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reaction of toluene with sulphuric acid.i want to knw if the any colour changes

reaction of toluene with sulphuric acid.i want to knw if the any colour changes

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1 Answers

Suraj Prasad IIT Patna
askIITians Faculty 286 Points
8 years ago
Methylbenzene is more reactive than benzene because of the tendency of the methyl group to "push" electrons towards the ring. Exactly how this increases the rate of reaction is beyond UK A level - it is rather more complicated than just an increase in the electron density of the ring.

The effect of this greater reactivity is that methylbenzene will react with fuming sulphuric acid at 0°C, and with concentrated sulphuric acid if they are heated under reflux for about 5 minutes.

As well as the effect on the rate of reaction, with methylbenzene you also have to think about where the sulphonic acid group ends up on the ring relative to the methyl group.

Methyl groups have a tendency to "direct" new groups into the 2- and 4- positions on the ring (assuming the methyl group is in the 1- position). Methyl groups are said to be 2,4-directing. The origin of this directing effect is also beyond UK A level.

So you get a mixture which mainly consists of two isomers. Only about 5 - 10% of the 3- isomer is formed.

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