[ernest1039401]

Currently, I am trying to investigate whether changing the acid catalyst used in the Fischer esterification of benzocaine changes its yield. However, so far, only concentrated sulfuric acid has worked in providing a positive yield of benzocaine, whereas others (phosphoric acid, nitric acid, hydrochloric acid) have not been successful in producing anything even after an hour of refluxing. Are any acids in general supposed to work for Fischer Esterification? Or is only concentrated sulphuric acid viable, as most sources recommend only sulphuric acid.

Thanks!

[wildfyr]

Most strong acids should work, however there is something quite specific about the makeup of how those acids are typically found in a lab that is the reason the yield is poor. Do you have a guess what makes typical lab grade sulfuric acid different from the others?

As an aside, it substrate dependent but nitric acid is somewhat more likely to degrade some of the starting materials than sulfuric is. This is a smaller consideration than my main point.