Grignard reactions - triphenylmethanol?

Hope you can help me with following questions : In the syntesis of triphenylmethanol, from phenylmagnesiumbromid and methylbenzoat. 1. Why do you use H2SO4 instead of just water to do the last step, where we decompose the triphenyl-CO-MgBr to triphenylmethanol? Now we had to extract the tri-phe-methanol... show more Hope you can help me with following questions :

In the syntesis of triphenylmethanol, from phenylmagnesiumbromid and methylbenzoat.

1. Why do you use H2SO4 instead of just water to do the last step, where we decompose the triphenyl-CO-MgBr to triphenylmethanol?

Now we had to extract the tri-phe-methanol from the water.
2. Why do we rinse with just a little bit (0.6% solution) of Na2SO3 (Sodiumsulfit).

Then we made a TLC of the final product :
3. How come that the stain on TLC becomes yellow, when its made in H2SO4 ?
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