alkane to a substituted cyclic alkane? and to add things you also have it named backwards IUPAC stipulates that in a cyclic alkane if you were to number the substituents and got equivalent numbers in whatever way you do it you give the priority to the one with alphabetical precedent so in your case 2-ethyl-1-methylcyclohexane should be 1-ethyl-2methylcyclohexane.

Now for the question, the mechanism happens free radical, you have some initiator either high intensity UV light or H2O2 which breaks homolytically, the radical bromine hijacks a hydrogen off the alkane forming the most stable radical that it can in this case there's possibility of radical formation at either C2 or C3 because of it would form a tertiary radical in both cases although theres added stabilization on C2 because the ethyl has more electron density than the methyl. Either way, the alkyl radical goes through the chain propagation step and attacks a Br2 molecule picking up a Br atom and spitting out a Br radical. This Br radical goes and reacts with more alkane. Once most of the Br2 is consumed you go through the chain termination step where the last two radicals be it the alkyl radical or the Br radical reacts with each other and the radical reaction ceases. If hasn't helped you'll probably be best looking it up in an organic chemistry textbook as it's hard to really describe reaction mechanisms without drawings.

Answer 4

Ah, you are right, thank you so much. I didnt know that while naming cycloalkanes, we give the lowest number to the second substituent. But the reaction itself begins with a cycloalkane not a linear one, and thus should end with a cycloalkane(and that's what I have done). The product is the same.

Answer 5

Pretty sure the starting material mentioned above was a substituted hexane and not cyclohexane.

Answer 6

Oh my...it doesnt seem like it's my day!

Answer 7

Thanks guys...