But he is not in Primary School, he is 15 years old. And if he cannot control himself after being instructed to be quiet (repeatedly) then he is being sent from the class (which is punnishment in it means he has to use his own time to catch up on what was missed, and get homework etc etc - exclusion from learning is a major form of discipline in High Schools)
Where is he being sent when he is excluded from class? They cannot be sent to the principal everytime, it is beyond impractical - we had Caution slips, 3 = detention of some form, and a year level co-ordinator. More often than not, we had to sit outside the class next to the door. Embarrassment.

Anyway, if he is repeatedly disrupting the class this IS something you need to address. It is disrespectful to not only the teachers, but to his fellow students and YOU - you don't send him to school for a party, he is there to learn and preventing other from doing so demonstrates he is NOT showing respect to the students, the teachers nor the insitution - or you for that matter.