arrange benzene,toluene,methoxybenzene,cholrobenzene in order of reactivity towards sulphonation (contd)?

Question

with fuming sulphuric acid.

Answer 1

Sulphonation is an electrophilic reaction (see http://www.chemguide.co.uk/mechanisms/elsub/sulphonation.html) for the mechanism. The first step requires attack by the electrons of the aromatic system onto the SO3 which is the actual reactive species. This puts a positive charge on the aromatic system, the order of reactivity will depend on the ability to stabilise the positive charge. Both the methyl group of toluene and the methoxy group can help stabilise the charge and so enhance reaction. This effect is known as the inductive effect (I effect) substituents that can donate electrons have a +I effect (methyl, methoxy), substituents that withdraw electrons have a -I effect (http://en.wikipedia.org/wiki/Inductive_effect) eg NO2. In addition some substituents have a mesomeric effect (M-effect) these substituents are able to stabilse the transition state by delocalisation (http://www.cem.msu.edu/~reusch/VirtualText/benzrx1.htm). So a lone pair on methoxy can help stabilise the transition state but methyl cannot. The end result is that methoxy will be the most reactive (but only for reaction at the ortho and para positions where the M-effect has influence), then toluene finally benzene.

Answer 2

You know, in a sense you are lucky for having realized this already (it seems like you are relatively young, right?). I'f im interpreting correctly, you haven't yet solidified your path to "becoming a productive member of society" and all that it entails. And as time goes on, you might find, you don't have to. I'm still relatively young too, (early 30s), but I played the game of becoming a productive member of society. I got the degree, got the big job, got the house and the nice car, and within 6 months of my accomplishments, I realized I was miserable. But I made major lifestyle changes towards things that made more sense "spiritually", and things have become much better. I think the thing to keep in mind is that there are multiple facets to us all; humans are dynamic. We are not in our spiritual mind all the time (although I try to keep this mindset as much as possible). Other parts of us have a desire to produce, to earn, to contribute, and other parts of us have a desire to exercise, be active, etc. I think its a spirit/body/mind balance (mind being the part that wants to produce and earn. All these things are necessary for a happy life, but the balance is the key. Before, mind(earning money/education) was top priority, with spirit and body neglected. Now, I found a job in my field in a small town, 10x less stress, with the time and opportunity to put spirit and body as a higher priority. I wouldn't be happy without a job, a way to earn and produce, but I am much happier that I have a good balance. My advice, find a job you can be passionate about, or something you at least have a desire for. Also, strongly consider how much of your life this field may consume. That is key. I mean, even if you love cooking, if you have to do it in a high stress environment 50-60 hours per week, it won't make you happy. On the other hand, teachning, for example, gives you a career to help impact childrens' lives, and also gives you holidays and summers off. What a great career that would be! Yeah, you still have to contribute to our system somewhat by paying taxes, following government guidelines, etc, but you have freedom within that, and it doesn't consume you. And, in your time away from the job (which is plentiful) you don't have to play in the system at all, it will be your timeto spend as you wish. Hope this helps somehow.

Answer 3

You need to look at the +I effects of the -CH3 group and the -OCH3 group. I think that you will find that -OCH3 wins, followed by -CH3. -OCH3 also has a -M effect, but that is outweighed by the +I effect.