firstly because it is very cheap, secondly because it has a low bp, third because its a very good azeotrope for water removal, combine with second affirmation, it means that you dont have to boil very high temps (like with toluene) preserving your precious compounds from decomposition, fourth, it has only one peak in 1H nmr and 13C nmr, finally six, even if it is toxic, a good chemist should NEVER die of cancer, it is prohibited.